Spatial and Temporal Changes of Aridity in Argentina and its Relationship with Some Oceanic-Atmospheric Teleconnection Patterns

Abstract This paper analyzes spatial and temporal changes of aridity in Argentina (1961–2018). The aridity degree, using CRU monthly data, was defined through six climate types classified by De Martonne Aridity Index (DMI). Argentina presents a very arid, arid and semiarid region that extends from Puna to Patagonia, alongside two humid and very humid regions: one located in the Chaco-Pampas Plains and Mesopotamia, and another in the Patagonian Andes. Between these regions, there are subhumid areas with marked aridity variations. These structures persist over time, but in their bordering areas advances or setbacks were observed, with major changes in the Andes (more arid conditions) and Buenos Aires southwest (more humid conditions) during the historical period. The contribution of temperature and precipitation changes to these DMI changes was quantified, indicating that precipitation modulated the DMI spatial changes, while temperature intensified or weakened the magnitudes of these changes. The extension variations of the arid and semiarid regions in Argentina were related to three climate variability modes (El Niño – Southern Oscillation [ENSO], Pacific Decadal Oscillation [PDO] and South Atlantic Ocean Dipole [SAOD]). Significant correlations were found with PDO (r  0), which indicate that an increase in the area occupied by arid and semiarid climates are associated with PDO negative phase or SAOD positive phase. Moreover, when these phases occur simultaneously, the expansion of arid and semiarid regions is larger than under the action of an individual forcing.