Wednesday, 17 January 2007: 4:30 PM
Effects of a diurnal sea surface temperature on surface fluxes and atmospheric variability
214C (Henry B. Gonzalez Convention Center)
A coupled atmosphere-ocean single-column model is used to evaluate the effects of diurnal sea surface temperature variability on the marine boundary layer. It has been shown that the use of a diurnally-varying sea surface temperature as opposed to a daily-averaged sea surface temperature can substantially impact the lower atmosphere by several degrees, and the upper atmosphere through convection. The extent to which a daily-averaged sea surface temperature changes the resulting atmospheric profiles depends on whether the diurnal variability was strong; under low-wind conditions the differences are the most dramatic. Such perturbations as the Madden-Julian Oscillation with active and suppressed phases in the tropical western Pacific can affect the magnitude of the diurnal warming. The two boundary layers are coupled through the air-sea fluxes of heat and moisture in these model simulations, but the mechanisms causing the extensive and long-lasting atmospheric variability have not yet been identified. These mechanisms and an analysis of the feedbacks at various scales and differing sea surface temperature diurnal warming regimes are shown.