基于Himawari-8卫星成像仪的深对流云BRDF特性建模  

Modeling of BRDF Characteristics of Deep Convective Cloud Based on Himawari-8 Satellite Imager

作　　者：周为伟 胡秀清[2,3] 杨磊库 Zhou Weiwei;Hu Xiuqing;Yang Leiku(School of Survey and Land Information Engineering,Henan Polytechnic University,Jiaozuo 454003,Henan,China;Key Laboratory of Radiometric Calibration and Validation for Environmental Satellites,National Satellite Meteorological Center(National Center for Space Weather),China Meteorological Administration,Beijing 100081,China;Innovation Center for FengYun Meteorological Satellite(FYSIC),Beijing 100081,China)

机构地区：[1]河南理工大学测绘与国土信息学院,河南焦作454003 [2]中国气象局中国遥感卫星辐射测量和定标重点开放实验室,国家卫星气象中心(国家空间天气监测预警中心),北京100081 [3]许健民气象卫星创新中心,北京100081

出　　处：《光学学报》2023年第12期265-275,共11页Acta Optica Sinica

基　　金：国家重点研发计划(2022YFB3902901,2018YFB0504901)。

摘　　要：深对流云是卫星传感器可见光与近红外波段替代定标的地球稳定目标,其方向反射特性是影响场地定标精度的重要参数。为了提高定标的准确性,需要双向反射率(BRDF)模型进行各向异性因子校正。基于Himawari-8卫星成像仪,利用提取的2016—2020年期间深对流云数据,依据查找表方法实现BRDF特征建模。在同一角度下对比业务化Hu模型归一化后的各向异性因子,分析两种模型降低深对流云响应标准误差的校正效果,并将经本文模型校正的长时间序列深对流云反射率数据和定标系数方法计算的仪器衰减率进行比较。研究结果表明,在可见-近红外波段范围内BRDF特性差异较小,与Hu模型相比,该方法表现出较高的一致性,使用本文模型校正后的深对流云响应标准误差小于Hu模型,且计算衰减率数值基本一致。在短波红外通道,本文模型与Hu模型相比,各向异性特征差异较大,使用Hu模型校正后标准误差增大,而使用本文模型校正后,标准误差最高可减少31%,在深对流云与定标系数计算衰减结果方面存在差异,这可能与短波红外通道的波动太大相关。因此,基于Himawari-8卫星成像仪对深对流云的BRDF特征建模是可行的。Objective Deep convective cloud has high,stable,and reliable reflectivity in the visiblenear infrared(VIS/NIR)band,which is suitable for radiometric calibration.In addition,the development of deep convective clouds is deeply located at the top of the troposphere and is less affected by water vapor absorption and aerosols.The deep convective cloud is mainly distributed in the equatorial region,which is suitable for the calibration of polar orbit and geostationary satellites.However,the deep convective cloud is not a real Lambertian target.When the satellite detects from different observation angles,the anisotropy characteristics of the deep convective cloud make the satellite observation biased,which leads to calibration errors.Therefore,it is necessary to analyze the directional reflectance characteristics of deep convective clouds and establish an effective bidirectional reflectance distribution function(BRDF)to correct the directional reflectance and improve the calibration accuracy.The operational Hu model is not only inapplicable to the shortwave infrared channel but also has a slight influence on the data stability in the VIS/NIR channel when the eigenvalue is selected as the mean reflectivity.Since the previously constructed model has been relatively long compared with the current one and may be affected by human activities,the anisotropic reflection factors of deep convective clouds will change to some extent.The operational Hu model and CERES thick ice cloud model are broadband models.Therefore,we use the latest data to model the BRDF characteristics of deep convective clouds,which can better characterize the directional characteristics of deep convective cloud reflectivity.Modeling each channel separately can make up for the deficiency that the Hu model and CERES thick ice cloud model are broadband models.For the modeling of the shortwave infrared channel,it can fill the gap that the Hu model used by the current business is not applicable to the shortwave infrared channel,and it is of great significance

关 键 词：传感器 大气散射 深对流云 后向散射 双向反射率函数 

分 类 号：P407[天文地球—大气科学及气象学]