The Experts below are selected from a list of 327 Experts worldwide ranked by ideXlab platform
Jason E Box - One of the best experts on this subject based on the ideXlab platform.
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mapping daily snow ice shortwave broadband albedo from moderate resolution imaging spectroradiometer modis the improved Direct Retrieval algorithm and validation with greenland in situ measurement
Journal of Geophysical Research, 2005Co-Authors: Shunlin Liang, Julienne Stroeve, Jason E BoxAbstract:[1] Snow/ice albedo is a critical variable in surface energy balance calculations. The Moderate Resolution Imaging Spectroradiometer (MODIS) data have been used routinely to provide global land surface albedo. The MODIS algorithm includes atmospheric correction, surface reflectance angular modeling, and narrowband to broadband albedo conversion. In an earlier study, a “Direct Retrieval” methodology was proposed to calculate instantaneous albedo over snow and ice-covered surfaces Directly from top-of-atmosphere (TOA) MODIS reflectance data. The method consists of extensive radiative transfer simulations for a variety of atmospheric and surface snow conditions and links the TOA reflectance with surface broadband albedo through regression analysis. Therefore the Direct Retrieval algorithm implicitly incorporates in a single step all three procedures used in the standard MODIS surface albedo algorithm. This study presents improvements to the Retrieval algorithm including validation with in situ measurements distributed over the Greenland ice sheet. Comparison with surface observations demonstrates that the Direct Retrieval algorithm can produce very accurate daily snow/ice albedo with mean bias of less than 0.02 and residual standard error of 0.04.
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Mapping daily snow/ice shortwave broadband albedo from Moderate Resolution Imaging Spectroradiometer (MODIS): The improved Direct Retrieval algorithm and validation with Greenland in situ measurement
Journal of Geophysical Research, 2005Co-Authors: Shunlin Liang, Julienne Stroeve, Jason E BoxAbstract:[1] Snow/ice albedo is a critical variable in surface energy balance calculations. The Moderate Resolution Imaging Spectroradiometer (MODIS) data have been used routinely to provide global land surface albedo. The MODIS algorithm includes atmospheric correction, surface reflectance angular modeling, and narrowband to broadband albedo conversion. In an earlier study, a “Direct Retrieval” methodology was proposed to calculate instantaneous albedo over snow and ice-covered surfaces Directly from top-of-atmosphere (TOA) MODIS reflectance data. The method consists of extensive radiative transfer simulations for a variety of atmospheric and surface snow conditions and links the TOA reflectance with surface broadband albedo through regression analysis. Therefore the Direct Retrieval algorithm implicitly incorporates in a single step all three procedures used in the standard MODIS surface albedo algorithm. This study presents improvements to the Retrieval algorithm including validation with in situ measurements distributed over the Greenland ice sheet. Comparison with surface observations demonstrates that the Direct Retrieval algorithm can produce very accurate daily snow/ice albedo with mean bias of less than 0.02 and residual standard error of 0.04.
W G Read - One of the best experts on this subject based on the ideXlab platform.
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Direct Retrieval of line of sight atmospheric structure from limb sounding observations
Geophysical Research Letters, 2000Co-Authors: N J Livesey, W G ReadAbstract:Optimal estimation of atmospheric temperature and composition from limb sounding observations is extended to the Direct Retrieval of line-of-sight atmospheric structure that can be obtained in certain limb viewing geometries. The approach is to divide the dataset into slightly overlapping chunks of several atmospheric profiles and retrieve estimates for all profiles concurrently. The method is made efficient due to the sparse nature of the matrices involved. In the case where the number of radiance measurements is significantly larger than the length of the state vector, the computational effort scales linearly with the number of profiles in the chunk. Prototype simulations, done for the EOS MLS experiment, show that application of this method can give significant improvements in accuracy.
