Editorial Type:
Article
Article Type:
Research Article

Sea Surface Temperature and Wind Stress Curl Variability near a Cape

Renato M. Castelao Department of Marine Sciences, The University of Georgia, Athens, Georgia

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Print Publication:
01 Nov 2012
DOI:
https://doi.org/10.1175/JPO-D-11-0224.1
Page(s):
2073–2087
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Abstract

The coupling between sea surface temperature (SST), SST gradients, and wind stress curl variability near a cape off Brazil is investigated using satellite observations and several different SST high-resolution analyses. The cape is characterized by strong SST fronts year-round, associated with upwelling and advection of warm water offshore in a western boundary current. Observations reveal a strong coupling between crosswind SST gradients and wind stress curl variability, with the predominantly negative crosswind gradients leading to negative, upwelling favorable wind stress curl anomalies. The spatial correlation between empirical orthogonal functions (EOF) of those variables is ~0.6, while the correlation between the EOF amplitude time series of the wind stress curl and crosswind SST gradients is larger than 0.7. The coupling occurs during summer and winter and is strongly modulated by variations in the wind stress directional steadiness. The intensity of the coupling is weaker than around capes on the California Current system, presumably because of higher variability in wind direction off Brazil. During periods of high wind stress directional steadiness off Cape Frio, the coupling is intensified by up to 40%–75%. Wind stress curl is also correlated with SST itself, especially in the vicinity of the cape, although not as strongly as with crosswind SST gradients. The analyses suggest that the observed wind stress curl anomalies can lead to surface cooling of as much as 1°C. If the enhanced upwelling leads to further strengthening of the upwelling front, negative wind stress curl anomalies may be intensified in a positive feedback mechanism.

Corresponding author address: Renato Castelao, Department of Marine Sciences, Marine Sciences Building, University of Georgia, Athens, GA 30602. E-mail: castelao@uga.edu

Abstract

The coupling between sea surface temperature (SST), SST gradients, and wind stress curl variability near a cape off Brazil is investigated using satellite observations and several different SST high-resolution analyses. The cape is characterized by strong SST fronts year-round, associated with upwelling and advection of warm water offshore in a western boundary current. Observations reveal a strong coupling between crosswind SST gradients and wind stress curl variability, with the predominantly negative crosswind gradients leading to negative, upwelling favorable wind stress curl anomalies. The spatial correlation between empirical orthogonal functions (EOF) of those variables is ~0.6, while the correlation between the EOF amplitude time series of the wind stress curl and crosswind SST gradients is larger than 0.7. The coupling occurs during summer and winter and is strongly modulated by variations in the wind stress directional steadiness. The intensity of the coupling is weaker than around capes on the California Current system, presumably because of higher variability in wind direction off Brazil. During periods of high wind stress directional steadiness off Cape Frio, the coupling is intensified by up to 40%–75%. Wind stress curl is also correlated with SST itself, especially in the vicinity of the cape, although not as strongly as with crosswind SST gradients. The analyses suggest that the observed wind stress curl anomalies can lead to surface cooling of as much as 1°C. If the enhanced upwelling leads to further strengthening of the upwelling front, negative wind stress curl anomalies may be intensified in a positive feedback mechanism.

Corresponding author address: Renato Castelao, Department of Marine Sciences, Marine Sciences Building, University of Georgia, Athens, GA 30602. E-mail: castelao@uga.edu
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  • Allard, P., 1955: Anomalies dans le temperature de l’eau de la mer observes au Cabo Frio au Bresil. Bull. Inf. Com. Oceanogr. Etude Cotes, 7, 58–63.

    • Search Google Scholar
    • Export Citation

  • Arthur, R. S., 1965: On the calculation of vertical motion in eastern boundary currents from determinations of horizontal motion. J. Geophys. Res., 70, 2799–2803.

    • Search Google Scholar
    • Export Citation

  • Campos, E., J. Gonçalves, and Y. Ikeda, 1995: Water mass characteristics and geostrophic circulation in the South Brazil Bight: Summer of 1991. J. Geophys. Res., 100 (C9), 18 537–18 550.

    • Search Google Scholar
    • Export Citation

  • Campos, E., D. Velhote, and I. da Silveira, 2000: Shelf break upwelling driven by Brazil Current cyclonic meanders. Geophys. Res. Lett., 27, 751–754.

    • Search Google Scholar
    • Export Citation

  • Castelao, R. M., and J. A. Barth, 2006: Upwelling around Cabo Frio, Brazil: The importance of wind stress curl. Geophys. Res. Lett., 33, L03602, doi:10.1029/2005GL025182.

    • Search Google Scholar
    • Export Citation

  • Castro, B. M., and L. B. Miranda, 1998: Physical oceanography of the western Atlantic continental shelf located between 4°N and 34°S. The Sea, A. R. Robinson and K. H. Brink, Eds., Vol. 11, Wiley and Sons, 209–251.

  • Chelton, D. B., and M. H. Freilich, 2005: Scatterometer-based assessment of 10-m wind analyses from the operational ECMWF and NCEP numerical weather prediction models. Mon. Wea. Rev., 133, 409–429.

    • Search Google Scholar
    • Export Citation

  • Chelton, D. B., and S.-P. Xie, 2010: Coupled ocean-atmosphere interactions at oceanic mesoscales. Oceanography (Washington, D.C.), 23, 52–69.

    • Search Google Scholar
    • Export Citation

  • Chelton, D. B., M. G. Schlax, M. H. Freilich, and R. F. Milliff, 2004: Satellite measurements reveal persistent small-scale features in ocean winds. Science, 303, 978–983.

