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Modeling Interactions between Large Scale Atmospheric Flows and Moist Convection

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Date and time:Ìý

Thursday, April 28, 2011 - 4:15pm

Abstract:Ìý

Many atmospheric phenomena such as the Madden-Julian Oscillation, Hadley cell, equatorially trapped waves, and storm tracks are manifestations of the interactions between atmospheric flows at multiple scales and convection. In this talk, a combination of mathematical modeling and numerical simulation is used to improve the understanding of the mechanisms of coupling between moist convection and atmospheric circulation. In particular, to gain basic insight on the response of the tropical atmosphere to heating, we use
a linear rotating shallow water model, coupled to a water vapor equation through a parametrization for precipitation. The physical requirement that precipitation can only be positive imposes a nonlinearity, because the reverse of a solution where precipitation has been active is not realizable. Within this context, we demonstrate two applications of this model. First, we investigate the coupling among earth's rotation, gravity waves, and moist convection, in the context of a geostrophic adjustment problem. Second, we derive analytical solutions for equatorial waves propagating along a basic state where precipitation is active on a limited portion of the domain. These studies demonstrate how precipitation affects both the length scale and the phase speed of the waves.