利用连云港海州湾2004年至2006年的水质监测资料,选取时间上完全同步的空间分辨率为500m的MODIS Terra 1B数据,对反射率的单波段因子和波段组合因子与可溶无机氮(DIN)质量浓度之间进行相关分析。从总体上看,单波段因子与DIN质量浓度的相关性较低,但在含氮基团倍频和合频吸收带附近的波段(波段2、7)反射率与DIN质量浓度呈负相关,显示了含氮基团对水体光谱特征的影响;在波段组合因子中,因子F11(3.4)和F13(3.4)与DIN质量浓度呈显著正相关,用这两个因子建立DIN质量浓度的回归模型,R^2都达到0.7以上,相对精度达70%左右,最终选择因子F11(3.4)的线性模型反演该海域的DIN质量浓度,其结果与实际情况非常吻合。
Red tides have been increasingly observed in the gulf of Haizhou and considered a serious environmental problem from the beginning of the new century. Eutrophication of water is an important reason of red tide occurrence. This paper used the observation data of the concentration of dissolved inorganic nitrogen (DIN) in Haizhou Gulf from 2004 to 2006 and selected MODIS Terra 1B data with 500m spatial resolution in this period of time. We established reflectance factors with single band and multi-bands, calculated correlation between each factor and the concentration of DIN. The correlations between single band factors and DIN concentration are low, but the reflectance of bands (band 2 and 7) near overtones and combination spectral lines of groups which contain nitrogen has a negative correlation with DIN concentration, this indicates the influence on spectrum of these groups. The multi-bands factors Fl1(3,4) and F13(3.4) have a positive correlation with DIN concentration notably, we chose these two factors to established regression models of DIN. The R2 of the models exceeded 0.7 and their relative accuracy reached about 70%, the results of the linear model by F11(3,4) were consistent well with the real conditions. These improve the feasibility of this model and the validity of monitoring DIN concentration by MODIS data.