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On the sensitivity of soil-vegetation-atmosphere transfer (SVAT) schemes: equifinality and the problem of robust calibration.

Franks, S. W. and Beven, Keith J. and Quinn, P. F. and Wright, I. (1997) On the sensitivity of soil-vegetation-atmosphere transfer (SVAT) schemes: equifinality and the problem of robust calibration. Agricultural and Forest Meteorology, 86 (1-2). pp. 63-75. ISSN 0168-1923

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Abstract

Current ‘physically based’ soil-vegetation-atmosphere transfer (SVAT) schemes use increasingly complex descriptions of the physical mechanisms governing evapotranspiration fluxes, thereby requiring the specification of a large number of parameters controlling the vertical fluxes over a single homogeneous area. Recent attention towards the incorporation of sub-grid scale spatial variability in SVAT parameterisations promises to increase the number of parameters for these models. In this paper, it is demonstrated that a simple patch scale SVAT model still permits too many degrees of freedom in terms of fitting the model predictions to calibration or validation data; it is shown that good model fits may be achieved in many areas of the parameter space. Using a Monte Carlo framework, a sensitivity analysis is performed for simulations of data sets from FIFE and Amazonian sites. This is employed to evaluate the role of each parameter for each forcing dataset, and to identify the controlling and redundant parameters and processes. The results suggest that equifinality of parameter sets in calibration to field data must be expected, that there will be a consequent uncertainty in predictive capability and that more emphasis will be required on identifying the critical controls on evapotranspiration in extending predictions from patch to landscape scale in different environments.

Item Type: Article
Journal or Publication Title: Agricultural and Forest Meteorology
Uncontrolled Keywords: Evapotranspiration ; Soil-vegetation-atmosphere transfer schemes ; Equifinality
Subjects: G Geography. Anthropology. Recreation > GE Environmental Sciences
Departments: Faculty of Arts & Social Sciences > Politics & International Relations (Merged into PPR 2010-08-01)
Faculty of Science and Technology > Lancaster Environment Centre
ID Code: 21919
Deposited By: ep_ss_importer
Deposited On: 11 Feb 2009 13:14
Refereed?: Yes
Published?: Published
Last Modified: 26 Jul 2012 15:53
Identification Number:
URI: http://eprints.lancs.ac.uk/id/eprint/21919

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