【作者】 陈莉琼；

【导师】 陈晓玲；

【作者基本信息】 武汉大学 ， 地图学与地理信息系统， 2011， 博士

【摘要】 水色遥感作为一种可以大范围同步获取湖泊水体水色参数信息的先进技术,在一定程度上解决了传统方法水体参数现场观测不便、数据获取难度大的困境,是进行湖泊水环境动态监测的重要手段,可为区域经济社会生产和全球变化研究提供重要的定量信息,对我国湖泊功能的可持续利用也具有重要意义。鄱阳湖是长江中下游最大的淡水湖,湖泊独特的“吞吐性、季节性”特征导致的湖泊面积变化剧烈、水体光学特性复杂、底质类型丰富多变,是进行水色遥感辐射传输机理研究的天然试验场,本文以鄱阳湖最受关注的水体参数——悬浮颗粒物浓度为切入点,针对鄱阳湖水体光学特性较强的季节性与区域性特征,研究悬浮颗粒物浓度遥感定量反演的机理和方法。本研究所完成的工作以及取得的创新性成果主要体现在如下几个方面：1.鄱阳湖水体光学特性的观测与测量方法研究：通过分析2005年、2008年、2009年、2011年四个航次的观测,研究了鄱阳湖水体观测方法的适用性。结果表明,水面以上观测法是适合鄱阳湖浅水湖泊的遥感反射率观测方法；鄱阳湖水体中大量细小的无机悬浮颗粒物导致目前常用的散射系数观测设备仅在悬浮颗粒物浓度低于75mg/L的水体中适用；相对于目前海洋与湖泊水体悬浮颗粒物吸收系数实验室测定中普遍采用的光透射法,光透射.反射法对于高浓度悬浮颗粒物水体中颗粒物光谱的提取更为有效。2.鄱阳湖水体悬浮颗粒物固有光学特性及其对水体光学特性的贡献：对鄱阳湖水体中有色溶解有机物(CDOM)、非藻类颗粒物和藻类颗粒物的吸收特性进行光谱特征分析,获取了鄱阳湖各水体组分吸收系数的空间分布规律与季节性差异,研究表明非藻类颗粒物是鄱阳湖水体吸收的主要贡献者,悬浮颗粒物浓度与总颗粒物吸收系数、非藻类颗粒物吸收系数之间均存在较好的相关关系：对水体总悬浮颗粒物散射系数进行有机颗粒物与无机颗粒物的散射光谱分解发现,鄱阳湖大部分水域无机颗粒物对鄱阳湖水体散射起主导作用。3.水动力学数值模拟与遥感结合的光学浅水区与光学深水区的判别方法研究：针对鄱阳湖水体深度、浑浊度季节性变化的特点,将水动力模型与遥感相结合进行鄱阳湖水体深度的模拟,并通过分析水体透明度与遥感反射率之间的关系,构建了水体透明度反演模型,并综合水深模拟结果与透明度反演结果实现了鄱阳湖水体光学浅水区、潜在光学浅水区以及光学深水区的判别,结果表明,鄱阳湖水体光学浅水区主要分布于鄱阳湖南部水域,且随着季节的变化,光学浅水区的分布存在差异。4.基于辐射传输理论的光学浅水区／光学深水区悬浮颗粒物浓度反演模型研究：根据鄱阳湖水体光学特性,分别对光学深水区与光学浅水区实测遥感反射率与水体固有光学特性的定量表达进行分析,建立了适合鄱阳湖水体特征的深水区半分析模型和浅水区迭代优化模型,并根据悬浮颗粒物浓度在不同季节、不同水域与水体固有光学特性的关系,构建了固有光学量与悬浮颗粒物浓度的反演模型。结果表明：采用实测数据构建的辐射传输模型比经验模型具有更高的精度和时相稳定性。5.悬浮颗粒物浓度反演模型的遥感实现与误差分析：采用神经网络方法对具有同步观测数据的MODIS陆地反射率影像进行大气校正,采用水动力学过程数值模拟与遥感结合的方法对影像上的光学深水区与光学浅水区进行判别：考虑MODIS卫星影像波段设置,在基于实测数据建立的悬浮颗粒物浓度辐射传输反演模型基础上,进行MODIS影像的悬浮颗粒物浓度遥感反演,利用现场同步观测结果对反演模型进行精度评价,结果表明：采用光学浅水区／光学深水区分别计算的辐射传输模型,可以有效地提高反演精度,并具有较好的时相稳定性,基本能够满足湖泊水质监测的应用需求。更多还原

