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The Interplay Between Transpiration and Runoff Formulations in Land Surface Schemes Used with Atmospheric ModelsThe Project for Intercomparison of Land-surface Parameterization Schemes (PILPS) has shown that different land surface models (LSMS) driven by the same meteorological forcing can produce markedly different surface energy and water budgets, even when certain critical aspects of the LSMs (vegetation cover, albedo, turbulent drag coefficient, and snow cover) are carefully controlled. To help explain these differences, the authors devised a monthly water balance model that successfully reproduces the annual and seasonal water balances of the different PILPS schemes. Analysis of this model leads to the identification of two quantities that characterize an LSM's formulation of soil water balance dynamics: (1) the efficiency of the soil's evaporation sink integrated over the active soil moisture range, and (2) the fraction of this range over which runoff is generated. Regardless of the LSM's complexity, the combination of these two derived parameters with rates of interception loss, potential evaporation, and precipitation provides a reasonable estimate for the LSM's simulated annual water balance. The two derived parameters shed light on how evaporation and runoff formulations interact in an LSM, and the analysis as a whole underscores the need for compatibility in these formulations.
Document ID
20000037966
Acquisition Source
Goddard Space Flight Center
Document Type
Reprint (Version printed in journal)
Authors
Koster, Rindal D.
(NASA Goddard Space Flight Center Greenbelt, MD United States)
Milly, P. C. D.
(National Oceanic and Atmospheric Administration Princeton, NJ United States)
Date Acquired
August 19, 2013
Publication Date
January 1, 1997
Publication Information
Publication: Laboratory of Hydrospheric Processes Research Publications
Subject Category
Meteorology And Climatology
Distribution Limits
Public
Copyright
Other

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