Surface forcing over the South West Atlantic according to NCEP and ECMWF reanalyses over the period 1979–1990

Escoffier, Christelle; Provost, Christine

doi:10.1016/s0079-1946(98)00067-6

Cited by 8 publications

(8 citation statements)

References 2 publications

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“…In general for a given location the difference between summer and winter cloud cover is lower than 10%. Similar spatiotemoral cloudiness pattern in the SWA was described by Escoffier and Provost [1998]. On the basis of the low differences in cloud cover between seasons described above, we consider that frontal characteristics (defined further in this section) are not affected by the seasonal cloud cover variability.…”

Section: Methodssupporting

confidence: 53%

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Brazil Malvinas Frontal System as seen from 9 years of advanced very high resolution radiometer data

2004

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[1] Surface thermal fronts in the southwestern Atlantic (SWA) Ocean are examined using 9 years (1987)(1988)(1989)(1990)(1991)(1992)(1993)(1994)(1995) of advanced very high resolution radiometer data. Fronts are detected considering a gradient based edge detector. Sea surface temperature gradients are calculated from 4 km resolution 5-day composite images covering the western Argentine Basin south of 30°S. Variability in the position and intensity of the fronts from seasonal to interannual timescales is characterized in six regions including different parts of the Brazil Current Front (BCF) and the Subantarctic Front (SAF): Shelf Break-Brazil (SB-B), Brazil Malvinas Collision (BM-C), Brazil Current-Overshoot (BC-O), Shelf BreakMalvinas (SB-M), Malvinas Return Flow (MRF), and Falkland Escarpment (FE). Fronts in the SB-B, SB-M, MRF, and FE regions are controlled by the bathymetry. In the BM-C region the BCF and SAF appear to merge as a single front. This front does not present large seasonal north-south excursions as previously described, though it pivots seasonally around a fixed point located approximately at 39.5°S, 53.5°W, changing its orientation from N-S in winter to NW-SE in summer. Consequently, on average, the front intersects the 1000 m isobath at 38°30 0 S in summer and north of 37°S in winter. In the BC-O region the BCF has a U-shape centered at 53°W. The intensity of the fronts in each region except in the FE region presents large seasonal variability. In the SB-B, BM-C, and BC-O regions the frontal intensity is highest (>0.35°C/km) during austral winter, the annual components explain 83, 67, and 71% of the total variance, respectively. In the SB-M and MRF regions the SAF is most intense (>0.25°C/km) in summer and fall; the annual component of the intensity fluctuations explains 29 and 38% of the total variance, respectively. In the FE region the annual component of frontal intensity explains only 17% of the variability. In the six regions, important interannual variability is found. The Zapiola Rise (centered at 45°S, 43°W) appears as a gradient-free region. Closed planetary potential vorticity contours in this area suggest it is dynamically isolated.

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Section: Methodssupporting

confidence: 53%

“…However, the winter SST reveals little temperature contrast with the MC. This could be due to the fact that the Malvinas return flow is located in a region of maximum winter heat loss to the atmosphere [ Escoffier and Provost , 1998].…”

Section: Discussionmentioning

confidence: 99%

Brazil Malvinas Frontal System as seen from 9 years of advanced very high resolution radiometer data

2004

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“…It is shown that the difference between summer and winter cloud cover is lower than 10%. Using NCEP (National Center of Environmental Prediction) and ECWMF (European Centre for Medium Weather Forecasting) reanalysis in the SWA, Escoffier and Provost [1998] find similar low seasonal variability in cloud cover. Thus we consider that the seasonal cloud cover variability does not affect the results.…”

Section: Methodsmentioning

confidence: 94%

On the relationship between satellite‐retrieved surface temperature fronts and chlorophyll a in the western South Atlantic

2005

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The time‐space distribution of chlorophyll a in the southwestern Atlantic is examined using 6 years (1998–2003) of sea surface color images from Sea‐viewing Wide Field of View Sensor (SeaWiFS). Chlorophyll a (chl a) distribution is confronted with sea surface temperature (SST) fronts retrieved from satellite imagery. Histogram analysis of the color, SST, and SST gradient data sets provides a simple procedure for pixel classification from which eight biophysical regions in the SWA are identified, including three new regions with regard to Longhurst (1998) work: Patagonian Shelf Break (PSB), Brazil Current Overshoot, and Zapiola Rise region. In the PSB region, coastal‐trapped waves are suggested as a possible mechanism leading to the intraseasonal frequencies observed in SST and chl a. Mesoscale activity associated with the Brazil Current Front and, in particular, eddies drifting southward is probably responsible for the high chl a values observed throughout the Brazil Current Overshoot region. The Zapiola Rise is characterized by a local minimum in SST gradient magnitudes and shows chl a maximum values in February, 3 months later than the austral spring bloom of the surroundings. Significant interannual variability is present in the color imagery. In the PSB, springs and summers with high chl a concentrations seem associated with stronger local northerly wind speed, and possible mechanisms are discussed. Finally, the Brazil‐Malvinas front is detected using both SST gradient and SeaWiFS images. The time‐averaged position of the front at 54.2°W is estimated at 38.9°S and its alongshore migration of about 300 km.

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“…The main ventilation window for the subtropical gyre is the Brazil Current overshoot, which corresponds to a local maximum of the net heat loss from the ocean to the atmosphere (Figure 6e) and to a local maximum of the net heat flux interannual variability [Escoffier and Provost, 1998]. The O-S diagrams obtained during the different confluence cruises document the variety of subtropical mode water vintages in the main ventilation window (Figures 3 and 7a-7c).…”

Section: Interannual Variability Of Stmws In the Brazil Current Oversmentioning

confidence: 92%

Subtropical mode waters in the South Atlantic Ocean

Provost¹,

Escoffier²,

Maamaatuaiahutapu³

et al. 1999

J. Geophys. Res.

104

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Surface forcing over the South West Atlantic according to NCEP and ECMWF reanalyses over the period 1979–1990

Cited by 8 publications

References 2 publications

Brazil Malvinas Frontal System as seen from 9 years of advanced very high resolution radiometer data

Brazil Malvinas Frontal System as seen from 9 years of advanced very high resolution radiometer data

On the relationship between satellite‐retrieved surface temperature fronts and chlorophyll a in the western South Atlantic

Subtropical mode waters in the South Atlantic Ocean

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