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• 1. [Article] Global Microwave Satellite Observations of Sea Surface Temperature for Numerical Weather Prediction and Climate Research

  Obtaining global sea surface temperature (SST) fields for the ocean boundary condition in numerical weather prediction (NWP) models and for climate research has long been problematic. Historically, such ...

  Citation × Citation Citation Abstract Copy Title: Global Microwave Satellite Observations of Sea Surface Temperature for Numerical Weather Prediction and Climate Research Author: Chelton, Dudley B., Wentz, Frank J. Obtaining global sea surface temperature (SST) fields for the ocean boundary condition in numerical weather prediction (NWP) models and for climate research has long been problematic. Historically, such fields have been constructed by a blending of in situ observations from ships and buoys and satellite infrared observations from the Advanced Very High Resolution Radiometer (AVHRR) that has been operational on NOAA satellites since November 1981. The resolution of these global SST fields is limited by the sparse coverage of in situ observations in many areas of the World Ocean and cloud contamination of AVHRR observations, which can exceed 75% over the subpolar oceans. As clouds and aerosols are essentially transparent to microwave radiation, satellite microwave observations can greatly improve the sampling and resolution of global SST fields. The Advanced Microwave Scanning Radiometer on the NASA Earth Observing System (EOS) Aqua satellite (AMSR-E) is providing the first highly accurate and global satellite microwave observations of SST. The potential for AMSR-E observations to improve the sampling, resolution, and accuracy of SST fields for NWP and climate research is demonstrated from example SST fields and from an investigation of the sensitivity of NWP models to specification of the SST boundary condition. Title: Global Microwave Satellite Observations of Sea Surface Temperature for Numerical Weather Prediction and Climate Research Author: Chelton, Dudley B., Wentz, Frank J. Obtaining global sea surface temperature (SST) fields for the ocean boundary condition in numerical weather prediction (NWP) models and for climate research has long been problematic. Historically, such fields have been constructed by a blending of in situ observations from ships and buoys and satellite infrared observations from the Advanced Very High Resolution Radiometer (AVHRR) that has been operational on NOAA satellites since November 1981. The resolution of these global SST fields is limited by the sparse coverage of in situ observations in many areas of the World Ocean and cloud contamination of AVHRR observations, which can exceed 75% over the subpolar oceans. As clouds and aerosols are essentially transparent to microwave radiation, satellite microwave observations can greatly improve the sampling and resolution of global SST fields. The Advanced Microwave Scanning Radiometer on the NASA Earth Observing System (EOS) Aqua satellite (AMSR-E) is providing the first highly accurate and global satellite microwave observations of SST. The potential for AMSR-E observations to improve the sampling, resolution, and accuracy of SST fields for NWP and climate research is demonstrated from example SST fields and from an investigation of the sensitivity of NWP models to specification of the SST boundary condition. Close

• 2. [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

• 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] High-Resolution Satellite Measurements of the Atmospheric Boundary Layer Response to SST Variations along the Agulhas Return Current

  The marine atmospheric boundary layer (MABL) response to sea surface temperature (SST) perturbations with wavelengths shorter than 30° longitude by 10° latitude along the Agulhas Return Current (ARC) is ...

  Citation × Citation Citation Abstract Copy Title: High-Resolution Satellite Measurements of the Atmospheric Boundary Layer Response to SST Variations along the Agulhas Return Current Author: Chelton, Dudley B., Esbensen, Steven K., Wentz, Frank J., O’Neill, Larry W. The marine atmospheric boundary layer (MABL) response to sea surface temperature (SST) perturbations with wavelengths shorter than 30° longitude by 10° latitude along the Agulhas Return Current (ARC) is described from the first year of SST and cloud liquid water (CLW) measurements from the Advanced Microwave Scanning Radiometer (AMSR) on the Earth Observing System (EOS) Aqua satellite and surface wind stress measurements from the QuikSCAT scatterometer. AMSR measurements of SST at a resolution of 58 km considerably improves upon a previous analysis that used the Reynolds SST analyses, which underestimate the short-scale SST gradient magnitude over the ARC region by more than a factor of 5. The AMSR SST data thus provide the first quantitatively accurate depiction of the SST-induced MABL response along the ARC. Warm (cold) SST perturbations produce positive (negative) wind stress magnitude perturbations, leading to short-scale perturbations in the wind stress curl and divergence fields that are linearly related to the crosswind and downwind components of the SST gradient, respectively. The magnitudes of the curl and divergence responses vary seasonally and spatially with a response nearly twice as strong during the winter than during the summer along a zonal band between 40° and 50°S. These seasonal variations closely correspond to seasonal and spatial variability of large-scale MABL stability and surface sensible heat flux estimated from NCEP reanalysis fields. SST-induced deepening of the MABL over warm water is evident in AMSR measurements of CLW. Typical annual mean differences in cloud thickness between cold and warm SST perturbations are estimated to be about 300 m Title: High-Resolution Satellite Measurements of the Atmospheric Boundary Layer Response to SST Variations along the Agulhas Return Current Author: Chelton, Dudley B., Esbensen, Steven K., Wentz, Frank J., O’Neill, Larry W. The marine atmospheric boundary layer (MABL) response to sea surface temperature (SST) perturbations with wavelengths shorter than 30° longitude by 10° latitude along the Agulhas Return Current (ARC) is described from the first year of SST and cloud liquid water (CLW) measurements from the Advanced Microwave Scanning Radiometer (AMSR) on the Earth Observing System (EOS) Aqua satellite and surface wind stress measurements from the QuikSCAT scatterometer. AMSR measurements of SST at a resolution of 58 km considerably improves upon a previous analysis that used the Reynolds SST analyses, which underestimate the short-scale SST gradient magnitude over the ARC region by more than a factor of 5. The AMSR SST data thus provide the first quantitatively accurate depiction of the SST-induced MABL response along the ARC. Warm (cold) SST perturbations produce positive (negative) wind stress magnitude perturbations, leading to short-scale perturbations in the wind stress curl and divergence fields that are linearly related to the crosswind and downwind components of the SST gradient, respectively. The magnitudes of the curl and divergence responses vary seasonally and spatially with a response nearly twice as strong during the winter than during the summer along a zonal band between 40° and 50°S. These seasonal variations closely correspond to seasonal and spatial variability of large-scale MABL stability and surface sensible heat flux estimated from NCEP reanalysis fields. SST-induced deepening of the MABL over warm water is evident in AMSR measurements of CLW. Typical annual mean differences in cloud thickness between cold and warm SST perturbations are estimated to be about 300 m Close