Polarimetric radar measurements and rainfall performance during an extreme rainfall event in complex terrain over Eastern China

A torrential flood event occurred over the complex terrain in Zhejiang on 23 June 2015 is investigated utilizing the first routinely operational C-band polarimetric radar in China. The polarimetric radar quantitative precipitation estimation (QPE) performance is verified using a local rain gauge network, and the microphysical characteristics of the rainstorm are revealed based on polarimetric radar variables. The results show that (i) radar QPE estimator based on $K_{\text{DP}}$ performs the best among all estimators; (ii) the rainstorm upon the rainfall center area was dominated by small-moderate sized raindrops with mean volume diameter less than 2 mm, but high raindrop concentration with $\text{log}10(N_{\mathrm{w}})$ exceeding 5 mm−1m−3, resulting in rather high liquid water content; (iii) small hailstones were falling and melting upon the intense rainfall area between gauge stations, which compounded the complex precipitation structure and enhanced raindrop concentration.