Research of the Characters of Doppler Velocity in the Typhoon Rananim's Strengthening and Heavy Rain

CINRAD/SA Doppler radar at Wenzhou City, Zhejiang province, made use of its advantaged location to probe the whole process of the development, evolvement, strengthening and speed-up near the seacoast, debarkation and declining of the 0414 Typhoon Rananim. The paper analyses the characters of the intensity field and the Doppler speed field of the typhoon detected by the radar, and discovers that the radar can catch the information of typhoon's strengthening in long-distance by using of those data probed by the radar and the data of typhoon-positioning and auto-noting rain amount. Heavy rains arose in Zhejiang province. The data of radar's Doppler velocity field reveals that the pulsation of the high altitude southwest jet, the strengthening of the upper divergence and triggering of the weak cold air near the northern side of the typhoon have a positive correlation with the special heavy rain on the background of the warm-core low pressure.