海洋卫星COMs-1(Communication, Ocean & Meteorological Satellite-1)上携带的GOCI(Geostationary Ocean Color Imager)传感器以海洋监测为主,也具备较好 的陆地监测潜力,但传感器陆地辐射特性存在偏差。为改善GOCI陆地辐射特性,基于MODIS数据,对GOCI可见光 和近红外波段开展交叉辐射定标,弥补场地定标成本较高、定标参数更新周期长的不足,拓展其陆地定量遥感监测能力。交叉辐射定标中,考虑了GOCI和MODIS传感 器相应波段光谱响应函数之间的匹配; 通过辐射传输模拟,订正两传感器观测角度对辐射定标的影响;通过选取两传感器同一过境时刻的数据,降低太阳角度对 辐射定标的影响,提高交叉定标精度。通过MODIS数据模拟的GOCI相应波段的表观辐亮度与GOCI实测结果比对, R2大于0.88。对定标结果进行初步验证,表明交 叉辐射定标后, GOCI陆地上的辐射特性满足基本的定量遥感需求。

The Korea Geostationary Ocean Color Imager (GOCI) onboard COMs-1 (Communication, Ocean & Meteorological Satellite-1) is mainly designed for ocean observation, and it has a good potential for land monitoring. Cross calibration between GOCI and the US Moderate Resolution Imaging Spectrometer (MODIS) can improve the land radiation characteristics of GOCI, which can expand its ability in land observation. In cross calibration, the effects from spectral response of two sensors are considered and the impacts of the differences between GOCI and MODIS viewing angles in calibration are revised by radiative transfer simulation. Meanwhile, satellite data in the same transit time of two sensors are chosen in order to reduce the effects from different sun zenith angles. Cross calibration results show that the simulated top of atmosphere (TOA) radiance from MODIS agrees well with GOCI measured TOA radiance, and the value of R2 is greater than 0.88. Preliminary validation of calibration results shows that the cross calibration method can meet the accuracy requirements of general quantitative remote sensing applications.