Characterization of Synoptic Systems Triggering Disasters in the State of Espírito Santo, Brazil

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The State is frequently affected by disasters of this nature. Therefore, this work aims to determine and characterize the types of synoptic systems that produce heavy rainfall and cause disasters in ES. Between 2013 and 2021, the S2ID database, synoptic charts from CPTEC, images from GOES 13 and 16 satellites, and precipitation data from INMET were used to select the dates and characterize the meteorological situation. Additionally, the ERA5 reanalysis was used for the construction of composite. It was found that disasters that affect ES occur mainly during the summer, which agrees with a thermodynamically more unstable atmosphere. The main systems identified can be described as follows: 1- Intense Frontal Systems related to blocking configuration in previous days that allow humid air advection from the Atlantic Ocean, through the presence of an anticyclone together with colder air at medium levels; 2- SACZ related to a warm anomalous anticyclone in the Atlantic and an intense low-pressure center located to the north, also showing a blocking pattern; 3- Troughs with slow displacement and low baroclinicity associated with high convective instability, acting as an extension of the Chaco Low and Thermo-Orographic Low, and 4- Cold core Cyclones with barotropic characteristics, located over ES, linked to warm blocking anticyclones, positioned south of about 40–45°S. In general, these patterns could be identified at least 48 hours in advance, observing disturbances at higher latitudes. Disasters. Heavy rainfall. Synoptic characterization Figures Figure 1 Figure 2 Figure 3 Figure 4 Figure 5 Figure 6 Figure 7 Figure 8 Figure 9 Figure 10 Figure 11 Figure 12 Introduction An extreme climate or weather event is defined by the occurrence of the record of values ​​close to the lower and upper thresholds in an observed range of an atmospheric variable (IPCC 2012 ). These events can trigger hydro-geo-meteorological disasters (UN-ISDR 2015 ), especially with population vulnerability and inefficient response actions (UN-ISDR 2009 ). Brazil is among the top 10 countries most affected by natural disasters, most of which are of hydrometeorological origin (EM-DAT 2023). Episodes of intense rainfall are mainly associated with the South Atlantic Convergence Zone (SACZ) and Cold Fronts (Marcelino et al. 2006 ), particularly affecting the Southeast Region of Brazil (Teixeira 2010 ; Moura et al. 2013 ). These systems can be influenced by tropical convection (Oliveira 1986 ) and the Brazilian orography (Kodama et al. 2012 ; Foss 2016 ), intensifying rainfall, mostly causing floods, inundations, and mass movements (CEPED 2012). An overwhelming majority of Brazilian municipalities, particularly those with smaller populations, exhibit the lowest development indices in direct proportion to the incidence of floods and landslides, with emphasis on the State of Espírito Santo (Saito et al. 2020; Ribeiro et al. 2022 ). Despite being heavily impacted by hydrometeorological disasters, many of these small cities lack a municipal risk reduction plan (Saito et al. 2020). Several studies point to the influence of synoptic systems on the occurrence of intense rainfall and the initiation of that cause in Southeast Brazil (SEB) (Espírito Santo and Satyamurty 2002 ; Lima et al. 2010 ; Gonçalves 2015 ; Aguiar and Cataldi 2021 ) in Serra do Mar in São Paulo (Seluchi and Chou 2009 ; Camarinha 2016 ), in the State of Rio de Janeiro (Dolif and Nobre 2012 ; Moura et al. 2013 ; Escobar et al. 2022 ), and in the State of Minas Gerais (Escobar 2014 ; Reboita et al. 2017; Silva et al. 2020). However, the State of Espírito Santo lacks the most studies on this topic. The State of Espírito Santo is frequently affected by synoptic systems that result in intense rainfall. Irregular land use in rugged terrain, combined with precipitation, can lead to natural disasters in the region. Therefore, the present study aims to identify the different types of meteorological systems associated with extreme rainfall and disasters in the State of Espírito Santo and to establish their key dynamics and thermodynamics characteristics as a tool to improve extreme precipitation forecasting in these conditions. The study area Figure 1 shows the State of Espírito Santo, which is in Brazil's largest economic development hub and is among the country's most developed states. (CAÇADOR and GRASSI 2009). The State ranks seventh in the National Human Development Index (HDI) with a value of 0.740 (IBGE 2022). Despite a small area of approximately 46,000 km 2 , the climate in Espírito Santo is quite diverse (REGOTO et al. 2018). The northern portion experiences a hot and dry climate, the central region has a cold and humid climate, and the southern part has a hot and humid climate. About 70% of the State's terrain consists of rugged lands (CERQUEIRA et al. 1999). As one moves further inland, it is possible to find peaks with altitudes exceeding 1,000 meters, such as the Serra do Caparaó, and the Serra do Castelo (REGOTO et al. 2018). The annual average precipitation provided by the Institute of Research, Technical Assistance, and Rural Extension of the State of Espírito Santo (INCAPER), for the period between 1984 and 2014, indicates values of approximately 1000 mm in the northern and northwestern regions, and over 1500 mm in the central-southern part (INCAPER 2023 ). Materials and methods For selecting cases of event occurrence, the Integrated System of Disaster Information (S2ID; AGUIAR and CATALDI 2021 ) was employed, which contains data from the reports on federal acknowledgments of emergencies and State of public calamity carried out by the Civil Defense of each municipality. Records of urban floods, landslides, floods, and debris flow that occurred from 2013 to 2021 were selected. In order to identify meteorological systems active on those dates, synoptic charts at several levels provided by the Center for Weather Forecasting and Climate Studies (CPTEC) at the National Institute for Space Research (INPE) were analyzed. Additionally, satellite images from GOES 13 and 16, as well as historical annual precipitation data from the Brazilian National Institute of Meteorology (INMET) automatic weather stations in Vitória and Linhares cities, were also collected. No objective method to identify the dates of disaster occurrences was used. The selection of dates was determined based on the identification of the moment when the synoptic system passed over the ESS. Flash flood events, resulting from intense precipitation associated with isolated convections (MADDOX et al. 1979; DOSWELL 1994), were excluded from the analysis, as they require a more specific methodology for examination and fall outside the scope of this study. ERA5, the fifth generation of the European Centre for Medium-Range Weather Forecasts (ECMWF) atmospheric reanalysis, was used to characterize the synoptic patterns associated with the disaster cases in composite maps. The chosen variables to construct the composite fields included 500/1000 hPa layer thickness and geopotential height (m 2 /s 2 ) at the surface, zonal and meridional winds (m/s) and temperature (°C) at the 300 hPa level, geopotential height (m 2 /s 2 ) and temperature (°C) at the 500 hPa level, specific humidity (g/kg) and geopotential height (m 2 /s 2 ) at the 850 hPa level and K index. Mean fields and anomalies were constructed for 2 days prior to an event and 1 day following an event. The climatology for the anomaly fields was also constructed employing ERA5 reanalysis data from 2013 to 2021. Once the mean fields and anomalies of the leading dynamic and thermodynamic variables for each type of synoptic system were employed, the corresponding counterparts for days when there were no disaster associations were constructed. Thus, the difference fields between disaster and non-disaster cases could be constructed in order to identify parameters that can assist in disaster prediction in the State of Espírito Santo. Results According to the criteria established for this research, 100 occurrences of disasters were found: 38 urban floods, 29 landslides, 24 floods, and 9 debris flows. Of these occurrences, 85 dates were identified, associated with the passage of 32 frontal systems, 31 South Atlantic Convergence Zone (SACZ), 18 surface Troughs, and 4 extratropical Cyclones. Table 1 shows the relation between the occurrences and the synoptic systems and Table 2 indicates the relation between the synoptic systems identified and their distribution throughout the seasons during the study period. Table 1 Distribution per Occurrences of Synoptic Systems Associated with Disasters between 2013 and 2021 in the State of Espírito Santo Occurrences/ Synoptic systems Frontal Systems SACZ Troughs Cyclones Total Debris Flows 2 4 3 0 9 Floods 2 14 8 0 24 Landslides 17 9 2 1 29 Urban Floods 16 11 8 3 38 Table 2 Seasonal Distribution of Synoptic Systems Associated with Disasters between 2013 and 2021 in the State of Espírito Santo Seasons/ Synoptic systems Frontal Systems SACZ Troughs Cyclones Total Summer 6 17 10 2 35 Autumn 8 1 2 1 12 Winter 3 0 0 1 4 Spring 15 13 6 0 34 It is possible to observe, according to Table 2 , that most of the records occurred during the austral summer and spring, which is in line with a warmer and moister atmosphere, thermodynamically more unstable. The SACZ and Frontal Systems represent most of the systems associated with disasters during the period. The following results represent the analyses of composite fields plotted on the dates of disaster events between 2013 and 2021. The composition of the cases helps identify the characteristics present in the atmosphere at the time of the system's occurrence. On the 85 identified dates, there is a clear presence of a baroclinic low-pressure system over the ESS, a region of maximum cyclonic curvature at mid-levels and upper-level wind divergence, accompanied by high humidity and thermodynamic instability from the Amazon. These conditions are consistent with the occurrence of heavy rainfall. The frontal cases are associated with most of the identified disaster cases during the period. The surface fields of cold fronts (Fig. 2a) display a trough associated with the front, with greater cyclonic horizontal shear, a more intense post-frontal anticyclone compared to overall averages, and intense gradients of thickness, geopotential height, and moisture to the south of the ES (not shown), indicating higher baroclinicity and contrast of air masses with different moisture content. Figure 2b shows a strong gradient of negative geopotential anomaly at 500 hPa, suggesting the existence of thermodynamic instability at this altitude. At higher levels (Fig. 2c), the high wind speed southeast of the ESS, associated with the surface cold front, promotes the ascent of air and consequent precipitation occurrence. The plotted fields for these cases show air instability from the Amazon to the Atlantic. The instances of SACZ, accounting for over 30% of the disaster-associated systems during this period, also display a distinct inverted trough situated over Rio de Janeiro (RJ) and the ES region (as shown in Fig. 3 a). Nevertheless, the higher pressure to the south is less intense, along with a less pronounced thickness gradient. These factors collectively indicate reduced baroclinicity in comparison to frontal systems. At the 850 hPa level (not shown), there is noticeable moisture convergence over the southeastern region, where the SACZ establishes itself (ESCOBAR and REBOITA 2022 ). At 500 hPa (Fig. 3 b), the temperature and geopotential gradients are less intense, and the maximum baroclinicity is located southeast of the ESS. At 300 hPa, wind divergence associated with the upward motion of air contributes to the moisture transport to higher levels, consequently enhancing instability within the layer and maintaining the cloudiness associated with precipitation observed during ZCAS episodes (QUADRO, 1994). It can also be observed that the presence of well-defined Upper-Tropospheric Cyclonic Vortexes (UTCV) acting over the extreme eastern region of northeastern Brazil and the Bolivian High located at approximately 15°S and 70°W are essential components in the configuration of SACZ for these occurrences. The mean surface fields shown in Fig. 4 a display a small trough with a warm axis over the ESS, a ridge around 40°S, and a small trough south of the 40°S parallel, along with the Chaco Low (CL) and the Thermal-Orographic Low (TOL) over the northwest region of Argentina. The weak thickness near the ES indicates an environment with little baroclinicity, with the ES immersed within an air mass of tropical characteristics. The surface trough cannot be identified at 500 hPa (Fig. 4 b), but a slightly more intense temperature gradient is seen to the southwest of the ES within a markedly zonal flow. At higher levels (Fig. 4 c), a maximum of wind divergence is identified over the ESS, linked to the eastern flank of the Bolivian High, and the Subtropical Jet is less intense and displaced farther south compared to overall means. Among the 85 cases of disaster, only 4 of them were related to extratropical cyclones. The composites of the cyclones show a low-pressure center at the surface (Fig. 5 a) over the SEB region. In the vicinity of the ESS, the cyclones acquire greater cyclonic curvature, and they are immersed in a region of weak thickness gradient, which is indicative of low baroclinicity. Over the Atlantic Ocean, the extension of the high-pressure region westward suggests the coupling between the South Atlantic Subtropical High (ASAS) and a high-pressure system positioned south of the low-pressure center. The high moisture values from the Amazon region to the Southern Region, combined with the intense geopotential gradient, indicate maximum moisture advection over the Southeast Region. At mid-levels, there is a scarce temperature gradient, and further south, a relatively long-wave ridge predominates over the Atlantic Ocean. In the wind field at 300 hPa, there is a deviation of the Subtropical Jet, around 30°S, indicating a southward displacement of the baroclinic zone. The region of maximum divergence is seen just south of the ESS, which is conducive to precipitation. 