An Intercomparison Of Basic Statistics Derived From Three Kinds Of Reanalysis Data

In order to access character and application value of meteorological data compiled by Chinese meteorology departments, the passage has used statistical methods to check difference notability about climatic mean value and interannual variance of 100hPa, 500hPa geopotential height in July and sea level pressure in January of Chinese data, NCEP/NCAR and ECMWF reanalysis data, and has compared diversity about interannual change and correlative degree about area, intensity and location indices of dominating atmospheric active centers in January and July in the Northern Hemisphere.Results show that: (1) The climatic mean value of 100hPa and 500hPa geopotential field in July from ECMWF reanalysis data is evidently smaller than which of Chinese data, and there is not a grid point that bigger than 1660 and 588 geopotential decameter in the historical value of ECMWF data, so it is not suited to research the South Asian High and the Subtropical High as compared with Chinese data. Climatic mean value of 500hPa geopotential height in July of NCEP/NCAR reanalysis data is also smaller than which of Chinese data in low latitudinal area. The notably different area of sea level pressure in January derived from three kinds of data mainly located in the South Asia and the Subtropical Pacific areas. (2)There are areas that interannual variance of Chinese data is bigger than which of NCEP/NCAR, ECMWF reanalysis data of 100hPa, 500hPa geopotential height field in July and sea level pressure field in January, but there are not areas that the latter is bigger than the former. Variance reflects intensity of interannual variability. Above results illustrate that NCEP/NCAR and ECMWF reanalysis data has been assimilated by global multilayer spectrum model, that is, has been smoothed partial interannual variability. But Chinese data is more suited to analyze interannual variability because of reserving partially regional and interannual change. (3)Similarity about interannual change of the Aleutian Low derived from three kinds of data is better than which of the South Asian High, the Subtropical High and the Mongolia High, so the difference of researching on the Aleutian Low by using three kinds of data is smallest. (4)The interannual change of the Mongolia High and the Aleutian Low in winter by using three kinds of data is more consistent than which of the South Asian High and the Subtropical High in summer. (5) Because Chinese data is directly read from isobaric surface graphs in the single layer, it is closer to actual observations and more suited to diagnose pressure systems in the single isobaric surface.