富营养化湛江近海关键水质要素的高分遥感反演及监测研究

发布时间：2018-09-07 21:22

【摘要】：近海区域具有丰富的自然资源,与人类的经济生产生活具有紧密联系。随着人类沿海活动的增加,近海海洋水质受到较为严重的影响。对于近海海洋水质要素的快速、准确的监测极其重要。相比传统走航采样监测耗费大量的人力、财力,利用遥感手段进行海洋水质要素的监测具有明显的优势。它具有快速、连续、监测面积大等诸多优点。本文采用LANDSAT 8卫星的遥感数据,对湛江近海表层叶绿素a浓度以及悬浮泥沙浓度进行反演研究。同时利用反演结果,通过结合海洋地形、气象等要素对叶绿素a浓度分布以及悬浮泥沙浓度分布的形成原因进行了探究,为湛江近海的水质要素研究提供了理论及数据基础。本文主要研究成果如下:1.湛江近海海域水面光谱具有二类水体的光谱特征。在近红外区域,由于悬浮泥沙等物质的影响使得在该区间的遥感反射率不为0。同时湛江湾内以及湛江湾外区域的水面光谱曲线均具有各自较为明显的光谱特征。湛江湾内外两个区域的光谱值在550nm的光谱峰往红光方向迅速减小,在685nm左右出现叶绿素的荧光峰。湛江湾外的光谱数据在440nm左右区域存在吸收现象,叶绿素a在此波段的强烈吸收和该波段的极小值存在相关性。对比其他相关海域,湛江湾近海存在760nm附近较为稳定的吸收谷,该波段可以作为识别湛江湾近海光谱曲线的波段特征。2.湛江湾内与湛江湾外光谱共同与实测水质要素数据进行相关性分析,计算结果显示相关性较低。由于水体水色要素组成成分浓度的不同会形成不同的表面光学特征。利用光谱特征的不同进行分区,对各个分区分别建模对提高反演精度具有重要作用。利用湾内与湾外光谱特征差异将研究区域分成湾内部分与湾外部分,分别进行相关性分析。计算结果显示,整体上相关性有了较大的提高。最高的相关性高达0.8。建立的模型相对误差值均在30%左右。具有较好的反演精度。3.总体上湛江近海海域叶绿素a浓度较高。湛江湾内叶绿素a浓度低于湛江湾外相关区域。悬浮泥沙含量在湛江湾内区域高于湛江湾外。湛江湾外悬浮泥沙含量随着与岸距离逐渐变大而降低。采样的两个航次在硇洲岛与东海岛之间的航道处均出现了较高的悬浮泥沙浓度的现象。研究区域5月叶绿素a平均浓度高于9月的平均浓度,悬浮泥沙平均含量5月低于9月。在两个航次中,湛江湾内水深较浅区域均出现了悬浮泥沙浓度较高,叶绿素a浓度相对较高的现象。在水深较小的区域,由于水浅,水体容易扰动,从而引起悬浮泥沙浓度较高的现象。同时水体搅动,促进整体水层的营养盐混合,对浮游植物的生长具有积极的促进作用。
[Abstract]:The offshore area is rich in natural resources and is closely related to the economic production and life of human beings. With the increase of human coastal activities, the coastal water quality is seriously affected. It is very important for the fast and accurate monitoring of offshore marine water quality elements. Compared with the traditional navigation sampling monitoring, it consumes a lot of manpower and financial resources, so it has obvious advantages to use remote sensing to monitor the ocean water quality elements. It has many advantages, such as fast, continuous, large monitoring area and so on. In this paper, LANDSAT 8 satellite remote sensing data are used to invert the concentration of chlorophyll a and suspended sediment in the surface layer of Zhanjiang offshore. At the same time, the reasons of chlorophyll a concentration distribution and suspended sediment concentration distribution are explored by combining the ocean topography, meteorology and other factors, which provides a theoretical and data basis for the study of water quality elements in Zhanjiang coastal waters. The main research results of this paper are as follows: 1: 1. The surface spectrum of Zhanjiang offshore area has the spectral characteristics of the second kind of water body. In the near infrared region, the reflectivity of remote sensing in this region is not 0. 0 because of the influence of suspended sediment and other substances. At the same time, the water surface spectral curves in Zhanjiang Bay and outside Zhanjiang Bay have their own obvious spectral characteristics. The spectral values of the two regions inside and outside Zhanjiang Bay decreased rapidly from the peak of 550nm to the direction of red light, and the fluorescence peak of chlorophyll appeared around 685nm. The spectral data outside Zhanjiang Bay are absorbed in the 440nm region, and the strong absorption of chlorophyll a in this band is correlated with the minimum value of the band. Compared with other related sea areas, there is a relatively stable absorption valley near 760nm in the coastal waters of Zhanjiang Bay, which can be regarded as the band characteristic of identifying the spectral curve of Zhanjiang Bay. The correlation analysis between the spectrum of Zhanjiang Bay and the measured data of water quality elements shows that the correlation is low. Due to the different composition concentration of water color elements, different surface optical characteristics can be formed. It is important to improve the inversion accuracy by using the different spectral features to partition, and to model each partition separately. The study area was divided into the inside and outside bay parts by using the difference of spectral characteristics between the bay and the bay, and the correlation analysis was carried out respectively. The results show that the overall correlation has been greatly improved. The highest correlation is as high as 0. 8. The relative errors of the models are all about 30%. It has good inversion accuracy. 3. On the whole, the concentration of chlorophyll a in the coastal waters of Zhanjiang is relatively high. The concentration of chlorophyll a in Zhanjiang Bay is lower than that outside Zhanjiang Bay. The suspended sediment content in Zhanjiang Bay is higher than that outside Zhanjiang Bay. The suspended sediment content outside Zhanjiang Bay decreases with increasing distance from shore. The suspended sediment concentration of the two voyages was higher in the waterway between the island of Naozhou and the eastern island. The average concentration of chlorophyll a in May was higher than that in September, and the average concentration of suspended sediment in May was lower than that in September. In the two voyages, the relatively high suspended sediment concentration and relatively high chlorophyll a concentration occurred in the shallow water depth area of Zhanjiang Bay. In the area with small water depth, the water is easily disturbed because of the shallow water, which leads to the phenomenon of high suspended sediment concentration. At the same time, the agitation of the water can promote the nutrient mixing of the whole water layer, which can promote the growth of phytoplankton.
【学位授予单位】：广东海洋大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：X52;X87

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