WHI的场地外定标和二类水体的大气纠正

WHI(Wide field-of-view Hyperspectral Imager)是具有5nm光谱分辨率的航空成像光谱仪,光谱范围从406nm到985nm。为评价该传感器在二类水体水质监测的性能,2006年1月9日在太湖地区进行航空飞行,并利用ASD和CE318同步测量水面光谱和大气参数。为比较准确的反演水质参数,对该传感器进行场地定标和替代定标,场地定标是对实验室定标后的辐亮度进行再次定标,替代定标利用同步点水面光谱计算的遥感反射率对图像计算的遥感反射率进行标定。最后对WHI进行大气纠正得到太湖的遥感反射率,并利用其他的准同步点进行精度检验,在532nm到750nm之间的大气纠正误差不超过5%。

WHI in-situ calibration and atmosphere correction in case-Ⅱwater

Wide field-of-view Hyperspectral Imager(WHI) is an airborne imaging spectrometer with a 5nm spectral resolution,of which the spectrum ranges from 406nm to 985nm.For evaluating its application in case-Ⅱwater,a flight was carried out in Taihu in January 9,2006.Meanwhile,the in-situ measured spectra by ASD and measured atmosphere parameters by sun photometer CE318 were also accomplished.Before retrieving water-quality parameters,two crucial recalibration processes were done:Field recalibration was accomplished by comparing the two calibration targets' modeling radiance at sensor level and their lab calibrated radiance;Vicari- ous calibration was done by comparing the 6S atmosphere corrected remote sensing reflectance (Rrs) with the in-situ measured Rrs of a synchronous station.Then,atmosphere correction Rrs was performed by 6S model to retrieve Rrs of Taihu and the accuracy was no more than 5% from 532nm to 750nm validated by other two synchronous stations.