Energy budget and actual evapotranspiration of an and oasis ecosystem: Palmyra (Syria)

Continuous measurements of evapotranspiration (LE) using eddy covariance method and energy budget were performed over more than 1 year above the heterogeneous canopy of an and oasis ecosystem in the central Syrian desert. irrigation practice was traditional flooding with a 28-day turn of water delivery. The work focused on seasonal variations of energy budget over a 2-year period with emphasis on effects of rainfall, wind speed and radiative budget and irrigation practice on evapotranspiration. A time lag of 3 days was observed between irrigation and transpiration response from the vegetation and maximum evapotranspiration was only 5 mm/day. Even with water input from irrigation, winter rainfall seems to have an important impact on LE: comparisons of two situations in June 2002 and June 2003 showed an increase of 13% in values of LE/Rn - G. In many situations averaged hourly values of evapotranspiration increased with wind speed up to 3 m/s, then decreased suggesting strong evaporative control from the vegetation. Results from the energy balance closure showed significant differences in the slope of H + LE against Rn - G relationships between cold and hot month which was explained by specific radiative budget of desert areas. (c) 2006 Elsevier B.V. All rights reserved.