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• 1. [Article] Observations of Coupling between Surface Wind Stress and Sea Surface Temperature in the Eastern Tropical Pacific

  Satellite measurements of surface wind stress from the QuikSCAT scatterometer and sea surface temperature (SST) from the Tropical Rainfall Measuring Mission Microwave Imager are analyzed for the three-month ...

  Citation × Citation Citation Abstract Copy Title: Observations of Coupling between Surface Wind Stress and Sea Surface Temperature in the Eastern Tropical Pacific Author: Chelton, Dudley B., McPhaden, Michael J., Schlax, Michael G., Freilich, Michael H., Thum, Nicolai, Esbensen, Steven K., Gentemann, Chelle L., Wentz, Frank J., Schopf, Paul S. Satellite measurements of surface wind stress from the QuikSCAT scatterometer and sea surface temperature (SST) from the Tropical Rainfall Measuring Mission Microwave Imager are analyzed for the three-month period 21 July–20 October 1999 to investigate ocean–atmosphere coupling in the eastern tropical Pacific. Oceanic tropical instability waves (TIWs) with periods of 20–40 days and wavelengths of 1000–2000 km perturb the SST fronts that bracket both sides of the equatorial cold tongue, which is centered near 1°S to the east of 130°W. These perturbations are characterized by cusp-shaped features that propagate systematically westward on both sides of the equator. The space–time structures of these SST perturbations are reproduced with remarkable detail in the surface wind stress field. The wind stress divergence is shown to be linearly related to the downwind component of the SST gradient with a response on the south side of the cold tongue that is about twice that on the north side. The wind stress curl is linearly related to the crosswind component of the SST gradient with a response that is approximately half that of the wind stress divergence response to the downwind SST gradient. The perturbed SST and wind stress fields propagate synchronously westward with the TIWs. This close coupling between SST and wind stress supports the Wallace et al. hypothesis that surface winds vary in response to SST modification of atmospheric boundary layer stability. Title: Observations of Coupling between Surface Wind Stress and Sea Surface Temperature in the Eastern Tropical Pacific Author: Chelton, Dudley B., McPhaden, Michael J., Schlax, Michael G., Freilich, Michael H., Thum, Nicolai, Esbensen, Steven K., Gentemann, Chelle L., Wentz, Frank J., Schopf, Paul S. Satellite measurements of surface wind stress from the QuikSCAT scatterometer and sea surface temperature (SST) from the Tropical Rainfall Measuring Mission Microwave Imager are analyzed for the three-month period 21 July–20 October 1999 to investigate ocean–atmosphere coupling in the eastern tropical Pacific. Oceanic tropical instability waves (TIWs) with periods of 20–40 days and wavelengths of 1000–2000 km perturb the SST fronts that bracket both sides of the equatorial cold tongue, which is centered near 1°S to the east of 130°W. These perturbations are characterized by cusp-shaped features that propagate systematically westward on both sides of the equator. The space–time structures of these SST perturbations are reproduced with remarkable detail in the surface wind stress field. The wind stress divergence is shown to be linearly related to the downwind component of the SST gradient with a response on the south side of the cold tongue that is about twice that on the north side. The wind stress curl is linearly related to the crosswind component of the SST gradient with a response that is approximately half that of the wind stress divergence response to the downwind SST gradient. The perturbed SST and wind stress fields propagate synchronously westward with the TIWs. This close coupling between SST and wind stress supports the Wallace et al. hypothesis that surface winds vary in response to SST modification of atmospheric boundary layer stability. Close

• 2. [Article] Summertime Coupling between Sea Surface Temperature and Wind Stress in the California Current System

  Satellite observations of wind stress and sea surface temperature (SST) are analyzed to investigate ocean–atmosphere interaction in the California Current System (CCS). As in regions of strong SST fronts ...

