Optical Classification of Lower Amazon Waters Based on In Situ Data and Sentinel-3 Ocean and Land Color Instrument Imagery

Autor(es)

Valerio, Aline de M. ^[1] ; Kampel, Milton ^[1] ; Vantrepotte, Vincent ^[2] ; Ward, Nicholas D. ^{[3, 4]} ; Richey, Jeffrey E. ^[4]

Afiliação do(s) autor(es)

^[1] Natl Inst Space Res INPE, Earth Observat & Geoinformat Div, BR-12227010 Sao Jose Dos Campos, SP - Brazil

^[2] Univ Littoral Cote dOpale, CNRS, Lab Oceanol & Geosci LOG, UMR 8187, F-59000 Lille - France

^[3] Pacific Northwest Natl Lab PNNL, Marine & Coastal Res Lab, Sequim, WA 99354 - USA

^[4] Univ Washington UW, Sch Oceanog, Seattle, WA 98195 - USA

• Tipo de documento: Artigo Científico
• Fonte: REMOTE SENSING; v. 13, n. 16 AUG 2021.
• Citações Web of Science: 0

Resumo

Optical water types (OWTs) were identified from an in situ dataset of concomitant biogeochemical and optical parameters acquired in the Amazon River and its tributaries, in the Lower Amazon region, at different hydrological conditions from 2014 to 2017. A seasonal bio-optical characterization was performed. The k-means classification was applied to the in situ normalized reflectance spectra (rn(lambda)), allowing the identification of four OWTs. An optical index method was also applied to the rn(lambda) defining the thresholds of the OWTs. Next, level-3 Sentinel-3 Ocean and Land Color Instrument images representative of the seasonal discharge conditions were classified using the identified in situ OWTs as reference. The differences between Amazon River and clearwater tributary OWTs were dependent on the hydrological dynamics of the Amazon River, also showing a strong seasonal variability. Each OWT was associated with a specific bio-optical and biogeochemical environment assessed from the corresponding absorption coefficient values of colored dissolved organic matter (a(CDOM)) and particulate matter (a(p)), chlorophyll-a and suspended particulate matter (SPM) concentrations, and a(CDOM)/a(p) ratio. The rising water season presented a unique OWT with high SPM concentration and high relative contribution of a(p) to total absorption compared to the other OWTs. This bio-optical characterization of Lower Amazon River waters represents a first step for developing remote sensing inversion models adjusted to the optical complexity of this region. (AU)

• 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