【Abstract】 Water color remote sensing is an advanced technique to acquire the synoptic view of lake. It has big advantage in water quality monitoring, which is difficult to acquire by the traditional filed investigation for its hard accessibility. Water color parameters retrieved from remote sensing images can provide quantitative information about regional economic, social development and global change. It is significant to sustainably exploit lakes.As the largest freshwater lake lies in the middle reach of Yangtze River in China, Poyang Lake is a seasonal and throughput lake, which leads to its dramatic water area changes, complex water optical properties, and various bottom types. Therefore, it becomes a natural study area for the mechanism of radiative transfer process under water. Taking the most concerned water color parameter, suspended particulate matter concentration as an example, the dissertation discusses the seasonal and spatial variations of the optical properties in the Poyang Lake, and investigates the mechanism and method of quantitative retrieval of water color parameters based on radiative transfer theory.The main contributions are shown as follows:1. Measurement of aquatic optical properties and analysis of the applicability of different measurement methods in Poyang Lake.Four cruises of observation were performed in2005,2008,2009and2011, and the applicability of measurement methods for inherent and apparent optical properties were studied. Comparisons of methods of remote sensing reflectance measurements show that the above-water method was suitable for the shallow Poyang Lake. Due to the large number of small tiny mineral particles in Poyang Lake, the usage of current in-situ observation equipment was limited and in-situ particle scattering coefficients were only available for samples which the suspended sediment concentrations is less than75mg/L. For laboratory analysis the suspended particulate absorption, the transmission-reflection method was more efficient in the spectrum extracting in turbid waters than the transmission method, which is widely used in the laboratory determination of the absorption coefficient of suspended particulate matter in ocean and coastal waters.2. Inherent optical properties of suspended particulate matters and their optical contributions in Poyang Lake.Spectral features of Colored Dissolved Organic Matter (CDOM), non-algal particles and algae particles absorption properties were analyzed. Spatial and seasonal variations in absorption of each water components were also discussed. The study showed that non-algal particulate matter is the major contributor to the total absorption, and a good correlation relationship was existed between concentration of suspended particulate matters, total suspended particulate absorption coefficients and non-algal particulate absorption coefficients. Scattering properties of suspended particle were also investigated.A regional model was developed for partitioning total particulate scattering into the contributions of organic and inorganic particles. The results of scattering spectrum partition show that inorganic particles scattering plays a dominant role in Poyang Lake.3. Identification of optical shallow and deep waters by coupling the hydrodynamic simulation and remote sensing.Considering the seasonal variability of water depth and turbidity in Poyang Lake, advantage of hydrodynamic simulation and remote sensing technology was fully used to derive the real time water depth. Water clarity retrieval model was established based on the relationship between water clarity and remote sensing reflectance. Combining the retrieved water clarity and simulated water depth, the optical shallow water area, potential shallow water area, and optical deep water area can be identified. The distribution pattern for different water types in Poyang Lake indicated that the optical shallow water is mainly locates in the south Poyang Lake and the spatial distribution pattern of shallow water varies seasonally.4. Retrieval of suspended particulate matter concentration in optical shallow and deep water respectively, based on radiative transfer theory.According to water optical properties of Poyang Lake, the relationship between remote sensing reflectance and inherent optical properties was examined with in-situ data in the optical shallow and deep water areas. Based on radiative transfer theory, a semi-analysis model for inherent optical parameter retrieval was established in optical deep water area, while an iterative optimization model in the shallow water area. There is a significant correlation between inherent optical properties and suspended particulate matter concentration in different seasons and different regions, and retrieval model of suspended particulate matter concentration was constructed base on the relationships. The results indicated that the radiative transfer model performed well for the in-situ data, and it was more accurate and stable than the empirical model.5. Implementation of suspended particulate matter retrieval model on remote sensing images and error analysis.In the dissertation, method of neural network was used to remove the atmospheric affection on MODIS land reflectance images. Water type classification combined with hydrodynamic and remote-sensing was carried out on corrected images acquired on October20,2008and July20,2011. Considering the band setting of MODIS sensor, radiative transfer model of suspended particulate matter retrieval from MODIS image was established. Evaluation of radiative transfer model using in-situ simultaneous observation data showed that calculated concentration of suspended particulate matter in optical shallow and deep water separately can effectively improve the retrieval accuracy and make the results temporally stable. The model developed in this paper can approximately meet the needs of water quality monitoring.更多还原