Atmospheric Measurement Techniques Discussions www.atmos-meas-tech-discuss.net 1867-8610 2 3 2009 10.5194/amtd-2-1383-2009 http://www.atmos-meas-tech-discuss.net/2/1383/2009/ http://www.atmos-meas-tech-discuss.net/2/1383/2009/amtd-2-1383-2009.html http://www.atmos-meas-tech-discuss.net/2/1383/2009/amtd-2-1383-2009.pdf 1383 1417 2009-06-05 Uncertainty analysis of computational methods for deriving sensible heat flux values from scintillometer measurements P. A. Solignac pasolignac@gmail.com A. Brut J.-L. Selves J.-P. Béteille J.-P. Gastellu-Etchegorry P. Keravec P. Béziat E. Ceschia CESBIO, 18, avenue Edouard Belin, bpi 2801, 31401 Toulouse Cedex 9, France The use of scintillometers to determine sensible heat fluxes is now common in studies of land-atmosphere interactions. The main interest in these instruments is due to their ability to quantify energy distributions at the landscape scale, as they can calculate sensible heat flux values over long distances, in contrast to Eddy Correlation systems. However, scintillometer data do not provide a direct measure of sensible heat flux, but require additional data, such as the Bowen ratio (β), to provide flux values. The Bowen ratio can either be measured using Eddy Correlation systems or derived from the energy balance closure. In this work, specific requirements for estimating energy fluxes using a scintillometer were analyzed, as well as the accuracy of two flux calculation methods. We first focused on the classical method (used in standard software). We analysed the impact of the Bowen ratio according to both time averaging and ratio values; for instance, an averaged Bowen ratio (β) of less than 1 proved to be a significant source of measurement uncertainty. 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