MERIS卫星数据定量反演长江河口的悬沙浓度

QUANTITATIVE RETRIEVAL FOR SUSPENDED SEDIMENT CONCENTRATION BY USING MERIS SATELLITE DATA IN THE YANGTZE RIVER ESTUARY

悬浮泥沙浓度是描述水质的重要参数,获取其空间和时间上的分布,有助于水环境监测及泥沙输运观测。首先介绍了欧空局(ESA)发射的ENVISAT上携带的中分辨率成像光谱仪(MERIS)基本特点,其数据较SeaWiFS、MODIS在水色波段设置和灵敏度上具有一定优势,然而在我国高浑浊河口如长江口,MERIS二级产品如离水辐射率和总悬浮物浓度的反演结果与实测数据有较大的偏差。故直接利用其一级数据即传感器接收到的辐射率,采用基于辐射传输模型的MODTRAN算法进行大气校正以获得水表遥感反射率。应用遥感反射率与悬沙浓度的关系模型,反演了2005年夏季三个寻常潮(7月30日、8月3日、8月9日)悬沙浓度。通过对反演结果与实测数据进行分析,得出反演偏差可由二级产品90%相对误差降低到53%左右。最后给出了2005年8月15日、9月16日悬沙浓度分布图,通过分析得出利用MERIS数据反演高浑浊河口悬沙浓度是可行的。

Suspended sediment concentration （SSC） is one of the most significant parameters of water quali- ty. Acquiring spatial and temporal distribution of SSC is helpful in water environment monitoring and sediment distribution investigation. In this paper,a brief introduction of data format of Medium Resolution Imaging Spectrometer （MERIS） is firstly made before the comparison among MERIS. SeaWiFS and MODIS. It has great advantage of band setting and the radiometric sensitivity,and will contribute enormously to the ocean color research. As the error between the MERIS Level 2 and in-situ data is large in China high-turbid coastal water,the retrieval algorithm should be modified according to the characteristics of case Ⅱ waters. And then the algorithm is applied to three summer normal tidal images in 2005 after atmosphere correction. The error between the retrieval and the in-situ data is descended to 53 percents,which is lower than the error between MERIS Level 2 and in-situ data. So the empirical model developed in this paper is superiority in the Yangtze River. At last,SSC distribution map of 15th. Aug. is given with some preliminary analysis.