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dc.contributor.author Garcia, Carlos Alberto Eiras
dc.contributor.author Garcia, Virginia Maria Tavano
dc.date.accessioned 2013-09-24T19:26:03Z
dc.date.available 2013-09-24T19:26:03Z
dc.date.issued 2008
dc.identifier.citation GARCIA, Carlos Alberto Eiras; GARCIA, Virginia Maria Tavano. Variability of chlorophyll-a from ocean color images in the La Plata continental shelf region. Continental Shelf Research, n. 28, p.1568-1578, 2008. Disponível em: <http://www.sciencedirect.com/science/article/pii/S0278434308000952>. Acesso em: 27 jul. 2012 pt_BR
dc.identifier.uri http://repositorio.furg.br/handle/1/3869
dc.description.abstract Satellite-derived chlorophyll-a fields have been used to investigate temporal and spatial variability of chlorophyll-a concentration over the continental shelf zone (25–401S and 60–451W) close to the La Plata River estuary. Ocean color data used in this study were obtained by the Sea-viewing Wide Field-of- view Sensor (SeaWiFS) and consisted of 368 weekly averaged Standard Mapped Images (SMI), from October 1997 to September 2005. Fourier harmonic and EOF analyses were used to study the variability of log-transformed chlorophyll-a concentration in the region. The harmonic analysis has shown that the annual cycle was the most dominant signal followed by the semi- and quadri-annual cycles, in certain areas. The strong annual cycle is mainly present in latitudes lower than 341S where relatively high amplitudes ($1.9 mg mÀ3) in pigment variation are seen over the southern Brazilian continental shelf. The semi-annual cycle is mainly associated with the Brazil–Malvinas frontal zone oscillation while the ̃ 4-year signal is related to positive La Plata discharge anomalies influenced by El Nino events. After removing the annual signal from the log-transformed chlorophyll anomalies, the EOF results showed that the first three modes captured 85.1% of the variability associated with the regional mean phytoplankton chlorophyll pattern in our smoothed data set. The first three modes explained, respectively, 63.4%, 14.1% and 7.6%. The EOF results showed that the long-term chlorophyll time/space patterns are associated with both La Plata discharge anomaly (mode 1) and alongshore wind stress (mode 2). A reconstruction of the chlorophyll anomaly fields has been made using the two leading EOF modes over two periods of high La Plata River discharge, during ENSO events. In the first event, the spatial patterns of high chlorophyll anomaly were confined to the southern portion of the region, associated with NE winds, which push the plume near the estuary mouth. The second period revealed an elongated tongue of positive chlorophyll anomalies over the Uruguayan and Brazilian middle continental shelves, associated with favorable SW winds. The analyses performed in this study allowed identification of the main modes of variability in SeaWiFS-derived chlorophyll in the region, which were consistent with modulations of important regional environmental forcing mechanisms. pt_BR
dc.language.iso eng pt_BR
dc.rights restrict access pt_BR
dc.subject Chlorophyll pt_BR
dc.subject SeaWiFS pt_BR
dc.subject Continental shelf pt_BR
dc.subject Harmonic series pt_BR
dc.subject EOF pt_BR
dc.subject ENSO pt_BR
dc.subject Southwestern Atlantic pt_BR
dc.subject La Plata River pt_BR
dc.title Variability of chlorophyll-a from ocean color images in the La Plata continental shelf region pt_BR
dc.type article pt_BR
dc.identifier.doi 10.1016/j.csr.2007.08.010 pt_BR


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