HAL : ird-00389812, version 1

DOI : 10.1016/j.hydrol.2009.01.010

Code IRD Horizon : fdi:010048240

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Journal of Hydrology (2009) 1-10

Combining scintillometer measurements and an aggregation scheme to estimate area-averaged latent heat flux during the AMMA Experiment

J. Ezzahar (  Auteur correspondant ) 1, A. Chehbouni 2, J.C.B. Hoedjes 2, D. Ramier 3, Nicolas Boulain 4, S. Boudkraoui 3, Bernard Cappelaere 4, L. Descroix 5, Bernard Mougenot 2, F. Timouk 2

(2009)

This paper deals with the issue of using scintillometry in conjunction with a simple aggregation scheme 23 to derive area-averaged sensible and latent heat fluxes over a small watershed in Niamey, Niger (Wank- 24 ama catchment). Data collected in the context of the African Monsoon Multidisciplinary Analysis (AMMA) 25 program has been used to test the proposed approach. For this purpose, a Large Aperture Scintillometer 26 (LAS) was set up over heterogeneous surface transect of about 3.2 km spanning three vegetation types. 27 The comparison between scintillometer-based estimates of area-averaged sensible heat fluxes and 28 those measured by a network of the classical eddy covariance (EC) devices showed good agreement, with 29 a relative error of about 20% (R2 = 0.85, RMSD = 22Wm2, and SEE = 21.39Wm2). This is a good result 30 considering the contrast in terms of the footprint scales associated with the two devices, which is ampli- 31 fied by the heterogeneity of the catchment. The results also showed that using the LAS-derived values of 32 area-average sensible heat flux in conjunction with a simple aggregation rule to estimate area-average 33 available energy led to a reasonable prediction of area-averaged latent heat flux (R2 = 0.75, 34 RMSD = 64Wm2 and SEE = 50Wm2), when compared to those measured using the EC network. This 35 is of interest since the LAS can potentially be used to validate estimates of surface fluxes, based on the 36 meso-scale model, as well as those estimated using coarse-scale remote sensing-based algorithm.

1 :	Laboratoire de Mécanique des Fluides et Energétique (LMFE)
	Faculté des Sciences Semlalia Marrakech
2 :	Centre d'études spatiales de la biosphère (CESBIO)
	CNRS : UMR5126 – Institut de recherche pour le développement [IRD] – CNES – Observatoire Midi-Pyrénées – INSU – Université Paul Sabatier [UPS] - Toulouse III
3 :	IRD, Centre Niamey, Niger
	Institut de recherche pour le développement [IRD]
4 :	Hydrosciences Montpellier (HSM)
	CNRS : UMR5569 – Institut de recherche pour le développement [IRD] – Université Montpellier II - Sciences et techniques
5 :	Laboratoire d'étude des transferts en hydrologie et environnement (LTHE)
	CNRS : UMR5564 – OSUG – INSU – Université Joseph Fourier - Grenoble I – Institut National Polytechnique de Grenoble (INPG) – Institut de recherche pour le développement [IRD] : UR012

domaine

:

Sciences du Vivant/Ecologie, Environnement/Ecosystèmes

mots-clés : Scintillometry – Eddy covariance – Regional surfaces fluxes – Non-uniform and heterogeneous surfaces – Aggregation schemes

ird-00389812, version 1

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Contributeur : Dominique Bruel <>

Soumis le : Jeudi 4 Juin 2009, 09:51:27

Dernière modification le : Jeudi 4 Juin 2009, 09:57:12