Ocean-atmosphere Coupling over the Eastern Tropical Pacific During EPIC2001

Observations from NASA's QuikSCAT scatterometer and the TRMM microwave imager have recently focussed attention on a remarkably tight coupling between sea surface temperature (SST) and the surface wind stress in the vicinity of the eastern Pacific equatorial cold tongue. Several hypotheses have been advanced to explain the coupling, including the effects of enhanced and suppressed turbulent mixing in the atmospheric boundary layer (ABL), the effects of SST induced horizontal pressure gradients in the ABL, and large-scale dynamical processes involving the coriolis force and its change of sign across the equator. It is difficult however to distinguish between hypotheses observationally without information on the vertical structure of the atmospheric boundary layer as the air flows across the equator and into the intertropical convergence zone. A field program to improve understanding and modeling of the ocean-atmosphere system in the eastern pacific region called EPIC2001 has been designed to address these questions. Special ship, aircraft and buoy observations are scheduled for 1 September 2001 to 15 October 2001. In this talk, we will present observations taken by miniature robotic aircraft over the SST front just to the north of the cold tongue and place them in the context of QuikSCAT wind stress fields during EPIC2001. The mechanisms that couple the ocean and atmosphere will be discussed in the context of these newly available data sets.