Horizontal Structure of the Near-Surface Temperature and Salinity Fields in the Western Equatorial Pacific Warm Pool

Horizontal structure of the near-surface temperature and salinity fields in the western equatorial Pacific warm pool on scales from 1 m to 1000 km is studied using the shipboard survey data collected during the TOGA Coupled Ocean-Atmosphere Response Experiment (COARE). The data obtained with a near-surface microstructure sensor system allows us to study the horizontal variability of the temperature and salinity fields almost up to the ocean surface. The horizontal variability is considered in relation to the atmospheric forcing and vertical structure of the upper ocean. Under both stable and unstable stratification, the horizontal wavenumber spectra of near-surface temperature on scales O(100 m) are consistent with the spectra previously obtained in the atmospheric turbulent boundary layer, when corrected for the enhanced turbulence caused by the surface waves breaking. During stable near-surface stratification, internal waves can contribute to the horizontal temperature variability in the near-surface layer of the ocean. During strong winds or/and unstable near-surface stratification, the internal waves are absorbed by the near-surface turbulence; this results in homogenization of the upper ocean in horizontal direction. Other important processes include response to the atmospheric forcing with meso- and small-scales (due to precipitation, squalls, solar insolation, wind bursts etc.) and multiscale interactions in the upper ocean. The results of the analysis provide a more complete picture of the horizontal variability of near-surface temperature and salinity in the western Pacific warm pool in a wide range of spatial scales and demonstrate its association with the air-sea interaction and vertical structure of the upper ocean.