雨滴谱仪资料在“温比亚”台风降水估测中的应用探究

Application of Raindrop Disdrometer Data in Rainfall Estimation of Typhoon Rumbia

利用台风温比亚(1808)登陆阶段受外围云系降水影响的上海、浙江、江苏、安徽四个省(直辖市)42个雨滴谱仪站点数据,对比分析雨滴谱仪数据计算获得的雷达反射率因子、降水强度分别与雷达实测、雨量计实测的差异;进行Z-R关系拟合,以探究台风降水回波与降水强度的关系;分别利用两种Z-R关系进行降水估测效果对比,以探究雨滴谱仪资料在台风雷达降水估测中的应用效果。结果表明:雨滴谱仪数据计算得到的雷达反射率因子与雷达观测一致性较好,两者相关系数为0.96,前者略小于后者。雨滴谱仪数据计算得到的降水强度与雨量计观测的降水强度相比,变化趋势一致,相关系数为0.94,但在量值上,部分区域仪器存在较大的差异,其可能原因:一是该区域内仪器本身系统误差,二是受台风大风影响,雨滴下落速度快,容易发生破碎、重叠等,使到达地面的雨滴直径、数目产生一定的误差。台风温比亚外围云系降水回波与强度的拟合公式:Z=188.85 R^(1.42),利用此关系的估测效果优于默认关系Z=300 R^(1.4),估测降水量提高近17%左右。

Based on the raindrop disdrometer data of 42 stations in Shanghai,Zhejiang,Jiangsu and Anhui during the precipitation process of Typhoon Rumbia(1808),this paper compares and analyzes the difference between the radar reflectivity calculated from raindrop size distribution and the actual measurement based on radar,and the difference between the raindrop size distribution inversion rain rate and gauge actual observation.The Z-R relationship fitting is carried out to explore the relationship between radar echo and the precipitation intensity of typhoon.Two kinds of Z-R relations are used for comparative analysis of precipitation estimation so as to explore the application effect of raindrop size distribution.The main results are as follows.The radar reflectivity factor of raindrop disdrometers inversion is consistent with radar observation,with correlation coefficient being 0.96,and the former is slightly smaller than the latter.Comparison suggests that the rainfall intensity observed by rain gauge and the precipitation intensity calculated by raindrop disdrometer data have the almost same varying trend,and their correlation coefficient is 0.94.However,the values from some instruments have great differences in some regions,which may be caused by the system error of the instrument itself in the region,and also by the influence of typhoon.When raindrops fall to the ground,the falling speed is fast so that they are easy to break,overlap,etc.This could cause some errors in the diameter and number of drops.In addition,the fitting formula of precipitation echo and intensity of the cloud system around the Typhoon Rumbia is Z=188.85 R^(1.42).The estimation effect by using this relationship is better than using the default relationship Z=300 R^(1.4),increasing by about 17%of precipitation estimation.