Evaluation Research On Chlorophyll Concentration Retrieval By FLH Algorithm In Bohai Sea

Bohai Sea is an approximately close sea with shallow water depth in China. It is typical Caseâ…¡water, and there are many difficulties in retrieving ocean color parameters. Chlorophyllconcentration retrieval in Bohai Sea is research focus until now. Fluorescence baseline height (FLH)algorithm is different with other ocean color algorithms; it may be obtained higher retrievalprecision because of using wave band that is responded only by chlorophyll fluorescence.Supported by China-Europe cooperation program i.e. Dragon Project, this paper choose BohaiSea as research sea area. Taking medium resolution imager MERIS as example, the paper studychlorophyll concentration retrieval ability of FLH algorithm. The main work and conclusions asfollows:Firstly, leaving water radiance of water body in different environmental conditions (chlorophyllconcentration, suspended matter concentration, yellow matter concentration and water depth) wassimulated by software Hydrolight. The influences of environmental conditions on FLH algorithmwere analyzed by the MERIS design bands. The results indicate that the variation of the yellowmatter concentration has little influence on FLH, and FLH is unsuitable when water depth is small(1m) or the suspended matter concentration is larger than 8mg/L. When the suspended matterconcentration is less and equal than 8mg/L, FLH algorithm may be suitable for the inversion ofChlorophyll concentration.Secondly, the algorithm expression FLH=0.327+0.106C/(1+0.052C) which is suitable forBohai Sea was obtained by regressing the simulating data, where FLH is the fluorescence baselineheight, C is chlorophyll concentration. The algorithm was verified by 18 groups data of ocean color, andmean relative error between inversion and real value is 34ï¼…. The precision satisfies the requirementof the Caseâ…¡water ocean color remote sensing basically.Lastly, FLH algorithm was used with one Bohai Sea MERIS image acquired on 13th April,2005. The results show that the algorithm is suitable, and it can be used in the area with lowsuspended matter concentration and mid-large water depth. But the algorithm used operationallywhether or not, need more experiments.