4.2– Anomalies In total anomaly fields, the trough over the ES appears precisely in the transition region between warm and cold anomalies, and anticyclonic anomalies over the Argentina region favor the maintenance of the post-frontal type anticyclone. The predominance of cyclonic anomalies over the ES indicates that the passage of more intense synoptic systems over the ocean influences the weather conditions along the Southeast Region's coast. In frontal cases' anomaly maps, very intense values are observed. Negative 500/1,000-hPa layer thickness anomalies extend from the Atlantic to the southern Amazon region, characterizing intense cold fronts (Fig. 6a). The point of maximum baroclinicity is precisely located over the ESS. Negative humidity anomalies coming from the south transport anomalously drier air, while positive anomalies position themselves over parts of the Southeast region of Brazil (not shown). At mid-levels (Fig. 6b), temperature and geopotential anomalies over the ocean extend to the continent, where the trough axis is located northwest of the State of São Paulo. It can be observed that the ES is in the front part of a baroclinic trough embedded in a synoptic-scale wave train. At upper levels (Fig. 6c), the abnormal change in wind direction south of the ES denotes the presence of the jet associated with the frontal system and, therefore, a condition of higher baroclinicity. Positive temperature anomalies at upper levels may indicate an anomalous lowering of the tropopause caused by the presence/intensification of low pressures (HIRSCHBERG and FRITSCH 1991). However, cold anomalies at upper levels indicate that the tropopause is located above that level, which is typical of a subtropical troposphere. Similar to the previous maps shown, the SACZ fields display at the surface (Fig. 7 a) a cyclonic/anticyclonic disturbance positioned southwest/northeast, with more intense positive humidity anomalies (not shown), along with a relative maximum immediately east of the Andes up to northern Argentina, indicating the probable influence of Low-Level Jets in the occurrence of SACZ. The temperature and geopotential height fields at 500 hPa (Fig. 7 b) appear displaced concerning the surface. The geopotential height gradient is intense but less than in the cases of cold fronts. At altitude (Fig. 7 c), a maximum wind divergence is observed north of the ESS, although it is lower compared to frontal situations. In cases where troughs were identified, surface anomaly maps (Fig. 8 a) display a broad, warm cyclonic anomaly in central-southern Brazil and neighboring countries, extending a small relative trough towards the ESS, visible from the curvature of the isobars. This situation reflects a cyclonic pattern with its center more to the south. The pattern observed at 500 hPa (Fig. 8 b) corresponds to the surface fields, showing again a situation of low baroclinicity due to the limited lag between the surface and mid-level systems. The negative temperature anomalies at mid-levels contribute to an increase in thermodynamic instability. At upper levels (Fig. 8 c), it is possible to observe again a maximum wind divergence over the ES but embedded in a general situation of weak and unremarkable anomalies, indicating a weak synoptic forcing. Nevertheless, the anomalous divergence at upper levels, promoting airlifting, combined with cold anomalies in the mid-troposphere, helps explain the occurrence of convective-type rainfall. Through the cyclone anomaly fields (Fig. 9 ), a surface low-pressure region with its center close to the ES can be identified (Fig. 9 a). An anomalously warm environment is observed over the continent and the Atlantic Ocean, with abundant moisture (not shown), scarce baroclinicity in the context of the low-pressure center, weak southwest cold advection over the State of Rio de Janeiro, and the presence of an anomalous anticyclone over the Atlantic with a warm core and low baroclinicity, typical of blocking-type systems. The 500 hPa anomalies close to the surface anomalies indicate a barotropic character (Fig. 9 b). The center of cyclonic vorticity can be seen in the altitude fields (Fig. 9 c) through the rotation of the streamlines, positioned southeast of the ESS, remarkably close to the surface low. 4.3 Previous days The fields plotted in the days preceding the passage of the systems over the ES (not shown) already signal characteristics that can be identified at higher latitudes. In the 48 hours before the passage of Frontal Systems in the ES region, they can be identified from the already quite intense anomalies to the south. The cold front is located over Santa Catarina State and advances toward the north-central region of Bolivia, following the pattern discussed by Garreaud ( 2000 ). In the preceding 24 hours, the propagation of the baroclinic wave in the northeast direction is observed, with the advancement of negative thickness anomaly towards the continent, the intensification of positive anomaly over the SEB, and the strengthening of negative geopotential anomaly over the same region. The presence of a low-pressure center near the coast with an axis over the ES in cases of SACZ 48 hours before the disaster event is similar to frontal cases. However, a notable difference is that in the cases of SACZ, the axis of the anomalous trough is already in the vicinity of the ES two days before the disasters occur, which is consistent with this type of situation. A clear dipole in geopotential anomalies is observed over the Atlantic Ocean, with negative values at latitudes south of Brazil and positive values at high latitudes, indicating a situation of low zonal circulation index, typical of dipole blocking configurations, where a low-pressure system, when approaching a high-pressure system, becomes stationary or moves along the periphery of the high (CASARIN, 1982). At the mid-levels, the high and low-pressure systems appear almost in the same position as their counterparts at lower levels, indicating a relatively barotropic situation, which is similar to the findings of Seluchi and Chou ( 2009 ) and Escobar ( 2014 ). The composite fields of the hours preceding the occurrence of identified trough cases show, at the surface, an anomalous cold southeast advection over the SEB coast linked to a cold-core high-pressure system over the Atlantic Ocean. On the other hand, a wide area of negative pressure anomalies at the surface and positive temperature anomalies prevails over the central-north regions of Argentina, Paraguay, and Bolivia, most likely associated with the action of BC and BTO, accompanied by abnormally large amounts of moisture in the 850 hPa region. In the mid-levels, the presence of cold troughs and warm ridges suggests a thermal-type situation. A small region of negative temperature anomaly is noted over the ESS, and a small negative geopotential anomaly lies just southeast of the cold anomaly region over the SEB. At higher levels, wind divergence already presents relative maxima. In cases of cyclones, the fields corresponding to the 48 hours prior do not present significant differences compared to day 0, confirming a blocking pattern of the dipole type. There is a slight eastward displacement of the system, weakening of high-pressure anomalies over the Atlantic, and intensification of negative geopotential anomalies over the continent, along with increased moisture convergence. The moment of disaster coincides with the positioning of the cyclone axis at 500 hPa over the ESS, besides the presence of southeast winds at the surface associated with the maritime circulation. 4.4 - Disaster and non-disaster difference fields The difference maps between disaster and non-disaster cases highlight the main characteristics of triggering systems, especially concerning their intensity. The main characteristics of these fields can be observed more clearly in the days leading up to the passage of the synoptic system. Figures 10, 11 , and 12 represent the State of the atmosphere two days before the occurrence was recorded. Figure 10 displays the main characteristics that differentiate the fields of Frontal Systems associated with disasters from those not associated with disasters. Generally, it can be inferred that the fronts related to disasters in the ES correspond with more giant amplitude waves, as the cyclonic and anticyclonic anomalies are more pronounced (Fig. 10a). Additionally, a warm anticyclonic anomaly over the Atlantic Ocean is noteworthy. On the other hand, there is a bigger temperature contrast over subtropical latitudes compared to non-disaster-causing cold fronts. However, cold air is present before the frontal system's passage. It is also worth noting the presence of a comparatively warmer environment at high latitudes and with more available moisture in the atmosphere (not shown). At 500 hPa (Fig. 10b), there is a pre-existing blocking situation in the days prior, characterized by a warm (cold) anticyclonic (cyclonic) anomaly at high (subtropical) latitudes, which is "broken" by a transient cyclonic wave of larger amplitude compared to situations not linked to disasters. The presence of colder air in the previous days may also contribute to the intensification of thermodynamic instability. In the 300 hPa wind field (Fig. 10c), in addition to the presence of the barotropic anticyclonic system over the Atlantic Ocean, a more intense cyclonic anomaly is observed over the Northeast Region, probably associated with the presence of UTCV's characteristic of this region. Regarding cold fronts associated with disasters, these UTCVs, along with the mentioned anticyclonic system, allow for bigger divergence at upper levels near the ESS. In summary, cold front cases are associated with blocking situations in the preceding days that allow the advection of moist air from the east through the anticyclone and colder air at mid-levels. This blocking situation is 'interrupted' by the passage of more intense cold fronts (especially in the pressure/geopotential field), accompanied by a stronger mid-level trough and more significant divergence in the upper atmosphere over a convectively more unstable air mass. One factor to consider regarding the occurrence of SACZ is that only nineteen events not associated with disasters occurred during the study period, compared to thirty dates recorded in the S2ID that were related to the system's occurrence. This factor favors the interpretation that SACZ events, for the most part, are responsible for triggering disasters in the ES region. Additionally, due to its long duration, disasters may not necessarily occur on day zero (the day of the disaster). The difference fields between disaster and non-disaster events for SACZ at the surface also show a high-pressure system with warm characteristics over the extratropical Atlantic Ocean and a low-pressure system directly associated with SACZ further to the north (Fig. 