The high spatial resolution and temporal observation frequency of HJ-1/CCD make it suitable for aerosol monitoring.However,because of the lack of a shortwave infrared band,it is difficult to use HJ-1/CCD imagery to re...The high spatial resolution and temporal observation frequency of HJ-1/CCD make it suitable for aerosol monitoring.However,because of the lack of a shortwave infrared band,it is difficult to use HJ-1/CCD imagery to retrieve aerosol optical depth(AOD).We developed a new algorithm for HJ-1/CCD AOD retrieval by introducing MODIS surface reflectance outputs(MOD09) as support.In this algorithm HJ-1/CCD blue band surface reflectance was retrieved through MOD09 blue band surface reflectance by band matching of the two sensors.AOD at 550 nm was then generated through a pre-calculated look-up table for HJ-1/CCD.Eighteen HJ-1/CCD images covering the Jing-Jin-Tang(Beijing-Tianjin-Tangshan) region were used to retrieve AOD using the new algorithm,and the AODs were then validated using AERONET ground measurements in Beijing and Xianghe.The validation shows that compared with AERONET ground measurements,27/29 AODs have error less than 0.1 in absolute value.展开更多
The leaf area index(LAI) is an important ecological parameter that characterizes the interface between vegetation canopy and the atmosphere.In addition,it is used by most process-oriented ecosystem models.This paper i...The leaf area index(LAI) is an important ecological parameter that characterizes the interface between vegetation canopy and the atmosphere.In addition,it is used by most process-oriented ecosystem models.This paper investigates the potential of HJ-1 CCD data combined with linear spectral unmixing and an inverted geometric-optical model for the retrieval of the shrub LAI in Wushen Banner of Inner Mongolia in the Mu Us Sandland.MODTRAN(Moderate Resolution Atmospheric Radiance and Transmittance Model) was used for atmospheric correction.Shrubland was extracted using the threshold of the normalized difference vegetation index,with which water bodies and farmland were separated,in combination with a vegetation map of the People's Republic of China(1:1000000).Using the geometric-optical model,we derive the per-pixel reflectance as a simple linear combination of two components,namely sunlit background and other.The fraction of sunlit background is related to the shrub LAI.With the support of HJ-1 CCD data,we employ linear spectral unmixing to obtain the fraction of sunlit background in an atmospherically corrected HJ image.In addition,we use the measured shrub canopy structural parameters for shrub communities to invert the geometric-optical model and retrieve the pixel-based shrub LAI.In total,18 sample plots collected in Wushen Banner of Inner Mongolia are used for validation.The results of the shrub LAI show good agreement with R2 of 0.817 and a root-mean-squared error of 0.173.展开更多
基金supported by National Natural Science Foundation of China (Grant No.40701112)National Key Technology R & D Program of China (Grant No.2008BAC34B03)National High-tech R & D Program of China (Grant No.2009AA12Z147)
文摘The high spatial resolution and temporal observation frequency of HJ-1/CCD make it suitable for aerosol monitoring.However,because of the lack of a shortwave infrared band,it is difficult to use HJ-1/CCD imagery to retrieve aerosol optical depth(AOD).We developed a new algorithm for HJ-1/CCD AOD retrieval by introducing MODIS surface reflectance outputs(MOD09) as support.In this algorithm HJ-1/CCD blue band surface reflectance was retrieved through MOD09 blue band surface reflectance by band matching of the two sensors.AOD at 550 nm was then generated through a pre-calculated look-up table for HJ-1/CCD.Eighteen HJ-1/CCD images covering the Jing-Jin-Tang(Beijing-Tianjin-Tangshan) region were used to retrieve AOD using the new algorithm,and the AODs were then validated using AERONET ground measurements in Beijing and Xianghe.The validation shows that compared with AERONET ground measurements,27/29 AODs have error less than 0.1 in absolute value.
基金supported by National Natural Science Foundation of China (Grant No.40871173)Special Grant for Prevention and Treatment of Infectious Diseases (Grant No.2008ZX10004-012)National State Basic Research Program of China (Grant No. 2007CB714404)
文摘The leaf area index(LAI) is an important ecological parameter that characterizes the interface between vegetation canopy and the atmosphere.In addition,it is used by most process-oriented ecosystem models.This paper investigates the potential of HJ-1 CCD data combined with linear spectral unmixing and an inverted geometric-optical model for the retrieval of the shrub LAI in Wushen Banner of Inner Mongolia in the Mu Us Sandland.MODTRAN(Moderate Resolution Atmospheric Radiance and Transmittance Model) was used for atmospheric correction.Shrubland was extracted using the threshold of the normalized difference vegetation index,with which water bodies and farmland were separated,in combination with a vegetation map of the People's Republic of China(1:1000000).Using the geometric-optical model,we derive the per-pixel reflectance as a simple linear combination of two components,namely sunlit background and other.The fraction of sunlit background is related to the shrub LAI.With the support of HJ-1 CCD data,we employ linear spectral unmixing to obtain the fraction of sunlit background in an atmospherically corrected HJ image.In addition,we use the measured shrub canopy structural parameters for shrub communities to invert the geometric-optical model and retrieve the pixel-based shrub LAI.In total,18 sample plots collected in Wushen Banner of Inner Mongolia are used for validation.The results of the shrub LAI show good agreement with R2 of 0.817 and a root-mean-squared error of 0.173.
基金National Key Research and Development Program of China(2018YFC1508301,2018YFC1508302)National Natural Science Foundation of China(31871516)Hubei Natural Science Foundation(2019CFB507)。
