Two parameters retrieval models of suspended sediment concentration of Bohai Sea based on MODIS data
Received date: 2007-03-23
Revised date: 2007-08-14
Online published: 2007-11-25
Supported by
国家自然科学基金资助项目(40771030、40571020);中国科学院知识创新工程领域前沿项目。
In recent decades, remote sensing has been proven to be an effective method to retrieve suspended sediment concentration. However, most retrieval methods developed today only based on the direct relationship between suspended sediment concentration and the remote sensing reflectance which is not reasonable when there is a big difference among the grain size of the study area. Bohai Sea is a relative closure region in which the grain size of the suspended sediment varies widely. This paper brought out a new method on the retrieval of suspended sediment concentration of Bohai Sea, which used both the reflectance from remote sensing data and the grain size of the suspended sediment. After analyzing the spectrum characteristics of suspended sediment, MODIS data characteristics and the relationship between suspended sediment concentration and grain size, the unary-parameter and binary-parameter PCA-based and NN-based models were constructed in Bohai Sea based on the data collected. The analytical results show that when introducing grain size parameter into the PCA-based models, model's correlation coefficient was increased from 0.697 to 0.724, while its predicting error was decreased from 0.383809 to 0.256722. This phenomenon also happened in the NN-based models where the predicting error was decreased from 0.390374 to 0.244427. The stability of the models with a grain size parameter being also better than the one without the grain size. It is proved that a model's retrieval precision and stability can be improved effectively by introducing grain size into the model. Therefore, it's necessary to add the grain size into the retrieval model in order to improve the precision of the prediction. Moreover, representative remotely sensed MODIS imagery was used to validate the model built in this paper which has the same conclusion with the previous researches. Generally speaking, in Bohai Sea, suspended sediment concentration in winter low water period is higher than that in summer abundant water period; and high concentration areas are located in Bohai Bay, Laizhou Bay and Liaodong Bay and their distributions are parallel to the shoreline.
WANG Fang, LI Guo-sheng . Two parameters retrieval models of suspended sediment concentration of Bohai Sea based on MODIS data[J]. GEOGRAPHICAL RESEARCH, 2007 , 26(6) : 1186 -1196 . DOI: 10.11821/yj2007060013
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