Estudo de distribuição de massas de Água na Cordilheira de Moçambique – observações feitas durante o cruzeiro conjunto entre China e Mozambique (Oceano Indico)

Abstract

The Mozambique Channel plays a fundamental role in the exchange of water masses between the Indian and Atlantic Oceans, reflecting a complex interaction among mixing processes, thermohaline circulation, eddies, and the influence of local topography. These interactions modulate the physical and chemical characteristics of the water masses according to their origin and depth. This study aimed to identify and describe the water masses present in the Mozridge region, contributing to the implementation of strategies for sustainable management of marine resources. The analysis was based on data collected during the Joint China–Mozambique Cruise (CJCM_II), conducted from 1 to 22 June 2021. Water masses were identified through thermohaline analysis and T–S diagrams, complemented by vertical sections of temperature, salinity and dissolved oxygen, which allowed the characterization of the vertical structure and stratification patterns in the region. Eight (8) water masses were identified in the Mozridge area, namely: Tropical Surface Water (TSW), Subtropical Surface Water (STSW), Antarctic Intermediate Water (AAIW), Red Sea Water (RSW), North Atlantic Deep Water (NADW), Indian Deep Water (IDW), Antarctic Bottom Water (AABW) and Australian Mediterranean Water (AAMW). The surface waters, warmer and well oxygenated, exhibited a dissolved oxygen peak ranging between 6.5 mg/l and 8.5 mg/l, and prevailed in the upper ~200 m layer. Below this depth, a progressive decrease in temperature, salinity and dissolved oxygen was observed, reflecting the presence of intermediate and deep water masses. Vertical sections also showed that surface waters are well oxygenated due to direct interaction with the atmosphere. Overall, the occurrence and distribution of water masses differ as a result of the complex processes involved in their formation and circulation.