【作者】 陈鹏；

【导师】 潘德炉；

【作者基本信息】 武汉大学 ， 摄影测量与遥感， 2015， 博士

【摘要】 随着我国国民经济的发展,保护生态环境和进行可持续发展的重要方面是对大型水体的合理保护和开发利用,因此对水体信息进行定量化遥感的需求日益迫切,同时也对水体成分信息的测量和反演提出了新的要求。靠近沿海的近岸二类水体是我们国家非常关注的地方,由于二类水体光学性质的复杂性,利用常规的水光学仪器测量得到二类水体中光学信息存在着较大的不确定性；卫星水色遥感手段测量水体成分浓度可以实现大范围测量,但在二类水体准确度较低,精度有待验证。与常规的生物化学站位监测手段和水色遥感手段相比,激光诱导荧光技术是一种向海水中主动发射激光,接收水体成分返回的荧光回波信号来反演水体参数浓度的探测技术,能够搭载在船上、固定平台以及飞机上,具有快速高效、实时监测、大面积测量的优点。当前,海洋环境监测大多是用水色遥感手段。与被动遥感手段相比,海洋激光诱导荧光具有以下特点：可选择性激发的；指向性的；可控制光源的；有内部基准光谱定标的以及提供时间分辨测量的优点。本文从激光诱导荧光水体参数探测机理、算法、仪器研制以及应用等几个方面系统进行了研究：1)便携式小型激光诱导荧光探测系统原型的研制。我们先介绍了激光以及荧光的原理,以及激光诱导荧光系统的一般结构组成及关键器件选择方案。然后我们搭建了一套基于正交光学结构的激光诱导荧光仪和一套基于共线聚焦结构的激光诱导荧光仪。并进行了仪器灵敏度和稳定性的测试实验,进行了激光荧光数据拉曼校正和温度校正算法的研究以及与RF-5301荧光光谱仪进行了测量结果比较。2)探索基于自制激光荧光探测实验系统实地测量近海二类水体的水色三要素的方法。基于荧光峰强度和基于光谱函数拟合的经验模型进行了反演研究,然后推导了基于辐射传输模型的半分析模型的公式。并且使用相同的数据,对两种经验模型的反演结果进行了对比和分析。针对CDOM吸收系数实测耗时耗力的缺点,我们使用了激光荧光仪在长江口,珠江口及邻近海区进行了CDOM吸收系数的反演研究,该仪器不需要对CDOM水样进行过滤等预处理,避免了因水样过滤和存储等过程造成的耗时耗力。接着我们使用便携式激光诱导荧光仪在杭州湾海区开展了水色三要素的反演研究,实验结果与传统测量手段相比,取得较好的结果,叶绿素、CDOM和悬浮泥沙与实测相关系数分别达到0.88、0.90、0.86。并应用于我国近海河口海区水体的生物光学参数荧光分布特征的分析和研究,发现了河口海区CDOM混合保守性行为,表明此时水团混合行为主宰CDOM生产和消退过程,实验结果取得了良好的效果。3)最后,我们利用激光诱导荧光技术进行了赤潮藻的识别研究。我们在实验室培养了藻种,并使用了Bi-Gaussian模型对荧光光谱进行分解,并提出一种新的光谱描述指数SSDI的方法用来进行特征荧光光谱识别,从而对实验室培养的8种藻类开展了识别研究。结果表明,该方法能从种属水平上对藻类进行很好的区分。最后对本文的研究内容和创新点进行了总结,并对未来的研究方向和研究设想进行了展望。更多还原

【Abstract】 With the rapid development of national economy, an important aspect of the ecological environment protection and sustainable development is the reasonable protection and utilization of large-scale water. The requirement of quantitative remote sensing of water parameters has become increasingly urgent. Meanwhile, new demands are made on the measurement and inversion of water parameters. The main focus of our country is coastal water which is closely related to coastal social and economic development. Because that these waters are much more complex optically than open ocean waters, there is a big uncertainty on the measurements using conventional optical instruments; a wide range of measurement can be realized using satellite ocean color remote sensing, this method is often with low accuracy and the accuracy is to tested and verified. Compared to the on-site biochemical measurements and ocean color remote sensing, laser remote sensing, which utilize laser induced fluorescence (LIF) and light backscattering to analyze bodies of water remotely and are installed as a payload on airborne, shipboard or stationary platforms, is an efficient, proven tool capable of providing quantitative, spatially-resolved, real-time data for over large water surface areas with high spatial resolution.At present, ocean color remote sensing is often used in marine environmental monitoring. Compared to passive remote sensing:selective excitation by monochromatic laser emission; directionality; controlled light source; the use of an inner spectroscopic bench mark; and the possibility of time-(distance)-resolved measurement by time-gating the echo-signal are all advantages of the LIF LIDAR technique. This paper studied the aspects of LIF detection mechanism, algorithms, instrument design and application, as follows:1) Development of portable LIF detection experimental system. Firstly the principle of laser induced fluorescence was discussed. The general optical configuration and optical component of LIF detectors were investigated. In addition, a laser fluoromter with confocal optical configuration and another with orthogonal Czerny-Turner optical configuration were developed. Subsequently, some parameters of the performance, such as baseline noise, baseline drift, sensitivity, limit of detection and dynamic range, were tested systematically. Then research on Raman normalization and temperature correction on lidar data were studied, and the comparison between by measurements by LIF system and those by RF-5301 was carried out.2) In situ measurements of ocean color parameters in Case 2 waters using the LIF systems. Two empirical models based on peak intensity and function fitting were used. In addtion, the formula of semi-empirical model based on radiative transfer were derived. Experiments for the two empirical algorithms with the same data were carried out, and the results were also compared and analyzed. Measuring in situ CDOM absorption coefficient is difficult because it requires prefiltration of water samples. A field-portable laser fluorometer for fast acquisition of in situ CDOM fluorescence data without sample filtering was used, artificial work resulting from sample filtration or storage can be avoided. Subsequently, simultaneous estimates of three important water quality parameters, namely, chlorophyll a (chl-a), colored dissolved organic matter (CDOM), and total suspended matter (TSM) measured by the laser fluorometer were observed to agree well with those measured by traditional methods (chl-a, R2= 0.88; CDOM absorption, R2= 0.90; and TSM, R2= 0.86) in Hangzhou Bay water. In addition, fluorescence optical characteristics in estuarine area were analysed and CDOM appear conservative in mid-salinity waters, suggesting that mixing dominates production and removal processes over time scales. The LIF technique achieved good effect.3) A portable laser-induced fluorescence system for discriminating phytoplankton species has been used. The measured fluorescent spectra were overlapped by various fluorescent components, and were then decomposed by a bi-Gaussian mixture model. A new spectral shape description index was designed to characterize fluorescent spectral shapes for discriminating the phytoplankton species cultured in our laboratory. The phytoplankton species were successfully distinguished from each other at genus level.Finally, we summarized our major work and innovations, and discussed our future research orientations on laser induced fluorescence detection technology.更多还原