The Precipitation Characteristics of a Winter Typhoon revealed by the NCU Polarimetric Radar

On Dec. 4th ,2004, a rare winter typhoon was passing through the southern tip of Taiwan. During its recurvature track near the island, the maximum rainfall accumulation reached 1000mm in two days. A newly set up dual polarization/Doppler radar in National Central University had observed one rainband induced by this typhoon. The DSD and the rainfall estimate had been derived from the dual Polarimetric radar variables including Zdr, Kdp and Rhohv. Three J-W disdrometers and one 2-D video disdrometer in northern Taiwan provide excellent ground observation of the DSD in this typhoon heavy precipitation event. The rainfall estimate agreed very well with the disdrometer and raingauge network. A modified method to correct both Zhh and Zdr error from the Kdp constrain equation has also been tested, the Gamma DSD parameters retrieval with attenuation correction and this method will be further verified with the disdrometer data. The characteristics of this winter typhoon precipitation will be presented with detail polarimetric data. The dual Doppler analysis and thermodynamic retrieval will also be carried out to study the internal structure. The cloud dynamics understanding together with the microphysical information from polarimetric data will be helpful for the precipitation mechnism of typhoon with strong orgraphic influence.