26th Conference on Hurricanes and Tropical Meteorology


Sea Surface Temperature, Cloud-Radiative Forcing, and Tropical Convection

Changhai Liu, NCAR, Boulder, CO; and M. W. Moncrieff

Although sea surface temperature (SST) forcing has a strong influence on observed tropical convection, considerable variation has been documented in the relationship of convection to the underlying SST distribution due to complex interactions of multi-scale processes in the real atmosphere. To unambiguously quantify the correlation between the spatial structure of tropical convection and the spatial distribution of SST (especially, the SST maximum and gradient), explicit two-dimensional numerical modeling of convection on an f-plane was conducted with a nonhydrostatic cloud-system-resolving model. Preliminary results reveal that the strongest convective activity often occurs at a few hundred kilometers (typically, 200~500 km) from the center of warm pools. This finding provides an alternative interpretation for the observations that peak convection is commonly located several degrees of latitude away from the maximum SST in some tropical regions. In addition, the maximum convection is further displaced several hundred more kilometers away from the warm pool as the radiative cooling/heating gradients between cloudy and clear regions is excluded in the simulations. It is speculated that the non-collocation of the highest SST and strongest convection results from the relatively weak evaporation rate around the SST peak which, in turn, is associated with the weak surface wind therein. Further diagnostic analyses and sensitivity tests are under way to substantiate the hypothesis.

Poster Session 1, Posters
Wednesday, 5 May 2004, 1:30 PM-1:30 PM, Richelieu Room

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