Spatial variability of drop size distribution over Indonesian maritime continent from global precipitation measurement HS V05 observation

Raindrops size distribution (DSD) is prominent in determining precipitation processes. It is also essential to construct analgorithm to estimate rainfall from weather radar. Spatial variability of DSD over the Indonesian Maritime Continent (IMC) has been observed from Global Precipitation Measurement (GPM) satellite with High-Scan (HS) mode Version 05 (V05) from January 2015 to August 2018. Spatial variability of DSD was observed from the modified gamma parameters, namely mass-weight mean diameter (Dm) and total drop concentration (Nw). The Dm and Nw data are classified based on the rain type and the rainfall intensity class in a 1-degree grid. It was found that the value of Dm(Nw) is greater (lower) over the land than over the ocean. Land-ocean contrast of Dm and Nw values was more clearly observed in convective than in stratiform rains, which is due to a stronger updraft over the land in convective rain than in stratiform rain. Furthermore, larger values of Dm with slightly smaller Nwwere observed in the eastern part of the island of Sumatra and the northern part of the island of Borneo. The area is located in the downwind flow area in the Barisan (Sumatra) and Muller (Kalimantan) Mountainous. It indicates a significant effect of orography wind on DSD variability. Thus, the spatial variability of the DSD must be a concern in estimating rainfall from weather radar over IMC.