The Relationship between Sea Surface Temperature and Latent Heat Flux in the Equatorial Pacific

Abstract Moored buoy data from the equatorial Pacific are analyzed to investigate the relationship between sea surface temperature (SST) and latent heat flux from the ocean. It is found that at low SST the latent heat flux increases with SST; at high SST the latent heat flux decreases with increasing SST, a relationship that cannot be explained by thermodynamic considerations alone. Analysis of the wind speeds and humidity differences between the surface air and the saturation humidity at the sea surface temperature indicates that while at low SST the humidity difference primarily determines the latent heat flux, and at high SST a sharp decrease in wind speed is mostly responsible for the low latent heat flux. A mechanism that leads to low latent heat flux at high SST is suggested; it involves the interaction between convection and the large-scale circulation. The longitudinal distribution of SST, wind speed, humidity difference, and latent heat flux is found to be similar to that in previous studies. In ...