Evaluation of multiple surface irradiance-based clear sky detection methods at Xianghe—A heavy polluted site on the North China Plain  

香河站太阳辐射识别晴空方法的评估

作　　者：Mengqi Liu Jinqiang Zhang Xiangao Xia 

机构地区：[1]Key Laboratory of Middle Atmosphere and Global Environment Observation,Institute of Atmospheric Physics,Chinese Academy of Sciences,Beijing,China [2]University of Chinese Academy of Sciences,Beijing,China [3]Collaborative Innovation Center on Forecast and Evaluation of Meteorological Disasters,Nanjing University of Information Science&Technology,Nanjing,China

出　　处：《Atmospheric and Oceanic Science Letters》2021年第2期7-12,共6页大气和海洋科学快报（英文版）

基　　金：supported by the National Key R&D Program of China grant number 2017YFA0603504;the Strategic Priority Research Program of the Chinese Academy of Sciences grant number XDA17010101;the National Natural Science Foundation of Chinagrant number 41875183。

摘　　要：Surface irradiance measurements with high temporal resolution can be used to detect clear skies,which is a critical step for further study,such as aerosol and cloud radiative effects.Twenty-one clear-sky detection(CSD)methods are assessed based on five years of 1-min surface irradiance data at Xianghe—a heavily polluted station on the North China Plain.Total-sky imager(TSI)discrimination results corrected by manual checks are used as the benchmark for the evaluation.The performance heavily relies on the criteria adopted by the CSD methods.Those with higher cloudy-sky detection accuracy rates produce lower clear-sky accuracy rates,and vice versa.A general tendency in common among all CSD methods is the detection accuracy deteriorates when aerosol loading increases.Nearly all criteria adopted in CSD methods are too strict to detect clear skies under polluted conditions,which is more severe if clear-sky irradiance is not properly estimated.The mean true positive rate(CSD method correctly detects clear sky)decreases from 45%for aerosol optical depth(AOD)≤0.2%to 6%for AOD>0.5.The results clearly indicate that CSD methods in a highly polluted region still need further improvements.根据位于华北平原的重污染站点——香河5年的分钟级别地表太阳辐射和人工订正的全天空成像仪数据,对21种晴空识别(CSD)方法进行了评估:晴空识别准确率较高的方法云天识别准确率较低,反之亦然;由于CSD方法采用的参数阈值不适用于污染情况,当气溶胶含量增加时,识别准确率呈下降趋势.研究结果显示,利用太阳辐射数据识别晴空的方法在高污染地区使用时需进行改进.

关 键 词：Clear-sky detection methods Surface irradiance POLLUTION Total-sky imager 

分 类 号：TK511[动力工程及工程热物理—热能工程] P422.1[天文地球—大气科学及气象学]