11 a). The passage of cyclonic disturbances at high latitudes does not interfere with the position of the systems mentioned above, which is consistent with a blocking pattern, as also found by Seluchi and Chou ( 2009 ). The thicker layer in disaster cases can be explained by the higher occurrence of these cases in summer compared to non-disaster cases. The 500 hPa fields in Fig. 11 b show a more intense trough over the SEB, especially on day − 2, and a broad area of warm high pressures in the Pacific and Atlantic, similar to the SF cases, but with even more intense anticyclones over the oceans during SACZ events, indicating a situation of low zonal circulation index. In the altitude maps (Fig. 11 c), it can be observed that the wind over subtropical latitudes shows differences from the east compared to non-disaster-associated cases, confirming a weaker zonal circulation associated with lower baroclinicity. The presence of UTCV over the eastern portion of the Northeast Region is responsible for a more significant divergence, working as a trigger for more voluminous rainfall. It can be observed that the cases of SACZ associated with disasters in the ES are linked to blocking situations, making them more prolonged. It is worth considering that disasters may result not only from a single day of rainfall but also from the gradual increase in soil moisture over multiple consecutive days. The trough/cyclone that "anchors" the SACZ is more intense in disaster cases, and the position of UTCV triggers more intense rainfall by increasing divergence at high levels. Generally, the troughs that cause disasters in the ES are related to the passage of more intense transient systems, as observed through the displacement of positive and negative centers over the Atlantic Ocean. Particularly noteworthy is a colder high-pressure system to the south of the ESS, likely of a post-frontal type (observed in Fig. 12 a as the trough to the east of the high), generating intense cold maritime advection over the region. Additionally, there are thickness maximums and geopotential height minimums over Argentina, indicating the presence of more intense CL and TOL systems. At the 850 hPa level (not shown), there is a higher amount of moisture over the ES on all days. This moisture would result from the eastward circulation generated by the passage of a frontal system over the ocean and the subsequent entry of high pressure, which determines a circulation pattern that favors an increase in moisture over southern Brazil and neighboring countries. The presence of more intense CL and TOL systems, compared to non-disaster cases, contributes to the increased moisture over the La Plata region. The difference fields at the 500 hPa level (Fig. 12 b) show that in cases associated with disasters, there are more intense transient waves. In the days prior, a colder trough moves south of the ESS, associated with the frontal system mentioned earlier. On day 0, a more intense ridge enters from the south of the continent, which modulates the circulation in the lower levels, favoring the transport of moisture. The rear part of the ridge and the subsequent entry of a relative trough favor the formation of low-pressure systems over western Argentina. In Fig. 12 c, it is possible to identify the transient waves described in the 500 hPa field. In the days prior, the westerly component of wind is stronger, indicating a greater baroclinicity compared to cases not associated with disasters. That highlights the importance of the frontal system that moves over the ocean. Specifically, over the ESS, there is relatively more divergence in disaster cases. Therefore, the troughs that cause disasters in the ES are characterized by higher humidity and instability, which allows for deducing the more convective nature of the precipitations. The higher humidity is associated with the persistence of oceanic circulation in the preceding days, related to the passage of a Frontal System and the subsequent entrance of a relatively intense post-frontal high (more intense than in cases not related to disasters), supported by the displacement of a higher-amplitude ridge over extratropical latitudes. The intensity of the ridge and the subsequent advancement of a trough through the western part of the continent favor the formation of CL and TOL that acquire significant amplitude and intensity, generating an area of low pressure over a large extent, contributing to the drop in pressure, including in the ESS, on the day of the disaster occurrence. The difference fields between disasters and non-disasters in the cases of cyclones were not included in this study, as the number of these events was small for comparative purposes. Conclusions Despite the wide range of studies on hydrometeorological disasters in Southeast Brazil, very few comprehensively address the State of Espírito Santo. The State, composed almost entirely of small municipalities, is frequently impacted by disasters, including landslides, floods, and flash floods. This study aimed to identify the systems responsible for triggering intense precipitation events leading to disasters in ESS, as well as their main characteristics, focusing on analyzing synoptic patterns associated with the occurrences recorded in the S2ID database. The events that represented the highest number of occurrences, in decreasing order, were urban floods (37), followed by landslides (29), floods (24), and finally, debris flows (9). The total number of occurrences (99) is greater than the number of selected dates to compose the cases (85) because multiple incidents can be recorded in various cities daily. The identified cases were classified into the four types of systems found, and none of them were related to isolated convection cases. Most recorded incidents occurred during the summer (35) and spring (34). It was observed that the South Atlantic Convergence Zone (31) and the passage of Frontal Systems (32) over the region accounted for approximately 75% of the systems related to disasters caused by intense rainfall. Additionally, Troughs (18) and Cyclones (4) also contributed to such occurrences. A common characteristic found in all occurrences was the presence of a cyclonic disturbance at the surface near Espírito Santo, strong moisture advection, and upper-level wind divergence, attributes consistent with heavy rainfall. The disaster cases show more intense patterns compared to non-disaster cases. The specifics of each system can be summarized as follows: a) Frontal systems associated with blocking situations in the preceding days, allowing the advection of moist air from the east through the anticyclone and colder air in the mid-levels. This blocking situation is "interrupted" by the passage of more intense cold fronts (especially in the pressure/geopotential fields) that extend widely (potentially reaching the southern Amazon region). These cold fronts are accompanied by a more intense trough in the mid-levels and more significant upper-level divergence over a convectively more unstable air mass. It is observed that the cold fronts that triggered disasters in Espírito Santo mainly occurred during the summer, even though this is a typical winter system. b) South Atlantic Convergence Zone with stronger eastward winds, associated with a low zonal circulation index, featuring an anomalous warm high-pressure system over the Atlantic and an intense low-pressure system further north. These systems are linked to a quasi-stationary barotropic pattern, typical of blocking situations, with extended durations and, consequently, a higher likelihood of triggering disasters. The positioning of the UTCV over the eastern coast of Northeast Brazil can act as a trigger for more intense rainfall due to increased upper-level divergence. It is worth noting that SACZ events, which mostly occur in the summer, are primarily responsible for causing disasters in Espírito Santo. c) Troughs accompanied by negative temperature anomalies in the mid-levels, with slow displacement and low baroclinicity, along with increased moisture and instability, associated with a more convective nature. The moisture is linked to cyclonic circulation present in the preceding days, explained by the passage of a frontal system and subsequent entry of a post-frontal high, more intense than in non-disaster cases, sustained by the displacement of a larger-amplitude ridge over extratropical latitudes. The strong influence of the CL and TOL over Northwestern Argentina is responsible for generating a widespread low-pressure area, influencing the ESS. d) Cold-core cyclones with barotropic characteristics, featuring intense moisture and thickness advection, and a northward axis over Espírito Santo, associated with a slow-moving blocking warm high-pressure system to the south, around 40–45°S. The timing of the disasters seems to coincide with the positioning of the cyclone's axis at 500 hPa over Espírito Santo, in addition to the presence of southeasterly surface winds associated with the maritime circulation. Additionally, there was the influence of another factor, in most cases, playing a significant role in the formation of the analyzed systems. A blocking high-pressure system, under specific conditions related to each system, could be identified before the passage of Frontal Systems (when the passage of these intense fronts disrupts the situation), also positioned south of the SACZ, contributing to the increased persistence of these events and south of barotropic structured cyclones. The synoptic patterns identified in each group of cases can generally be predicted at least 48 hours before reaching Espírito Santo, given the higher intensity of these systems even from higher latitudes in the preceding days. Declarations Acknowledgements The research leading to these results received funding from Coordenação de Aperfeiçoamento de Pessoal de Nível Superior - Brasil (CAPES) - Finance Code 001. Declaration of exclusivity I declare that this work has not been previously published, neither in English nor in any other language, ensuring its exclusivity References Aguiar LF, Cataldi M (2021) Social and environmental vulnerability in Southeast Brazil associated with the South Atlantic Convergence Zone. Nat Hazards 109:2423–2437. https://doi.org/10.1007/s11069-021-04926-z Camarinha PIM (2016) Vulnerabilidade aos desastres naturais decorrentes de deslizamentos de terra em cenários de mudanças climáticas na porção paulista da Serra do Mar. Thesis, National Institute for Space Research CEPED UFSC (2013) Brazilian Atlas of Natural Disasters 1991 to 2012. Centro de Estudos e Pesquisas em Engenharia e Defesa Civil - Universidade Federal de Santa Catarina, Brazil, 2°:126 Dolif G, Nobre C (2012) Improving extreme precipitation forecasts in Rio de Janeiro, Brazil: are synoptic patterns efficient for distinguishing ordinary from heavy rainfall episodes? Atmospheric Science Letters, 13:216–222 https://rmets.onlinelibrary.wiley.com/doi/pdf/10.1002 /asl.385 EMERGENCY EVENTS DATABASE (EM-DAT). Data. https://public.emdat.be/data . Accessed 26 January 2022 Escobar GCJ (2014) Rev Bras Meteorol 29:105–124. https://doi.org/10.1590/S0102-77862014000100011 . Padrões de circulação em superfície e em 500 hPa na América do Sul e eventos de anomalias positivas de precipitação no estado de Minas Gerais durante o mês de dezembro de 2011 Escobar GCJ, Marques ACA, Dereczynski CP (2022) Synoptic patterns of South Atlantic Convergence Zone episodes associated with heavy rainfall events in the city of Rio de Janeiro. Brazil Atmós 35(2):287–305. https://doi.org/10.20937/atm.52942 Escobar GCJ, REBOITA MS (2022) Relationship between daily atmospheric circulation patterns and South Atlantic Convergence Zone (SACZ) events. Atmós. 35(1):1–25. https://doi.org/10.20937/atm.52936 Espírito Santo CM, Satyamurty P (2002) Eventos extremos de precipitação na região sudeste do Brasil e redondezas no período de 1997–2001. XII Congresso Brasileiro de Meteorologia, Foz de Iguaçu Foss M (2016) Efeitos da orografia do sudeste da América do Sul na estrutura dos sistemas frontais. Thesis, National Institute for Space Research Garreaud RD (2000) Cold air incursions over subtropical South America: mean structure and dynamics. Monthly Weather Review, v. 128, n. 7. 