Land surface models (LSMs) must accurately simulate observed energy and water fluxes during droughts in order to provide reliable estimates of future water resources. We evaluated 8 different LSMs (14 model versions) for simulating evapotranspiration (ET) during periods of evaporative drought (Edrought) across six flux tower sites. Using an empirically defined Edrought threshold (a decline in ET below the observed 15th percentile), we show that LSMs simulated 58 Edrought days per year, on average, across the six sites, ~3 times as many as the observed 20 d. The simulated Edrought magnitude was ~8 times greater than observed and twice as intense. Our findings point to systematic biases across LSMs when simulating water and energy fluxes under water-stressed conditions. The overestimation of key Edrought characteristics undermines our confidence in the models' capability in simulating realistic drought responses to climate change and has wider implications for phenomena sensitive to soil moisture, including heat waves.
ARC Centre of Excellence for Climate System Science, University of New South Wales, Kensington, NSW 2052, Australia;Department of Biological Sciences, Macquarie University, North Ryde, NSW 2109, Australia;ARC Centre of Excellence for Climate System Science, University of New South Wales, Kensington, NSW 2052, Australia;Climate Change Research Centre, University of New South Wales, Kensington, NSW 2052, Australia;Met Office, Fitzroy Road, Exeter, Devon, EX6 7AX, UK;ARC Centre of Excellence for Climate System Science, University of New South Wales, Kensington, NSW 2052, Australia;Climate Change Research Centre, University of New South Wales, Kensington, NSW 2052, Australia;CSIRO Oceans and Atmosphere, GPO Box 3023, Canberra ACT 2601, Australia;ARC Centre of Excellence for Climate System Science, University of New South Wales, Kensington, NSW 2052, Australia;ARC Centre of Excellence for Climate System Science, University of New South Wales, Kensington, NSW 2052, Australia
Recommended Citation:
A M Ukkola,M G De Kauwe,A J Pitman,et al. Land surface models systematically overestimate the intensity, duration and magnitude of seasonal-scale evaporative droughts[J]. Environmental Research Letters,2016-01-01,11(10)