Mês: maio 2021

Foi publicado em maio de 2021 o relatório completo do TAOS (Tropical Atlantic Observing System) que teve entre seus autores principais o prof. Moacyr Araujo, coordenador do do GT3.0 (Variabilidade climática, ciclos biogeoquímicos e fluxo de CO2 no oceano Atlântico tropical) do inctAmbtropic. O relatório resume os resultados de duas oficinas realizadas e discussões subsequentes do comitê revisor, incluindo contribuições de outros membros da comunidade de pesquisadores que atuam no Atlântico Tropical (você pode fazer o “download”do relatório ao final desta postagem).

Abaixo alguns trechos do Resumo Executivo:

“The tropical Atlantic is the smallest of Earth’s tropical ocean basins, one half the width, west to east, of the tropical Indian Ocean and less than one fifth that of the tropical Pacific. Thus, the tropical Atlantic interacts intimately with its bordering lands, strongly influencing their weather and climates, and it is readily accessible by the region’s inhabitants. At the same time, the tropical Atlantic plays an outsized role in the global climate system. Through the Atlantic Meridional Overturning Circulation (AMOC), it delivers nearly half a petawatt of energy from the Southern to the Northern Hemisphere, and it has marked, if still not fully understood, impacts on globally significant variations in the tropical Indian and Pacific Oceans”

“All countries bordering the tropical Atlantic experience important societal challenges driven by regional ocean processes and air-sea-land interactions. These are exacerbated by climate change, which induces new emerging threats. Examples include floods and droughts in South America and West Africa, more intense storms and hurricanes, and continuing sea-level rise that increases flooding risks and episodes of coastal erosion. Other regional emerging extreme events such as ocean heat-waves and episodes of anoxia and acidification amplify the vulnerabilities of regional marine ecosystems – systems already stressed by overfishing and pollution. Moreover, recent studies show that the tropical Atlantic has two-way connections with the Pacific and appears to play a driver role in mid- and high-latitude climatic events including the occurrence of impactful mid-latitude extremes throughout the year)”.

“The present TAOS review comes at an inflexion point for the tropical Atlantic, where scientific progress, demands on its resources, and environmental changes resulting from local and global stressors simultaneously are accelerating. At this juncture, there are great rewards to be reaped from an enhanced and invigorated TAOS, rationally planned and responsibly governed and coordinated. This report offers the rationale and the strategy for achieving a TAOS that will be well suited to serve the societal and scientific needs of the Atlantic basin and the globe over the coming decades. The recommended enhancements to the observing system across the range of platforms, with their associated sampling timescales, variables measured, and ranges of depths is expected lead to improved forecasts and projections of phenomena ranging from daily weather, fisheries and coastal managements, to anthropogenic climate change over multiple decades”.

O GT3.0 (Variabilidade Climática, Ciclos Biogeoquímicos e Fluxo de CO2 no Oceano Atlântico Tropical) publicou em abril de 2021 um novo artigo na Frontiers in Marine Science (IF: 3.661) intitulado “Surface Circulation and Vertical Structure of Upper Ocean Variability Around Fernando de Noronha Archipelago and Rocas Atoll During Spring 2015 and Fall 2017″ de autoria de Alex Costa da Silva, Alexis Chaigneau, Alina N. Dossa, Gerard Eldin, Moacyr Araujo e Arnaud Bertrand

ABSTRACT

Using current, hydrographic and satellite observations collected off Northeast Brazil around the Fernando de Noronha Archipelago and Rocas Atoll during two oceanographic cruises (spring 2015 and fall 2017), we investigated the general oceanic circulation and its modifications induced by the islands. In spring 2015, the area was characterized by lower SST (26.6◦C) and deep mixed-layer (∼90 m). At this depth, a strong current shear was observed between the central branch of the eastward flowing near-surface South Equatorial Current and the westward flowing South Equatorial Undercurrent. In contrast, in fall 2017, SST was higher (∼28.8◦C) and the mixed-layer shallower (∼50 m). The shear between the central South Equatorial Current and the South Equatorial Undercurrent was weaker during this period. Interestingly, no oxygen- rich water from the south (retroflection of the North Brazil undercurrent) was observed in the region in fall 2017. In contrast, we revealed the presence of an oxygen-rich water entrained by the South Equatorial Undercurrent reaching Rocas Atoll in spring 2015. Beside these global patterns, island wake effects were noted. The presence of islands, in particular Fernando de Noronha, strongly perturbs central South Equatorial Current and South Equatorial Undercurrent features, with an upstream core splitting and a reorganization of single current core structures downstream of the islands. Near islands, flow disturbances impact the thermohaline structure and biogeochemistry, with a negative anomaly in temperature (−1.3◦C) and salinity (−0.15) between 200 and 400 m depth in the southeast side of Fernando Noronha (station 5), where the fluorescence peak (>1.0 mg m−3) was shallower than at other stations located around Fernando de Noronha, reinforcing the influence of flow-topography. Satellite maps of sea- surface temperature and chlorophyll-a confirmed the presence of several submesoscale features in the study region. Altimetry data suggested the presence of a cyclonic

O artigo foi acessado no formato “Open Access”e pode ser acessado no seguinte “link”: https://doi.org/10.3389/fmars.2021.598101