92nd American Meteorological Society Annual Meeting (January 22-26, 2012)

Tuesday, 24 January 2012: 2:45 PM
Organization of Tropical Convection: Behavior of Self-Aggregation in An Idealized Modeling Study
Room 355 (New Orleans Convention Center )
Allison A. Wing, MIT, Cambridge, MA; and K. Emanuel

Convective cloud clusters are responsible for most of the rainfall and cloudiness over the tropics, therefore modulating the radiative heating and cooling rates of the surface and atmosphere and influencing the large-scale circulation and moisture distribution. Therefore, understanding how and why tropical convection organizes is important for understanding both tropical and global climate variability. In this study, the problem is approached through the context of idealized modeling of convective organization in radiative- convective equilibrium using a cloud resolving model. Previous studies have investigated interactions between the environment and the convection that allow convection to self-aggregate into a single cluster, and have found this self-aggregation to be dependent on a sea surface temperature (SST) threshold. To examine the nature of this threshold, the System for Atmospheric Modeling is used to perform 3-d cloud resolving simulations within a doubly periodic horizontal domain of 576 km x 576 km , interactive radiation and surface fluxes, and no rotation. Simulations at different SSTs are run for a period of 100 days. Simulations in which aggregation does occur are then closely compared to those in which it does not. Perturbations are then applied to the non-aggregated simulations to determine what is needed to force the system to aggregate, including changing the humidity, atmospheric temperature, solar insolation, background wind, and rotation.

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