Large-Scale Atmospheric Moisture Transport as Evaluated in the NCEP/NCAR and the NASA/DAO Reanalyses

Abstract
Large-scale aspects of the atmospheric moisture transport and the overall moisture budget we studied using data from the National Centers for Environmental Prediction (NCEP) reanalysis. Our objective is to critically evaluate the usefulness of the reanalysis products for studies of the global hydrologic cycle. The study period is from January 1985 to December 1993. Monthly mean water vapor transport, evaporation, and precipitation are compared to the NASA Data Assimilation Office (DAO) reanalysis for roughly the same period and with satellite estimates and station observations. Comparisons of the moisture flux fields form the NCEP and the DAO reanalyses show general agreement in most aspects, but there are regional differences. Discrepancies in tropical moisture transport are largely due to uncertainties in the divergent winds. The DAO reanalysis shows a weaker Hadley circulation and weaker cross-equatorial flow, particularly during the Northern Hemisphere winter. Global patterns of evaporation f... Abstract Large-scale aspects of the atmospheric moisture transport and the overall moisture budget we studied using data from the National Centers for Environmental Prediction (NCEP) reanalysis. Our objective is to critically evaluate the usefulness of the reanalysis products for studies of the global hydrologic cycle. The study period is from January 1985 to December 1993. Monthly mean water vapor transport, evaporation, and precipitation are compared to the NASA Data Assimilation Office (DAO) reanalysis for roughly the same period and with satellite estimates and station observations. Comparisons of the moisture flux fields form the NCEP and the DAO reanalyses show general agreement in most aspects, but there are regional differences. Discrepancies in tropical moisture transport are largely due to uncertainties in the divergent winds. The DAO reanalysis shows a weaker Hadley circulation and weaker cross-equatorial flow, particularly during the Northern Hemisphere winter. Global patterns of evaporation f...