基于GOCI影像的太湖水体漫衰减系数遥感反演

Remote Sensing Inversion of Diffuse Attenuation Coefficient in Lake Taihu Based on the GOCI Images

漫衰减系数是水体光学中的一个重要参数.采用2006~2009年的太湖野外实测数据,分析了太湖水体漫衰减系数光谱特性及其影响因子,在此基础上,结合GOCI传感器数据,分别构建漫衰减系数经验模型和半分析模型,寻找适合GOCI影像的太湖漫衰减系数反演模型,并分析太湖水体漫衰减系数的时空变化特征.结果表明:1太湖水体漫衰减系数主要受非色素颗粒物吸收主导,以GOCI第4、5、7波段构建的多元线性模型反演漫衰减系数,效果最好;2太湖水体漫衰减系数值域主要分布在0~15 m-1,大体可以分为3个等级,低值区:0~4 m-1,中值区:4~8 m-1,高值区:8~15 m-1,部分高值区高于15 m-1;3太湖水体漫衰减系数存在一定时空差异性,从空间上来说,太湖水体漫衰减系数呈现一定的梯度性,从东部到西部逐渐变高;从时间上来说,早上太湖漫衰减系数相对较高,从上午到下午,大体上呈现逐渐降低的趋势.

Diffuse attenuation coefficient( Kd) is an important parameter in water body optics. The spectral characteristics of Kdin Lake Taihu and its impact factors were analyzed using the in situ measured data from 2006-2009. Then,empirical models and semianalysis models were built based on the GOCI data to estimate Kd,in order to find a suitable retrieval model for GOCI and analyze the spatial and temporal variations of diffuse attenuation coefficient in Lake Taihu. The result indicates that: 1 The main impact factor of diffuse attenuation coefficient at 490 nm is the non-algal particles absorption coefficient,and the combination model with GOCI bands4,5 and 7,namely the near infrared band,the red band and the green band,has the highest precision for the inversion of Kd( 490);2 the range of Kdof Lake Taihu distributes between 0 to 15 m- 1,and that can be divided into three levels generally,i. e.,the range of the low value between 0-4 m- 1,the range of the medium value between 4-8 m- 1,and the range of the high value between 8-15m- 1. While,occasionally,some values are higher than 15 m- 1; 3 the Kdof Lake Taihu distributes with notable spatial and temporal difference. At the view of spatial distribution,the Kdvalues get higher from the east to the west of Lake Taihu; from the perspective of time,the Kdis relatively high in the morning and then shows a tendency of gradually reduce with the time.