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Chlorophyll-a dynamics in the lower Amazon River: insights from in situ and hyperspectral remote sensing using OCI-PACE

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Autor(es):
De Matos Valerio, Aline ; Montanari, Joao L. ; Kampel, Milton ; Ward, Nicholas D. ; Richey, Jeffrey E. ; Cunha, Alan C.
Número total de Autores: 6
Tipo de documento: Artigo Científico
Fonte: International Journal of Remote Sensing; v. 47, n. 1, p. 26-pg., 2025-12-08.
Resumo

Chlorophyll-a concentration (Chla) is a key indicator of phytoplankton biomass and aquatic trophic status. However, satellite-derived Chla in sediment-rich waters, such as those found in the Lower Amazon River, remains challenging. The present study characterizes in situ Chla levels and their relationships with geographic, physical, and biogeochemical parameters in the Lower Amazon. Data collected between 2014 and 2017 across four hydrological seasons included measurements of Chla, remote sensing reflectance, and water quality parameters such as total suspended sediment, conductivity, water surface temperature, dissolved oxygen, pH, dissolved organic carbon and coloured dissolved organic matter. An empirical model was developed to estimate Chla using simulated hyperspectral bands from NASA's PACE mission, achieving high performance (R2 = 0.76; RMSE = 0.11 mu g<middle dot>L-1). Red bands proved particularly effective for Chla retrieval, while the addition of ultraviolet bands further enhanced model accuracy. The application of the developed model to satellite imagery yielded results consistent with in situ observations for the same hydrologic season. Seasonal variation and geographic location were major factors influencing Chla dynamics. This study provides a novel contribution to Chla estimation in optically complex, highly turbid waters and highlights the potential of the PACE mission to enhance global aquatic ecosystem monitoring. By offering freely available hyperspectral data with high radiometric resolution, PACE represents a significant advancement in the realm of remote sensing of aquatic environments. (AU)

Processo FAPESP: 20/08148-0 - Variabilidade espaço-temporal do pCO2 no Rio Amazonas por sensoriamento remoto da cor da água: do rio à pluma
Beneficiário:Aline de Matos Valerio
Modalidade de apoio: Bolsas no Brasil - Pós-Doutorado
Processo FAPESP: 12/51187-0 - Trocas líquidas do ecossistema baixo Rio Amazonas: da terra para o oceano e atmosfera
Beneficiário:Jeffrey Edward Richey
Modalidade de apoio: Auxílio à Pesquisa - Programa de Pesquisa sobre Mudanças Climáticas Globais - SPEC
Processo FAPESP: 18/18491-4 - Pontos cegos biogeoquímicos ao longo do continuum do baixo Rio Amazonas: da terra para a atmosfera e oceano
Beneficiário:Jeffrey Edward Richey
Modalidade de apoio: Auxílio à Pesquisa - Programa SPEC
Processo FAPESP: 21/04128-8 - Caracterização da evolução da qualidade biogeoquímica das águas costeiras brasileiras nas últimas duas décadas a partir da observação de satélites: impacto de forçantes naturais e antrópicas
Beneficiário:Milton Kampel
Modalidade de apoio: Auxílio à Pesquisa - Regular