Interacção da pluma do Rio Zambeze com os ciclones tropicais durante a aterrissagem na Costa de Moçambique

Abstract

This study analyzed the interaction between the Zambezi River plume and tropical cyclones during landfall on the coast of Mozambique, with the main objective of understanding the impact of the Zambezi River plume on tropical cyclones that landfall in Mozambique. The study was conducted in the Mozambique Channel and used salinity and sea surface temperature data, as well as historical data on cyclonic events, with emphasis on trajectory and wind speed, from the last 16 years, from 2008 to 2023. The delimitation of the Zambezi River plume was through the calculation of the salinity anomaly. The results indicate that of the 229 cyclonic events formed in the Southwest Indian Ocean, 41 entered the Channel and 17 made landfall on the coast of Mozambique. The seasonal distribution highlights the period from January to March as the period of greatest landfall of events on the Mozambican coast, with the central region of the country being the preferred location for landfall of cyclonic events. The coincidences between the periods of greatest plume extension and greatest cyclonic activity show that the Zambezi River plume can influence such preferences. The analysis of sea surface temperature showed distinct responses inside and outside the plume area. Points outside the plume experienced a rapid decrease, while at points inside the plume, the barrier layer induced by the plume provided high resistance to the decrease in sea surface temperature. The analysis of the interaction of the Zambezi River plume with tropical cyclones that made landfall on the Mozambican coast showed that tropical cyclones increase in intensity when interacting with the plume. The results also show the existence of a high linear and directly proportional relationship between the salinity anomaly and the intensity of cyclones passing through the region, with a correlation coefficient of approximately 0.85, evidencing the significant contribution of the Zambezi River plume to the variation in the intensity of tropical cyclones that land on the coast of Mozambique.