长江口春季潮周期内总悬浮颗粒物浓度的光学遥感反演
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摘要
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.同一潮周期内大潮时总悬浮颗粒物浓度能达到0.5 kg/m~3以上,而小潮时最大总悬浮颗粒物浓度只有大潮的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取得良好的反演效果.为了能适应该区域特殊水体特性,通过改进总悬浮颗粒物的复杂指数模式,建立了适合长江口地区的改进模式.利用2014年5月航次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,在原有7个备选波段的基础上引入了806nm和858 nm两个备选波段,补充近红外波段峰面积指数作为复杂指数模式的第五个指数,将复杂指数与总悬浮颗粒物浓度的对数之间线性关系改进为二次多项式关系,针对不同潮情的水体特性建立了分潮情的改进模型.结果表明:改进的模型可以适用于长江口水域,大、小潮分别建模得到的反演精度较大小潮统一模型更高,能更好地刻画潮周期内离水辐射的变化,反映总悬浮颗粒物浓度的潮周期变动.
Due to the interaction between the river discharge and the tide,as well as the high suspended sediment concentration in the surface water,the optical property of the Yangtze Estuary waters is different from the open sea waters.In a single tidal cycle,the total suspended maters(TSM) concentration can reach 0.5 kg/m3 or more during spring tide,while in neap tide the maximum TSM concentration is only 1/3 of the spring tides.High TSM concentrations and a greater variation in single tidal cycle make a lot of empirical inversion algorithm unavailable in this region.A new algorithm was developed in the Yangtze Estuary,named improved complex proxy TSM(ICPTSM) model to improve the complex proxy TSM model.Using in situ synchronous optical and TSM concentration data collected in the survey in May 2014,we analyze the characteristic of sediment concentration changing in the Yangtze Estuary associated within entire tidal cycle.Based on the original seven alternative bands,we introduce two alternative bands,806 nm and858 nm,as a supplement.We add a near-infrared peak area index as the fifth index to the complex proxy(CP).Linear relationship between the CP index and TSM concentration is improved into quadratic relationship.For water characteristics of different tidal conditions,individual ICPTSM models have been established.The results show that:ICPTSM model is adaptable in the Yangtze Estuary,distinction model toward spring and neap tidal have higher retrieval accuracy than unified model for a whole tide cycle,distinction model can better describe changes of water-leaving radiance,and TSM concentration changes in a tidal cycle.
Due to the interaction between the river discharge and the tide,as well as the high suspended sediment concentration in the surface water,the optical property of the Yangtze Estuary waters is different from the open sea waters.In a single tidal cycle,the total suspended maters(TSM) concentration can reach 0.5 kg/m3 or more during spring tide,while in neap tide the maximum TSM concentration is only 1/3 of the spring tides.High TSM concentrations and a greater variation in single tidal cycle make a lot of empirical inversion algorithm unavailable in this region.A new algorithm was developed in the Yangtze Estuary,named improved complex proxy TSM(ICPTSM) model to improve the complex proxy TSM model.Using in situ synchronous optical and TSM concentration data collected in the survey in May 2014,we analyze the characteristic of sediment concentration changing in the Yangtze Estuary associated within entire tidal cycle.Based on the original seven alternative bands,we introduce two alternative bands,806 nm and858 nm,as a supplement.We add a near-infrared peak area index as the fifth index to the complex proxy(CP).Linear relationship between the CP index and TSM concentration is improved into quadratic relationship.For water characteristics of different tidal conditions,individual ICPTSM models have been established.The results show that:ICPTSM model is adaptable in the Yangtze Estuary,distinction model toward spring and neap tidal have higher retrieval accuracy than unified model for a whole tide cycle,distinction model can better describe changes of water-leaving radiance,and TSM concentration changes in a tidal cycle.
引文
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[12]MAO Z,CHEN J,PAN D,et al.A regional remote sensing algorithm for total suspended matter in the East China Sea[J].Remote Sensing of Environment,2012,124:819-831.
[13]樊辉,黄海军.黄、东海二类水体春季表观光谱特性与表层悬浮体浓度反演模式[J].海洋与湖沼,2010(2):161-166.
[14]刘红,何青,王亚,等.长江河口悬浮泥沙的混合过程[J].地理学报,2012,67(9):1269-1281.
[15]孙德勇,李云梅,乐成峰,等.太湖水体散射特性及其与悬浮物浓度关系模型[J].环境科学,2007(12):2688-2694.
[16]MA W,XING Q,CHEN C,et al.Using the normalized peak area of remote sensing reflectance in the nearinfrared region to estimate total suspended matter[J].International Journal of Remote Sensing,2011,32:7479-7486.
[2]CURRAN P J.The semivariogram in remote sensing:An introduction[J].Remote Sensing of Environment,1988,24(3):493-507.
[3]DOXARAN D,FROIDEFOND J,LAVENDER S,et al.Spectral signature of highly turbid waters:Application with SPOT data to quantify suspended particulate matter concentrations[J].Remote Sensing of Environment,2002,81(1):149-161.
[4]DOXARAN D,FROIDEFOND J M,CASTAING P.A reflectance band ratio used to estimate suspended matter concentrations in sediment-dominated coastal waters[J].International Journal of Remote Sensing,2002,23(23):5079-5085.
[5]NOVO EMLM,STEFFEN C A,BRAGA C Z F.Results of a laboratory experiment relating spectral reflectance to total suspended solids[J].Remote Sensing of Environment,1991,36(1):67-72.
[6]陈勇,韩震,杨丽君,等.长江口水体表层悬浮泥沙时空分布对环境演变的响应[J].海洋学报:中文版,2012(1):145-152.
[7]孟灵,屈凡柱,毕晓丽.二类水体悬浮泥沙遥感反演算法综述[J].浙江海洋学院学报(自然科学版),2011,30(5):443-449.
[8]刘红,何青,王亚,等.长江河口悬浮泥沙的混合过程[J].地理学报,2012(9):1269-1281.
[9]唐军武,田国良,汪小勇,等.水体光谱测量与分析I:水面以上测量法[J].遥感学报,2004,8(1):37-44.
[10]MOBLEY C D.Estimation of the remote-sensing reflectance from above-surface measurements[J].Applied Optics,1999,36(38):7442-7455.
[11]RUDDICK K G,DE CAUWER V,PARK Y,et al.Seaborne measurements of near infrared water-leaving reflectance:The similarity spectrum for turbid waters[J].Limnology and Oceanography,2006,51(2):1167-1179.
[12]MAO Z,CHEN J,PAN D,et al.A regional remote sensing algorithm for total suspended matter in the East China Sea[J].Remote Sensing of Environment,2012,124:819-831.
[13]樊辉,黄海军.黄、东海二类水体春季表观光谱特性与表层悬浮体浓度反演模式[J].海洋与湖沼,2010(2):161-166.
[14]刘红,何青,王亚,等.长江河口悬浮泥沙的混合过程[J].地理学报,2012,67(9):1269-1281.
[15]孙德勇,李云梅,乐成峰,等.太湖水体散射特性及其与悬浮物浓度关系模型[J].环境科学,2007(12):2688-2694.
[16]MA W,XING Q,CHEN C,et al.Using the normalized peak area of remote sensing reflectance in the nearinfrared region to estimate total suspended matter[J].International Journal of Remote Sensing,2011,32:7479-7486.
目录