validasi data trmm terhadap data curah hujan aktual di tiga das di indonesia

Validasi data TRMM telah dilakukan dengan data curah hujan di tiga DAS di wilayah Indonesia. Ketiga DAS tersebut adalah: DAS Citarum-Jawa Barat, DAS Sutami-Brantas Jawa Timur dan DAS Larona-Sulawesi Selatan. Dari analisis dua jenis tipe data TRMM NASA (3B42RT) dan TRMM Jaxa (GSMap_NRT) menunjukkan bahwa TRMM Jaxa lebih mendekati data pengamatan dibandingkan dengan TRMM NASA. Secara umum dari hasil analisis untuk ketiga DAS memperlihatkan bahwa nilai curah hujan TRMM Jaxa (GSMap_NRT) mempunyai pola yang mengikuti curah hujan pengamatan (aktual) meskipun nilainya cenderung di bawah perkiraan. Perbedaan ini salah satunya bisa diakibatkan karena pemasangan penakar hujan yang kurang representatif terhadap DAS sehingga rerata curah hujan wilayahnya kurang merepresentasikan DAS tersebut. Untuk plot scatter bulanan nilai korelasinya lebih baik dibandingkan dengan plot scatter harian (dari 0.13~0.14 meningkat menjadi 0.58~0.75) dan nilai RMSE menurun (dari rerata 11.6 mm/hari menjadi 7.6 mm/hari), sehingga analisis TRMM bulanan lebih merepresentasikan kondisi aktual.   TRMM data validation has been done with rainfall data in three watersheds of Indonesia. There are: Citarum (West Java), Sutami-Brantas (East Java) and Larona (South Sulawesi). There are two types of TRMM data; TRMM NASA (3B42RT) and TRMM Jaxa (GSMap_NRT). From the analysis of both types of the data indicate that the TRMM Jaxa closer to observed data. In general the results of analysis for all three catchments showed that the value of TRMM rainfall Jaxa (GSMap_NRT) has better agreement to the pattern of observed rainfall data although it's value tend to under estimate. This difference could be caused due to the installation of the rain gauge less representative of catchment so that the average rainfall less territory represents the catchment. Scatter plot for the monthly data have better correlation coefficient than the daily plot (0.13~0.14 raise 0.58~0.75) and decreasing RMSE value (from average 11.6 mm/day to 7.6 mm/day), so monthly analysis of TRMM has more represents the actual conditions.