APPLICABILITY OF GSMAP CORRECTION METHOD TO TYPHOON "MORAKOT" IN TAIWAN

Satellite-based rainfall data such as GSMaP are expected to be adapted to flood forecasting in ungauged basins since they can be obtained world-wide in near real-time for free. However, GSMaP is often underestimated comparing with ground gauged precipitation, which poses a problem in applying the product to flood management. To solve this problem, Shiraishi et al. developed GSMaP correction method based on its movement of rainfall area and successfully reduced the error rate in a Japanese river basin.   In this study, the GSMaP correction method was applied to typhoon Morakot in Kaoping River Basin and the entire Taiwan. The results showed that the correction formula for the Yoshinogawa River Basin can be applied to the Kaoping River Basin because of the similar basin scale and rainfall type and it cannot be applied to the entire Taiwan because of the much larger basin scale.   What is more, the influence of the frequency of microwave radiometer observations on the accuracy of corrected GSMaP was validated and the outcome implied the importance of the elapsed time of microwave radiometer observation as a reliability indicator for corrected GSMaP_NRT used in flood forecasting systems.