2544–2559. https://doi.org/10.1175/1520-0493(2000)128 Gonçalves JPC (2015) Caracterização e variabilidade de situações sinóticas associadas a episódios de chuva intensa e chuva persistente durante a estação chuvosa na região sudeste do Brasil. Dissertation, National Instutute for Space Research Instituto Brasileiro de Geografia e Estatística—IBGE (2022) Censo Brasileiro de 2022, Rio de Janeiro Kodama Y, Sagawa T, Ishida S, Yoshikane T (2012) Roles of the Brazilian plateau in the formation of the SACZ. J Clim v 25:1745–1758. https://doi.org/10.1175/2011JCLI3785.1 Lima KC, Satyamurty P, Fernández JPR (2010) Large-scale atmospheric conditions associated with heavy rainfall episodes in Southeast Brazil. Theor Appl Climatol 101:121–135. https://doi.org/10.1007/s00704-009-0207-9 Marcelino EV, Nunes LH, Kobiyama M (2006) Banco de dados de desastres naturais: análise de dados globais e regionais. Caminhos de Geografia, v. 7, n. 19:130–149. https://doi.org/10.14393/RCG71915495 Moura CRW, Escobar GCJ, Andrade KM (2013) Padrões de circulação em superfície e altitude associados a eventos de chuva intensa na Região Metropolitana do Rio de Janeiro. Rev Bras de Meteorol v 28:267–280. https://doi.org/10.1590/S0102-77862013000300004 Oliveira AS (1986) Interações entre sistemas frontais na América do Sul e a convecção na Amazônia. Dissertation, National Institute for Space Research Teixeira MS (2010) Caracterização física e dinâmica de episódios de chuvas intensas nas regiões Sul e Sudeste do Brasil. Thesis – National Institute for Space Research IPCC (2012) Managing the risks of extreme events and disasters to advance climate change adaptation: a special report of working groups i and ii of the intergovernmental panel on climate change. Cambridge University Press, 582 p. https://www.ipcc.ch/report/managing-the-risks-of-extreme-events-and-disasters-to-advance-climate-change-adaptation/ Accessed 02 February 2022 Ribeiro DF, Saito SM, Alvalá RCS (2022) Disaster vulnerability analysis of small towns in Brazil. Int J Disaster Risk Reduct 68:e102726. https://doi.org/10.1016/j.ijdrr.2021.102726 SAITO SM, RIBEIRO DIASMCA, ALVALÁ DF, SOUZA RCS, SANTANA DB, SOUZA RASM, RIBEIRO PA, STENNER JVM, C (2021) Disaster risk areas in Brazil: outcomes from an intra-urban scale analysis. Int J Disaster Resil Built Environ v 12 n 2238–250. https://doi.org/10.1108/IJDRBE-01-2020-0008 Seluchi ME, Chou SC (2009) Synoptic patterns associated with landslide events in the Serra do Mar, Brazil. Theor Appl Climatol 98:67–77. https://doi.org/10.1007/s00704-008-0101-x UN-ISDR (2009) Terminology on Disaster Risk Reduction. Publishing United Nations Office for Disaster Risk Reduction. https://www.undrr.org/publication/2009-unisdr-terminologydisaster-risk-reduction . Accessed 17 May 2022 UN-ISDR (2015) Sendai framework for disaster risk reduction 2015–2030. Publishing United Nations Office for Disaster Risk Reduction. https://www.undrr.org/publication/sendai-framework-disaster-risk-reduction-2015-2030 Accessed 17 May 2022 INCAPER (2023) Annual average precipitation (1984 to 2014) https://meteorologia.incaper.es.gov.br/mapas-de-chuva-normal-climatologica-album Cite Share Download PDF Status: Published Journal Publication published 06 May, 2025 Read the published version in Natural Hazards → Version 1 posted Editorial decision: Major revisions 26 Jan, 2025 Reviewers agreed at journal 23 Mar, 2024 Reviewers invited by journal 19 Feb, 2024 Editor assigned by journal 10 Jan, 2024 First submitted to journal 09 Jan, 2024 You are reading this latest preprint version Research Square lets you share your work early, gain feedback from the community, and start making changes to your manuscript prior to peer review in a journal. As a division of Research Square Company, we’re committed to making research communication faster, fairer, and more useful. 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Also discoverable on Platform About Our Team In Review Editorial Policies Advisory Board Help Center Resources Author Services Accessibility API Access RSS feed Manage Cookie Preferences © Research Square 2026 | ISSN 2693-5015 (online) Privacy Policy Terms of Service Do Not Sell My Personal Information {"props":{"pageProps":{"initialData":{"identity":"rs-3851739","acceptedTermsAndConditions":true,"allowDirectSubmit":false,"archivedVersions":[],"articleType":"Research Article","associatedPublications":[],"authors":[{"id":273976324,"identity":"cf5846fc-c35e-461a-a38b-bc271fde436d","order_by":0,"name":"Lindsay Silva","email":"data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAZAAAAAyAQMAAABI0h/eAAAABlBMVEX///8AAABVwtN+AAAACXBIWXMAAA7EAAAOxAGVKw4bAAAA7klEQVRIiWNgGAWjYBACPmYGBgkwi5m5gYGhAsxmw6uFDaGFEajlDDFaGGBaGIBaGNvggni0sPMevPmj5jCDfDtjm8TPeRZ55uwNbI8r8DqML9ma59hhBoPDjG2Svdskii17DrAbnsGrhcdMmoENqIWZsdmAd5tE4oYbCWySDQS0SP74B3RYM2Oz4d85QC33HxDWIsHbdpiB4TBj42PeBpAtDAS1GFvz9qXzGIC0yByTSNzZk9huiE8LP/8Zw5s/vlnLyfcfPnDwTU1d4nb2w8ce4tMCBc08cKYBKIKIAHUIpgEx6kfBKBgFo2BEAQBuLUNojjW1oAAAAABJRU5ErkJggg==","orcid":"https://orcid.org/0009-0003-8268-7669","institution":"National Institute for Space Research: Instituto Nacional de Pesquisas Espaciais","correspondingAuthor":true,"prefix":"","firstName":"Lindsay","middleName":"","lastName":"Silva","suffix":""},{"id":273976325,"identity":"a8833f8e-7530-424e-abe7-4ad516b3fef4","order_by":1,"name":"Marcelo Enrique Seluchi","email":"","orcid":"","institution":"Centro Nacional de Monitoramento e Alertas de Desastres Naturais","correspondingAuthor":false,"prefix":"","firstName":"Marcelo","middleName":"Enrique","lastName":"Seluchi","suffix":""}],"badges":[],"createdAt":"2024-01-10 23:48:36","currentVersionCode":1,"declarations":"","doi":"10.21203/rs.3.rs-3851739/v1","doiUrl":"https://doi.org/10.21203/rs.3.rs-3851739/v1","draftVersion":[],"editorialEvents":[{"content":"https://doi.org/10.1007/s11069-025-07307-y","type":"published","date":"2025-05-06T15:57:47+00:00"}],"editorialNote":"","failedWorkflow":false,"files":[{"id":51512672,"identity":"c0aab525-eabf-4f78-b6ae-d5c500e2c54e","added_by":"auto","created_at":"2024-02-22 21:18:55","extension":"jpg","order_by":1,"title":"Figure 1","display":"","copyAsset":false,"role":"figure","size":824840,"visible":true,"origin":"","legend":"\u003cp\u003eLocation of study area\u003c/p\u003e","description":"","filename":"locationmap.jpg","url":"https://assets-eu.researchsquare.com/files/rs-3851739/v1/f2477347c6147fe0acd288b8.jpg"},{"id":51512674,"identity":"5bb2b796-0476-4ed1-8d8a-476aaeb7d2c8","added_by":"auto","created_at":"2024-02-22 21:18:56","extension":"png","order_by":2,"title":"Figure 2","display":"","copyAsset":false,"role":"figure","size":289981,"visible":true,"origin":"","legend":"\u003cp\u003e1000-hPa geopotential height (m, solid line) and 500/1,000-hPa layer thickness (m, shaded) (a), 500-hPa geopotential height (m, solid line) and temperature (ºC, shaded) (b), and 300-hPa streamlines (m s\u003csup\u003e-1\u003c/sup\u003e, colors) and temperature (°C, solid line) (c). Fields are average over the frontal cases.\u003c/p\u003e","description":"","filename":"Fig2.SF.png","url":"https://assets-eu.researchsquare.com/files/rs-3851739/v1/b66b65df71e2f99d3cb05a3c.png"},{"id":51512673,"identity":"7f6e92f9-a36b-4846-af29-377277c55709","added_by":"auto","created_at":"2024-02-22 21:18:55","extension":"png","order_by":3,"title":"Figure 3","display":"","copyAsset":false,"role":"figure","size":298220,"visible":true,"origin":"","legend":"\u003cp\u003eAs in Figure 2, but for SACZ cases\u003c/p\u003e","description":"","filename":"Fig3ZCAS.png","url":"https://assets-eu.researchsquare.com/files/rs-3851739/v1/4c641e9afcc45bea8a5dc044.png"},{"id":51513290,"identity":"3b005863-4576-4ca6-92c1-68bd14d87dc0","added_by":"auto","created_at":"2024-02-22 21:26:56","extension":"png","order_by":4,"title":"Figure 4","display":"","copyAsset":false,"role":"figure","size":285021,"visible":true,"origin":"","legend":"\u003cp\u003eAs in Figure 2, but for Trough cases\u003c/p\u003e","description":"","filename":"Fig4CAV.png","url":"https://assets-eu.researchsquare.com/files/rs-3851739/v1/e28d397d9cfae49816b11fa5.png"},{"id":51512682,"identity":"269ef40a-4e9d-4bfd-a066-8d2857afe869","added_by":"auto","created_at":"2024-02-22 21:18:56","extension":"png","order_by":5,"title":"Figure 5","display":"","copyAsset":false,"role":"figure","size":279003,"visible":true,"origin":"","legend":"\u003cp\u003eAs in Figure 2, but for Cyclones cases\u003c/p\u003e","description":"","filename":"Fig5CIC.png","url":"https://assets-eu.researchsquare.com/files/rs-3851739/v1/6d692f61a843b329ff6a6dcf.png"},{"id":51512678,"identity":"b063c3b0-e1ee-4eff-bbb0-92468da2a96b","added_by":"auto","created_at":"2024-02-22 21:18:56","extension":"png","order_by":6,"title":"Figure 6","display":"","copyAsset":false,"role":"figure","size":311643,"visible":true,"origin":"","legend":"\u003cp\u003e1000-hPa geopotential height (m, solid line) and 500/1,000-hPa layer thickness (m, shaded) (a), 500-hPa geopotential height (m, solid line) and temperature (ºC, shaded) (b), and 300-hPa streamlines (m s\u003csup\u003e-1\u003c/sup\u003e, colors) and temperature (°C, solid line) (c). Fields are anomalies over the frontal cases.\u003c/p\u003e","description":"","filename":"Fig6SF.png","url":"https://assets-eu.researchsquare.com/files/rs-3851739/v1/0197f73ea6362709680e3c42.png"},{"id":51513291,"identity":"587fab62-208d-43b7-a10b-556ba3be71f5","added_by":"auto","created_at":"2024-02-22 21:26:56","extension":"png","order_by":7,"title":"Figure 7","display":"","copyAsset":false,"role":"figure","size":305157,"visible":true,"origin":"","legend":"\u003cp\u003eAs in Figure 6, but for SACZ cases\u003c/p\u003e","description":"","filename":"Fig7ZCAS.png","url":"https://assets-eu.researchsquare.com/files/rs-3851739/v1/d8cc48bb22b5c24a1a8b73b6.png"},{"id":51512684,"identity":"f86593b7-52bc-490a-8b79-929f9abbd889","added_by":"auto","created_at":"2024-02-22 21:18:56","extension":"png","order_by":8,"title":"Figure 8","display":"","copyAsset":false,"role":"figure","size":304683,"visible":true,"origin":"","legend":"\u003cp\u003eAs in Figure 6, but for troughs cases\u003c/p\u003e","description":"","filename":"Fig8CAV.png","url":"https://assets-eu.researchsquare.com/files/rs-3851739/v1/258895830779557ef7db5c07.png"},{"id":51512679,"identity":"901c4ae9-a513-4662-b8c7-aa0ba65e0a71","added_by":"auto","created_at":"2024-02-22 21:18:56","extension":"png","order_by":9,"title":"Figure 9","display":"","copyAsset":false,"role":"figure","size":343687,"visible":true,"origin":"","legend":"\u003cp\u003eAs in Figure 6, but for troughs cases\u003c/p\u003e","description":"","filename":"Fig9CIC.png","url":"https://assets-eu.researchsquare.com/files/rs-3851739/v1/197e2ff808c9f987c8dd363c.png"},{"id":51512683,"identity":"325c7faa-ec7d-492f-9ef8-56eae2487e3c","added_by":"auto","created_at":"2024-02-22 21:18:56","extension":"png","order_by":10,"title":"Figure 10","display":"","copyAsset":false,"role":"figure","size":316227,"visible":true,"origin":"","legend":"\u003cp\u003e1000-hPa geopotential height (m, solid line) and 500/1,000-hPa layer thickness (m, shaded) (a), 500-hPa geopotential height (m, solid line) and temperature (ºC, shaded) (b) and 300-hPa streamlines (m s\u003csup\u003e-1\u003c/sup\u003e, colors) and temperature (°C, solid line) (c). Fields are differences between disaster and non-disaster Frontal Systems cases.\u003c/p\u003e","description":"","filename":"Fig10SFdnd.png","url":"https://assets-eu.researchsquare.com/files/rs-3851739/v1/c215d7150a1ab0411c27fda2.png"},{"id":51512681,"identity":"ef93c4ae-ac79-409a-bc13-b246cb073e2e","added_by":"auto","created_at":"2024-02-22 21:18:56","extension":"png","order_by":11,"title":"Figure 11","display":"","copyAsset":false,"role":"figure","size":326464,"visible":true,"origin":"","legend":"\u003cp\u003eAs in Figure 10, but for SACZ cases\u003c/p\u003e","description":"","filename":"Fig11ZCASdnd.png","url":"https://assets-eu.researchsquare.com/files/rs-3851739/v1/fb5cc89d58a7b3fd43ba070d.png"},{"id":51512685,"identity":"bcbea891-5658-4236-a30c-a3c9d6b0917c","added_by":"auto","created_at":"2024-02-22 21:18:56","extension":"png","order_by":12,"title":"Figure 12","display":"","copyAsset":false,"role":"figure","size":333655,"visible":true,"origin":"","legend":"\u003cp\u003eAs in Figure 10, but for trough cases\u003c/p\u003e","description":"","filename":"Fig12CAVdnd.png","url":"https://assets-eu.researchsquare.com/files/rs-3851739/v1/09419494d955d95311037b29.png"},{"id":82538483,"identity":"94fd1347-9753-4013-a349-bebc4488d5d8","added_by":"auto","created_at":"2025-05-12 16:11:05","extension":"pdf","order_by":0,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":4174198,"visible":true,"origin":"","legend":"","description":"","filename":"manuscript.pdf","url":"https://assets-eu.researchsquare.com/files/rs-3851739/v1/ad437257-3558-4043-8adc-8cf530d98bbe.pdf"}],"financialInterests":"","formattedTitle":"\u003cp\u003eCharacterization of Synoptic Systems Triggering Disasters in the State of Espírito Santo, Brazil\u003c/p\u003e","fulltext":[{"header":"Introduction","content":"\u003cp\u003eAn extreme climate or weather event is defined by the occurrence of the record of values ​​close to the lower and upper thresholds in an observed range of an atmospheric variable (IPCC \u003cspan citationid=\"CR20\" class=\"CitationRef\"\u003e2012\u003c/span\u003e). These events can trigger hydro-geo-meteorological disasters (UN-ISDR \u003cspan citationid=\"CR25\" class=\"CitationRef\"\u003e2015\u003c/span\u003e), especially with population vulnerability and inefficient response actions (UN-ISDR \u003cspan citationid=\"CR24\" class=\"CitationRef\"\u003e2009\u003c/span\u003e).