D. Pascual1*, M. Johansson1, A. Pongracz1, & J. Tang1,2
1Department of Physical Geography and Ecosystem Science, Lund University, Lund Sweden
2Section of Terrestrial Ecology, Department of Biology, University of Copenhagen. Copenhagen, Denmark
* Corresponding author. E-mail: Didac.pascual@nateko.lu.se - Affiliation address: Sölvegatan 12, 223 62 Lund, Sweden - Telephone dir 0046 720324595
Key Points:
Abstract
Winter warming events (WWEs) are short-lasting events of unusually warm weather, occasionally combined with rainfall, which can cause severe ecosystem impacts by altering ground temperatures and water fluxes. These impacts are generally overlooked in large-scale ecosystem models. The frequency and intensity of WWEs will likely increase further in the future. We used an ecosystem model, LPJ-GUESS, to investigate the responses of four subarctic ecosystems to different levels of predicted WWEs, and identify model gaps hindering accurate estimates of these responses. In response to WWEs, the model simulated substantial ground cooling (up to 2 °C in winter) in contrast to the observed warming, leading to changes in biogeochemical fluxes often comparable in magnitude to those from altered winter climatologies. The mismatch between the modelled and the observed ground temperature changes may be due to the 1) lacking surface energy balance, 2) daily timestep, and 3) simplistic water retention scheme in LPJ-GUESS.