Comparisons of Two Cloud-Detection Schemes for Infrared Radiance Observations  

作　　者：XU Dong-Mei HUANG Xiang-Yu LIU Zhi-Quan MIN Jin-Zhong 

机构地区：[1]Collaborative Innovation Center on Forecast and Evaluation of Meteorological Disasters, Nanjing University of Information Science & Technology [2]National Center for Atmospheric Research

出　　处：《Atmospheric and Oceanic Science Letters》2014年第4期358-363,共6页大气和海洋科学快报（英文版）

基　　金：sponsored by the National Basic Research Program of China (973 Program, 2013CB430102);the Program of Scientific Innovation Research of College Graduate in Jiangsu Province (Grant Nos. CXZZ12-0490 and CXZZ11-0606);The National Center for Atmospheric Research is sponsored by the National Science Foundation

摘　　要：The cloud-detection procedure developed by McNally and Watts(MW03) was added to the Weather Research and Forecasting Data Assimilation System. To provide some guidelines for setting up cloud-detection schemes, this study compares the MW03 scheme to the Multivariate and Minimum Residual(MMR) scheme for both simulated and real Advanced Infrared Sounder(AIRS) radiances. Results show that there is a high level of consistency between the results from simulated and real AIRS data. As expected, both cloud-detection schemes perform well in finding the cloud-contaminated channels based on the channels' peak levels. The clouddetection results from MW03 are sensitive to the prescribed brightness temperature innovation threshold and brightness temperature gradient threshold. When increasing the brightness temperature innovation threshold for MW03 to roughly eight times the default threshold, the two cloud-detection schemes produce consistent data rejection distributions overall for high channels. MMR generally retains more data for long-wave channels. For both cloud-detection schemes, there is a high level of consistency between the cloud-free pixels and the visible/near-IR(Vis/NIR) cloud mask.The cloud-detection procedure developed by McNally and Watts （MW03） was added to the Weather Research and Forecasting Data Assimilation System. To provide some guidelines for setting up cloud-detection schemes, this study compares the MW03 scheme to the Multivariate and Minimum Residual （MMR） scheme for both simulated and real Advanced Infrared Sounder （AIRS） radiances. Results show that there is a high level of consistency between the results from simulated and real AIRS data. As expected, both cloud-detection schemes perform well in finding the cloud-contaminated channels based on the channels＇ peak levels. The cloud- detection results from MW03 are sensitive to the prescribed brightness temperature innovation threshold and brightness temperature gradient threshold. When increasing the brightness temperature innovation threshold for MW03 to roughly eight times the default threshold, the two cloud-detection schemes produce consistent data rejection distributions overall for high channels. MMR generally retains more data for long-wave channels. For both cloud-detection schemes, there is a high level of consistency between the cloud-free pixels and the visible/near-IR （Vis/NIR） cloud mask.

关 键 词：AIRS WRF data assimilation system cloud detection brightness temperature departure 

分 类 号：P407.6[天文地球—大气科学及气象学]