Assinatura térmica da pluma do Rio Zambeze avaliada por sensoriamento remoto

Abstract

In this study, the thermal signature of the Zambeze River plume in the Sofala Bank was analyzed using daily Brightness Temperature (BT) images from the SLSTR sensor (S9 channel) onboard the Sentinel-3 satellite, between 2020 and 2024. Threshold analysis indicated that BT = 21.6 °C yielded the highest coefficient of determination (R² = 0.35), representing the most suitable threshold to delineate the plume’s spatial extent. The relationship between plume area, considering this threshold, and river discharge showed a moderate coefficient of determination (R² = 0.31), indicating that discharge only partially explains the observed variability. The images revealed three dominant morphological patterns: rounded plumes or with bulges, associated with intense offshore dispersion; elongated plumes confined to the coast; and intermediate forms modulated by mesoscale eddies and coastal currents. Limitations in cloud coverage restricted sampling during certain periods. The results demonstrate that, although SLSTR BT is effective for mapping the plume, its spatial and temporal dynamics are strongly modulated by the interaction of river discharge, winds, currents, and mesoscale structures, highlighting the need to integrate oceanographic data and numerical modeling for a robust understanding of fluvial and oceanic dynamics.