\u003c/p\u003e \u003cp\u003eBrazil is among the top 10 countries most affected by natural disasters, most of which are of hydrometeorological origin (EM-DAT 2023). Episodes of intense rainfall are mainly associated with the South Atlantic Convergence Zone (SACZ) and Cold Fronts (Marcelino et al. \u003cspan citationid=\"CR16\" class=\"CitationRef\"\u003e2006\u003c/span\u003e), particularly affecting the Southeast Region of Brazil (Teixeira \u003cspan citationid=\"CR19\" class=\"CitationRef\"\u003e2010\u003c/span\u003e; Moura et al. \u003cspan citationid=\"CR17\" class=\"CitationRef\"\u003e2013\u003c/span\u003e). These systems can be influenced by tropical convection (Oliveira \u003cspan citationid=\"CR18\" class=\"CitationRef\"\u003e1986\u003c/span\u003e) and the Brazilian orography (Kodama et al. \u003cspan citationid=\"CR14\" class=\"CitationRef\"\u003e2012\u003c/span\u003e; Foss \u003cspan citationid=\"CR10\" class=\"CitationRef\"\u003e2016\u003c/span\u003e), intensifying rainfall, mostly causing floods, inundations, and mass movements (CEPED 2012).\u003c/p\u003e \u003cp\u003eAn overwhelming majority of Brazilian municipalities, particularly those with smaller populations, exhibit the lowest development indices in direct proportion to the incidence of floods and landslides, with emphasis on the State of Esp\u0026iacute;rito Santo (Saito et al. 2020; Ribeiro et al. \u003cspan citationid=\"CR21\" class=\"CitationRef\"\u003e2022\u003c/span\u003e). Despite being heavily impacted by hydrometeorological disasters, many of these small cities lack a municipal risk reduction plan (Saito et al. 2020).\u003c/p\u003e \u003cp\u003eSeveral studies point to the influence of synoptic systems on the occurrence of intense rainfall and the initiation of that cause in Southeast Brazil (SEB) (Esp\u0026iacute;rito Santo and Satyamurty \u003cspan citationid=\"CR9\" class=\"CitationRef\"\u003e2002\u003c/span\u003e; Lima et al. \u003cspan citationid=\"CR15\" class=\"CitationRef\"\u003e2010\u003c/span\u003e; Gon\u0026ccedil;alves \u003cspan citationid=\"CR12\" class=\"CitationRef\"\u003e2015\u003c/span\u003e; Aguiar and Cataldi \u003cspan citationid=\"CR1\" class=\"CitationRef\"\u003e2021\u003c/span\u003e) in Serra do Mar in S\u0026atilde;o Paulo (Seluchi and Chou \u003cspan citationid=\"CR23\" class=\"CitationRef\"\u003e2009\u003c/span\u003e; Camarinha \u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e2016\u003c/span\u003e), in the State of Rio de Janeiro (Dolif and Nobre \u003cspan citationid=\"CR4\" class=\"CitationRef\"\u003e2012\u003c/span\u003e; Moura et al. \u003cspan citationid=\"CR17\" class=\"CitationRef\"\u003e2013\u003c/span\u003e; Escobar et al. \u003cspan citationid=\"CR7\" class=\"CitationRef\"\u003e2022\u003c/span\u003e), and in the State of Minas Gerais (Escobar \u003cspan citationid=\"CR6\" class=\"CitationRef\"\u003e2014\u003c/span\u003e; Reboita et al. 2017; Silva et al. 2020). However, the State of Esp\u0026iacute;rito Santo lacks the most studies on this topic.\u003c/p\u003e \u003cp\u003eThe State of Esp\u0026iacute;rito Santo is frequently affected by synoptic systems that result in intense rainfall. Irregular land use in rugged terrain, combined with precipitation, can lead to natural disasters in the region. Therefore, the present study aims to identify the different types of meteorological systems associated with extreme rainfall and disasters in the State of Esp\u0026iacute;rito Santo and to establish their key dynamics and thermodynamics characteristics as a tool to improve extreme precipitation forecasting in these conditions.\u003c/p\u003e"},{"header":"The study area","content":"\u003cp\u003eFigure \u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003e shows the State of Esp\u0026iacute;rito Santo, which is in Brazil's largest economic development hub and is among the country's most developed states. (CA\u0026Ccedil;ADOR and GRASSI 2009). The State ranks seventh in the National Human Development Index (HDI) with a value of 0.740 (IBGE 2022).\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003eDespite a small area of approximately 46,000 km\u003csup\u003e2\u003c/sup\u003e, the climate in Esp\u0026iacute;rito Santo is quite diverse (REGOTO et al. 2018). The northern portion experiences a hot and dry climate, the central region has a cold and humid climate, and the southern part has a hot and humid climate. About 70% of the State's terrain consists of rugged lands (CERQUEIRA et al. 1999). As one moves further inland, it is possible to find peaks with altitudes exceeding 1,000 meters, such as the Serra do Capara\u0026oacute;, and the Serra do Castelo (REGOTO et al. 2018). The annual average precipitation provided by the Institute of Research, Technical Assistance, and Rural Extension of the State of Esp\u0026iacute;rito Santo (INCAPER), for the period between 1984 and 2014, indicates values of approximately 1000 mm in the northern and northwestern regions, and over 1500 mm in the central-southern part (INCAPER \u003cspan citationid=\"CR26\" class=\"CitationRef\"\u003e2023\u003c/span\u003e).\u003c/p\u003e"},{"header":"Materials and methods","content":"\u003cp\u003eFor selecting cases of event occurrence, the Integrated System of Disaster Information (S2ID; AGUIAR and CATALDI \u003cspan citationid=\"CR1\" class=\"CitationRef\"\u003e2021\u003c/span\u003e) was employed, which contains data from the reports on federal acknowledgments of emergencies and State of public calamity carried out by the Civil Defense of each municipality. Records of urban floods, landslides, floods, and debris flow that occurred from 2013 to 2021 were selected. In order to identify meteorological systems active on those dates, synoptic charts at several levels provided by the Center for Weather Forecasting and Climate Studies (CPTEC) at the National Institute for Space Research (INPE) were analyzed. Additionally, satellite images from GOES 13 and 16, as well as historical annual precipitation data from the Brazilian National Institute of Meteorology (INMET) automatic weather stations in Vit\u0026oacute;ria and Linhares cities, were also collected. No objective method to identify the dates of disaster occurrences was used. The selection of dates was determined based on the identification of the moment when the synoptic system passed over the ESS.\u003c/p\u003e \u003cp\u003eFlash flood events, resulting from intense precipitation associated with isolated convections (MADDOX et al. 1979; DOSWELL 1994), were excluded from the analysis, as they require a more specific methodology for examination and fall outside the scope of this study.\u003c/p\u003e \u003cp\u003eERA5, the fifth generation of the European Centre for Medium-Range Weather Forecasts (ECMWF) atmospheric reanalysis, was used to characterize the synoptic patterns associated with the disaster cases in composite maps. The chosen variables to construct the composite fields included 500/1000 hPa layer thickness and geopotential height (m\u003csup\u003e2\u003c/sup\u003e/s\u003csup\u003e2\u003c/sup\u003e) at the surface, zonal and meridional winds (m/s) and temperature (\u0026deg;C) at the 300 hPa level, geopotential height (m\u003csup\u003e2\u003c/sup\u003e/s\u003csup\u003e2\u003c/sup\u003e) and temperature (\u0026deg;C) at the 500 hPa level, specific humidity (g/kg) and geopotential height (m\u003csup\u003e2\u003c/sup\u003e/s\u003csup\u003e2\u003c/sup\u003e) at the 850 hPa level and K index.\u003c/p\u003e \u003cp\u003eMean fields and anomalies were constructed for 2 days prior to an event and 1 day following an event. The climatology for the anomaly fields was also constructed employing ERA5 reanalysis data from 2013 to 2021. Once the mean fields and anomalies of the leading dynamic and thermodynamic variables for each type of synoptic system were employed, the corresponding counterparts for days when there were no disaster associations were constructed. Thus, the difference fields between disaster and non-disaster cases could be constructed in order to identify parameters that can assist in disaster prediction in the State of Esp\u0026iacute;rito Santo.\u003c/p\u003e"},{"header":"Results","content":"\u003cp\u003eAccording to the criteria established for this research, 100 occurrences of disasters were found: 38 urban floods, 29 landslides, 24 floods, and 9 debris flows. Of these occurrences, 85 dates were identified, associated with the passage of 32 frontal systems, 31 South Atlantic Convergence Zone (SACZ), 18 surface Troughs, and 4 extratropical Cyclones. Table\u0026nbsp;\u003cspan refid=\"Tab1\" class=\"InternalRef\"\u003e1\u003c/span\u003e shows the relation between the occurrences and the synoptic systems and Table\u0026nbsp;\u003cspan refid=\"Tab2\" class=\"InternalRef\"\u003e2\u003c/span\u003e indicates the relation between the synoptic systems identified and their distribution throughout the seasons during the study period.\u003c/p\u003e \u003cp\u003e \u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab1\" border=\"1\"\u003e \u003ccaption language=\"En\"\u003e \u003cdiv class=\"CaptionNumber\"\u003eTable 1\u003c/div\u003e \u003cdiv class=\"CaptionContent\"\u003e \u003cp\u003eDistribution per Occurrences of Synoptic Systems Associated with Disasters between 2013 and 2021 in the State of Esp\u0026iacute;rito Santo\u003c/p\u003e \u003c/div\u003e \u003c/caption\u003e \u003ccolgroup cols=\"6\"\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c4\" colnum=\"4\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c5\" colnum=\"5\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c6\" colnum=\"6\"\u003e\u003c/div\u003e \u003cthead\u003e \u003ctr\u003e \u003cth align=\"left\" colname=\"c1\"\u003e \u003cp\u003eOccurrences/\u003c/p\u003e \u003cp\u003eSynoptic systems\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c2\"\u003e \u003cp\u003eFrontal Systems\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c3\"\u003e \u003cp\u003eSACZ\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c4\"\u003e \u003cp\u003eTroughs\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c5\"\u003e \u003cp\u003eCyclones\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c6\"\u003e \u003cp\u003eTotal\u003c/p\u003e \u003c/th\u003e \u003c/tr\u003e \u003c/thead\u003e \u003ctbody\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eDebris Flows\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e2\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e4\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e3\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e0\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e9\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eFloods\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e2\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e14\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e8\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e0\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e24\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eLandslides\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e17\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e9\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e2\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e1\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e29\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eUrban Floods\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e16\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e11\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e8\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e3\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e38\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003c/tbody\u003e \u003c/colgroup\u003e \u003c/table\u003e\u003c/div\u003e \u003c/p\u003e \u003cp\u003e \u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab2\" border=\"1\"\u003e \u003ccaption language=\"En\"\u003e \u003cdiv class=\"CaptionNumber\"\u003eTable 2\u003c/div\u003e \u003cdiv