Seasonality of the Agulhas Front's Position and Intensity based on a ‘range-gratitude’ method

Abstract Understanding the dynamics of the chlorophyll-a concentration (CC) along the oceanic front is crucial for predicting oceanic productivity and carbon sequestration capacity. This study proposes a 'range-gradient' methodology to investigate the seasonality of Agulhas Front (AF) using both sea surface temperature (SST) and CC data obtained from Moderate Resolution Imaging Spectroradiometer (MODIS) sensor. Result reveals that the spatial distribution of the CC-defined AF and SST-defined AF exhibits consistency. The position of AF is around 40°S from December to May, and the intensity of AF dwindles with isothermal southward shift. During June-July-August (JJA) the AF migrates north and intensifies, accompanied with maximum SST gradient. However, the meridional CC gradient peaks during September-October-November (SON). Such intensified meridional CC gradient is fueled by southward sunlight condition, northward sea surface currents and nutrient-rich upwelling. Thus, this study underscores the complex interplay of solar insolation and marine ecological dynamics in shaping the seasonal behavior of the AF.