Intercomparison Of Precipitation Feature Over Tibetan Plateau, Asion Monsoon Region And Subtropical North America In Boreal Summer Using TRMM Data

Using TRMM (Tropical Rainfall Measure Mission) data from1998to2011, Spatial andtemporal distribution and structural features of precipitation system over Tibetan Plateau, Asionmonsoon region and subtropical north America in boreal summer (June-August) are analyzed.We define the RPF (Radar Precipitation Feature) as precipitation feature, and RPF is anindividual composed by pixels of precipitation near the ground plumbed by TRMMPrecipitation Radar. Two groups of regions ara divided. One group is Tibetan Plateau (TP), eastof Asia (EA), west of subtropical north America (WNA) and east of subtropical north America(ENA), in this group, RPFs are divided into3groups: all RPF, large RPF (area more than1000km2) and small RPF (area less equal400km2), and occurrence frequency of RPF numberand occurrence frequency of RPF pixel number are analyzed. Another group is TP, the southernslope of the plateau (PSS), south Asion monsoon region (SAMR), EA and tropical northwesternPacifc, and RPFs are divided into large RPF (area more than400km2) and small RPF (area lessequal400km2), they are used to analysis the structure features of precipitaition system (such as:horizontal scale, vertical structure, falsh, and so on).The main results of precipitation system occurrence frequency in TP, EA, WNA and ENAregions are as follows:1) The maximum and minimum occurrence frequency of RPF numberare respectively in TP and ENA; the maximum and minimum occurrence frequency of RPFpixel number are respectively in EA and TP.2) Diurnal variation of occurrence frequency ofRPF located in4regions are mainly with single peak in afternoon to late-afternoon, and thepeak of large RPF is later than small RPF. Specifically, diurnal variation of occurrencefrequency of RPF pixel number located in EA is with double peaks.3) Results of rainfall basedon the rain gauge analyzed before and occurrence frequency of RPF pixel number are similar.The main results of precipitation system structure in TP, PSS, SAMR, EA, and NWP regions are asfollows:1) RPF in5regions can be divided into3types: subtropical continental RPF (PSS and EA); tropical marine monsoon RPF (SAMR and NWP); subtropical plateau RPF (TP). To subtropical continental RPF, thearea is biggest, the convection is strongest, but ropical marine monsoon RPF is opposite, subtropical plateauRPF is between subtropical continental RPF and ropical marine monsoon RPF.2) In terms of horizontal scale,the proportion of small RPF in all RPF is about3/4in study regions. However, precipitation contribution rateof small RPF in TP (23%) is much more than other4regions (7-10%). In terms of vertical structure, RPF inTP is more shallow relative to other4regions, but TP’s updraft in middle layer (mixed phase layer) is a littlestrong (stronger than NWP and SAMR), as a result, there are many big ice and water particles, that means:RPF in TP has concentrated and dense convective core. The main body of RPF in TP is cold cloud.