  Citation × Citation Citation Abstract Copy Title: Summertime Coupling between Sea Surface Temperature and Wind Stress in the California Current System Author: Chelton, Dudley B., Schlax, Michael G., Samelson, Roger M. Satellite observations of wind stress and sea surface temperature (SST) are analyzed to investigate ocean–atmosphere interaction in the California Current System (CCS). As in regions of strong SST fronts elsewhere in the World Ocean, SST in the CCS region is positively correlated with surface wind stress when SST fronts are strong, which occurs during the summertime in the CCS region. This ocean influence on the atmosphere is apparently due to SST modification of stability and mixing in the atmospheric boundary layer and is most clearly manifest in the derivative wind stress fields: wind stress curl and divergence are linearly related to, respectively, the crosswind and downwind components of the local SST gradient. The dynamic range of the Ekman upwelling velocities associated with the summertime SST-induced perturbations of the wind stress curl is larger than that of the upwelling velocities associated with the mean summertime wind stress curl. This suggests significant feedback effects on the ocean, which likely modify the SST distribution that perturbed the wind stress curl field. The atmosphere and ocean off the west coast of North America must therefore be considered a fully coupled system. It is shown that the observed summertime ocean–atmosphere interaction is poorly represented in the NOAA North American Mesoscale Model (formerly called the Eta Model). This is due, at least in part, to the poor resolution and accuracy of the SST boundary condition used in the model. The sparse distribution of meteorological observations available over the CCS for data assimilation may also contribute to the poor model performance. Title: Summertime Coupling between Sea Surface Temperature and Wind Stress in the California Current System Author: Chelton, Dudley B., Schlax, Michael G., Samelson, Roger M. Satellite observations of wind stress and sea surface temperature (SST) are analyzed to investigate ocean–atmosphere interaction in the California Current System (CCS). As in regions of strong SST fronts elsewhere in the World Ocean, SST in the CCS region is positively correlated with surface wind stress when SST fronts are strong, which occurs during the summertime in the CCS region. This ocean influence on the atmosphere is apparently due to SST modification of stability and mixing in the atmospheric boundary layer and is most clearly manifest in the derivative wind stress fields: wind stress curl and divergence are linearly related to, respectively, the crosswind and downwind components of the local SST gradient. The dynamic range of the Ekman upwelling velocities associated with the summertime SST-induced perturbations of the wind stress curl is larger than that of the upwelling velocities associated with the mean summertime wind stress curl. This suggests significant feedback effects on the ocean, which likely modify the SST distribution that perturbed the wind stress curl field. The atmosphere and ocean off the west coast of North America must therefore be considered a fully coupled system. It is shown that the observed summertime ocean–atmosphere interaction is poorly represented in the NOAA North American Mesoscale Model (formerly called the Eta Model). This is due, at least in part, to the poor resolution and accuracy of the SST boundary condition used in the model. The sparse distribution of meteorological observations available over the CCS for data assimilation may also contribute to the poor model performance. Close

• 3. [Article] Satellite Microwave SST Observations of Transequatorial Tropical Instability Waves

  Satellite measurements of sea-surface temperature (SST) by the TRMM Microwave Imager reveal previously unreported features of tropical instability waves (TIWs). In the Pacific, TIW-related variability ...

  Citation × Citation Citation Abstract Copy Title: Satellite Microwave SST Observations of Transequatorial Tropical Instability Waves Author: Chelton, Dudley B., Schlax, Michael G., Genremann, Chelle L., Wentz, Frank J., de Szoeke, Roland A. Satellite measurements of sea-surface temperature (SST) by the TRMM Microwave Imager reveal previously unreported features of tropical instability waves (TIWs). In the Pacific, TIW-related variability is observed from the eastern boundary to at least 160°E. Cusp-shaped distortions of SST fronts and associated trains of anticyclonic vortices both north and south of the equator propagate westward at ~0.5 m s-1 with approximately 50% larger meridional displacements in the north. In the Atlantic, TIWs and associated anticyclonic vortices are clearly observed only on the north side of the equator where they propagate from the eastern boundary to the western boundary at ~0.3 m s-1. Title: Satellite Microwave SST Observations of Transequatorial Tropical Instability Waves Author: Chelton, Dudley B., Schlax, Michael G., Genremann, Chelle L., Wentz, Frank J., de Szoeke, Roland A. Satellite measurements of sea-surface temperature (SST) by the TRMM Microwave Imager reveal previously unreported features of tropical instability waves (TIWs). In the Pacific, TIW-related variability is observed from the eastern boundary to at least 160°E. Cusp-shaped distortions of SST fronts and associated trains of anticyclonic vortices both north and south of the equator propagate westward at ~0.5 m s-1 with approximately 50% larger meridional displacements in the north. In the Atlantic, TIWs and associated anticyclonic vortices are clearly observed only on the north side of the equator where they propagate from the eastern boundary to the western boundary at ~0.3 m s-1. Close

