The role of the wind-evaporation-sea surface temperature (WES) feedback in air–sea coupled tropical variability

The Wind-Evaporation-Sea surface temperature (WES) feedback is believed to play an important role in tropical climate variability. We report on studies using a modified version of the NCAR-Community Climate Model (CCM3) coupled to a slab ocean model, where the WES feedback is deliberately suppressed in the bulk aero-dynamic formulation for surface heat fluxes. A comparison of coupled integrations using the modified CCM3 to those carried out using the standard CCM3 conclusively identifies the role of the WES feedback in enhancing the inter-annual variability over deep tropical oceans. We are also able to clearly identify the role of the WES feedback in the westward propagation of the equatorial annual cycle. Our study also reveals an important role for near surface humidity in tropical climate variability, in enhancing inter-annual variability and in sustaining the equatorial annual cycle.