class=\"CaptionContent\"\u003e \u003cp\u003eSeasonal Distribution of Synoptic Systems Associated with Disasters between 2013 and 2021 in the State of Esp\u0026iacute;rito Santo\u003c/p\u003e \u003c/div\u003e \u003c/caption\u003e \u003ccolgroup cols=\"6\"\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c4\" colnum=\"4\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c5\" colnum=\"5\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c6\" colnum=\"6\"\u003e\u003c/div\u003e \u003cthead\u003e \u003ctr\u003e \u003cth align=\"left\" colname=\"c1\"\u003e \u003cp\u003eSeasons/\u003c/p\u003e \u003cp\u003eSynoptic systems\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c2\"\u003e \u003cp\u003eFrontal Systems\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c3\"\u003e \u003cp\u003eSACZ\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c4\"\u003e \u003cp\u003eTroughs\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c5\"\u003e \u003cp\u003eCyclones\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c6\"\u003e \u003cp\u003eTotal\u003c/p\u003e \u003c/th\u003e \u003c/tr\u003e \u003c/thead\u003e \u003ctbody\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eSummer\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e6\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e17\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e10\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e2\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e35\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eAutumn\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e8\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e1\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e2\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e1\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e12\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eWinter\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e3\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e0\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e0\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e1\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e4\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eSpring\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e15\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e13\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e6\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e0\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e34\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003c/tbody\u003e \u003c/colgroup\u003e \u003c/table\u003e\u003c/div\u003e \u003c/p\u003e \u003cp\u003eIt is possible to observe, according to Table\u0026nbsp;\u003cspan refid=\"Tab2\" class=\"InternalRef\"\u003e2\u003c/span\u003e, that most of the records occurred during the austral summer and spring, which is in line with a warmer and moister atmosphere, thermodynamically more unstable. The SACZ and Frontal Systems represent most of the systems associated with disasters during the period.\u003c/p\u003e \u003cp\u003eThe following results represent the analyses of composite fields plotted on the dates of disaster events between 2013 and 2021. The composition of the cases helps identify the characteristics present in the atmosphere at the time of the system's occurrence.\u003c/p\u003e \u003cp\u003eOn the 85 identified dates, there is a clear presence of a baroclinic low-pressure system over the ESS, a region of maximum cyclonic curvature at mid-levels and upper-level wind divergence, accompanied by high humidity and thermodynamic instability from the Amazon. These conditions are consistent with the occurrence of heavy rainfall.\u003c/p\u003e \u003cp\u003eThe frontal cases are associated with most of the identified disaster cases during the period. The surface fields of cold fronts (Fig.\u0026nbsp;2a) display a trough associated with the front, with greater cyclonic horizontal shear, a more intense post-frontal anticyclone compared to overall averages, and intense gradients of thickness, geopotential height, and moisture to the south of the ES (not shown), indicating higher baroclinicity and contrast of air masses with different moisture content. Figure\u0026nbsp;2b shows a strong gradient of negative geopotential anomaly at 500 hPa, suggesting the existence of thermodynamic instability at this altitude. At higher levels (Fig.\u0026nbsp;2c), the high wind speed southeast of the ESS, associated with the surface cold front, promotes the ascent of air and consequent precipitation occurrence. The plotted fields for these cases show air instability from the Amazon to the Atlantic.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003eThe instances of SACZ, accounting for over 30% of the disaster-associated systems during this period, also display a distinct inverted trough situated over Rio de Janeiro (RJ) and the ES region (as shown in Fig.\u0026nbsp;\u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e3\u003c/span\u003ea). Nevertheless, the higher pressure to the south is less intense, along with a less pronounced thickness gradient. These factors collectively indicate reduced baroclinicity in comparison to frontal systems. At the 850 hPa level (not shown), there is noticeable moisture convergence over the southeastern region, where the SACZ establishes itself (ESCOBAR and REBOITA \u003cspan citationid=\"CR8\" class=\"CitationRef\"\u003e2022\u003c/span\u003e).\u003c/p\u003e \u003cp\u003eAt 500 hPa (Fig.\u0026nbsp;\u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e3\u003c/span\u003eb), the temperature and geopotential gradients are less intense, and the maximum baroclinicity is located southeast of the ESS. At 300 hPa, wind divergence associated with the upward motion of air contributes to the moisture transport to higher levels, consequently enhancing instability within the layer and maintaining the cloudiness associated with precipitation observed during ZCAS episodes (QUADRO, 1994).\u003c/p\u003e \u003cp\u003eIt can also be observed that the presence of well-defined Upper-Tropospheric Cyclonic Vortexes (UTCV) acting over the extreme eastern region of northeastern Brazil and the Bolivian High located at approximately 15\u0026deg;S and 70\u0026deg;W are essential components in the configuration of SACZ for these occurrences.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003eThe mean surface fields shown in Fig.\u0026nbsp;\u003cspan refid=\"Fig4\" class=\"InternalRef\"\u003e4\u003c/span\u003ea display a small trough with a warm axis over the ESS, a ridge around 40\u0026deg;S, and a small trough south of the 40\u0026deg;S parallel, along with the Chaco Low (CL) and the Thermal-Orographic Low (TOL) over the northwest region of Argentina. The weak thickness near the ES indicates an environment with little baroclinicity, with the ES immersed within an air mass of tropical characteristics.\u003c/p\u003e \u003cp\u003eThe surface trough cannot be identified at 500 hPa (Fig.\u0026nbsp;\u003cspan refid=\"Fig4\" class=\"InternalRef\"\u003e4\u003c/span\u003eb), but a slightly more intense temperature gradient is seen to the southwest of the ES within a markedly zonal flow. At higher levels (Fig.\u0026nbsp;\u003cspan refid=\"Fig4\" class=\"InternalRef\"\u003e4\u003c/span\u003ec), a maximum of wind divergence is identified over the ESS, linked to the eastern flank of the Bolivian High, and the Subtropical Jet is less intense and displaced farther south compared to overall means.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003eAmong the 85 cases of disaster, only 4 of them were related to extratropical cyclones. The composites of the cyclones show a low-pressure center at the surface (Fig.\u0026nbsp;\u003cspan refid=\"Fig5\" class=\"InternalRef\"\u003e5\u003c/span\u003ea) over the SEB region. In the vicinity of the ESS, the cyclones acquire greater cyclonic curvature, and they are immersed in a region of weak thickness gradient, which is indicative of low baroclinicity. Over the Atlantic Ocean, the extension of the high-pressure region westward suggests the coupling between the South Atlantic Subtropical High (ASAS) and a high-pressure system positioned south of the low-pressure center. The high moisture values from the Amazon region to the Southern Region, combined with the intense geopotential gradient, indicate maximum moisture advection over the Southeast Region.\u003c/p\u003e \u003cp\u003eAt mid-levels, there is a scarce temperature gradient, and further south, a relatively long-wave ridge predominates over the Atlantic Ocean. In the wind field at 300 hPa, there is a deviation of the Subtropical Jet, around 30\u0026deg;S, indicating a southward displacement of the baroclinic zone. The region of maximum divergence is seen just south of the ESS, which is conducive to precipitation.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cdiv id=\"Sec5\" class=\"Section2\"\u003e \u003ch2\u003e4.2\u0026ndash; Anomalies\u003c/h2\u003e \u003cp\u003eIn total anomaly fields, the trough over the ES appears precisely in the transition region between warm and cold anomalies, and anticyclonic anomalies over the Argentina region favor the maintenance of the post-frontal type anticyclone. The predominance of cyclonic anomalies over the ES indicates that the passage of more intense synoptic systems over the ocean influences the weather conditions along the Southeast Region's coast.\u003c/p\u003e \u003cp\u003eIn frontal cases' anomaly maps, very intense values are observed. Negative 500/1,000-hPa layer thickness anomalies extend from the Atlantic to the southern Amazon region, characterizing intense cold fronts (Fig.\u0026nbsp;6a). The point of maximum baroclinicity is precisely located over the ESS. Negative humidity anomalies coming from the south transport anomalously drier air, while positive anomalies position themselves over parts of the Southeast region of Brazil (not shown). At mid-levels (Fig.\u0026nbsp;6b), temperature and geopotential anomalies over the ocean extend to the continent, where the trough axis is located northwest of the State of S\u0026atilde;o Paulo. It can be observed that the ES is in the front part of a baroclinic trough embedded in a synoptic-scale wave train. At upper levels (Fig.\u0026nbsp;6c), the abnormal change in wind direction south of the ES denotes the presence of the jet associated with the frontal system and, therefore, a condition of higher baroclinicity. Positive temperature anomalies at upper levels may indicate an anomalous lowering of the tropopause caused by the presence/intensification of low pressures (HIRSCHBERG and FRITSCH 1991). However, cold anomalies at upper levels indicate that the tropopause is located above that level, which is typical of a subtropical troposphere.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003eSimilar to the previous maps shown, the SACZ fields display at the surface (Fig.\u0026nbsp;\u003cspan refid=\"Fig7\" class=\"InternalRef\"\u003e7\u003c/span\u003ea) a cyclonic/anticyclonic disturbance positioned southwest/northeast, with more intense positive humidity anomalies (not shown), along with a relative maximum immediately east of the Andes up to northern Argentina, indicating the probable influence of Low-Level Jets in the occurrence of SACZ. The temperature and geopotential height fields at 500 hPa (Fig.\u0026nbsp;\u003cspan refid=\"Fig7\" class=\"InternalRef\"\u003e7\u003c/span\u003eb) appear displaced concerning the surface. The geopotential height gradient is intense but less than in the cases of cold fronts. At altitude (Fig.\u0026nbsp;\u003cspan refid=\"Fig7\" class=\"InternalRef\"\u003e7\u003c/span\u003ec), a maximum wind divergence is observed north of the ESS, although it is lower compared to frontal situations.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003eIn cases where troughs were identified, surface anomaly maps (Fig.\u0026nbsp;\u003cspan refid=\"Fig8\" class=\"InternalRef\"\u003e8\u003c/span\u003ea) display a broad, warm cyclonic anomaly in central-southern Brazil and neighboring countries, extending a small relative trough towards the ESS, visible from the curvature of the isobars. This situation reflects a cyclonic pattern with its center more to the south. The pattern observed at 500 hPa (Fig.\u0026nbsp;\u003cspan refid=\"Fig8\" class=\"InternalRef\"\u003e8\u003c/span\u003eb) corresponds to the surface fields, showing again a situation of low baroclinicity due to the limited lag between the surface and mid-level systems. The negative temperature anomalies at mid-levels contribute to an increase in thermodynamic instability. At upper levels (Fig.