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Observations of Coupling between Surface Wind Stress and Sea Surface Temperature in the Eastern Tropical Pacific Authors: Dudley B. Chelton, Steven K. Esbensen, Michael G. Schlax, Nicolai Thum and Michael H. Freilich First Published: December 27th, 1999 Published on line: April 1st, 2001 Abstract: 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. Link to full paper: https://journals.ametsoc.org/doi/pdf/10.1175/1520-0442(2001)014<1479%3AOOCBSW>2.0.CO%3B2
Westerly Wind Events in the Tropical Pacific and their Influence on the Coupled Ocean‐Atmosphere System: A Review Authors: Matthieu Lengaigne, Jean‐Philippe Boulanger, Christophe Menkes, Pascale Delecluse, Julia Slingo, C. Wang, S.P. Xie and J.A. Carton Published: 19th March, 2013 Abstract: Observational and modeling aspects about Westerly Wind Events (WWEs) and their influence on the tropical Pacific Ocean-atmosphere system are reviewed. WWEs are a large part of the intraseasonal zonal wind activity over the warm pool. They have typical amplitudes of 7 m s-1, zonal width of 20° longitude and duration of about 8 days. Their root causes are often a combination of various factors including the Madden-Julian Oscillation, cold surges from mid-latitudes, tropical cyclones and other mesoscale phenomena. The relationship between WWEs and the ENSO cycle is complex, involving among others the equatorial characteristics of the WWEs, the oceanic background state and the internal atmospheric variability. Both observational and modeling studies demonstrate that WWEs tend to cool the far western Pacific, shift the warm pool eastward and warm the central-eastern Pacific through the generation of Kelvin waves. They are therefore important processes for the central and eastern Pacific warming during the onset and development phase of El Niño. The strong atmospheric feedbacks that are likely to be generated by the ocean response to WWEs even suggest that a single WWE is capable of establishing the conditions under which El Niño can occur. The important role played by WWEs in the evolution and amplitude of recent El Niño events may therefore strongly limit the predictability of El Niño. Link to full paper: thttps://www.researchgate.net/profile/Matthieu_Lengaigne/publication/43155421_Westerly_wind_events_in_the_Tropical_Pacific_and_their_influence_on_the_coupled_ocean-atmosphere_system_A_review/links/543ec9340cf2e76f02243850.pdf