Abstract: To find a proper reanalysis dataset which could best agree with the precipitation characteristics of the Dongting lake basin (107°13'-114°18' E、24°35'-30°27' N), reanalysis precipitation data from ERA-intreim, CRU-TS3.21, GPCP V2.2 and TRMM 3B43(V7) were collected to be compared with the actual observation precipitation from CMD to assess their fitting and dispersion degree, by the analysis of mean, precipitation difference (PD), the percentage of precipitation differences (PPD) and standard deviation of PD (SD-PD) and PPD (SD-PPD). All the four reanalysis precipitation datasets were interpolated to the same 27 meteorological stations as CMD provides. The results indicated that: 1) annual and seasonal variations of the four reanalysis precipitation datasets were consistent with that of CMD, while the reanalysis precipitation data in autumn and winter fitted more closely with CMD than other seasons did;2) during 2000-2012, the average annual precipitation in Dongting lake basin of ERA-Interim, CRU, GPCP, TRMM, and CMD, are 1 648.71, 1 322.87, 1 317.76, 1 403.13 and 1 332.69 mm, respectively. Correspondingly, PPDs between four reanalysis precipitation datasets and the CMD data were 23.71%, -0.74%, -1.12% and 5.29%. In addition, spatial distribution of PD between them ranged from 1 000.21 to 649.51 mm, 333.89 to 643.82 mm, 292.55 to -686.85 mm, 256.20 to -561.27 mm, respectively, while their SD-PDs ranged from 445.89 to to 97.35 mm, 365.53 to 48.66 mm, 251.42 to 43.12 mm and 204.11 to 32.76 mm;3) of the four reanalysis precipitation datasets, ERA-interim exhibited the greatest overestimation on value and on time scale during the two periods, and its annual variation of PPD and dispersion degree were the largest. The average precipitation of CRU was more similar to CMD than that of GPCP,while the interannual variation of PPD as well as dispersion degree of GPCP were smaller than those of CRU. TRMM overestimated the precipitation slightly on time scale, and possessed stable interannual variation and minimum dispersion degree;4) precipitation in Hengyang basin, with Nanyue station as the center, were underestimated by all reanalysis datasets. The spatial distribution of overestimated value had significant difference. Overestimated extremum for ERA-interim occurred in western mountain area, however, for CRU and GPCP, in southern mountain area, and the overestimated area was not obvious for TRMM. There was distinct difference in spatial distribution of dispersion degree for ERA-interim data, followed by CRU, then GPCP, and there was no significant difference for TRMM. The maximum dispersion degree of all reanalysis data existed in western and southern mountain area of the Dongting lake basin. According to the analysis above, although TRMM data overestimated the mean value slightly, it was found that TRMM data presented the best consistency with CMD data than GPCP and CRU data did, and ERA-Interim data was the worst.

Key words: Reanalysis precipitation data, the Dongting Lake Basin, Evaluation