Global spatial and annual distribution of surface water vapour density were estimated using 2005 -2016 monthly air temperature and relative humidity at 1° ×1° resolution obtained from Era interim and NCEP/NCAR database products. Obtained results from reanalysis were statistically tested using in situ data from Tropospheric Data Acquisition Network (TRODAN) of The Center for Atmospheric Research (CAR). Four seasonal variations of surface water vapour density (winter (DJF), spring (MAM), summer

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... JA) and autumn (SON)) was examined. Observed result from the two reanalysis follow similar trends with value from Era interim leading. High values ranges between 50 g/m 2 and 68 g/m 2 were observed in tropical regions and humid sub-tropical regions. Low values ranges between 8 g/m 2 and 38 g/m 2 were observed in Ice cap, Tundra and arid regions. High warming may be experienced in tropical and sub-tropical regions, similarly, climate change with alarming rate may be experienced in locations with low values. The annual cycle of surface water vapor density is clearly established from two reanalysis across world classified into twelve regions. The statistical test for the reanalysis present good result with a mean bias error, MBE, root mean square error, RMSE and R square of 20.56, 18.29, 0.87 and 5.87, 0.98, 0.93 for Era interim and NCEP/NCAR respectively.