长江口及邻近海域悬浮颗粒物对叶绿素a遥感反演算法的影响分析

利用水介质光辐射传输数值模型Hydrolight,结合前人对长江口及邻近海域水体的生物—光学模型研究,模拟不同光学水体的遥感反射率,并分析遥感反射率对悬浮颗粒物(SPM)的敏感性以及SPM对4种叶绿素a(Chla)反演算法(二波段、三波段、荧光基线高度(FLH)和综合叶绿素指数(SCI)算法)的影响。结果表明:由Hydrolight模拟得到的遥感反射率与现场同步实测的遥感反射率的均方根误差小于0.01sr-1,其中可实现遥感反射率在550~725nm波段较精确的模拟。遥感反射率对SPM的敏感性随着Chla浓度的升高而降低。二波段、三波段算法适合低SPM浓度水体的Chla浓度反演,FLH算法反演Chla浓度时易受SPM的影响,而SCI算法在中、高SPM浓度水体中消除SPM的影响进而反演Chla的潜力较好。

Influence of Suspended Particulate Matter on Chlorophyll\|a Retrieval Algorithms in Yangtze River Estuary and Adjacent Turbid Waters

Combined with bio\|optical model of the Yangtze River Estuary and adjacent water,this study utilized underwater light filed simulation model Hydrolight to obtain remote sensing reflectance spectra of various water types.The sensitivity of remote sensing reflectance to suspended particulate matter(SPM)and the influence on four kinds of chlorophyll\|a(Chla)retrieval algorithms(two\|band algorithms,three\|band algorithm,fluorescent light height(FLH)algorithm,synthetic chlorophyll index(SCI)algorithm)by SPM were analyzed.Results showed that the RSME between the Hydrolight simulated remote sensing reflectance and that of in situ measurements were smaller than 0.01 sr-1,with higher simulation accuracy of remote sensing reflectance from 550 nm to 725 nm.The impact of SPM on remote sensing reflectance decreased with an increase of Chla concentration,which means a decrease of sensitivity.The two\|band and three\|band algorithms were suitable for chlorophyll\|a retrieval with low SPM concentration.FLH was highly influenced by SPM when retrieving Chla,while SCI exhibited better potential of dismissing the influence of SPM when retrieving Chla in highly turbid waters.