U.S. Dept. of Commerce / NOAA / OAR / PMEL / Publications
In this study we examine the surface layer heat balance using wind, current, and
temperature data from equatorial moorings along 165°E. The analysis focuses primarily on
daily to monthly time scale variations during the 1986-1987 El Niño/Southern Oscillation
event. The period is one of high mean sea surface temperatures (29°C) and frequent outbreaks of westerly winds. We infer
that evaporative cooling related to wind speed variations accounts for a significant
fraction of the observed sea surface temperature (SST) and upper ocean heat content
variability. This evaporative heat flux converges nonlinearly in the surface layer, giving
rise to larger temperature variations in the upper 10 m than below. Other processes
examined (wind-forced vertical advection and entrainment, lateral advection) were
negligible or of secondary importance relative to evaporative cooling. A large fraction of
the SST and surface layer heat content variance could not be directly related to wind
fluctuations; this unexplained variance is probably related to shortwave radiative fluxes
at the air-sea interface.
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