A Comparison Analysis of Three Reanalysis Datasets in the Change of Atmospheric Water Vapor Content in the Summer of the Tibetan Plateau

Based on ERA-Interim, MERRA and NCEP/NCAR reanalysis datasets, the spatial and temporal variations of atmospheric water vapor content in Tibetan plateau from 1979 to 2014 were discussed. Comparison and performance analyses of these three reanalysis data were given. The obtained results are as follows. (1) The atmospheric water vapor content in Tibetan plateau in summer had presented significant upward trend by ERA-Interim and MERRA reanalysis datasets. There was a significant mutation in about 1994 to 1995, the change of atmospheric water vapor content from the low period to the high period. The NCEP/NCAR data did not show a similar significant upward trend or any significant mutation year. The correlation between the ERA-Interim data and the MERRA data of the wet pool index in the summer of the Tibetan Plateau was stronger than the correlation between that of the NCEP/NCAR data and each of them. (2) In the summer, the atmospheric water vapor content in the Tibetan Plateau presented a decreasing distribution from the southeast to the northwest of the plateau. However, the atmospheric water vapor content distribution which shown by the MERRA data and ERA-Interim data were more similar, and NCEP/NCAR data reflect the decline of the atmospheric water vapor content in the middle of the plateau was not obvious, the center of the humidity is more dispersed. (3) MERRA data and ERA-Interim data show that the atmospheric water vapor content in most parts of the Tibetan Plateau in summer showed a significant increase trend, while the NCEP/NCAR data only in the northeast part of the plateau had a significant increase trend. (4) From the analysis of the characteristics of the interannual variation of atmospheric water vapor over the Tibetan Plateau in summer, compared with the NCEP/NCAR data, ERA-Interim data and MERRA data were more close to each other.