遥感影像的大气校正是遥感定量化研究的难点之一。以曹妃甸近岸海域为研究区,以水体悬浮泥沙浓度(suspended sediment concentration,SSC)定量反演为目标,采用6S(second simulation of the satellite signal in the solar spectrum)模型...遥感影像的大气校正是遥感定量化研究的难点之一。以曹妃甸近岸海域为研究区,以水体悬浮泥沙浓度(suspended sediment concentration,SSC)定量反演为目标,采用6S(second simulation of the satellite signal in the solar spectrum)模型和FLAASH模型对研究区MODIS影像的大气校正方法进行对比实验,对2个模型校正前后的影像质量以及对目标地物信息的校正效果进行了评价。研究结果表明:2种模型均能在一定程度上削弱大气对水体信息的影响;相比之下,6S模型校正后影像质量优于FLAASH模型,能更真实地反映目标地物,可更好地实现对近岸海域遥感影像的高精度大气校正;将6S模型大气校正后的MODIS影像应用于悬浮泥沙浓度的遥感反演,反演结果的平均相对误差为24.79%,均方根误差为4.32 mg/L。研究结果可为近岸海域Ⅱ类水体大气校正方法的选择提供依据,为深化泥沙运移规律研究及水质、水环境评价提供技术支持。展开更多
Cloud-free moderate-resolution imaging spectroradiometer(MODIS) images of the Zhujiang(Pearl) River Estuary(ZRE) taken between 2002 and 2012 are retrieved and used to study the spatial and temporal patterns of suspend...Cloud-free moderate-resolution imaging spectroradiometer(MODIS) images of the Zhujiang(Pearl) River Estuary(ZRE) taken between 2002 and 2012 are retrieved and used to study the spatial and temporal patterns of suspended sediment concentrations(SSCs) across the estuary under runoff, wind, and tropical storm conditions.Five typical dispersal patterns of suspended sediments in the estuary are defined: Case I shows generally low SSCs under low dynamics; Case Ⅱ shows a river-dominant dispersal pattern of suspended sediments from the outlets,particularly from Modaomen, Jiaomen, Hengmen, and others; Case Ⅲ shows wind-dominant dispersal of high SSCs derived from the west shoal and southwesterly transport under a strong NE wind; Case IV is the combination of relatively large runoff and wind; and Case V is caused by a strong tropical storm with high river discharge and wind, which is characterized by the high SSCs across the entire estuary that are transported eastward by winddriven and buoyancy currents outside the estuary. Runoff is a dominant factor that controls seasonal and annual SSC variations in the ZRE, with the area of high SSCs being largest in the summer and smallest in the spring. The correlation coefficients between the monthly averaged river-suspended sediment discharge and the area of the high SSCs are approximately 0.6. The wind power over the west shoal increases with a wind speed, which induces more sediment resuspension and shows a close relationship between the wind speed and high SSC area.展开更多
文摘遥感影像的大气校正是遥感定量化研究的难点之一。以曹妃甸近岸海域为研究区,以水体悬浮泥沙浓度(suspended sediment concentration,SSC)定量反演为目标,采用6S(second simulation of the satellite signal in the solar spectrum)模型和FLAASH模型对研究区MODIS影像的大气校正方法进行对比实验,对2个模型校正前后的影像质量以及对目标地物信息的校正效果进行了评价。研究结果表明:2种模型均能在一定程度上削弱大气对水体信息的影响;相比之下,6S模型校正后影像质量优于FLAASH模型,能更真实地反映目标地物,可更好地实现对近岸海域遥感影像的高精度大气校正;将6S模型大气校正后的MODIS影像应用于悬浮泥沙浓度的遥感反演,反演结果的平均相对误差为24.79%,均方根误差为4.32 mg/L。研究结果可为近岸海域Ⅱ类水体大气校正方法的选择提供依据,为深化泥沙运移规律研究及水质、水环境评价提供技术支持。
基金The National Natural Science Foundation of China under contract Nos 41106015 and 41476073the National Key Research and Development Program of China under contract No.2016YFC0402600
文摘Cloud-free moderate-resolution imaging spectroradiometer(MODIS) images of the Zhujiang(Pearl) River Estuary(ZRE) taken between 2002 and 2012 are retrieved and used to study the spatial and temporal patterns of suspended sediment concentrations(SSCs) across the estuary under runoff, wind, and tropical storm conditions.Five typical dispersal patterns of suspended sediments in the estuary are defined: Case I shows generally low SSCs under low dynamics; Case Ⅱ shows a river-dominant dispersal pattern of suspended sediments from the outlets,particularly from Modaomen, Jiaomen, Hengmen, and others; Case Ⅲ shows wind-dominant dispersal of high SSCs derived from the west shoal and southwesterly transport under a strong NE wind; Case IV is the combination of relatively large runoff and wind; and Case V is caused by a strong tropical storm with high river discharge and wind, which is characterized by the high SSCs across the entire estuary that are transported eastward by winddriven and buoyancy currents outside the estuary. Runoff is a dominant factor that controls seasonal and annual SSC variations in the ZRE, with the area of high SSCs being largest in the summer and smallest in the spring. The correlation coefficients between the monthly averaged river-suspended sediment discharge and the area of the high SSCs are approximately 0.6. The wind power over the west shoal increases with a wind speed, which induces more sediment resuspension and shows a close relationship between the wind speed and high SSC area.
