Space-time variability of the Amazon River plume based on satellite ocean color |
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| Authors: | Gustavo SF Molleri Evlyn MLde M Novo Milton Kampel |
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| Institution: | 1. Department of Atmospheric and Oceanic Science, University of Maryland, College Park, MD, USA;2. Laboratoire d''Océanographie et de Climatologie par Expérimentation et Analyse Numérique, Institut Pierre Simon Laplace, CNRS/UPMC/IRD/MNHN, Paris, France;3. University of Maryland Center for Environmental Science, Horn Point Laboratory, Cambridge, MD, USA;1. Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA, USA;2. National Oceanography Centre, Southampton, UK;3. Institut de Ciències del Mar, CSIC, Barcelona, Spain;4. University of Warsaw, Warsaw, Poland;1. CNRM, UMR 3589, Météo-France & CNRS, Toulouse, France;2. CNRS, Ifremer, IRD, UBO / Laboratoire d’Océanographie Physique et Spatiale (LOPS), IUEM, Plouzané UMR 6523, France;3. Department of Physical and Chemical Sciences, University of L’Aquila, L’Aquila, Italy;4. Aix Marseille Univ., Université de Toulon, CNRS, IRD, MIO UM 110, Antenne de la Seyne, 83500, La Seyne, France;5. Centre de Météorologie Spatiale, Météo-France, Lannion, France;1. School of Oceanography, University of Washington, Box 355351, Seattle, WA, USA;2. Centro de Energia Nuclear na Agricultura, Universidade de São Paulo, Av. Centenário, 303, Piracicaba, SP 13400-970, Brazil;3. Departamento de Meio Ambiente e Desenvolvimento, Universidade Federal do Amapá, Rodovia Juscelino Kubitschek, KM 02, 68902-280 Macapá, AP, Brazil;4. Universidade Federal do Oeste do Pará, 68035-110 Santarém, PA, Brazil;5. Department of Marine Sciences, University of Georgia, Athens, GA 30602-3636, USA |
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| Abstract: | Satellite ocean color images were used to determine the space-time variability of the Amazon River plume from 2000–2004. The relationship between sea-surface salinity (SSS) and the Sea-viewing Wide Field-of-view Sensor (SeaWiFS) absorption coefficient for dissolved and detrital material (adg) (r2=0.76, n=30, rmse=0.4) was used to identify the Amazon River plume low-salinity waters (<34 psu). The plume's spatial information was extracted from satellite bi-weekly time series using two metrics: plume area and plume shape. These metrics identified the seasonal variability of plume dimensions and dispersion patterns. During the study period, the plume showed the largest areas from July to August and the smallest from December to January. The mean annual amplitude and the mean, maximum and minimum plume areas were 1020×103 km2, 680×103 km2, 1506×103 km2 and 268×103 km2, respectively. Three main shapes and dispersion pattern periods were identified: (1) flow to the northeastern South American coast, in a narrow band adjacent to the continental shelf, from January to April; (2) flow to the Caribbean region, from April to July; and (3) flow to the Central Equatorial Atlantic Ocean, from August to December. Cross-correlation techniques were used to quantify the relationship between the plume's spatial variability and environmental forcing factors, including Amazon River discharge, wind field and ocean currents. The results showed that (1) river discharge is the main factor influencing plume area variability, (2) the wind field regulates the plume's northwestward flow velocity and residence time near the river mouth, and (3) surface currents have a strong influence over river plume dispersion patterns. |
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