气象2017，Vol.43Issue(2)：213-220,8.DOI:10.7519/j.issn.1000-0526.2017.02.009
高光谱红外云检测方案阈值的客观判定方法
Objective Determination Scheme of Threshold in High-Spectral-Resolution Infrared Cloud Detection
摘要
Abstract
The clear channel scheme presented by McNally and Watts (2003 )is used to detect cloud radi-ances in GRAPES-3Dvar system measured by high-spectral-resolution infrared sounders.This scheme is based on the bias of simulated radiances and actual radiances,and the determination of bias is related to forecast model.Traditionally,we use subjective determination schemes to select threshold in cloud detec-tion,such as image contrast analysis.This paper presents two new and objective schemes based on the subjective scheme.(1)Analysis of view field bias:observe the cloud top pressure under different thresh-olds to evaluate the rationality by analyzing the vertical distribution of bias between simulated observation and actual observation.(2 )Evaluation of cloud detection index:establish a series of cloud evaluation indi-ces to select appropriate thresholds.By combining the three methods mentioned above,we determine the IASI radiances cloud detection.The gradient threshold keeps the same value as that from European Center for it has a weak effect in cloud detection.The bias threshold is determined by a comprehensive analysis method,thus overcoming the visual error of the pure use of image.The results show that bias threshold selects 2.0 K,gradient threshold selects 0.4 K for window channels and 0.02 K for non-window channels. Finally,a month-long experiment shows that the cloud detection bias threshold is effective by comparing the assimilation results.关键词
云检测阈值/偏差/客观判定/IASIKey words
threshold of cloud detection/bias/objective determination/IASI (Infrared Atmospheric Sounding Interferometer)分类
天文与地球科学引用本文复制引用
邓松,李刚,张华..高光谱红外云检测方案阈值的客观判定方法[J].气象,2017,43(2):213-220,8.基金项目
公益性行业(气象)科研专项(GYHY201206002 和GYHY201506003)共同资助 （气象）