\u0026nbsp;\u003cspan refid=\"Fig8\" class=\"InternalRef\"\u003e8\u003c/span\u003ec), it is possible to observe again a maximum wind divergence over the ES but embedded in a general situation of weak and unremarkable anomalies, indicating a weak synoptic forcing. Nevertheless, the anomalous divergence at upper levels, promoting airlifting, combined with cold anomalies in the mid-troposphere, helps explain the occurrence of convective-type rainfall.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003eThrough the cyclone anomaly fields (Fig.\u0026nbsp;\u003cspan refid=\"Fig9\" class=\"InternalRef\"\u003e9\u003c/span\u003e), a surface low-pressure region with its center close to the ES can be identified (Fig.\u0026nbsp;\u003cspan refid=\"Fig9\" class=\"InternalRef\"\u003e9\u003c/span\u003ea). An anomalously warm environment is observed over the continent and the Atlantic Ocean, with abundant moisture (not shown), scarce baroclinicity in the context of the low-pressure center, weak southwest cold advection over the State of Rio de Janeiro, and the presence of an anomalous anticyclone over the Atlantic with a warm core and low baroclinicity, typical of blocking-type systems. The 500 hPa anomalies close to the surface anomalies indicate a barotropic character (Fig.\u0026nbsp;\u003cspan refid=\"Fig9\" class=\"InternalRef\"\u003e9\u003c/span\u003eb). The center of cyclonic vorticity can be seen in the altitude fields (Fig.\u0026nbsp;\u003cspan refid=\"Fig9\" class=\"InternalRef\"\u003e9\u003c/span\u003ec) through the rotation of the streamlines, positioned southeast of the ESS, remarkably close to the surface low.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec6\" class=\"Section2\"\u003e \u003ch2\u003e4.3 Previous days\u003c/h2\u003e \u003cp\u003eThe fields plotted in the days preceding the passage of the systems over the ES (not shown) already signal characteristics that can be identified at higher latitudes. In the 48 hours before the passage of Frontal Systems in the ES region, they can be identified from the already quite intense anomalies to the south. The cold front is located over Santa Catarina State and advances toward the north-central region of Bolivia, following the pattern discussed by Garreaud (\u003cspan citationid=\"CR11\" class=\"CitationRef\"\u003e2000\u003c/span\u003e). In the preceding 24 hours, the propagation of the baroclinic wave in the northeast direction is observed, with the advancement of negative thickness anomaly towards the continent, the intensification of positive anomaly over the SEB, and the strengthening of negative geopotential anomaly over the same region.\u003c/p\u003e \u003cp\u003eThe presence of a low-pressure center near the coast with an axis over the ES in cases of SACZ 48 hours before the disaster event is similar to frontal cases. However, a notable difference is that in the cases of SACZ, the axis of the anomalous trough is already in the vicinity of the ES two days before the disasters occur, which is consistent with this type of situation. A clear dipole in geopotential anomalies is observed over the Atlantic Ocean, with negative values at latitudes south of Brazil and positive values at high latitudes, indicating a situation of low zonal circulation index, typical of dipole blocking configurations, where a low-pressure system, when approaching a high-pressure system, becomes stationary or moves along the periphery of the high (CASARIN, 1982). At the mid-levels, the high and low-pressure systems appear almost in the same position as their counterparts at lower levels, indicating a relatively barotropic situation, which is similar to the findings of Seluchi and Chou (\u003cspan citationid=\"CR23\" class=\"CitationRef\"\u003e2009\u003c/span\u003e) and Escobar (\u003cspan citationid=\"CR6\" class=\"CitationRef\"\u003e2014\u003c/span\u003e).\u003c/p\u003e \u003cp\u003eThe composite fields of the hours preceding the occurrence of identified trough cases show, at the surface, an anomalous cold southeast advection over the SEB coast linked to a cold-core high-pressure system over the Atlantic Ocean. On the other hand, a wide area of negative pressure anomalies at the surface and positive temperature anomalies prevails over the central-north regions of Argentina, Paraguay, and Bolivia, most likely associated with the action of BC and BTO, accompanied by abnormally large amounts of moisture in the 850 hPa region. In the mid-levels, the presence of cold troughs and warm ridges suggests a thermal-type situation. A small region of negative temperature anomaly is noted over the ESS, and a small negative geopotential anomaly lies just southeast of the cold anomaly region over the SEB. At higher levels, wind divergence already presents relative maxima.\u003c/p\u003e \u003cp\u003eIn cases of cyclones, the fields corresponding to the 48 hours prior do not present significant differences compared to day 0, confirming a blocking pattern of the dipole type. There is a slight eastward displacement of the system, weakening of high-pressure anomalies over the Atlantic, and intensification of negative geopotential anomalies over the continent, along with increased moisture convergence. The moment of disaster coincides with the positioning of the cyclone axis at 500 hPa over the ESS, besides the presence of southeast winds at the surface associated with the maritime circulation.\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec7\" class=\"Section2\"\u003e \u003ch2\u003e4.4 - Disaster and non-disaster difference fields\u003c/h2\u003e \u003cp\u003eThe difference maps between disaster and non-disaster cases highlight the main characteristics of triggering systems, especially concerning their intensity. The main characteristics of these fields can be observed more clearly in the days leading up to the passage of the synoptic system. Figures\u0026nbsp;10, \u003cspan refid=\"Fig11\" class=\"InternalRef\"\u003e11\u003c/span\u003e, and \u003cspan refid=\"Fig12\" class=\"InternalRef\"\u003e12\u003c/span\u003e represent the State of the atmosphere two days before the occurrence was recorded.\u003c/p\u003e \u003cp\u003eFigure 10 displays the main characteristics that differentiate the fields of Frontal Systems associated with disasters from those not associated with disasters. Generally, it can be inferred that the fronts related to disasters in the ES correspond with more giant amplitude waves, as the cyclonic and anticyclonic anomalies are more pronounced (Fig.\u0026nbsp;10a). Additionally, a warm anticyclonic anomaly over the Atlantic Ocean is noteworthy. On the other hand, there is a bigger temperature contrast over subtropical latitudes compared to non-disaster-causing cold fronts. However, cold air is present before the frontal system's passage. It is also worth noting the presence of a comparatively warmer environment at high latitudes and with more available moisture in the atmosphere (not shown).\u003c/p\u003e \u003cp\u003eAt 500 hPa (Fig.\u0026nbsp;10b), there is a pre-existing blocking situation in the days prior, characterized by a warm (cold) anticyclonic (cyclonic) anomaly at high (subtropical) latitudes, which is \"broken\" by a transient cyclonic wave of larger amplitude compared to situations not linked to disasters. The presence of colder air in the previous days may also contribute to the intensification of thermodynamic instability.\u003c/p\u003e \u003cp\u003eIn the 300 hPa wind field (Fig.\u0026nbsp;10c), in addition to the presence of the barotropic anticyclonic system over the Atlantic Ocean, a more intense cyclonic anomaly is observed over the Northeast Region, probably associated with the presence of UTCV's characteristic of this region. Regarding cold fronts associated with disasters, these UTCVs, along with the mentioned anticyclonic system, allow for bigger divergence at upper levels near the ESS.\u003c/p\u003e \u003cp\u003eIn summary, cold front cases are associated with blocking situations in the preceding days that allow the advection of moist air from the east through the anticyclone and colder air at mid-levels. This blocking situation is 'interrupted' by the passage of more intense cold fronts (especially in the pressure/geopotential field), accompanied by a stronger mid-level trough and more significant divergence in the upper atmosphere over a convectively more unstable air mass.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003eOne factor to consider regarding the occurrence of SACZ is that only nineteen events not associated with disasters occurred during the study period, compared to thirty dates recorded in the S2ID that were related to the system's occurrence. This factor favors the interpretation that SACZ events, for the most part, are responsible for triggering disasters in the ES region. Additionally, due to its long duration, disasters may not necessarily occur on day zero (the day of the disaster).\u003c/p\u003e \u003cp\u003eThe difference fields between disaster and non-disaster events for SACZ at the surface also show a high-pressure system with warm characteristics over the extratropical Atlantic Ocean and a low-pressure system directly associated with SACZ further to the north (Fig.\u0026nbsp;\u003cspan refid=\"Fig11\" class=\"InternalRef\"\u003e11\u003c/span\u003ea). The passage of cyclonic disturbances at high latitudes does not interfere with the position of the systems mentioned above, which is consistent with a blocking pattern, as also found by Seluchi and Chou (\u003cspan citationid=\"CR23\" class=\"CitationRef\"\u003e2009\u003c/span\u003e). The thicker layer in disaster cases can be explained by the higher occurrence of these cases in summer compared to non-disaster cases.\u003c/p\u003e \u003cp\u003eThe 500 hPa fields in Fig.\u0026nbsp;\u003cspan refid=\"Fig11\" class=\"InternalRef\"\u003e11\u003c/span\u003eb show a more intense trough over the SEB, especially on day \u0026minus;\u0026thinsp;2, and a broad area of warm high pressures in the Pacific and Atlantic, similar to the SF cases, but with even more intense anticyclones over the oceans during SACZ events, indicating a situation of low zonal circulation index.\u003c/p\u003e \u003cp\u003eIn the altitude maps (Fig.\u0026nbsp;\u003cspan refid=\"Fig11\" class=\"InternalRef\"\u003e11\u003c/span\u003ec), it can be observed that the wind over subtropical latitudes shows differences from the east compared to non-disaster-associated cases, confirming a weaker zonal circulation associated with lower baroclinicity. The presence of UTCV over the eastern portion of the Northeast Region is responsible for a more significant divergence, working as a trigger for more voluminous rainfall.\u003c/p\u003e \u003cp\u003eIt can be observed that the cases of SACZ associated with disasters in the ES are linked to blocking situations, making them more prolonged. It is worth considering that disasters may result not only from a single day of rainfall but also from the gradual increase in soil moisture over multiple consecutive days. The trough/cyclone that \"anchors\" the SACZ is more intense in disaster cases, and the position of UTCV triggers more intense rainfall by increasing divergence at high levels.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003eGenerally, the troughs that cause disasters in the ES are related to the passage of more intense transient systems, as observed through the displacement of positive and negative centers over the Atlantic Ocean. Particularly noteworthy is a colder high-pressure system to the south of the ESS, likely of a post-frontal type (observed in Fig.\u0026nbsp;\u003cspan refid=\"Fig12\" class=\"InternalRef\"\u003e12\u003c/span\u003ea as the trough to the east of the high), generating intense cold maritime advection over the region. Additionally, there are thickness maximums and geopotential height minimums over Argentina, indicating the presence of more intense CL and TOL systems.\u003c/p\u003e \u003cp\u003eAt the 850 hPa level (not shown), there is a higher amount of moisture over the ES on all days. This moisture would result from the eastward circulation generated by the passage of a frontal system over the ocean and the subsequent entry of high pressure, which determines a circulation pattern that favors an increase in moisture over southern Brazil and neighboring countries. The presence of more intense CL and TOL systems, compared to non-disaster cases, contributes to the increased moisture over the La Plata region.\u003c/p\u003e \u003cp\u003eThe difference fields at the 500 hPa level (Fig.