• 4. [Article] Geographical Variability of the First Baroclinic Rossby Radius of Deformation

  Global 1° × 1° climatologies of the first baroclinic gravity-wave phase speed c¹ and the Rossby radius of deformation λ1 are computed from climatological average temperature and salinity profiles. These ...

  Citation × Citation Citation Abstract Copy Title: Geographical Variability of the First Baroclinic Rossby Radius of Deformation Author: El Naggar, Karim, Chelton, Dudley B., Schlax, Michael G., Siwertz, Nicolas, deSzoeke, Roland A. Global 1° × 1° climatologies of the first baroclinic gravity-wave phase speed c¹ and the Rossby radius of deformation λ1 are computed from climatological average temperature and salinity profiles. These new atlases are compared with previously published 5° × 5° coarse resolution maps of λ₁ for the Northern Hemisphere and the South Atlantic and with a 1° × 1° fine-resolution map of c₁ for the tropical Pacific. It is concluded that the methods used in these earlier estimates yield values that are biased systematically low by 5%–15% owing to seemingly minor computational errors. Geographical variations in the new high-resolution maps of c₁ and λ₁ are discussed in terms of a WKB approximation that elucidates the effects of earth rotation, stratification, and water depth on these quantities. It is shown that the effects of temporal variations of the stratification can be neglected in the estimation of c₁ and λ₁ at any particular location in the World Ocean. This is rationalized from consideration of the WKB approximation. Title: Geographical Variability of the First Baroclinic Rossby Radius of Deformation Author: El Naggar, Karim, Chelton, Dudley B., Schlax, Michael G., Siwertz, Nicolas, deSzoeke, Roland A. Global 1° × 1° climatologies of the first baroclinic gravity-wave phase speed c¹ and the Rossby radius of deformation λ1 are computed from climatological average temperature and salinity profiles. These new atlases are compared with previously published 5° × 5° coarse resolution maps of λ₁ for the Northern Hemisphere and the South Atlantic and with a 1° × 1° fine-resolution map of c₁ for the tropical Pacific. It is concluded that the methods used in these earlier estimates yield values that are biased systematically low by 5%–15% owing to seemingly minor computational errors. Geographical variations in the new high-resolution maps of c₁ and λ₁ are discussed in terms of a WKB approximation that elucidates the effects of earth rotation, stratification, and water depth on these quantities. It is shown that the effects of temporal variations of the stratification can be neglected in the estimation of c₁ and λ₁ at any particular location in the World Ocean. This is rationalized from consideration of the WKB approximation. Close

• 5. [Article] Satellite Observations of Mesoscale Eddy-Induced Ekman Pumping

  This is the publisher’s final pdf. The published article is copyrighted by the American Meteorological Society and can be found at: http://journals.ametsoc.org/loi/phoc.

  Citation × Citation Citation Abstract Copy Title: Satellite Observations of Mesoscale Eddy-Induced Ekman Pumping Author: Gaube, Peter, Chelton, Dudley B., Schlax, Michael G., Samelson, Roger M., O'Neill, Larry W. This is the publisher’s final pdf. The published article is copyrighted by the American Meteorological Society and can be found at: http://journals.ametsoc.org/loi/phoc. Title: Satellite Observations of Mesoscale Eddy-Induced Ekman Pumping Author: Gaube, Peter, Chelton, Dudley B., Schlax, Michael G., Samelson, Roger M., O'Neill, Larry W. This is the publisher’s final pdf. The published article is copyrighted by the American Meteorological Society and can be found at: http://journals.ametsoc.org/loi/phoc. Close