Explicitly simulated tropical convection over idealized warm pools

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Abstract

[1] Two-dimensional cloud-system-resolving simulations of convection over idealized warm pools are conducted to examine the relationship between the spatial patterns of tropical convection and the sea surface temperature (SST) distributions. Results show that the most active convection resides near the edge of warm pools, with a local minimum around the warmest center. This finding might provide an interpretation for the observations that peak convection is commonly located several degrees of latitude off the maximum SST over some tropical oceans. Factors potentially affecting the convective patterns are explored through sensitivity experiments. It is found that convection expands significantly and rainfall peaks are further displaced several hundred more kilometers away from the warmest water when the radiative cooling/heating is applied homogeneously across the domain. Conversely, when the wind-induced surface flux variability is excluded, convective activity is confined within a much narrower area of high SSTs, but the overall spatial pattern is largely retained. Moreover, the surface friction exerts profound effects on the simulated convection and attendant large-scale flow and is mostly responsible for the dual-maximum precipitation and two-cell circulation structure in the horizontal. These results suggest that as well as the temperature/pressure gradients resulting from the non-uniform SSTs, other processes must be taken into consideration in the interpretation of observed tropical convection and circulation.

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