珠江河口海水表层盐度光学遥感反演研究

A Study on Optical Remote Sensing Inversion of Sea Surface Salinity in the Pearl River Estuary

以光学遥感数据反演海水表层盐度时,常以有色可溶性有机物(CDOM)为中介指示盐度的变化。但因河口水动力环境的时空异质性,指示盐度的中介参数并不恒定。该文以珠江河口为研究区,于洪水季、枯水季以走航方式获取水质及同步光谱数据,通过不同时空条件下表层盐度与各水质参数的相关性分析,确定相应的表层盐度敏感因子;利用相关性分析与回归分析建立研究区表层盐度光学遥感反演模型,并结合咸情站实时数据对反演结果进行标定。结果表明:1)珠江河口表层盐度反演的敏感因子具有时空变异性,洪季以总悬浮物(TSM)为宜,枯季伶仃洋及上游水域以高锰酸盐指数(CODMn)为宜、磨刀门水域以叶绿素a(Chla)为宜;2)经咸情站标定后遥感反演结果的标准误差被控制在1‰以下,提高了光学遥感反演表层盐度的绝对精度;3)涨潮时珠江河口表层盐度普遍高于落潮阶段,盐度分布呈南高北低、自口外向口内递减趋势。

When using optical remote sensing data to retrieve the sea surface salinity,Colored Dissolved Organic Matter(CDOM)is usually required as an intermediary to indicate its change.However,the spatiotemporal variability of estuarine hydrodynamic environment results in the instability of intermediate parameters indicating salinity.In this paper,water quality parameters and in-situ reflection spectrum were acquired during the dry and flood seasons of the Pearl River Estuary.The correlation analysis was made between water quality parameters and the sea surface salinity under the different space-time conditions,and then the sensitive parameters of salinity were determined.Accordingly,the optical remote sensing inversion models for salinity were established via correlation and regression analysis.The results were further calibrated by measured data of salinity stations.It′s found as follows.1)The Total Suspended Matter(TSM)is advisable to retrieve surface salinity in flood season for the entire estuarine region,and the Chemical Oxygen Demand tested by Mn(CODMn)and Chlorophyll-a(Chla)are suited to be employed as sensitive factors in dry season for Lingdingyang Bay and Modaomen Estuary respectively.2)The calibration results have showed higher absolute accuracy,the RMSE is less than 1‰.3)Sea surface salinity of the estuary during flood tide is generally higher than that during ebb tide.Spatially,the salinity declines from the south open waters to the north coastal regions,and declines from the regions outside the estuary to regions inside the estuary.