珠江口海域总无机氮的遥感提取研究

Retrieval of total inorganic nitrogen concentration in pearl river estuary by remote sensing

利用珠江口海域2个航次36个站位的实测遥感反射率和总无机氮(TIN)数据,基于偏最小二乘回归思想,建立了珠江口海域无机氮浓度估算的遥感模型.建模中考虑了6种比值法.结果发现,不同波段与第6波段比值所建立的模型精度最高,故选用该比值法所建立的模型作为珠江口海域无机氮遥感提取模型.利用该模型得到的珠江口海域18站位无机氮浓度和实测值相比,其总体平均相对误差为9.06%,相对误差最大值为18.2%.将该模型用于1998年12月31日的SeaWiFS资料,得到了较好的估算结果.与1998年12月31日的实测资料进行对比分析,实测值与估算值的平均相对误差为31.9%,说明该模型的稳定性较好,能够适用于不同时相的SeaWiFS图像,可为珠江口海域无机氮含量的分布以及富营养化问题研究提供了实时监测的依据.

In this paper, an algorithm for retrieval of Total Inorganic Nitrogen （TIN） concentration was developed by Partial Least Squares （PLS） regression, based on the remote sensing reflectance data and TIN data measured at 36 stations in Pearl River Estuary during two cruises which were conducted in January 2003 and January 2004 respectively, Six cases of band-ratio were considered on the algorithm development, and the band-ratio with band 6 as the denominator was used for the algorithm. The estimated TIN concentration was compared with sea-truth TIN data at 18 stations in the Pearl River estuary, The average relative error is 9.06% , and maximum relative error is 18.2%. Then the algorithm was also applied to SeaWiFS data of Dec. , 31, 1998. The SeaWiFS-retrieved TIN results were compared with measured TIN data, which were collected in Dec. , 31, 1998 and the average relative error is 31.9%. The result shows that the algorithm has good stability, and could be applied to satellite data acquired in different time. The algorithm could be employed for estimation of TIN concentration and for research of eutrophication in the Pearl River estuary.