24th Conference on Hurricanes and Tropical Meteorology

15C.5

A study of 2–3 day convective processes in the tropical western Pacific warm pool

Brian Strahl, Purdue University, West Lafayette, IN; and C. A. Clayson and J. Schrage

In the western Pacific warm pool region, convection is organized on many different temporal and spatial scales. One interesting phenomenon is convection which occurs in 2-3 day cycles during the convectively active periods of the the Intraseasonal Oscillation (ISO). On day 1, active cloud systems grow thoughout the course of the day and subsequent evening. Day 2 is characterized by the decay of these large convective systems, as the atmosphere tries to return to a non-convective state. During this recovery period, detrainment brings air with lower moist static energy to the boundary layer, and decaying cloud shields serve to reduce incoming solar radiation (Chen and Houze, 1997). The net effect is a stabilization of the surrounding environment, resulting in a suppression of convective activity until day 3, as this process begins again.

This research is a two-part study. First, a high resolution study was done using 3-hourly, 0.5x0.5 degree OLR data from the TOGA COARE Intensive Observation Period (IOP). These data were bandpass filtered to determine periods of 2-3 day convective cycles. An examination of the characteristics and life cycle of these convective events is performed. Next, an 11 year study was done over the entire tropical western Pacific using filtered values of IR brightness temperature. The spatial and temporal variability of the 2-3 day convective cycle is examined using statistical methods.

Session 15C, Convective processes I (Parallel with Sessions 15A and 15B)
Friday, 26 May 2000, 3:30 PM-5:30 PM

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