高浊度长江河口水色三要素的光学特征及其对TSM反演的影响
发布时间：2018-08-02 08:56
【摘要】：二类水体中水色三要素的光学特性对于建立水色遥感反演算法至关重要,长江河口水域由于受径潮流相互作用和高含沙量影响,水体光学特性具有特殊性。基于现场光学和同步水文数据分析了洪枯季长江河口地区水色要素随着潮周期的变化特征。利用2014年5月和12月航次定点观测数据的分析结果表明：总悬浮物浓度是影响长江口高浑浊水体遥感反射率的主导因素,枯季悬沙浓度分布范围、变差和平均值都要高于洪季；无论洪枯季该地区叶绿素浓度都非常低,对遥感反射率的影响十分有限,其吸收系数很难通过现有实验方法准确测出,在高浊度水体光谱特征中几乎体现不出叶绿素对光谱反射率的影响,可以忽略不计；在分析了CDOM浓度和吸收系数模型的基础上,发现CDOM吸收的时空变化较大,但来源基本一致。分析了三要素在长江口高浊度水域的光学效应及其时空变化规律,发现在反演泥沙浓度时,口内水域可以忽略CDOM和叶绿素的影响,而在口外水域必须剥离其影响。同一潮周期内大潮时总悬浮颗粒物浓度最大能达到0.5kg/1113以上,而小潮时最大TSM浓度只有大潮的1/3,高总悬浮颗粒物浓度和潮周期内较大的变差,使得很多经验算法无法在该地区取得良好的效果。通过对三要素吸收特性的分析,以及与遥感反射率之间的相关性分析,可以发现口门内外存在截然不同的固有光学特性,使得总悬浮颗粒物反演精度受到一定影响。基于Landsat8的波段设置,利用38组现场光学和同步水沙数据分析了长江河口地区总悬浮颗粒物浓度随着潮周期的变化特征,比较了多种反演模式。结果表明：3S模型可以适用于长江口水域,实测数据验证大、小潮精度较其它模型更高,能更好地刻画潮周期内离水辐射的变化,反演总悬浮颗粒物浓度的潮周期变动。利用3S半分析模型,使用Landsat8红光和红外波段建立模型,能适应长江口口内不同潮情,在一定程度上可以剥离CDOM和叶绿素在总悬浮颗粒物浓度较低区域的影响,在口内徐六泾站点实测数据验证相对误差仅有9%。利用八景跨度为一年的Landsat8遥感影像,反演了长江口总悬浮颗粒物浓度,验证了3S算法在长江口地区的适用性,结果符合长江口地区悬沙的变化规律,可为上海市悬浮泥沙浓度监测业务化运行提供参考。
[Abstract]:The optical properties of the three elements of water color in the second kind of water body are very important for the establishment of the inversion algorithm of water color remote sensing. Due to the interaction of diameter tidal current and high sediment content, the optical characteristics of the water body in the estuary of the Yangtze River have its particularity. Based on the field optical and synchronous hydrological data, the variation characteristics of water color elements with tidal cycle in the Yangtze River estuary during the flood and dry season are analyzed. The results obtained from the fixed-point observation data in May and December 2014 show that the concentration of suspended sediment is the dominant factor affecting the remote sensing reflectance of high-turbidity water in the Changjiang Estuary, and the distribution range, variation and average value of suspended sediment concentration in the dry season are higher than those in the flood season. The chlorophyll concentration in this area is very low in flood and dry season, and the effect on remote sensing reflectivity is very limited. The absorption coefficient is difficult to be accurately measured by existing experimental methods. The effect of chlorophyll on spectral reflectance can be ignored in the spectral characteristics of high turbidity water body. Based on the analysis of CDOM concentration and absorption coefficient model, it is found that the absorption of CDOM varies greatly in time and space, but the sources are basically the same. The optical effects of the three elements in the high turbidity waters of the Yangtze River Estuary and their temporal and spatial variations are analyzed. It is found that the effects of CDOM and chlorophyll can be ignored in the water area of the mouth when the sediment concentration is retrieved, but the influence must be stripped off in the waters outside the mouth. In the same tidal cycle, the maximum concentration of total suspended particulates in the spring tide can reach above 0.5kg/1113, while the maximum TSM concentration in the low tide is only 1 / 3 of that of the spring tide, and the concentration of high total suspended particulate matter is worse than that in the tidal cycle. Many empirical algorithms can not achieve good results in this area. Through the analysis of the absorption characteristics of the three elements and the correlation analysis between the reflectivity and the remote sensing reflectivity, it can be found that there are distinct inherent optical properties inside and outside the entrance, which affects the retrieval accuracy of the total suspended particulates to a certain extent. Based on the band setting of Landsat8, the variation characteristics of total suspended particulate concentration with tidal cycle in the Yangtze River estuary are analyzed by using 38 sets of field optical and synchronous water and sediment data, and various inversion models are compared. The results show that the ratio 3s model can be applied to the Yangtze River Estuary. The measured data are verified greatly, the accuracy of the small tide is higher than that of the other models, and the variation of the off-water radiation in the tidal cycle can be better described, and the tidal period variation of the total suspended particulate concentration can be retrieved. By using 3s semi-analytical model and using Landsat8 red light and infrared band, the model can adapt to different tidal conditions in the mouth of the Yangtze River, and to some extent peel off the effects of CDOM and chlorophyll on the lower concentration of total suspended particulates. The relative error of data verification in Xuliujing station is only 9. Based on the Landsat8 remote sensing images with a span of one year, the total suspended particle concentration in the Changjiang Estuary is retrieved, and the applicability of the 3s algorithm in the Yangtze Estuary is verified. The results are in accordance with the law of suspended sediment in the Changjiang Estuary. It can provide reference for the operational operation of suspended sediment concentration monitoring in Shanghai.
