基于高光谱资料对FY-1C/1D气象卫星进行交叉定标

Cross-calibration of FY-1C/1D satellite based on hyper-spectral data

中文关键词:  交叉定标，光谱匹配，红外定标，FY-1C/1D

英文关键词:Cross-calibration, Spectral matching, Infrared calibration, FY-1C/1D

中文摘要:

      介绍了利用AQUA卫星高光谱AIRS资料对FY-1C、FY-1D气象卫星热红外通道进行交叉定标的方法及定标结果。首先利用卫星轨道预报软件预报出AQUA与FY-1C以及AQUA与FY-1D卫星交叉点，再对交叉区域卫星资料进行像元投影和像元匹配，像元匹配包括时间、观测角度、环境均匀性等检验。以AIRS探测结果作为辐射基准，利用其观测值和FY-1卫星热红外通道光谱响应函数进行光谱匹配，最终得到FY-1卫星热红外通道的准真值并与FY-1卫星的业务产品进行比较分析。对FY-1C、FY-1D两年多卫星资料进行多次交叉比对，结果表明FY-1C通道4比AIRS观测亮温低1.3 K左右，通道5低3.6 K左右；而FY-1D通道4比AIRS观测亮温低0.3 K左右，通道5低3.6 K左右。这个准真值与FY-1观测的计数值进行再定标得到新的定标系数。

英文摘要:

      Cross-calibration aims to inter-calibrate a diverse range of satellite instruments to produce corrections ensuring their data consistency, allowing them to be used to produce globally homogeneous products for environmental monitoring. To ensure the maximum consistency and traceability of FY-1C/FY-1D satellite data, it is desirable to perform the inter calibration using the AIRS (Atmospheric Infrared Sounder，AIRS) data and the algorithms based on the principles: Observations are collocated, and pixels are matched with the spectral, spatial and temporal as well as viewing geometry matching included，and then compared and analysed to produce calibration correction functions, transforming the observations to common references. Inter-calibration results indicate that observations of channel 4 and 5 of FY-1C are 1.3 K lower and 3.6 K lower than those of AIRS, respectively, and for FY-1D there are 0.3 K and 3.6 K lower, respectively. Re calibration which aims to produce revised sets of calibration coefficients for FY-1C/1D following its inter calibration against the reference instrument was also done. These would make data from FY-1C/1D to be consistent with the reference instrument.