Comprehensive applicability evaluation of multi-source snow depth datasets over the Tibetan Plateau

• Snow cover over the Tibetan Plateau has an important impact on the regional climate and water cycle. At present, the existing snow cover datasets have great uncertainty across this region, so the applicability assessment is indispensable in order to make best use of the advantages and bypass the disadvantages. In this study, a comprehensive quantitative evaluation of multiple variables and multiple evaluation indicators was carried out for three snow depth datasets over the Tibetan Plateau against the meteorological station observations（OBS）. The three snow depth datasets include one passive microwave remote sensing dataset（CHE）and two reanalysis datasets（ERA5-Land and MERRA2）. The variables are the annual mean snow depth, the annual maximum snow depth, and the annual snow cover days. In addition, the evaluation indicators are seasonal cycle, climatology, maximum value, standard deviation, interannual variation, and trend. A rank score（RS）value of 0~1 is computed for each evaluation indicator of each variable, the larger value of RS indicate relatively better performance of a snow depth dataset. Assessment results imply that, comprehensively considered, MERRA2 exhibits best agreement with OBS, followed by ERA5-Land, and finally CHE. Evaluate based on the RS of each variable, MERRA2 shows better performance on annual maximum snow depth and annual snow cover days, CHE shows better performance on annual mean snow depth. Evaluate based on the RS of each evaluation indicator, CHE shows advantages in describing trend, ERA5-Land exhibits better agreement with OBS on interannual variation, and MERRA2 show better performance on the rest of the indicators including seasonal cycle, climatology, maximum value and standard deviation. The RS statistics in terms of regional average and spatial distribution show that CHE performs better in the former, and ERA5-Land performs better in the latter. On the other hand, there are obvious deficiencies in all three snow depth datasets. MERRA2 has insufficient ability to characterize the interdecadal variation in snow cover, and its qualitative results for trend in snow cover is inconsistent with OBS, the reason for the first deficiency needs to be further studied and the second deficiency may be mainly related to its simulation capability to precipitation trend. ERA5-Land significantly overestimates the snow cover over the Tibetan Plateau, this may be mostly related to its data assimilation scheme. CHE has poor ability to characterize the spatial distribution of snow cover, coarse spatial resolution of passive microwave remote sensing may be the main reason. The conclusions are only applicable to the central and eastern part of the Tibetan Plateau due to the scarcity of meteorological station in west part of the Tibetan Plateau. Based on the remote sensing and reanalysis data, there is great uncertainty in the trend of snow cover in the western part of the Tibetan Plateau. These systematic classification evaluation of the three representative snow depth datasets provides information on data selection and data refinement.

Ämnesord

NATURVETENSKAP  -- Geovetenskap och miljövetenskap (hsv//swe)

NATURAL SCIENCES  -- Earth and Related Environmental Sciences (hsv//eng)

Nyckelord

applicability assessment

reanalysis

remote sensing

snow cover

Tibetan Plateau

Publikations- och innehållstyp

ref (ämneskategori)

art (ämneskategori)