HMRFS–TP: long-term daily gap-free snow cover products over the Tibetan Plateau from 2002 to 2021 based on hidden Markov random field model

[摘要] Snow cover plays an essential role in climate change andthe hydrological cycle of the Tibetan Plateau. The widely used ModerateResolution Imaging Spectroradiometer (MODIS) snow products have two majorissues: massive data gaps due to frequent clouds and relatively low estimateaccuracy of snow cover due to complex terrain in this region. Here wegenerate long-term daily gap-free snow cover products over the TibetanPlateau at 500 m resolution by applying a hidden Markov random field (HMRF)technique to the original MODIS snow products over the past two decades. Thedata gaps of the original MODIS snow products were fully filled by optimallyintegrating spectral, spatiotemporal, and environmental information withinHMRF framework. The snow cover estimate accuracy was greatly increased byincorporating the spatiotemporal variations of solar radiation due tosurface topography and sun elevation angle as the environmental contextualinformation in HMRF-based snow cover estimation. We evaluated our snowproducts, and the accuracy is 98.29 % in comparison with in situ observations, and91.36 % in comparison with high-resolution snow maps derived from Landsatimages. Our evaluation also suggests that the incorporation ofspatiotemporal solar radiation as the environmental contextual informationin HMRF modeling, instead of the simple use of surface elevation as theenvironmental contextual information, results in the accuracy of the snowproducts increases by 2.71 % and the omission error decreases by 3.59 %.The accuracy of our snow products is especially improved during snowtransitional period, and over complex terrains with high elevation andsunny slopes. The new products can provide long-term and spatiotemporallycontinuous information of snow cover distribution, which is critical forunderstanding the processes of snow accumulation and melting, analyzing itsimpact on climate change, and facilitating water resource management inTibetan Plateau. This dataset can be freely accessed from the NationalTibetan Plateau Data Center at https://doi.org/10.11888/Cryos.tpdc.272204 (Huang and Xu, 2022).

[学科分类] 眼科学