基于GOCI遥感影像的长江入海口悬浮沉沙浓度反演及其时空动态分析

发布时间：2018-05-03 03:35

本文选题：大气校正 + MODTRAN　；参考：《长安大学》2015年硕士论文

【摘要】：长江入海口,位于中国的东部,是一个对渔业和经济都影响很大的生态系统。然而,入海口一带经常出现高负荷的悬浮沉沙。这不仅影响了水质,还影响了地貌演变。此外,泥沙的浓度还有很大的动态变化。因此,对入海口一带悬浮沉沙的时空动态变化进行实时监测就显得非常重要。为了实现对悬浮沉沙空间动态和昼夜循环的监测,本研究使用地球同步轨道海洋水色成像仪GOCI(Geostationary Ocean Color Imager)卫星数据。通过对GOCI数据进行校正,去除大气吸收和散射作用对辐射光谱的影响,获取来自水体目标物的离水反射率(Rrs,water leaving reflectance)。采用MODTRAN辐射传输模型,设置多种大气校正方案,计算不同方案下的校正结果,得到Rrs图集。同时,通过设定一系列连续的悬浮沉沙浓度(SSC,suspended sediment concentrations),用2SeaColor模型计算对应浓度下的Rrs,生成一个查询表。用匹配的方法分别选出影像每个像素点的最优大气校正方案并反演出泥沙浓度。使用实测数据检测遥感反演结果,Rrs的相关系数达到0.81,SSC的相关系数为0.68。可见本方法在反演高度浑浊水体泥沙浓度的研究上与其他SSC产品相比有很大的改进。用本方法处理同一天不同时刻的GOCI影像,对悬浮沉沙进行空间动态和昼夜循环的分析。在空间上,根据不同的沉沙浓度,研究区域呈现三个区域:高浓度区(泥沙浓度高达2000 mg/l)、中等浓度区(泥沙浓度范围是50 mg/l-100 mg/l)和低浓度区(远离海岸的区域,也是含沙量最低的区域,其浓度一般低于10 mg/l)。在时间范畴上,研究结果揭示了泥沙浓度昼夜变化与潮汐的关系:水体的最大浑浊度与海水水位有一定的滞后关系;当潮水上涨时,悬浮沉沙的浓度先下降后上升,这与外来海水的稀释作用和底泥的再悬浮作用有很大的关系。
[Abstract]:The estuary of the Yangtze River, located in the eastern part of China, is an ecological system which has a great impact on both the fishery and the economy. However, high load suspended sediment and sediment often occur in the mouth of the sea. This not only affects the water quality, but also affects the evolution of the geomorphology. In addition, the sediment concentration has a great dynamic change. Therefore, when the sediment is suspended in the mouth of the sea, the sediment is suspended. The real-time monitoring of air dynamic changes is very important. In order to realize the monitoring of the space dynamic and circadian cycle of suspended sediment and sediment, this study uses the GOCI (Geostationary Ocean Color Imager) satellite data of the geostationary orbit ocean color imager. Through the correction of the GOCI data, the atmospheric absorption and scattering effects are removed to the radiation. The reflectance (Rrs, water leaving reflectance) from the object of the water body is obtained. The MODTRAN radiation transmission model is used to set up a variety of atmospheric correction schemes, and the correction results under different schemes are calculated and the Rrs atlas is obtained. At the same time, a series of continuous suspended sediment concentration (SSC, suspended sediment concentrati) is set. ONS), we use the 2SeaColor model to calculate the Rrs under the corresponding concentration and generate a query table. The optimal atmospheric correction scheme for each pixel point of the image is selected by the matching method and the sediment concentration is reversed. The correlation coefficient of Rrs is 0.81 and the correlation coefficient of SSC is 0.68. visible. The study on sediment concentration in highly turbidity water has been greatly improved compared with other SSC products. Using this method to deal with GOCI images at different times of the same day, the spatial dynamics and circadian circulation of suspended sediment are analyzed. In space, the study area presents three regions according to the different sediment concentration: high concentration area (high concentration of sediment is reached). 2000 mg/l), the medium concentration area (the range of sediment concentration is 50 mg/l-100 mg/l) and the low concentration zone (the region far away from the coast is the area with the lowest sediment content, and the concentration is generally lower than 10 mg/l). In the time category, the results reveal the relationship between the diurnal change of the sediment concentration and the tide: the maximum turbidity of the water body and the water level of the sea water are certain. When the tide rises, the concentration of suspended sediment drops first and then rises, which is closely related to the dilution effect of the foreign sea water and the effect of the sediment resuspension.

【学位授予单位】：长安大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：P715.7;P737.1

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