Satellite observations of tropical precipitation patterns and their relationship with sea surface temperature
Chandra M Kishtawal (1), Kooiti Masuda (1), T Yasunari (3)
(1) Frontier Research System for Global Change, Yokohama
(3) Director, Hydrological Cycle Research Group, Frontier Research System for Global Change, Yokohama
Three years (1998-2000) of observations from Tropical Rainfall Measuring Mission (TRMM) have been analyzed using the monthly averaged gridded observations from 3A-25 data set. Measurements of Storm Height and rainfall from TRMM Precipitation Radar (PR) were used to identify the "active" and "suppressed" modes of precipitation over the global tropical oceans. We define precipitation mode as "active" when the storm height population over a 5 X 5 degree grid point is larger than 1600 per month, while a "suppressed mode" refers to storm height population smaller than 300 counts per month per grid cell. Our analysis indicates a clear partitioning of these modes with respect to sea surface temperature (SST) measured by TRMM Microwave Imager (TMI). For SST values between 25-30 C, and 14-19 C, the active mode dominates, while for SST range 19-25 C, we observe a suppressed mode of precipitation. Time series of storm height population in these three SST zones show interesting correlations with each other, at different time lags. There is a drastic and continuous increase in storm height ( indicating increasing depth of convection) and precipitaion for sea surface etemperatures above 27 C. However, the column integrated water vapor does not show any abrupt increase above this temperature, and its growth with SST remains steady. This indicates that the moisture budget above this particular SST threshold is dominated by the penetrating convection and precipitaion.
Submittal Information
Name :
Date :
Chandra M Kishtawal
31-May-01-17:06:23
Organization :
Theme :
Frontier Research System for Global Change, Yokohama
Theme 4
Address :
Presentation :
FRSGC, Yokohama Institute for Earth Sciences, 3173-25 Showa-machi Kanazawa-ku, Yokohama-city, Kanagawa, 236-0001, Japan.
