Abstract/Summary

Tropical eastern Pacific sea surface temperature plays a pivotal role in mechanisms that determine global mean surface temperature variability. In this study, the surface flux contribution to recent cooling of the tropical eastern Pacific is investigated using data from three atmospheric reanalyses with full assimilation of observations, an observations-based net surface energy flux reconstruction and fifteen atmospheric-only climate model simulations. For the ERA-Interim reanalysis, 78% of the decrease in net surface flux (-0.65 Wm-2/yr over 1988-2008) is explained by the latent heat flux variability. Latent heat flux variability differs between datasets and this is investigated using a bulk formula. We find that discrepancies in wind speed change explain contrasting latent heat flux trends across datasets. The significant increase of 0.26 m/s/decade in wind speed over the tropical eastern Pacific in the ERA-Interim reanalysis is not reproduced by satellite or buoy observations and atmospheric-only climate model simulations, casting questions on the reliability of reanalysis-based surface fluxes over the tropical eastern Pacific.