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Direct Retrieval of line‐of‐sight atmospheric structure from limb sounding observations
Geophysical Research Letters, 2000Co-Authors: N J Livesey, W G ReadAbstract:Optimal estimation of atmospheric temperature and composition from limb sounding observations is extended to the Direct Retrieval of line-of-sight atmospheric structure that can be obtained in certain limb viewing geometries. The approach is to divide the dataset into slightly overlapping chunks of several atmospheric profiles and retrieve estimates for all profiles concurrently. The method is made efficient due to the sparse nature of the matrices involved. In the case where the number of radiance measurements is significantly larger than the length of the state vector, the computational effort scales linearly with the number of profiles in the chunk. Prototype simulations, done for the EOS MLS experiment, show that application of this method can give significant improvements in accuracy.
Shunlin Liang - One of the best experts on this subject based on the ideXlab platform.
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mapping daily snow ice shortwave broadband albedo from moderate resolution imaging spectroradiometer modis the improved Direct Retrieval algorithm and validation with greenland in situ measurement
Journal of Geophysical Research, 2005Co-Authors: Shunlin Liang, Julienne Stroeve, Jason E BoxAbstract:[1] Snow/ice albedo is a critical variable in surface energy balance calculations. The Moderate Resolution Imaging Spectroradiometer (MODIS) data have been used routinely to provide global land surface albedo. The MODIS algorithm includes atmospheric correction, surface reflectance angular modeling, and narrowband to broadband albedo conversion. In an earlier study, a “Direct Retrieval” methodology was proposed to calculate instantaneous albedo over snow and ice-covered surfaces Directly from top-of-atmosphere (TOA) MODIS reflectance data. The method consists of extensive radiative transfer simulations for a variety of atmospheric and surface snow conditions and links the TOA reflectance with surface broadband albedo through regression analysis. Therefore the Direct Retrieval algorithm implicitly incorporates in a single step all three procedures used in the standard MODIS surface albedo algorithm. This study presents improvements to the Retrieval algorithm including validation with in situ measurements distributed over the Greenland ice sheet. Comparison with surface observations demonstrates that the Direct Retrieval algorithm can produce very accurate daily snow/ice albedo with mean bias of less than 0.02 and residual standard error of 0.04.
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Mapping daily snow/ice shortwave broadband albedo from Moderate Resolution Imaging Spectroradiometer (MODIS): The improved Direct Retrieval algorithm and validation with Greenland in situ measurement
Journal of Geophysical Research, 2005Co-Authors: Shunlin Liang, Julienne Stroeve, Jason E BoxAbstract:[1] Snow/ice albedo is a critical variable in surface energy balance calculations. The Moderate Resolution Imaging Spectroradiometer (MODIS) data have been used routinely to provide global land surface albedo. The MODIS algorithm includes atmospheric correction, surface reflectance angular modeling, and narrowband to broadband albedo conversion. In an earlier study, a “Direct Retrieval” methodology was proposed to calculate instantaneous albedo over snow and ice-covered surfaces Directly from top-of-atmosphere (TOA) MODIS reflectance data. The method consists of extensive radiative transfer simulations for a variety of atmospheric and surface snow conditions and links the TOA reflectance with surface broadband albedo through regression analysis. Therefore the Direct Retrieval algorithm implicitly incorporates in a single step all three procedures used in the standard MODIS surface albedo algorithm. This study presents improvements to the Retrieval algorithm including validation with in situ measurements distributed over the Greenland ice sheet. Comparison with surface observations demonstrates that the Direct Retrieval algorithm can produce very accurate daily snow/ice albedo with mean bias of less than 0.02 and residual standard error of 0.04.
N J Livesey - One of the best experts on this subject based on the ideXlab platform.
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Direct Retrieval of line of sight atmospheric structure from limb sounding observations
Geophysical Research Letters, 2000Co-Authors: N J Livesey, W G ReadAbstract:Optimal estimation of atmospheric temperature and composition from limb sounding observations is extended to the Direct Retrieval of line-of-sight atmospheric structure that can be obtained in certain limb viewing geometries. The approach is to divide the dataset into slightly overlapping chunks of several atmospheric profiles and retrieve estimates for all profiles concurrently. The method is made efficient due to the sparse nature of the matrices involved. In the case where the number of radiance measurements is significantly larger than the length of the state vector, the computational effort scales linearly with the number of profiles in the chunk. Prototype simulations, done for the EOS MLS experiment, show that application of this method can give significant improvements in accuracy.
