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A new parameterisation scheme of ground heat flux for land surface flux retrieval from remote sensing information

Tanguy, M.; Baille, A.; Gonzalez-Real, M.M.; Lloyd, C.; Cappelaere, B.; Kergoat, L.; Cohard, J.-M.. 2012 A new parameterisation scheme of ground heat flux for land surface flux retrieval from remote sensing information. Journal of Hydrology, 454-455. 113-122. 10.1016/j.jhydrol.2012.06.002

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Abstract/Summary

The objective of the study was to assess the performance of a new parameterisation scheme of ground heat flux (G) for retrieving surface fluxes from remote sensing data (MODIS-Terra). Formulae that are based on empirical relationships relating G to net radiation, Rn (G = αRn, α being a function of a vegetation index, VI) are currently used, but presented drawbacks, especially in bare or sparse vegetation areas because of the poor adequacy of VI-based relationships to account for changes in soil moisture. In this study, we proposed to link α to the evaporative fraction, EF. In a first step, using a non-dimensional form of the surface energy balance, we demonstrated that α is functionally related to EF and to the ratio γ = G/H (H = sensible heat flux). In a second step, we proposed an EF-based parameterisation of α, using ground fluxes data sets collected throughout the years 2005, 2006 and 2007 at four flux-tower sites in West African countries (Mali, Benin, Niger) that differ in surface conditions and Monsoon influence. The analysis indicated that the average site-specific values of α and EF were well described by a linear relationship of the type α = a EF + b, with a = −0.22 and b = 0.23. In a third stage, we investigated whether ET-retrieval from remote sensing information (MODIS-Terra) using the new parameterisation of α perform better than the classical formulation through VI-based relationships. We found that the retrieved values of H using the new parameterisation supplied the best agreement with the observed ground data and significant improvement with respect to estimates from α–VI relationships. Advantages and limitations of the proposed parameterisation scheme were discussed.

Item Type: Publication - Article
Digital Object Identifier (DOI): 10.1016/j.jhydrol.2012.06.002
Programmes: CEH Topics & Objectives 2009 - 2012 > Water
CEH Sections: CEH fellows
Reynard
ISSN: 0022-1694
Additional Information. Not used in RCUK Gateway to Research.: The attached document is the author’s version of a work that was accepted for publication in Journal of Hydrology. Changes resulting from the publishing process, such as peer review, editing, corrections, structural formatting, and other quality control mechanisms may not be reflected in this document. Changes may have been made to this work since it was submitted for publication. A definitive version was subsequently published in Journal of Hydrology, 454-455. 113-122. 10.1016/j.jhydrol.2012.06.002
Additional Keywords: remote sensing, ground heat flux, sensible heat flux, evaporative fraction, vegetation index
NORA Subject Terms: Earth Sciences
Date made live: 07 Jan 2013 12:55 +0 (UTC)
URI: http://nora.nerc.ac.uk/id/eprint/20904

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