Evapotranspiration and crop coefficient for a temperate desert steppe ecosystem using eddy covariance in Inner Mongolia, China

Evapotranspiration ( ET ), which links water, energy and the carbon cycle in terrestrial ecosystems, is an important eco‐hydrological process, especially in arid and semi‐arid regions. To determine the crop coefficient ( K c ) over a 2‐year period for a temperate desert steppe in Inner Mongolia, China, ET was measured using the eddy covariance method and the reference evapotranspiration ( ET 0 ) was estimated from site meteorological data. The results showed that the seasonal variation of ET differed on an annual timescale between the 2 consecutive years, exhibiting a multi‐peak curve in 2008 and a single peak in 2009. The mean daily K c values were 0·15 and 0·17 in 2 years, varying from 0·009 to 0·75 in 2008 and from 0·005 to 0·58 in 2009. The 5‐day moving average for K c values was mainly affected by SWC 10cm and R n , and the regression coefficients ( R 2 ) were 58·9 and 69·5%, respectively. These results will aid in making accurate and quantitative assessments of the vulnerability of the sparse vegetation to climate change. Copyright © 2011 John Wiley & Sons, Ltd.