American Geophysical Union, Journal of Geophysical Research: Atmospheres, 1(122), p. 79-103, 2017
DOI: 10.1002/2016jd025476
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Interactions between the land surface and the atmosphere play a fundamental role in the weather and climate system through their influence on the energy and water cycles. Here we present results of summertime land-atmosphere coupling strength in a subset of the ERA-Interim driven EURO-CORDEX model ensemble (1989-2008) including an evaluation of the coupling related variables soil moisture and surface energy fluxes of latent heat (LE) and sensible heat (H). Most of the regional climate models (RCMs) reproduce soil moisture and surface fluxes for the different European climate zones reasonably well. However, for some regions and models differences are identified, also compared to FLUXNET surface flux measurements used as observational reference. To quantify the coupling strength the H-LE-correlation method has been confirmed as useful and valid for the comparison of different RCMs. An important advantage of the method is that it can be applied to standard RCM output variables (H, LE) as well as to observations, although long time series of high quality flux measurement data are needed, which are available only for a few locations across Europe. For the full 20-year period of summer seasons the EURO-CORDEX simulations agree in the large-scale patterns, with strong coupling in Southern Europe and weak coupling for Northern Europe, also in agreement with the FLUXNET observations. For large parts of Central Europe, however, the model ensemble diverges between strong and weak coupling strength. Compared to the FLUXNET measurements more models tend to overestimate than underestimate the coupling strength. Higher model resolution leads to more small-scale heterogeneity but not necessarily to a change in the large-scale patterns. Diversity in the ensemble can be both explained by the different characteristics of the individual land surface models (LSMs) as well as different climate conditions in the models.