Improving Polarimetric C-Band Radar Rainfall Estimation with Two-Dimensional Video Disdrometer Observations in Eastern China
Improving Polarimetric C-Band Radar Rainfall Estimation with Two-Dimensional Video Disdrometer Observations in Eastern China
复制标题
利用二维视频测速仪观测中国东部地区改进偏振 C 波段雷达降雨量估算
DOI：
10.1175/jhm-d-16-0215.1
复制
发表时间：
2017-05-01
影响因子：
3.8
通讯作者：
Zhu, Wenjian
中科院分区：
文献类型：
--
作者：
Chen, Gang;Zhao, Kun;Zhu, Wenjian
In this study, the capability of using a C-band polarimetric Doppler radar and a two-dimensional video disdrometer (2DVD) to estimate monsoon-influenced summer rainfall during the Observation, Prediction and Analysis of Severe Convection of China (OPACC) field campaign in 2014 and 2015 in eastern China is investigated. Three different rainfall R estimators, for reflectivity at horizontal polarization [R(Z(h))], for reflectivity at horizontal polarization and differential reflectivity factor [R(Z(h), Z(dr))], and for specific differential phase [R(K-DP)], are derived from 2-yr 2DVD observations of summer precipitation systems. The radar-estimated rainfall is compared to gauge observations from eight rainfall episodes. Results show that the two polarimetric estimators, R(Z(h), Z(dr)) and R(K-DP), perform better than the traditional Z(h)-R relation [i.e., R(Z(h))]. The K-DP-based estimator [i.e., R(K-DP)] produces the best rainfall accumulations. The radar rainfall estimators perform differently across the three organized convective systems (mei-yu rainband, typhoon rainband, and squall line). Estimator R(Z(h)) overestimates rainfall in the mei-yu rainband and squall line, and R(Z(h), Z(dr)) mitigates the overestimation in the mei-yu rainband but has a large bias in the squall line. QPE from R(K-DP) is the most accurate among the three estimators, but it possesses a relatively large bias for the squall line compared to the mei-yu case. The high variability of drop size distribution (DSD) related to the precipitation microphysics in different types of rain is largely responsible for the case-dependent QPE performance using any single radar rainfall estimator. The squall line has a distinct ice-phase process with a large mean size of raindrops, while the mei-yu rainband and typhoon rainband are composed of smaller raindrops. Based on the statistical QPE error in the Z(H)-Z(DR) space, a new composite rainfall estimator is constructed by combining R(Z(h)), R(Z(h), Z(dr)), and R(K-DP) and is proven to outperform any single rainfall estimator.