\u0026nbsp;\u003cspan refid=\"Fig12\" class=\"InternalRef\"\u003e12\u003c/span\u003eb) show that in cases associated with disasters, there are more intense transient waves. In the days prior, a colder trough moves south of the ESS, associated with the frontal system mentioned earlier. On day 0, a more intense ridge enters from the south of the continent, which modulates the circulation in the lower levels, favoring the transport of moisture. The rear part of the ridge and the subsequent entry of a relative trough favor the formation of low-pressure systems over western Argentina.\u003c/p\u003e \u003cp\u003eIn Fig.\u0026nbsp;\u003cspan refid=\"Fig12\" class=\"InternalRef\"\u003e12\u003c/span\u003ec, it is possible to identify the transient waves described in the 500 hPa field. In the days prior, the westerly component of wind is stronger, indicating a greater baroclinicity compared to cases not associated with disasters. That highlights the importance of the frontal system that moves over the ocean. Specifically, over the ESS, there is relatively more divergence in disaster cases.\u003c/p\u003e \u003cp\u003eTherefore, the troughs that cause disasters in the ES are characterized by higher humidity and instability, which allows for deducing the more convective nature of the precipitations. The higher humidity is associated with the persistence of oceanic circulation in the preceding days, related to the passage of a Frontal System and the subsequent entrance of a relatively intense post-frontal high (more intense than in cases not related to disasters), supported by the displacement of a higher-amplitude ridge over extratropical latitudes. The intensity of the ridge and the subsequent advancement of a trough through the western part of the continent favor the formation of CL and TOL that acquire significant amplitude and intensity, generating an area of low pressure over a large extent, contributing to the drop in pressure, including in the ESS, on the day of the disaster occurrence.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003eThe difference fields between disasters and non-disasters in the cases of cyclones were not included in this study, as the number of these events was small for comparative purposes.\u003c/p\u003e \u003c/div\u003e"},{"header":" Conclusions","content":"\u003cp\u003eDespite the wide range of studies on hydrometeorological disasters in Southeast Brazil, very few comprehensively address the State of Esp\u0026iacute;rito Santo. The State, composed almost entirely of small municipalities, is frequently impacted by disasters, including landslides, floods, and flash floods. This study aimed to identify the systems responsible for triggering intense precipitation events leading to disasters in ESS, as well as their main characteristics, focusing on analyzing synoptic patterns associated with the occurrences recorded in the S2ID database.\u003c/p\u003e\n\u003cp\u003eThe events that represented the highest number of occurrences, in decreasing order, were urban floods (37), followed by landslides (29), floods (24), and finally, debris flows (9). The total number of occurrences (99) is greater than the number of selected dates to compose the cases (85) because multiple incidents can be recorded in various cities daily.\u003c/p\u003e\n\u003cp\u003eThe identified cases were classified into the four types of systems found, and none of them were related to isolated convection cases. Most recorded incidents occurred during the summer (35) and spring (34). It was observed that the South Atlantic Convergence Zone (31) and the passage of Frontal Systems (32) over the region accounted for approximately 75% of the systems related to disasters caused by intense rainfall. Additionally, Troughs (18) and Cyclones (4) also contributed to such occurrences.\u003c/p\u003e\n\u003cp\u003eA common characteristic found in all occurrences was the presence of a cyclonic disturbance at the surface near Esp\u0026iacute;rito Santo, strong moisture advection, and upper-level wind divergence, attributes consistent with heavy rainfall. The disaster cases show more intense patterns compared to non-disaster cases.\u003c/p\u003e\n\u003cp\u003eThe specifics of each system can be summarized as follows:\u003c/p\u003e\n\u003cp\u003ea) Frontal systems associated with blocking situations in the preceding days, allowing the advection of moist air from the east through the anticyclone and colder air in the mid-levels. This blocking situation is \u0026quot;interrupted\u0026quot; by the passage of more intense cold fronts (especially in the pressure/geopotential fields) that extend widely (potentially reaching the southern Amazon region). These cold fronts are accompanied by a more intense trough in the mid-levels and more significant upper-level divergence over a convectively more unstable air mass. It is observed that the cold fronts that triggered disasters in Esp\u0026iacute;rito Santo mainly occurred during the summer, even though this is a typical winter system.\u003c/p\u003e\n\u003cp\u003eb) South Atlantic Convergence Zone with stronger eastward winds, associated with a low zonal circulation index, featuring an anomalous warm high-pressure system over the Atlantic and an intense low-pressure system further north. These systems are linked to a quasi-stationary barotropic pattern, typical of blocking situations, with extended durations and, consequently, a higher likelihood of triggering disasters. The positioning of the UTCV over the eastern coast of Northeast Brazil can act as a trigger for more intense rainfall due to increased upper-level divergence. It is worth noting that SACZ events, which mostly occur in the summer, are primarily responsible for causing disasters in Esp\u0026iacute;rito Santo.\u003c/p\u003e\n\u003cp\u003ec) Troughs accompanied by negative temperature anomalies in the mid-levels, with slow displacement and low baroclinicity, along with increased moisture and instability, associated with a more convective nature. The moisture is linked to cyclonic circulation present in the preceding days, explained by the passage of a frontal system and subsequent entry of a post-frontal high, more intense than in non-disaster cases, sustained by the displacement of a larger-amplitude ridge over extratropical latitudes. The strong influence of the CL and TOL over Northwestern Argentina is responsible for generating a widespread low-pressure area, influencing the ESS.\u003c/p\u003e\n\u003cp\u003ed) Cold-core cyclones with barotropic characteristics, featuring intense moisture and thickness advection, and a northward axis over Esp\u0026iacute;rito Santo, associated with a slow-moving blocking warm high-pressure system to the south, around 40\u0026ndash;45\u0026deg;S. The timing of the disasters seems to coincide with the positioning of the cyclone\u0026apos;s axis at 500 hPa over Esp\u0026iacute;rito Santo, in addition to the presence of southeasterly surface winds associated with the maritime circulation.\u003c/p\u003e\n\u003cp\u003eAdditionally, there was the influence of another factor, in most cases, playing a significant role in the formation of the analyzed systems. A blocking high-pressure system, under specific conditions related to each system, could be identified before the passage of Frontal Systems (when the passage of these intense fronts disrupts the situation), also positioned south of the SACZ, contributing to the increased persistence of these events and south of barotropic structured cyclones.\u003c/p\u003e\n\u003cp\u003eThe synoptic patterns identified in each group of cases can generally be predicted at least 48 hours before reaching Esp\u0026iacute;rito Santo, given the higher intensity of these systems even from higher latitudes in the preceding days.\u003c/p\u003e"},{"header":"Declarations","content":"\u003cp\u003eAcknowledgements\u003c/p\u003e\n\u003cp\u003eThe research leading to these results received funding from Coordena\u0026ccedil;\u0026atilde;o de Aperfei\u0026ccedil;oamento de Pessoal de N\u0026iacute;vel Superior - Brasil (CAPES) - Finance Code 001.\u003c/p\u003e\n\u003cp\u003eDeclaration of exclusivity\u003c/p\u003e\n\u003cp\u003eI declare that this work has not been previously published, neither in English nor in any other language, ensuring its exclusivity\u003c/p\u003e"},{"header":"References","content":"\u003col\u003e\u003cli\u003e\u003cspan\u003eAguiar LF, Cataldi M (2021) Social and environmental vulnerability in Southeast Brazil associated with the South Atlantic Convergence Zone. 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Heavy rainfall. Synoptic characterization","lastPublishedDoi":"10.21203/rs.3.rs-3851739/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-3851739/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003cp\u003eDespite the large amount of research about hydrometeorological disasters in southern Brazil, only a tiny part covers the State of Esp\u0026iacute;rito Santo. The State is frequently affected by disasters of this nature. Therefore, this work aims to determine and characterize the types of synoptic systems that produce heavy rainfall and cause disasters in ES. Between 2013 and 2021, the S2ID database, synoptic charts from CPTEC, images from GOES 13 and 16 satellites, and precipitation data from INMET were used to select the dates and characterize the meteorological situation. Additionally, the ERA5 reanalysis was used for the construction of composite. It was found that disasters that affect ES occur mainly during the summer, which agrees with a thermodynamically more unstable atmosphere. The main systems identified can be described as follows: 1- Intense Frontal Systems related to blocking configuration in previous days that allow humid air advection from the Atlantic Ocean, through the presence of an anticyclone together with colder air at medium levels; 2- SACZ related to a warm anomalous anticyclone in the Atlantic and an intense low-pressure center located to the north, also showing a blocking pattern; 3- Troughs with slow displacement and low baroclinicity associated with high convective instability, acting as an extension of the Chaco Low and Thermo-Orographic Low, and 4- Cold core Cyclones with barotropic characteristics, located over ES, linked to warm blocking anticyclones, positioned south of about 40\u0026ndash;45\u0026deg;S. In general, these patterns could be identified at least 48 hours in advance, observing disturbances at higher latitudes.\u003c/p\u003e","manuscriptTitle":"Characterization of Synoptic Systems Triggering Disasters in the State of Espírito Santo, Brazil","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2024-02-22 21:18:50","doi":"10.21203/rs.3.rs-3851739/v1","editorialEvents":[{"type":"communityComments","content":0},{"type":"decision","content":"Major revisions","date":"2025-01-26T22:55:34+00:00","index":"","fulltext":""},{"type":"reviewerAgreed","content":"","date":"2024-03-23T15:36:07+00:00","index":0,"fulltext":""},{"type":"reviewersInvited","content":"","date":"2024-02-19T23:09:23+00:00","index":"","fulltext":""},{"type":"editorAssigned","content":"","date":"2024-01-10T12:17:39+00:00","index":"","fulltext":""},{"type":"submitted","content":"Natural Hazards","date":"2024-01-09T15:40:40+00:00","index":"","fulltext":""}],"status":"published","journal":{"display":true,"email":"[email protected]","identity":"natural-hazards","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"nhaz","sideBox":"Learn more about [Natural Hazards](https://www.springer.com/journal/11069)","snPcode":"11069","submissionUrl":"https://submission.nature.com/new-submission/11069/3","title":"Natural Hazards","twitterHandle":"","acdcEnabled":true,"dfaEnabled":true,"editorialSystem":"em","reportingPortfolio":"Springer Hybrid","inReviewEnabled":true,"inReviewRevisionsEnabled":false}}],"origin":"","ownerIdentity":"5f64cfde-820a-4c00-910b-fcf804747243","owner":[],"postedDate":"February 22nd, 2024","published":true,"recentEditorialEvents":[],"rejectedJournal":[],"revision":"","amendment":"","status":"published-in-journal","subjectAreas":[],"tags":[],"updatedAt":"2025-05-12T16:09:44+00:00","versionOfRecord":{"articleIdentity":"rs-3851739","link":"https://doi.org/10.1007/s11069-025-07307-y","journal":{"identity":"natural-hazards","isVorOnly":false,"title":"Natural Hazards"},"publishedOn":"2025-05-06 15:57:47","publishedOnDateReadable":"May 6th, 2025"},"versionCreatedAt":"2024-02-22 21:18:50","video":"","vorDoi":"10.1007/s11069-025-07307-y","vorDoiUrl":"https://doi.org/10.1007/s11069-025-07307-y","workflowStages":[]},"version":"v1","identity":"rs-3851739","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-3851739","identity":"rs-3851739","version":["v1"]},"buildId":"qtupq5eGEP_6zYnWcrvyt","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}