Local ocean response to a multiphase westerly wind burst .2. Thermal and freshwater responses

A westerly wind burst observed in the warm pool of the western equatorial Pacific Ocean cooled the ocean's surface layer by about 0.8 degrees C. Turbulent entrainment at the base of this layer caused cooling but also heating due to the reversal of the vertical temperature gradient during rain events. Consequently, the cumulative effect of turbulent entrainment was minimized. Following the wind burst, a sustained eastward surface current contributed to high current shear and turbulent dissipation rates at the top of the thermocline. As a result, most of the heat transfer into the thermocline occurred after the wind burst had ended. The cruise-averaged turbulent flux into the thermocline was 17 +/- 10 W m(-2), which suggests that the annual mean is only a few watts per square meter. The restratification of the upper ocean in the aftermath of the wind burst is accounted for partly (but not wholly) by local turbulent entrainment. Despite heavy precipitation, upper ocean salinity generally increased during the cruise. Advection appears to have been the dominant factor governing local salinity changes.