The broadband diffuse radiation method is improved to retrieve the aerosol refractive index imaginary part （AIP） and broadband （400-1000 nm mean） single scattering albedo （SSA）. In this method, four sets of SSA ...The broadband diffuse radiation method is improved to retrieve the aerosol refractive index imaginary part （AIP） and broadband （400-1000 nm mean） single scattering albedo （SSA）. In this method, four sets of SSA selection criteria are proposed for quality control. The method is used to retrieve AIP, SSA and absorptive optical thickness （AbOT） from routine hourly-exposed pyrheliometer and paranometer measurements over 11 sites （meteorological observatories） in China during 1998-2003. Apart from one suburban site （Ejin Qi）, the other urban sites are all located around big or medium cities. As shown in the retrieval results, annual mean SSA during 1998-2003 changes from 0.941 （Wuhan） to 0.849 （Lanzhou）, and AIP from 0.0054 to 0.0203. The 11-site average annual mean SSA and AIP are 0.898 and 0.0119, respectively. SSA during winter is smaller for most sites. There is an evidently positive correlation between SSA and aerosol optical thickness （AOT） for all sites. There is also a positive correlation between SSA and relative humidity for most sites, but a negative correlation for a few sites, such as Kashi and ǚrǚmqi in Northwest China.展开更多
Land surface albedo is an important parameter to describe the radiant forcing in the climate system.A long-time series of global albedo products is needed to understand the mechanism of climate change.Aiming to suppor...Land surface albedo is an important parameter to describe the radiant forcing in the climate system.A long-time series of global albedo products is needed to understand the mechanism of climate change.Aiming to support global change and Earth system studies,GLASS(Global LAnd Surface Satellites)provides long-term global land surface albedo product from 1981 to 2010,which are generated from multisource remote sensing data and newly developed algorithms.It is critical to assess the quality of the GLASS product when it is released to the public.This paper first introduced the algorithms and then analyzed the integrity,accuracy,and robustness of the GLASS albedo product.The results show that the GLASS albedo product is a gapless,long-term continuous,and self-consistent data-set with an accuracy similar to that of the widely acknowledged MODIS MCD43 product.The quality flag,which is provided along with the black-sky and white-sky albedo,gives a pertinent indication of the expected uncertainty in the product.展开更多
文摘利用增强的专题制图仪＋（Enhanced Thematic Mapper Plus,ETM＋）数据,先针对各种下垫面反射率特征不同,对地物类型进行分类,以便减少邻近效应和模拟传感器未包含的谱段数据。借助卫星同步观测的气象数据,通过6S（Second Simulation of Satellite Signal inthe Solar Spectrum）模型对ETM＋可见光、近红外6个波段数据进行了大气纠正。以ETM＋可见光和近红外波段波谱范围为单位谱段,将整个短波波段（0.3-4μm）分为13个光谱域,利用ASTER光谱数据库和实测地表反射率数据,6S模拟获取各ETM＋观测波段和未观测波段地表入射光通量密度和反射光通量密度,计算每一个光谱域入射能量占整个短波入射能量中的权重,并反演地表窄波段反照率。然后,各波段能量权重作为转换参数,实现窄波段反照率向宽波段反照率的转换。结果表明,模型反演和卫星同步观测的实测地表反照率之间最大相对误差17.9%,作者提出的方法可行。
文摘The broadband diffuse radiation method is improved to retrieve the aerosol refractive index imaginary part （AIP） and broadband （400-1000 nm mean） single scattering albedo （SSA）. In this method, four sets of SSA selection criteria are proposed for quality control. The method is used to retrieve AIP, SSA and absorptive optical thickness （AbOT） from routine hourly-exposed pyrheliometer and paranometer measurements over 11 sites （meteorological observatories） in China during 1998-2003. Apart from one suburban site （Ejin Qi）, the other urban sites are all located around big or medium cities. As shown in the retrieval results, annual mean SSA during 1998-2003 changes from 0.941 （Wuhan） to 0.849 （Lanzhou）, and AIP from 0.0054 to 0.0203. The 11-site average annual mean SSA and AIP are 0.898 and 0.0119, respectively. SSA during winter is smaller for most sites. There is an evidently positive correlation between SSA and aerosol optical thickness （AOT） for all sites. There is also a positive correlation between SSA and relative humidity for most sites, but a negative correlation for a few sites, such as Kashi and ǚrǚmqi in Northwest China.
基金the National High Technology Research and Development Program of China(Grant No.2009AA122100)the authors also want to thank the FLUXNET community for providing the radiometric measurements。
文摘Land surface albedo is an important parameter to describe the radiant forcing in the climate system.A long-time series of global albedo products is needed to understand the mechanism of climate change.Aiming to support global change and Earth system studies,GLASS(Global LAnd Surface Satellites)provides long-term global land surface albedo product from 1981 to 2010,which are generated from multisource remote sensing data and newly developed algorithms.It is critical to assess the quality of the GLASS product when it is released to the public.This paper first introduced the algorithms and then analyzed the integrity,accuracy,and robustness of the GLASS albedo product.The results show that the GLASS albedo product is a gapless,long-term continuous,and self-consistent data-set with an accuracy similar to that of the widely acknowledged MODIS MCD43 product.The quality flag,which is provided along with the black-sky and white-sky albedo,gives a pertinent indication of the expected uncertainty in the product.
