Net primary productivity （NPP） and evapotranspiration （ET） are two key variables in the carbon and water cycles of terrestrial ecosystems. In this study, to test a newly developed NPP algorithm designed for H J-1 ...Net primary productivity （NPP） and evapotranspiration （ET） are two key variables in the carbon and water cycles of terrestrial ecosystems. In this study, to test a newly developed NPP algorithm designed for H J-1 A/B data and to evaluate the usage of HJ-1 A/B data in the quantitative assessment of environments, NPP and ET in Jinggangshan city, Jiangxi province, are calculated using H J-1 A/B data. The results illustrate the following： （1） The NPP and ET in Jinggangshan city in 2olo both show obvious seasonal variation, with the highest values in summer and the lowest values in winter, and relatively higher values were observed in autumn than in spring. （2） The spatial pattern indicates that the annual NPP is high in the southern area in Jinggangshan city and low in the northern area. Additionally, high NPP is distributed in forests located in areas with high elevation, and low NPP is found in croplands at low elevations. ET has no significant north-south difference, with high values in the southeast and northwest and low values in the southwest, and high ET is distributed in forests at low elevations in contrast to low ET in forests in high-elevation areas and in cropland and shrub grassland in low-elevation areas. （3） Compared to the MODIS product, the range of H J-1 NPP is larger, and the spatial pattern is more coincident with the topography. The range of H J-1 ET is smaller than that of the MODIS product, and ET is underestimated to some extent but can reflect the effect of topography. This study suggests that the algorithm can be used to estimate NPP and ET in a subtropical monsoon climate if remotely sensed images with high spatial resolution are available.展开更多
针对基于单一阈值的大范围水体提取同时存在着漏提与误提的局限性,提出了基于大津法的局部范围阈值自适应确定的方法。通过分析水体与其背景地物的光谱特征,发现归一化水体指数(Normalized Difference Water Index,NDWI)直方图呈现明显...针对基于单一阈值的大范围水体提取同时存在着漏提与误提的局限性,提出了基于大津法的局部范围阈值自适应确定的方法。通过分析水体与其背景地物的光谱特征,发现归一化水体指数(Normalized Difference Water Index,NDWI)直方图呈现明显的双峰分布,对NDWI使用大津法可以较准确地自动计算出水体与非水体的阈值。在初始阈值提取的水体信息的基础上,通过窗体提取局部范围的水体及其背景并进行局部自适应阈值的计算,实现自适应阈值水体信息的提取。使用环境小卫星影像对闽江流域进行水体提取实验,结果表明该方法可实现大范围水体快速提取,提取精度为95.25%,较全局统一阈值提取精度提高5.25%,并能在一定程度上消除地形阴影与建筑物等的影响,对细小水体的提取精度有所提高。展开更多
From the viewpoint of environmental remote-sensing applications,this article explains the overall technical characteristics of the Chinese HJ-1A and HJ-1B satellites.It also investigates the spectral characteristics a...From the viewpoint of environmental remote-sensing applications,this article explains the overall technical characteristics of the Chinese HJ-1A and HJ-1B satellites.It also investigates the spectral characteristics and potential applications of charge-coupled devices,and the infrared and hyperspectral data obtained by the satellites.Examples of applications,such as the remote-sensing monitoring of algal bloom in Taihu Lake,straw burning in southern China,and aerosol optical depth in the area around Bohai sea are presented.These examples illustrate the application characteristics of the HJ-1A and HJ-1B satellite data.展开更多
This paper demonstrates an atmospheric correction method to process HJ-1A/B CCD images over Chinese coastal waters with the aid of MODIS-Terra aerosol information.Based on the assumption of zero water-leaving radiance...This paper demonstrates an atmospheric correction method to process HJ-1A/B CCD images over Chinese coastal waters with the aid of MODIS-Terra aerosol information.Based on the assumption of zero water-leaving radiance at the two near-infrared (NIR)bands or the shortwave infrared(SWIR)bands,the atmospheric aerosol optical depth(AOD)is firstly retrieved from MODIS-Terra with a simple extension of the NIR-SWIR combined atmospheric correction approach embedded in SeaDAS (SeaWiFS data analysis system).Then the"turbid"and"non-turbid"waters are separated by the turbid water index.Maximum probability of AOD at 551 nm band is derived based on the NIR information over"non-turbid"waters and FLAASH model is selected to do the atmospheric correction of the HJ-1A/B CCD imagery using the AOD values of highest probabilities as input.Similarly,according to the histogram of the AOD distribution at 551 nm band,the studied turbid water area is divided into several blocks and HJ-1A/B CCD imagery is corrected with the corresponding AOD values displayed with the highest frequency in each block.This method has been applied to several HJ-1A/B images over Chinese coastal waters and validated by synchronous in-situ data.The results have shown that this method is effective in the atmospheric correction process of HJ-1A/B CCD images for ocean color remote sensing study and application in the coastal waters.展开更多
基金funded by the National Natural Science Foundation of China (Grant no. 40971221)the National High Technology Research and Development Program of China (863 Program) (Grant no. 2012AA12A304)
文摘Net primary productivity （NPP） and evapotranspiration （ET） are two key variables in the carbon and water cycles of terrestrial ecosystems. In this study, to test a newly developed NPP algorithm designed for H J-1 A/B data and to evaluate the usage of HJ-1 A/B data in the quantitative assessment of environments, NPP and ET in Jinggangshan city, Jiangxi province, are calculated using H J-1 A/B data. The results illustrate the following： （1） The NPP and ET in Jinggangshan city in 2olo both show obvious seasonal variation, with the highest values in summer and the lowest values in winter, and relatively higher values were observed in autumn than in spring. （2） The spatial pattern indicates that the annual NPP is high in the southern area in Jinggangshan city and low in the northern area. Additionally, high NPP is distributed in forests located in areas with high elevation, and low NPP is found in croplands at low elevations. ET has no significant north-south difference, with high values in the southeast and northwest and low values in the southwest, and high ET is distributed in forests at low elevations in contrast to low ET in forests in high-elevation areas and in cropland and shrub grassland in low-elevation areas. （3） Compared to the MODIS product, the range of H J-1 NPP is larger, and the spatial pattern is more coincident with the topography. The range of H J-1 ET is smaller than that of the MODIS product, and ET is underestimated to some extent but can reflect the effect of topography. This study suggests that the algorithm can be used to estimate NPP and ET in a subtropical monsoon climate if remotely sensed images with high spatial resolution are available.
