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near-infrared (NIR) waveband; b denotes direct beam ( b = dir) or diffuse ( b = dif) albedos; and f u ,sno is the fraction of surface covered with snow ( Bonan 1996 ). The snow-free urban albedos α b u ,Λ are input parameters. Snow albedos are set to α b sno,VIS = 0.66 and α b sno,NIR = 0.56, which fall about in the middle of the range given by Oke (1987) . 2) Incident-direct solar radiation The direct beam solar radiation incident on the roof is simply the atmospheric solar radiation
near-infrared (NIR) waveband; b denotes direct beam ( b = dir) or diffuse ( b = dif) albedos; and f u ,sno is the fraction of surface covered with snow ( Bonan 1996 ). The snow-free urban albedos α b u ,Λ are input parameters. Snow albedos are set to α b sno,VIS = 0.66 and α b sno,NIR = 0.56, which fall about in the middle of the range given by Oke (1987) . 2) Incident-direct solar radiation The direct beam solar radiation incident on the roof is simply the atmospheric solar radiation
-infrared, so that negative values of the vegetation index may correspond to snow or ice cover, whereas the difference in reflectance is almost zero for bare soils such as deserts. As a result, NDVI values can range from −1.0 to 1.0, but typical ranges are from 0.1 up to 0.7, with higher values associated with greater density and greenness of plant canopies. We have also made comparisons with another NDVI dataset derived from Global Inventory Modeling and Mapping Studies (GIMMS; Tucker et al. 2005 ) and
-infrared, so that negative values of the vegetation index may correspond to snow or ice cover, whereas the difference in reflectance is almost zero for bare soils such as deserts. As a result, NDVI values can range from −1.0 to 1.0, but typical ranges are from 0.1 up to 0.7, with higher values associated with greater density and greenness of plant canopies. We have also made comparisons with another NDVI dataset derived from Global Inventory Modeling and Mapping Studies (GIMMS; Tucker et al. 2005 ) and