Evaluation of GSMaP and Trmm Monthly Rainfall Satellite Data in Wadi Ahin, Sohar Area, Sultante of Oman

Abstract

This research compares the accuracy of Forecasting Global Precipitation Measurement (GPM)-derived satellite precipitation estimates (SPEs) for Wadi Ahin in Sohar area in Sultanate of Oman with Tropical Rainfall Measurement Mission (TRMM). To do so, GSMaP version 7 and TRMM data sets were evaluated at their regional 0.10 and 0.250 spatial resolution respectively. Both the wet and dry seasons were assessed on a monthly basis for each month. A grid cell with two gauges, one ground and the other GSMAP or TRMM, is calculated with the CC, the %RMSE, and the %B for all the considered datasets. Statistical measurements are provided here in more detail. The monthly analysis takes into account the whole period, dry season, and wet season separately for Mean regional and Mean spatial. Verification of monthly rainfall at a spatial level shows that GSMaP underestimates with a correlation coefficient, 0.704, bias-7.88% and RMSE 117.4%. Verification with the regional level shows that GSMAP performs well with a correlation coefficient of higher than 0.9. On the other hand, analysis of TRMM data sets shows a good verification in the spatial level and low accuracy in the regional level where the selected gauges are far from each other. The results indicate the need for improvement of GSMaP and TRMM estimates by doing some combinations between the datasets before application in this wadi.