Closing the Global Water Vapor Budget with AIRS Water Vapor, MERRA Reanalysis, TRMM and GPCP Precipitation, and GSSTF Surface Evaporation

Abstract

he authors investigate if atmospheric water vapor from remote sensing retrievals obtained from the Atmospheric Infrared Sounder/Advanced Microwave Sounding Unit (AIRS) and the water vapor budget from the NASA Goddard Space Flight Center (GSFC) Modern Era Retrospective-analysis for Research and Applications (MERRA) are physically consistent with independently synthesized precipitation data from the Tropical Rainfall Measuring Mission (TRMM) or the Global Precipitation Climatology Project (GPCP) and evaporation data from the Goddard Satellite-based Surface Turbulent Fluxes (GSSTF). The atmospheric total water vapor sink (Σ) is estimated from AIRS water vapor retrievals with MERRA winds (AIRS?MERRA Σ) as well as directly from the MERRA water vapor budget (MERRA?MERRA Σ). The global geographical distributions as well as the regional wavelet amplitude spectra of Σ are then compared with those of TRMM or GPCP precipitation minus GSSTF surface evaporation (TRMM?GSSTF and GPCP?GSSTF P ? E, respectively). The AIRS?MERRA and MERRA?MERRA Σs reproduce the main large-scale patterns of global P ? E, including the locations and variations of the ITCZ, summertime monsoons, and midlatitude storm tracks in both hemispheres. The spectra of regional temporal variations in Σ are generally consistent with those of observed P ? E, including the annual and semiannual cycles, and intraseasonal variations. Both AIRS?MERRA and MERRA?MERRA Σs have smaller amplitudes for the intraseasonal variations over the tropical oceans. The MERRA P ? E has spectra similar to that of MERRA?MERRA Σ in most of the regions except in tropical Africa. The averaged TRMM?GSSTF and GPCP?GSSTF P ? E over the ocean are more negative compared to the AIRS?MERRA, MERRA?MERRA Σs, and MERRA P ? E.