Regional Characteristics of Scale-based Precipitation Systems from Ten Years of TRMM PR Data

抄録

  The regional characteristics of scale-based precipitation systems on the basis of the size of the systems were investigated using a 10-year dataset from the Precipitation Radar aboard the Tropical Rainfall Measuring Mission satellite. The size of a precipitation system is defined as the number of contiguous rain pixels.
  The first result is on the diurnal features of precipitation systems stratified by size as small (<10² km²) and large (>10⁴ km²) rain area and stratiform/convective types, respectively. It was found that large overland precipitation systems developed mostly in the evening, following the early-afternoon rainfall maxima of small systems. While large systems showed clear migration properties, small systems had rain peaks at nearly the same local time, that is, without propagation. The diurnal features of small systems were almost uniform over the land or oceans. However, the vertical profiles of rainfall rates obtained for small systems exhibited regional variations.
  The second result is on the spatial and interannual variations in extreme events. The extreme events are defined as 1000 systems with the highest volumetric rainfall. These events were unevenly distributed and appeared particularly around the mouth of the La Plata basin and the northwestern and western Pacific. The year-to-year variations in these extreme events over the global tropics were consistent with the occurrence of tropical cyclones over the western Pacific.