【学位授予单位】：华东师范大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：X87
本文编号：2158907
[Abstract]:The optical properties of the three elements of water color in the second kind of water body are very important for the establishment of the inversion algorithm of water color remote sensing. Due to the interaction of diameter tidal current and high sediment content, the optical characteristics of the water body in the estuary of the Yangtze River have its particularity. Based on the field optical and synchronous hydrological data, the variation characteristics of water color elements with tidal cycle in the Yangtze River estuary during the flood and dry season are analyzed. The results obtained from the fixed-point observation data in May and December 2014 show that the concentration of suspended sediment is the dominant factor affecting the remote sensing reflectance of high-turbidity water in the Changjiang Estuary, and the distribution range, variation and average value of suspended sediment concentration in the dry season are higher than those in the flood season. The chlorophyll concentration in this area is very low in flood and dry season, and the effect on remote sensing reflectivity is very limited. The absorption coefficient is difficult to be accurately measured by existing experimental methods. The effect of chlorophyll on spectral reflectance can be ignored in the spectral characteristics of high turbidity water body. Based on the analysis of CDOM concentration and absorption coefficient model, it is found that the absorption of CDOM varies greatly in time and space, but the sources are basically the same. The optical effects of the three elements in the high turbidity waters of the Yangtze River Estuary and their temporal and spatial variations are analyzed. It is found that the effects of CDOM and chlorophyll can be ignored in the water area of the mouth when the sediment concentration is retrieved, but the influence must be stripped off in the waters outside the mouth. In the same tidal cycle, the maximum concentration of total suspended particulates in the spring tide can reach above 0.5kg/1113, while the maximum TSM concentration in the low tide is only 1 / 3 of that of the spring tide, and the concentration of high total suspended particulate matter is worse than that in the tidal cycle. Many empirical algorithms can not achieve good results in this area. Through the analysis of the absorption characteristics of the three elements and the correlation analysis between the reflectivity and the remote sensing reflectivity, it can be found that there are distinct inherent optical properties inside and outside the entrance, which affects the retrieval accuracy of the total suspended particulates to a certain extent. Based on the band setting of Landsat8, the variation characteristics of total suspended particulate concentration with tidal cycle in the Yangtze River estuary are analyzed by using 38 sets of field optical and synchronous water and sediment data, and various inversion models are compared. The results show that the ratio 3s model can be applied to the Yangtze River Estuary. The measured data are verified greatly, the accuracy of the small tide is higher than that of the other models, and the variation of the off-water radiation in the tidal cycle can be better described, and the tidal period variation of the total suspended particulate concentration can be retrieved. By using 3s semi-analytical model and using Landsat8 red light and infrared band, the model can adapt to different tidal conditions in the mouth of the Yangtze River, and to some extent peel off the effects of CDOM and chlorophyll on the lower concentration of total suspended particulates. The relative error of data verification in Xuliujing station is only 9. Based on the Landsat8 remote sensing images with a span of one year, the total suspended particle concentration in the Changjiang Estuary is retrieved, and the applicability of the 3s algorithm in the Yangtze Estuary is verified. The results are in accordance with the law of suspended sediment in the Changjiang Estuary. It can provide reference for the operational operation of suspended sediment concentration monitoring in Shanghai.
【学位授予单位】：华东师范大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：X87
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