文摘针对基于单一阈值的大范围水体提取同时存在着漏提与误提的局限性,提出了基于大津法的局部范围阈值自适应确定的方法。通过分析水体与其背景地物的光谱特征,发现归一化水体指数(Normalized Difference Water Index,NDWI)直方图呈现明显的双峰分布,对NDWI使用大津法可以较准确地自动计算出水体与非水体的阈值。在初始阈值提取的水体信息的基础上,通过窗体提取局部范围的水体及其背景并进行局部自适应阈值的计算,实现自适应阈值水体信息的提取。使用环境小卫星影像对闽江流域进行水体提取实验,结果表明该方法可实现大范围水体快速提取,提取精度为95.25%,较全局统一阈值提取精度提高5.25%,并能在一定程度上消除地形阴影与建筑物等的影响,对细小水体的提取精度有所提高。
基金supported by National Key Project of China (Grant No.2009ZX07527-6)National Key Technology R&D Program of China (Grant No.2008BAC34B05)National Natural Science Foundation of China (Grant No.41001245)
文摘From the viewpoint of environmental remote-sensing applications,this article explains the overall technical characteristics of the Chinese HJ-1A and HJ-1B satellites.It also investigates the spectral characteristics and potential applications of charge-coupled devices,and the infrared and hyperspectral data obtained by the satellites.Examples of applications,such as the remote-sensing monitoring of algal bloom in Taihu Lake,straw burning in southern China,and aerosol optical depth in the area around Bohai sea are presented.These examples illustrate the application characteristics of the HJ-1A and HJ-1B satellite data.
基金supported by the National Basic Research Program of China("973"Project)(Grant No.2006CB701300)the National Hi-Tech Research and Development Program of China("863"Project)(Grant Nos.2007AA12Z161,2007AA120203)+4 种基金the National Natural Science Foundation of China(Grant Nos.40906092,40721001,40706060)the National Science Foundation of Hubei Province(Grant No.2009CDB107)MOST China(Grant No.2007BAC23B05)LIESMARS Special Research Funding,Open Research Fund,The Key Lab of Poyang Lake Ecological Environ-ment and Resource Development,Nanchang University(Grant No.Z03975)the"985"Project of Wuhan University,and the Special Funds of State Key Laboratory for Equipment
文摘This paper demonstrates an atmospheric correction method to process HJ-1A/B CCD images over Chinese coastal waters with the aid of MODIS-Terra aerosol information.Based on the assumption of zero water-leaving radiance at the two near-infrared (NIR)bands or the shortwave infrared(SWIR)bands,the atmospheric aerosol optical depth(AOD)is firstly retrieved from MODIS-Terra with a simple extension of the NIR-SWIR combined atmospheric correction approach embedded in SeaDAS (SeaWiFS data analysis system).Then the"turbid"and"non-turbid"waters are separated by the turbid water index.Maximum probability of AOD at 551 nm band is derived based on the NIR information over"non-turbid"waters and FLAASH model is selected to do the atmospheric correction of the HJ-1A/B CCD imagery using the AOD values of highest probabilities as input.Similarly,according to the histogram of the AOD distribution at 551 nm band,the studied turbid water area is divided into several blocks and HJ-1A/B CCD imagery is corrected with the corresponding AOD values displayed with the highest frequency in each block.This method has been applied to several HJ-1A/B images over Chinese coastal waters and validated by synchronous in-situ data.The results have shown that this method is effective in the atmospheric correction process of HJ-1A/B CCD images for ocean color remote sensing study and application in the coastal waters.
