Use of Reanalysis Land Surface Water Budget Variables in Hydrologic Studies

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International GEWEX Project Office


Reanalyses provide the land surface modeling community with a comprehensive global set of land surface water and energy fluxes and associated state variables at a sub-daily time interval over extended periods of one or more decades. For example, the NCEP/NCAR reanalysis (Kalnaý et al., 1996) has been completed for 1948–2000 and the more recent NCEP/DOE reanalysis (Kanamitsu et al., 2000) has been completed for 1979–2000. Because global data based directly on observations for most land surface moisture and energy fluxes are either not available, or are plagued by sparse observation networks, the use of reanalysis "data" for characterization of continental to global scale hydrologic features is an attractive (and in some cases the only) option, notwithstanding known biases in reanalysis surface variables (see Kalnay et al., 1996).