Spatiotemporal variability of chlorophyll-a concentration in the South Brazil Bight using 25 years of multi-sensor orbital data (1998-2022)

Cardoso Dos Santos, João Felipe; Kampel, Milton; Vantrepotte, Vincent

doi:10.3389/frsen.2025.1544375

ORIGINAL RESEARCH article

Front. Remote Sens.

Sec. Remote Sensing Time Series Analysis

Volume 6 - 2025 | doi: 10.3389/frsen.2025.1544375

This article is part of the Research Topic Trends and Techniques in Ocean Color Remote Sensing: A Time Series Analysis View all articles

Spatiotemporal variability of chlorophyll-a concentration in the South Brazil Bight using 25 years of multi-sensor orbital data (1998-2022)

Provisionally accepted

João Felipe Cardoso Dos Santos ^1*

Milton Kampel ^1*

Vincent Vantrepotte ²

¹ National Institute of Space Research (INPE), São José dos Campos, Brazil
² UMR8187 Laboratoire d'océanologie et de géosciences (LOG), Wimereux, Nord-Pas-de-Calais, France

The final, formatted version of the article will be published soon.

Chlorophyll-a (Chl-a) concentration is a key climate variable, as its variability is associated with meteorological and oceanographic processes. This study analyzed 25 years of Chl-a data from the ESA OC-CCI multi-sensor archive for the South Brazil Bight. Temporal variability and trends were assessed using the Census X11 method, Mann-Kendall, and Sen's slope tests. The OC-CCI data highlight reliable regional performance, although Chl-a concentrations above 10 mg.m^-3 were underestimated. Temporal analyses showed the lowest Chl-a variability (29%) in open ocean waters, with 81% of the variability attributed to seasonal dynamics influenced by the South Atlantic Subtropical Gyre (SASG). A negative Chl-a trend of -11.0% was observed over the 25-year period, attributed to the expansion of the oligotrophic area of the SASG. In the shelf areas southwest of São Sebastião Island, Chl-a variability was moderate (34-39%), with no discernible long-term trend, but significant interannual variability (44%). The Cabo Frio upwelling region shows an increasing Chl-a trend (14.5% in the last 25 years), driven by atmospheric circulation affecting local winds. The highest Chl-a variability (74%) occurred along the southern continental shelf, associated with seasonal nutrient inputs from the Subtropical Shelf Front, with a Chla-a trend increase of 7.5% in 25 years. These results highlight the dynamic and variable Chl-a responses to environmental forcing across the South Brazil Bight.

Keywords: chlorophyll-a, Ocean Color, multi-sensor product, time series analysis, South Brazil Bight

Received: 12 Dec 2024; Accepted: 12 Feb 2025.

Copyright: © 2025 Cardoso Dos Santos, Kampel and Vantrepotte. This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) or licensor are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms.

* Correspondence:
João Felipe Cardoso Dos Santos, National Institute of Space Research (INPE), São José dos Campos, Brazil
Milton Kampel, National Institute of Space Research (INPE), São José dos Campos, Brazil

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