富营养化湖泊藻类垂向分布类型及其对水体遥感反射比的影响

Algal bloom is one of the typical characteristics in eutrophic lakes. However, the algal bloom area is always detected dramatic changes in hours, according to which the intensity of algal bloom couldn't be well assessed. Consequently, estimation of algae gross stock in lakes is a novel way to achieve algae variation and its future trends. In eutrophic lakes, algae vertical distributions are diverse because cyanobacteria could change its position by its buoyancy, suspension or swimming. Remote sensing monitoring algae vertical distribution is one of the key steps to estimate algae gross stock. In this proposal, taking Lake Chaohu as the study area, we will first construct a function dataset to describe algae vertical distribution in the lake according to the in-situ data, and then by the aid of Monte Carlo radiation transmission simulation, we will reveal the characteristics and objective law of underwater light field and water surface reflectance under the influence of different algae vertical distribution. This research is a new attempt to theoretically solve the hard problem of water color remote sensing in eutrophic lakes, that will expand the application of water color remote sensing, and provide important supports to the decision-makers from government and its administration sections.

藻类大量繁殖引起的水华现象是湖泊水体富营养化的重要特征，然而水体表层藻华面积会在数小时内发生剧烈变化，因此水体藻华面积无法全面真实地表征藻类水体特征和代表水华蓝藻强度，精确估算水体内藻类总存量，成为准确把握蓝藻变化情势的必然趋势。富营养化湖泊中水华蓝藻的上下自由迁移造成藻类垂向分布类型复杂多样，利用遥感技术获取藻类的垂向分布结构是估算水体内藻类总存量的前提和基础。本课题以巢湖为试验区，以野外实验观测和Monte Carlo辐射传输模拟为手段，分析富营养化湖泊中藻类垂向分布特征，建立藻类垂向分布类型的定量表征函数库，揭示不同藻类垂向分布类型对水下光场、水体遥感反射比的影响。本研究尝试从基础理论角度解决富营养化湖泊水色遥感研究中面临的问题，既丰富了湖泊水色遥感的研究内涵，扩展了湖泊水色遥感的应用深度和广度，又为水环境管理部门准确把握水华蓝藻情势、正确决策提供重要的科技支撑。

藻类大量繁殖引起的水华现象是湖泊水体富营养化的重要特征，然而水体表层藻华面积会在数小时内发生剧烈变化，因此水体藻华面积无法全面真实地表征藻类水体特征和代表水华蓝藻强度，精确估算水体内藻类总存量，成为准确把握蓝藻变化情势的必然趋势。富营养化湖泊中水华蓝藻的上下自由迁移造成藻类垂向分布类型复杂多样，利用遥感技术获取藻类的垂向分布结构是估算水体内藻类总存量的前提和基础。本课题以巢湖为试验区，以野外实验观测和 Monte Carlo 辐射传输模拟为手段，基于野外实测数据，分析了巢湖水体光学活性物质浓度的垂向分布规律，概化了藻类垂向分布类型，并对水体光学特性进行了分析；然后，基于水体辐射传输数值模拟，研究了不同类型的藻类垂向非均匀分布对遥感反射比及叶绿素a浓度反演算法的影响；最后，构建了藻类垂向非均匀水体的遥感反射比的校正算法，并应用于巢湖的实测高光谱数据。本研究尝试从基础理论角度解决富营养化湖泊水色遥感研究中面临的问题，既丰富了湖泊水色遥感的研究内涵，扩展了湖泊水色遥感的应用深度和广度，又为水环境管理部门准确把握水华蓝藻情势、正确决策提供重要的科技支撑。