    • Search Google Scholar
    • Export Citation

  • Chelton, D. B., M. G. Schlax, and R. Samelson, 2007: Summertime coupling between sea surface temperature and wind stress in the California current System. J. Phys. Oceanogr., 37, 495–517.

    • Search Google Scholar
    • Export Citation

  • Donlon, C., and Coauthors, 2007: The global ocean data assimilation experiment high-resolution sea surface temperature pilot. Bull. Amer. Meteor. Soc., 88, 1197–1213.

    • Search Google Scholar
    • Export Citation

  • Emílsson, I., 1961: The shelf and coastal waters off southern Brazil. Bull. Inst. Oceanogr., 11, 101–112.

  • Franchito, S., V. Rao, J. Stech, and J. Lorenzzetti, 1998: The effect of coastal upwelling on the sea-breeze circulation at Cabo Frio, Brazil: A numerical experiment. Ann. Geophys., 16, 866–881.

    • Search Google Scholar
    • Export Citation

  • Freilich, M. H., and R. S. Dunbar, 1999: The accuracy of the NSCAT 1 vector winds: Comparisons with National Data Buoy Center buoys. J. Geophys. Res., 104 (C5), 11 231–11 246.

    • Search Google Scholar
    • Export Citation

  • Ikeda, Y., L. B. Miranda, and I. C. Miniussi, 1974: Observations on stages of upwelling in the region of Cabo Frio (Brazil) as conducted by continuous surface temperature and salinity measurements. Bull. Inst. Oceanogr., 23, 33–46.

    • Search Google Scholar
    • Export Citation

  • Jin, X., C. Dong, J. Kurian, J. McWilliams, D. Chelton, and Z. Li, 2009: SST–wind interaction in coastal upwelling: Oceanic simulation with empirical coupling. J. Phys. Oceanogr., 39, 2957–2970.

    • Search Google Scholar
    • Export Citation

  • Large, W. G., J. C. McWilliams, and S. C. Doney, 1994: Oceanic vertical mixing: A review and a model with a nonlocal boundary layer parameterization. Rev. Geophys., 32, 363–403.

    • Search Google Scholar
    • Export Citation

  • Matsuura, Y., 1996: A probable cause of recruitment failure of Brazilian Sardine (Sardinella aurita) population during the 1974/75 spawning season. S. Afr. J. Mar. Sci., 17, 29–35.

    • Search Google Scholar
    • Export Citation

  • Matsuura, Y., 1998: Brazilian Sardine (Sardinella brasiliensis) spawning in the southeast bight over the period 1976/93, Rev. Brasil. Oceanography, 46, 33–43.

    • Search Google Scholar
    • Export Citation

  • Naderi, F. M., M. H. Freilich, and D. G. Long, 1991: Spaceborne radar measurement of wind velocity over the ocean: An overview of the NSCAT scatterometer system. Proc. IEEE, 79, 850–866.

    • Search Google Scholar
    • Export Citation

  • O’Neill, L. W., D. B. Chelton, and S. K. Esbensen, 2003: Observations of SST–induced perturbations of the wind stress field over the Southern Ocean on seasonal time scales. J. Climate, 16, 2340–2354.

    • Search Google Scholar
    • Export Citation

  • O’Neill, L. W., D. B. Chelton, S. K. Esbensen, and F. J. Wentz, 2005: High-resolution satellite observations of SST modification of the marine atmospheric boundary layer over the Agulhas Return Current. J. Climate, 18, 2706–2723.

    • Search Google Scholar
    • Export Citation

  • O’Neill, L. W., D. B. Chelton, and S. K. Esbensen, 2010: The effects of SST-induced horizontal surface wind speed and direction gradients on midlatitude vorticity and divergence. J. Climate, 18, 2706–2723.

    • Search Google Scholar
    • Export Citation

  • Palma, E., and R. Matano, 2009: Disentangling the upwelling mechanisms of the South Brazil Bight. Cont. Shelf Res., 29, 1525–1534.

  • Perlin, N., E. Skyllingstad, and R. Samelson, 2011: Coastal atmospheric circulation around an idealized cape during wind-driven upwelling studied from a coupled ocean–atmosphere model. Mon. Wea. Rev., 139, 809–829.

    • Search Google Scholar
    • Export Citation

  • Pickett, M. H., and J. D. Paduan, 2003: Ekman transport and pumping in the California Current based on the U.S. Navy’s high-resolution atmospheric model (COAMPS). J. Geophys. Res., 108, 3327, doi:10.1029/2003JC001902.

    • Search Google Scholar
    • Export Citation

  • Piola, A., E. Campos, O. Möller Jr., M. Charo, and C. Martinez, 2000: Subtropical shelf front off eastern South America. J. Geophys. Res., 105, 6565–6578.

    • Search Google Scholar
    • Export Citation

  • Reynolds, R., and D. Chelton, 2010: Comparisons of daily sea surface temperature analyses for 2007/08. J. Climate, 23, 3545–3562.

  • Rodrigues, R. R., and J. A. Lorenzzetti, 2001: A numerical study of the effects of bottom topography and coastline geometry on the Southeast Brazilian coastal upwelling. Cont. Shelf Res., 21, 371–394.

    • Search Google Scholar
    • Export Citation

  • Stech, J., and J. Lorenzzetti, 1992: The response of the South Brazil Bight to the passage of wintertime cold fronts. J. Geophys. Res., 97 (C6), 9507–9520.

    • Search Google Scholar
    • Export Citation

  • Xie, S.-P., 2004: Satellite observations of cool ocean–atmosphere interaction. Bull. Amer. Meteor. Soc., 85, 195–208.

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