| 贵州地区CMORPH卫星降水产品的误差订正 |
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| 引用本文： | 王福增,何山,谷晓平,于飞,杨玲.贵州地区CMORPH卫星降水产品的误差订正[J].热带气象学报,2021,37(2):166-174. |
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| 作者姓名： | 王福增 何山 谷晓平 于飞 杨玲 |
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| 作者单位： | 1.成都信息工程大学电子工程学院，四川成都 610225 |
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| 基金项目： | 国家重点研发计划2018YFC1507201 |
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| 摘 要： | CMORPH卫星反演降水产品具有全天候、全球覆盖的特点，其时空分布相对均匀、独立，但是CMORPH本质上是通过间接手段反演得到，其降水精度无法与地面观测降水精度相比，并且存在一定的系统误差。结合地面自动站降水资料采用概率密度匹配法对贵州地区CMORPH卫星反演降水产品进行系统误差订正，该方法将每个格点的卫星降水累积概率分布曲线和地面降水概率密度分布曲线匹配，获取降水误差订正值；其中误差订正效果受降水累积概率分布拟合曲线的影响，而考虑到降水累积概率分布是非正态分布，因此选用Gamma分布拟合降水累积概率分布曲线。通过对2018年5月三次降水过程的订正结果分析得到如下结论:(1) 逐时的CMORPH卫星反演降水产品存在明显的非独立系统误差，误差范围随降水量级的变化而变化，存在低值高估的特点；(2) 在小时尺度下地面降水的累积概率密度呈指数衰减分布，而CMORPH的降水累积概率密度分布更加复杂，其在中雨、大雨区间内的降水概率较高；(3) 通过概率密度匹配法订正后的CMORPH与订正前相比降水空间结构更加贴近地面降水，强降水中心的量级和范围明显减小，平均绝对误差和均方根误差均减小，其中偏差订正值在0.114~0.468 mm/h，均方根误差订正在0.24~1.49 mm/h之间。经概率密度匹配法订正后的CMORPH卫星反演降水产品精度明显提升，更加接近于实际降水。
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| 关 键 词： | CMORPH卫星反演降水产品 地面降水 概率密度匹配法 误差订正 Gamma分布函数 |
| 收稿时间： | 2020-07-30 |
BIAS CORRECTION OF CMROPH SATELLITE PRECIPITATION PRODUCTS OVER GUIZHOU |
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| WANG Fu-zeng,HE Shan,GU Xiao-ping,YU Fei,YANG Ling.BIAS CORRECTION OF CMROPH SATELLITE PRECIPITATION PRODUCTS OVER GUIZHOU[J].Journal of Tropical Meteorology,2021,37(2):166-174. |
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| Authors: | WANG Fu-zeng HE Shan GU Xiao-ping YU Fei YANG Ling |
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| Institution: | 1.College of Electronic Engineering, Chengdu University of Information Technology, Chengdu 610225, China2.Guizhou Ecological Meteorology and Satellite Remote Sensing Center, Guiyang 550002, China3.Guizhou Institute of Mountainous Climate and Environment, Guiyang 550002, China |
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| Abstract: | The CMORPH satellite-retrieved precipitation products feature all-weather and global coverage, and their spatio-temporal distribution is relatively uniform and independent. However, CMORPH products are obtained using indirect methods, their accuracy is lower than that of ground observations, and there is systematic bias. Using the precipitation data from ground automatic stations, this paper adopts the probability density matching method to correct the system bias of the CMORPH satellite precipitation products over Guizhou. The satellite precipitation cumulative probability distribution curve of each grid point is matched with the surface precipitation probability density distribution curve to correct precipitation bias, and the process is influenced by the precipitation cumulative probability distribution fitting curve. Given that the precipitation cumulative probability distribution is non-normal, Gamma distribution is selected to fit the precipitation cumulative probability distribution curve. Through the analysis of the correction results of three precipitation processes in May 2018, following conclusions are obtained: (1) There is obvious and non-independent systematic bias in the hourly CMORPH satellite-retrieved precipitation products. The bias varies with the level of precipitation, and sometimes precipitation is overestimated. (2) On the hourly scale, the cumulative probability density of surface precipitation shows an exponential decay distribution, while the cumulative probability density distribution of CMORPH products is more complicated, and the probability of precipitation in the interval of moderate rain and heavy rain is higher. (3) The CMORPH products corrected by using the probability density matching method are closer to ground precipitation than those before the correction. The magnitude and range of heavy precipitation center are significantly reduced, and the average absolute error and root mean square error are reduced. The deviation correction value is between 0.114~0.468 mm/h, and the root means square error is between 0.24~1.49 mm/h. The accuracy of the CMORPH satellite precipitation products after correction by using the probability density matching method has been significantly improved and is closer to actual precipitation. |
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| Keywords: | CMROPH precipitation product surface precipitation probability density matching method error correction gamma distribution function |
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