杭州湾HJ CCD影像悬浮泥沙遥感定量反演

利用环境小卫星CCD(HJ CCD)影像对杭州湾悬浮泥沙浓度(SSC)进行了反演研究。通过对杭州湾水体遥感反射率(Rrs)与SSC进行相关性分析发现,在690nm和830nm左右出现显著的反射峰,分别位于HJ CCD影像的第3和第4波段范围内;大于700nm波长处的Rrs与SSC相关性较好。基于实测Rrs和SSC之间的相关关系,利用第4和第3波段比值作为遥感因子建立SSC反演模型,模型决定系数达到0.90。借鉴近红外-短波红外(NIR-SWIR)结合的大气校正方法反演出的准同步MODIS气溶胶数据,实现了HJ CCD影像的大气校正,第3、第4波段的大气校正结果相对误差分别为5.54%和6.97%。结果显示,HJ CCD影像反演的SSC相对误差为7.12%;杭州湾悬浮泥沙浓度要显著高于长江口,且内部差异明显。研究表明,通过适当的大气校正方法和反演算法,HJ CCD影像可用于杭州湾悬浮泥沙浓度的估计。

Assessment of suspended sediment concentration at the Hangzhou Bay using HJ CCD imagery

This research explored the potential of the use of the CCD image of the HJ satellite to derive Suspended Sediment Concentrations (SSC) of dynamic water bodies at Hangzhou Bay, which is a typical turbid water body in China. Through the analysis on the correlation between Remote Sensing Reflectance (R_rs) and SSC, two apparent reflectance peaks at approximately 690 and 830 nm have been found in the third and fourth bands, respectively. The result also shows that a good correlation exists between R_rs and SSC when the wavelength is more than 700 nm. Based on the measured correlation between SSC and R_rs, the retrieval model is established using the ratio of band4 and band3 as remote sensing factor, and the model determination coefficient of 0.90 is reached. Through the Moderate Resolution Imaging Spectroradiometer (MODIS)-derived Aerosol Optical Depth (AOD) data, which are calculated from the Near Infrared-Short Wave Infrared (NIR-SWIR) atmospheric correction, the atmospheric correction of HJ CCD imagery is realized. The correction-relative errors of the third and fourth bands are 5.54% and 6.97%, respectively. The result demonstrates that the relative error of SSC derived from HJ CCD imagery is 7.12%, and SSC at Hangzhou Bay, which also has significant internal diversity, is much higher than that in the entrance of the Yangtze River. This research demonstrated that HJ CCD imagery can be used to evaluate SSC at Hangzhou Bay, if the appropriate atmospheric correction method and retrieval algorithm are used.