89th American Meteorological Society Annual Meeting

Tuesday, 13 January 2009
Assessing tropical cyclone contribution to annual global rainfall
Hall 5 (Phoenix Convention Center)
Christopher L. Williams, NCAR, Boulder, CO; and F. D. Marks Jr.
Any change in tropical cyclone (TC) rainfall could positively and/or adversely impact the well-being of humans worldwide. This first global 10-year Rainfall Climatology and Persistence (R-CLIPER) model TC rainfall study seeks to enhance the basic understanding of TC contribution to annual global rainfall. The Tropical Rainfall Measuring Mission (TRMM) satellite data provided accurate rainfall rates that were incorporated in R-CLIPER and were used in conjunction with rain gauge data by the TRMM global rainfall algorithm (3B-43) to make monthly mean global precipitation rate best estimates between 50N and 50S. R-CLIPER integrated the TRMM-derived climatological rainfall distribution at every 10-minute time step over the lifetime of each TC to estimate the individual TC rainfall. Annual TC and global rainfall estimates were integrated on 0.25 x 0.25 latitude/longitude grids for the years between 1998 and 2007. The annual TC rainfall totals were compared to annual global rainfall totals to assess TC rainfall percent contribution to global rainfall. The results suggest TCs contributed between ~2-3% of the annual global rainfall during the 10-year period with regionally higher percentages reaching 10-15% in the subtropics and as high as 25-40% in certain local areas. The results of this study could be useful to risk and water management agencies for identifying which regions around the world depend upon TC rainfall for agriculture and other uses and have added value considering that TC rainfall contributions may fluctuate as a result of climate change.

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