ADEOS-II/GLI雪氷プロダクツとその科学的意味〔英文〕

抄録

The algorithm principles, calibration and validation (Cal/Val) experiments, and retrieval results of ADEOS-II/GLI snow/ice products are reported. The GLI snow/ice products are snow surface temperature, two types of snow grain sizes for topmost and shallow snow layers, and mass fraction of snow impurities. The snow grain size and snow impurities as satellite standard products are unique, but very important because snow surface albedo essentially depends on those parameters. From the analyses of GLI snow/ice products, the new findings on spatial distributions of clean snow, drastic spatial and seasonal evolution of snow grain size, and the possibility of detecting spatial distributions of vertical inhomogeneity in the top several centimeters of snow cover in the northern hemisphere were obtained. These snow parameters are expected to be used an indicator of climate change by long-period monitoring. From the Cal/Val experiments in Alaska and eastern Hokkaido, Japan from 2001 to 2005 using MODIS and GLI data, it was found that snow surface temperature and grain size for shallow layer agreed well with in-situ measured values, while the accuracies of mass fractions of snow impurities and grain size at topmost layer were not so good compared with those for the former two products. The Cal/Val experiments also revealed some scientific results which are spectral or broadband snow albedos depending on snow grain size and snow impurities, relationship between snow surface temperature and snow grain size, and spectral and directional features of emissivity depending on snow types.