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Direct Retrieval of line‐of‐sight atmospheric structure from limb sounding observations
Geophysical Research Letters, 2000Co-Authors: N J Livesey, W G ReadAbstract:Optimal estimation of atmospheric temperature and composition from limb sounding observations is extended to the Direct Retrieval of line-of-sight atmospheric structure that can be obtained in certain limb viewing geometries. The approach is to divide the dataset into slightly overlapping chunks of several atmospheric profiles and retrieve estimates for all profiles concurrently. The method is made efficient due to the sparse nature of the matrices involved. In the case where the number of radiance measurements is significantly larger than the length of the state vector, the computational effort scales linearly with the number of profiles in the chunk. Prototype simulations, done for the EOS MLS experiment, show that application of this method can give significant improvements in accuracy.
Julienne Stroeve - One of the best experts on this subject based on the ideXlab platform.
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mapping daily snow ice shortwave broadband albedo from moderate resolution imaging spectroradiometer modis the improved Direct Retrieval algorithm and validation with greenland in situ measurement
Journal of Geophysical Research, 2005Co-Authors: Shunlin Liang, Julienne Stroeve, Jason E BoxAbstract:[1] Snow/ice albedo is a critical variable in surface energy balance calculations. The Moderate Resolution Imaging Spectroradiometer (MODIS) data have been used routinely to provide global land surface albedo. The MODIS algorithm includes atmospheric correction, surface reflectance angular modeling, and narrowband to broadband albedo conversion. In an earlier study, a “Direct Retrieval” methodology was proposed to calculate instantaneous albedo over snow and ice-covered surfaces Directly from top-of-atmosphere (TOA) MODIS reflectance data. The method consists of extensive radiative transfer simulations for a variety of atmospheric and surface snow conditions and links the TOA reflectance with surface broadband albedo through regression analysis. Therefore the Direct Retrieval algorithm implicitly incorporates in a single step all three procedures used in the standard MODIS surface albedo algorithm. This study presents improvements to the Retrieval algorithm including validation with in situ measurements distributed over the Greenland ice sheet. Comparison with surface observations demonstrates that the Direct Retrieval algorithm can produce very accurate daily snow/ice albedo with mean bias of less than 0.02 and residual standard error of 0.04.
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Mapping daily snow/ice shortwave broadband albedo from Moderate Resolution Imaging Spectroradiometer (MODIS): The improved Direct Retrieval algorithm and validation with Greenland in situ measurement
Journal of Geophysical Research, 2005Co-Authors: Shunlin Liang, Julienne Stroeve, Jason E BoxAbstract:[1] Snow/ice albedo is a critical variable in surface energy balance calculations. The Moderate Resolution Imaging Spectroradiometer (MODIS) data have been used routinely to provide global land surface albedo. The MODIS algorithm includes atmospheric correction, surface reflectance angular modeling, and narrowband to broadband albedo conversion. In an earlier study, a “Direct Retrieval” methodology was proposed to calculate instantaneous albedo over snow and ice-covered surfaces Directly from top-of-atmosphere (TOA) MODIS reflectance data. The method consists of extensive radiative transfer simulations for a variety of atmospheric and surface snow conditions and links the TOA reflectance with surface broadband albedo through regression analysis. Therefore the Direct Retrieval algorithm implicitly incorporates in a single step all three procedures used in the standard MODIS surface albedo algorithm. This study presents improvements to the Retrieval algorithm including validation with in situ measurements distributed over the Greenland ice sheet. Comparison with surface observations demonstrates that the Direct Retrieval algorithm can produce very accurate daily snow/ice albedo with mean bias of less than 0.02 and residual standard error of 0.04.