One-Minute Rain Rate Distribution in Indonesia Derived from TRMM, GPM and GSMAP Data

Abstract

Accurate estimation of 1-min rainfall rate is important for modeling specific rain attenuation. This research examined the use of Tropical Rainfall Measuring Mission (TRMM) 3B42 and 3B43 data as input of the International Telecommunication Union-Radiocommunication Sector (ITU-R) prediction model (Annex 1 of recommendation P.837-6), to estimate the rainfall rate over Indonesia. The latest TRMM 3B43 and 3B42 products version 7 from January 1998 to December 2014 were used. In addition to the TRMM data, the use of Global Satellite Mapping of Precipitation (GSMaP) and the Integrated Multi-satellitE Retrievals for GPM (IMERG) data were also examined. The 1-min rainfall rate obtained by new input was compared with the rain gauge data at Kototabang, west Sumatra, and with the value derived by a previous study based on the TRMM 3B43 and 3A25. It was found that the use of average annual rainfall (Mt) and probability to have rain in an average year (P 0 ) derived from the TRMM 3B43 and 3B42 for the ITU-R model input, provides 1-min rainfall rate which is closer to the value measured by the rain gauge, especially for percentage times less than 0.001. For larger percentages such as 0.1% and 1%, the standard inputs of ITU-R model provides 1-min rainfall rate which is closer to rain gauge. In general, the use of TRMM 3B42 to calculate P 0 is better than the TRMM 3A25 in which the rainfall rate estimated using P 0 from the TRMM 3B42 is closer to rain gauge except for a very small percentage of time (0.001%). Finally, it is generally found that the M t value calculated from the GPM data is different from those of TRMM and GSMaP, especially for ocean. On other hand, the P 0 calculated from the GPM data is smaller than those of TRMM and GSMaP data.