Variação interanual e sazonal das massas d’água sobre a Plataforma Continental Norte do Brasil

Abstract

This study aimed to analyze the spatial and temporal variability of water masses over the Northern Continental Shelf of Brazil (PCNB), relating it to local dynamics and freshwater inputs. The PCNB extends from Cape Orange to the Bay of São Marcos and is characterized as highly energetic, due to the combined action of the north current of Brazil (CNB), trade winds, waves, tides and the water discharge from the Amazon rivers and Pará. Temperature, salinity and density data for the interannual analysis were obtained from the Brazilian Navy's national database (BNDO), during six oceanographic cruises: Amasseds I, II and III, North Ocean I, MCT VII and CBO in different years: 1989, 1990, 2001, 2016 and for the seasonal analysis, five months of the Costa Norte Project were used: March, July, November, December 2018 and January 2019. The TS parameters were intended to characterize and identify the water masses that occurred on the platform over the years, as well as observe the existing interannual and seasonal variability. The PCNB showed large variations in TS over the years and periods analyzed, and it is possible to observe the occurrence of four types of water bodies interannually: Pluma Estuarina (PE), Coastal Water (AC), Central Water of the South Atlantic (ACAS) and Tropical Water (AT) and seasonally, five water bodies were identified as occurring: AF (front water), AC, AT, ACAS and Pluma etuarina (PE). From the analysis of the TS diagrams it was possible to identify a thermohaline index for the estuarine plume and its metrics over time, where it occurred in March - 2018 and January - 2019, and their respective thermohaline indices were 27.5 °C to 28 °C and 0 g/kg to 33 g/kg.