Evolution of Physical and Biological Patterns Along the Tropical and South Atlantic Western Boundary: A Satellite Perspective

We investigate the spatial and temporal patterns of satellite‐derived sea surface temperature, salinity and chlorophyll‐a concentration along the eastern South American coast. Two decade‐long time series (2002–2019; except for the salinity) allowed us to investigate changes from seasonal to interann...

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Bibliographic Details
Published in:Journal of geophysical research. Oceans 2022-03, Vol.127 (3), p.n/a
Main Authors: Pacheco, Mariana M., Polito, Paulo S., Sato, Olga T., Rocha, Maurício R.
Format: Article
Language:English
Subjects:
Arrays
Chlorophyll
Chlorophyll a
Circulation patterns
Climate
Climatic indexes
Coastal circulation
Coastal currents
Coastal zone
Coasts
Correlation
Geophysics
Isobaths
Methodology
Ocean circulation
Ocean circulation patterns
Ocean currents
Oceans
Properties
River discharge
River flow
Rivers
Salinity
Salinity effects
Satellite data
Satellites
Sea surface
Sea surface temperature
Seasonal variation
Surface temperature
Time series
Trends
Tropical climate
Variability
Water circulation
Water discharge
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Summary:We investigate the spatial and temporal patterns of satellite‐derived sea surface temperature, salinity and chlorophyll‐a concentration along the eastern South American coast. Two decade‐long time series (2002–2019; except for the salinity) allowed us to investigate changes from seasonal to interannual time scales on an array that stretches from the south (42°S) to the north (10°N) of the continent and from isobaths ranging from −50 to −1000 m away from the coast. The novelty of our approach is to assess comparatively the magnitude, variability, and spectrum of these variables following the same isobaths and using the same methodology. This allowed us to examine the influence of large scale ocean circulation patterns entangled with the local forcing systems such as river discharge and coastal currents, and to quantify to what extent these patterns are spatially and temporally consistent. The seasonal cycle of the temperature explains more variance than that of salinity and chlorophyll on average. Comparatively, salinity has a weak seasonal signal, except near major rivers. Significant long‐term trends were observed in specific regions in the salinity time series. Our study revealed distinct interannual changes at 2‐ and 4‐year period in the whole array with the largest spectral peaks near the La Plata and the Amazon Rivers. Within this period band, thermal signals propagate northward along the whole array. Statistical correlations between satellite‐derived variables and several climate indices suggest remote forcing. Plain Language Summary Studies based on satellite data are useful to assess surface ocean properties on a continuous and regular basis, with global coverage and consistent methodology. In this article we analyzed sea surface temperature and salinity, and chlorophyll‐a concentration retrieved from satellite measurements along the eastern South American coast with 20‐year satellite data (except for the salinity). That allowed us to investigate how those variables are affected by regional and coastal circulations, major river discharges and oceanic source input of properties, helping us to understand their propagation patterns and connection with atmospheric remote processes. The seasonal cycle dominated the fluctuation patterns of the variables, but distinct interannual signal could also be identified in specific regions like the Amazon or La Plata river mouths. In some regions, the salinity presented significant long‐term trends. We found signi
ISSN:2169-9275
2169-9291
DOI:10.1029/2021JC017714