Representing the effects of subgrid variability of soil moisture on runoff generation in a land surface model

Clark, Douglas B. ORCID:; Gedney, Nicola. 2008 Representing the effects of subgrid variability of soil moisture on runoff generation in a land surface model. Journal of Geophysical Research, 113, D10111.

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Different representations of runoff generation processes were implemented in the MOSES land surface model which is used with mesoscale and global atmospheric models. The standard model was compared with versions in which runoff generation was described by parameterizations based on either the Probability Distributed Model (PDM) or modified forms of TOPMODEL, all of which used probability functions to describe the subgrid distribution of soil moisture. The model results were compared with observed streamflow in three catchments in southern France. After calibration, the PDM- and TOPMODEL-based parameterizations performed substantially better than the standard model. The TOPMODEL approach gave the best results through allowing a more responsive subsurface flow that contributed to peak flows and also better captured the slower changes during recessions. This approach was sensitive to uncertainty in the value of the topographic index. The PDM-based model only changed the calculation of surface runoff and retained the standard description of subsurface runoff, and this limited the possible improvement in performance. In principle the values of the new parameters can be determined from observations, but in practice calibration is likely to be required. However, for each new parameterization, a single set of parameter values was found that performed well in all catchments. The simulated soil moisture and surface heat fluxes during summer dry periods were affected by the choice of runoff parameterization.

Item Type: Publication - Article
Digital Object Identifier (DOI):
Programmes: CEH Programmes pre-2009 publications > Biogeochemistry > CC01B Land-surface Feedbacks in the Climate System > CC01.6 Development of the Joint Unified Land Exchange Scheme (JULES) land-surface model
UKCEH and CEH Sections/Science Areas: Harding (to July 2011)
ISSN: 0148-0227
Additional Keywords: Runoff, soil moisture, streamflow, model calibration
NORA Subject Terms: Meteorology and Climatology
Date made live: 22 Dec 2008 12:14 +0 (UTC)

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