Friday, 30 September 2011: 11:00 AM
Urban Room (William Penn Hotel)
To improve the accuracy of radar based Quantitative Precipitation Estimation (QPE) for typhoon systems in Taiwan, a new empirical R(KDP) relation and a new KDP correction method are proposed for C-band dual-polarization radars. It was reported that the drop size distribution (DSD) and drop shape relation (DSR) in typhoon systems presented unique characteristics in Taiwan. The existing R(KDP) relations based on typical maritime or continental precipitation system may not be suitable for radar QPEs in the typhoon environment. A new relation between the rainfall rate and KDP for C-band polarimetric radars is derived through numerical simulations in the current study. Another focus of this work is to develop a KDP correction method based on analyses of vertical profiles of the specific differential phase. The corrected KDP from high altitudes is used to replace the missing or unreliable KDP at low altitudes caused by radar beam shielding. Both of the new R(KDP) relation and correction method are tested and validated on two operational C-band polarimetric radars in Taiwan with typhoon cases of Morakot and Fanapi. With the proposed techniques, the C-band dual-polarization radars were shown to provide more accurate QPEs than S-band single-polarization operational radars.
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