Applicability Evaluation for Several Reanalysis Datasets Using the Upper-Air Observations over China

Intercomparison of temperature and geopotential heights from ERA-40, NCEP/NCAR and NCEP/DOE reanalyzed products with the upper-air observations is made in eight regions over China. The results show that the differences of the mean values and interannual variations represented by the reanalysis and the observations exist mainly in the summer, especially obvious in southwestern and western China before the mid-1970s. The discrepancies of temperature are more obviously presented in the upper troposphere, but in terms of the geopotential heights, their absolute differences are larger in the upper troposphere too, however, the more obvious differences of their interannual variations and long-term trends are mainly found in the middle-lower troposphere, especially, the NCEP/NCAR reanalysis shows tremendously summer geopotential heights in the middle-lower troposphere before the 1970s, and overestimates interdecadal changes in most regions of China. For most regions of China, the applicability of the ERA-40 reanalysis is better than that of the NCEP/NCAR counterparts in climate change researches, especially in the researches on interdecadal variations. The results also show that few differences of the interannual variations can be detected from the NCEP/DOE and NCEP/NCAR reanalysis, except that of the mean values between them.