从NOAA卫星AVHRR资料反演中国区域地表反照率

Retrieving Surface Albedos over China from NOAA AVHRR Data

由NOAA卫星AVHRR短波通道1、2反射率反演地表反照率需要3个反演模式,分别是窄-宽波段反射率转换模式、大气顶双向反射模式、大气订正模式.基于模式和国家卫星气象中心接收处理的NOAA-18 AVHRR1B数据,处理了2006年1月至2010年12月的中国区域地表反照率,由于云的影响,15天合成技术用来形成周期为15天的地表反照率数据文件.2006年、2010年2年的处理结果与MODIS同类产品对比,RMS为0.028～0.074、相关系数为0.76～0.93,误差较大出现在冬季,原因是两者15天合成方法不同；5年的日平均地表反照率与21个中国地面气象一级辐射站的观测测值作对比,结果是：RMS为0.053、相关系数为0.88.反演模式系统误差以及云和气溶胶影响是卫星反演地表反照率的主要误差来源.

The TOA narrow to broadband conversion model, bidirectional reflectance model, and atmospheric correction model are the necessary models for retrieving surface albedos with reflectance from NOAA AVHRR. Based on the models and NOAA-18 AVHRR 1B data, the clear-sky surface albedos in the area of 10°to 60°N and 65°to 145°E with a resolution of 0. 01° × 0.01°lat/lon from January 2006 to December 2010 are calculated. A 15-day data combination technology is used to produce the albedo products in a 15-day cycle. Comparison is conducted between the two-year products and MODIS measurements. The RMSs are 0. 028 to 0. 074, correlation coefficients are 0.76 to 0.93. The larger errors occurred in winter are caused by the different combination technologies adopted by the two products. The daily mean surface albedos from 21 first-class surface meteorological radiation stations over China are selected and compared with the produced data. The results show： RMS is 0. 053, and the correlation coefficient is 0. 8808. The impacts of Clouds and aerosols are the main error sources of surface albedo retrieval from satellite.