Impacts of Raindrop Fall Velocity and Axis Ratio Errors on Dual-Polarization Radar Rainfall Estimation
Impacts of Raindrop Fall Velocity and Axis Ratio Errors on Dual-Polarization Radar Rainfall Estimation
复制标题
雨滴下落速度和轴比误差对双偏振雷达雨量估算的影响
DOI：
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发表时间：
2014
期刊：
影响因子：
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通讯作者：
M. Gebremichael
中科院分区：
文献类型：
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作者：
Bin Pei;F. Testik;M. Gebremichael
通过对雨滴降落速度和轴比偏差的观测，研究了雨滴降落速度和轴比偏差对双极化雷达降水估计的影响。雷达降雨量检索算法[科罗拉多州立大学-水文气象识别降雨优化（CSU-HIDRO）]用作测试床。随后的调查确定，可用的现场测量，这是非常有限的范围内，下降速度和轴比偏差表明降雨率估计误差约为20%。基于这些发现，然后使用预测值周围的不相关的跌倒速度和轴比偏差进行敏感性研究。显着的降雨率估计误差的下降速度和轴比偏差的现实组合。结果表明，当风速和轴比偏差（每个组合模拟5000个雨滴粒径分布样本）在预测值的210%~ 110%之间时，雨率估计的最大误差可达200%左右。对于相同的下落速度和轴比偏差组合，误差的最大标准差高达75%。作者发现，在自然降雨过程中，使用双极化雷达准确估计降雨量，也需要对雨滴下落速度和轴比的参数化进行分析。这些参数化应考虑这两个参数之间的耦合和可能引入这些参数的预测值的任何可能偏差的因素。
Motivated bythefieldobservations offallvelocity andaxis ratio deviationsfrom predictedterminal velocity and equilibrium axis ratio values, the combined effects of raindrop fall velocity and axis ratio deviations on dual-polarization radar rainfall estimations were investigated. A radar rainfall retrieval algorithm [Colorado State University‐Hydrometeor Identification Rainfall Optimization (CSU-HIDRO)] served as the test bed. Subsequentinvestigationsdeterminedthattheavailablefieldmeasurements,whichwereverylimitedinscope, of the fall velocity and axis ratio deviations indicated rain-rate estimation errors of approximately 20%. Based on these findings, a sensitivity study was then performed using uncorrelated fall velocity and axis ratio deviations around the predicted values. Significant rain-rate estimation errors were observed for the realistic combinations of fall velocity and axis ratio deviations. It was shown that the maximum rain-rate estimation errorcanreachuptoapproximately200%forcombinationsoffallvelocityandaxisratiodeviations(5000drop size distribution samples were simulated for each combination) between 210% and 110% of the predicted values for each. The maximum standard deviation of errors was as great as 75% for the same combinations of fall velocity and axis ratio deviations. The authors found that use of dual-polarization radars to accurately estimaterainfall,duringnaturalrainevents,alsorequiresareanalysisoftheparameterizationsforraindropfall velocity and axis ratio. These parameterizations should consider both the coupling between these two parameters and factors that may introduce any possible deviations of the predicted values of these parameters.