基于GOCI影像的太湖水体漫衰减系数遥感估算研究

发布时间：2018-01-14 17:27

本文关键词：基于GOCI影像的太湖水体漫衰减系数遥感估算研究　出处：《南京师范大学》2015年硕士论文　论文类型：学位论文

【摘要】：漫衰减系数Kd (Diffuse Attenuation Coefficient)是水体光学中的一个重要参数,也是水生态系统的重要影响因素。水体漫衰减系数的遥感估算,能够揭示区域水体光场的变化,对水质及水生态环境监测具有重要意义。本研究以太湖为研究对象,根据不同季节太湖地面遥感实验的实测数据,分析了太湖水体的表观光学特性和固有光学特性,同时分析了水体各组分的吸收系数和后向散射系数对漫衰减系数的贡献率,确定漫衰减系数的影响因子,然后基于GOCI波段设置构建太湖水体漫衰减系数估算经验模型和半分析模型,分析对比模型的精度,将最优模型应用于GOCI影像,估算得到太湖全湖水体漫衰减系数,进而分析太湖水体漫衰减系数的时空变化特征。论文主要得出以下结论：(1)太湖漫衰减系数影响因子490 nm处漫衰减系数的主要影响因子是非色素颗粒物的吸收系数,其贡献率远远高于其他影响因子,色素颗粒物吸收系数的贡献率位居第二,后向散射系数和CDOM吸收系数对漫衰减系数的贡献相对较小,其中后向散射的贡献率大体上高于CDOM吸收的贡献率。(2) GOCI数据漫衰减系数估算模型GOCI第7波段可以突出悬浮物的特征信息,将其引入到经验模型中,可以很好地提高太湖漫衰减系数估算模型的精度。GOCI第4、5、7波段即近红外波段、红波段和绿波段的组合模型Kd(490)=436.581R745+290.84R660-448.66 R555+6.970精度最高,模型拟合结果R2为0.737,验证结果平均相对误差和均方根误差分别为28.6%和1.495,并且模型对漫衰减系数的变化敏感性不强,具有较高的普适性。半分析模型估算精度很大程度上依赖于固有光学量的估算精度,基于实测固有光学量构建的半分析模型精度相对较高,基于QAA和Doron方法估算固有光学量构建的半分析模型估算结果出现较大误差。将所构建的最优经验模型运用到GOCI影像估算太湖漫衰减系数,利用同步地面观测结果进行检验,结果表明该经验模型具有较高的估算精度和较好的普适性,是比较适合GOCI影像数据的太湖水体漫衰减系数估算模型。(3)太湖水体漫衰减系数时空变化特征利用2013年5月14日、2014年8月5日和2014年10月24日的GOCI影像,对太湖从上午8点到下午3点的漫衰减系数进行估算,综合不同日期太湖水体漫衰减系数空间分布及日变化特征分析的结果,总体来说太湖水体漫衰减系数值域主要分布在0～15m-1,大体可以分为三个等级,低值区值域分布在0～4m-1,中值区值域分布在4～8m-1,高值区主要分布在8～15m-1,少部分湖区高于15m-1。太湖水体漫衰减系数存在一定的时空差异性。从空间上来说,太湖水体漫衰减系数呈现一定的梯度性,即从东部到西部逐渐变高,呈现西部高于东部的趋势。从时间上来说,不同日期太湖水体漫衰减系数的日变化呈现出相似的规律性,即早上太湖漫衰减系数相对较高,之后随着时间变化大体上呈现逐渐降低的趋势。
[Abstract]:Diffuse attenuation coefficient (KD) Diffuse Attenuation coefficient is an important parameter in water optics. The remote sensing estimation of water diffuse attenuation coefficient can reveal the variation of regional water light field. This study takes Taihu Lake as the research object, according to the ground remote sensing data of Taihu Lake in different seasons. The apparent sightseeing characteristics and intrinsic optical properties of Taihu Lake were analyzed, and the contribution rate of absorption coefficient and backscattering coefficient to diffuse attenuation coefficient were analyzed, and the influence factors of diffuse attenuation coefficient were determined. Then the empirical model and semi-analytical model are constructed based on the GOCI band setting to estimate the diffuse attenuation coefficient of Taihu Lake. The accuracy of the model is analyzed and the optimal model is applied to the GOCI image. The water mass diffuse attenuation coefficient of Taihu Lake is estimated. Furthermore, the temporal and spatial characteristics of the diffuse attenuation coefficient of Taihu Lake are analyzed. The following conclusions are drawn in this paper: 1). Diffuse attenuation coefficient of Taihu Lake the main influence factor of diffuse attenuation coefficient at 490 nm is the absorption coefficient of non-pigment particles. The contribution rate was much higher than other factors, the contribution rate of pigment particulate absorption coefficient was the second, backscattering coefficient and CDOM absorption coefficient had relatively little contribution to diffuse attenuation coefficient. The contribution rate of backscattering is generally higher than that of CDOM absorption. 2) the diffuse attenuation coefficient estimation model of GOCI data can highlight the characteristic information of suspended matter in band 7 of GOCI. By introducing it into the empirical model, the accuracy of the estimation model of the diffuse attenuation coefficient of Taihu Lake can be improved very well. The combination model of red band and green band Kd(490)=436.581R745 290.84R660-448.66R555 6.970 has the highest precision. The model fitting result R2 is 0.737, the average relative error and root mean square error are 28.6% and 1.495respectively, and the model is not sensitive to the change of diffuse attenuation coefficient. The estimation accuracy of semi-analytical model depends on the estimation accuracy of intrinsic optical quantity to a great extent, and the semi-analytical model based on measured intrinsic optical quantity has a relatively high accuracy. The estimation results of the semi-analytical model based on the QAA and Doron methods to estimate the intrinsic optical quantities have a large error. The best empirical model is applied to estimate the diffuse attenuation coefficient of Taihu Lake in the GOCI image. The results of synchronous ground observation show that the empirical model has higher estimation accuracy and better universality. It is a model for estimating the diffuse attenuation coefficient of Taihu Lake, which is more suitable for GOCI image data.) the temporal and spatial variation characteristics of the diffuse attenuation coefficient of Taihu Lake are used in May 14th 2013. The diffuse attenuation coefficients of Taihu Lake from 8 am to 3 pm were estimated by GOCI images on August 5th 2014 and October 24th 2014. According to the results of spatial distribution and diurnal variation analysis of the diffuse attenuation coefficient of Taihu Lake on different dates, the range of diffuse attenuation coefficient of Taihu Lake water body is mainly distributed in 0 ~ 15m ~ (-1), which can be divided into three grades. The range of the low value region is 0 ~ 4m ~ (-1), the median region is 4 ~ 8m ~ (-1), and the high value region is mainly 8 ~ (15) m ~ (-1). A few lakes are higher than 15m ~ (-1). There are some spatial and temporal differences in the diffuse attenuation coefficient of Taihu Lake water body. In space, the diffuse attenuation coefficient of Taihu Lake water body presents a certain gradient, that is, from the east to the west, the water body diffuse attenuation coefficient gradually becomes higher. From the time point of view, the diurnal variation of the overspread attenuation coefficient of Taihu Lake on different dates showed a similar regularity, that is, the diffuse attenuation coefficient of Taihu Lake in the morning was relatively high. Then, with the change of time, the trend is gradually decreasing.
【学位授予单位】：南京师范大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：X87

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