Geographic variability in the export of moist static energy in the Tropical Pacific
Larissa E. Back, MIT, Cambridge, MA
A number of theories about deep tropical conection have been based on using moist static energy (MSE) budgets. Since column MSE is not changed by convective circulations within the column itself, it is expected that time-mean sources of tropospheric column-integrated MSE are balanced by advective export of MSE. Previous work with MSE budgets has used the assumption that temperature perturbations associated with convection follow a moist adiabat to create simple models that reproduce some of the essential features of the tropical circulation. This can also be used to connect observed wavespeeds of convectively-coupled equatorial waves and the speeds predicted by shallow-water theory.
In this study, we use several reanalyses to compute MSE budgets and study whether it is consistent with these ideas. We look at the export of MSE by both vertical and horizontal motions in the tropical Pacific and find, suprisingly, that there is a 2000 km wide region in the ITCZ where vertical circulations may import MSE. To understand this finding, we further examine how vertical motion profiles vary across the Pacific ITCZ.
Session 7D, Tropical Convection I
Wednesday, 26 April 2006, 8:00 AM-10:00 AM, Big Sur
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