Theor. Appl. Climatol. 80, 229–243 (2005) DOI 10.1007/s00704-004-0102-3 Institute for Atmospheric and Climate Science, Z€ urich, Switzerland Modeling diurnal to seasonal water and heat exchanges at European Fluxnet sites R. Sto ¨ckli and P. L. Vidale With 8 Figures Received October 27, 2003; accepted June 23, 2004 Published online December 15, 2004 # Springer-Verlag 2004 Summary The importance of linking measurements, modeling and remote sensing of land surface processes has been increas- ingly recognized in the past years since on the diurnal to seasonal time scale land surface–atmosphere feedbacks can play a substantial role in determining the state of the near-surface climate. The worldwide Fluxnet project pro- vides long term measurements of land surface variables useful for process-based modeling studies over a wide range of climatic environments. In this study data from six European Fluxnet sites distrib- uted over three latitudinal zones are used to force three gen- erations of LSMs (land surface models): the BUCKET, BATS 1E and SiB 2.5. Processes simulating the exchange of heat and water used in these models range from simple bare soil parameterizations to complex formulations of plant biochemistry and soil physics. Results show that – dependent on the climatic environment – soil storage and plant biophysical processes can determine the yearly course of the land surface heat and water budgets, which need to be included in the modeling system. The Med- iterranean sites require a long term soil water storage capa- bility and a biophysical control of evapotranspiration. In northern Europe the seasonal soil temperature evolution can influence the winter energy partitioning and requires a long term soil heat storage scheme. Plant biochemistry and vegeta- tion phenology can drive evapotranspiration where no atmo- spheric-related limiting environmental conditions are active. 1. Introduction The interactions between the land surface and the atmosphere have been studied in a manifold way in climate research during the past decades. As described in Running et al. (1999) integrated approaches using tower flux measurements, satel- lite remote sensing and numerical modeling can help to understand the dynamics of the biosphere and land surface processes on various spatial and temporal scales. This approach has been used in major campaigns (e.g. FIFE: Sellers et al., 1988; BOREAS: Sellers et al., 1997b; LBA: Avissar et al., 2002). The exchange processes taking place at the land surface include short term feedbacks like vegetation transpiration con- trols over the bowen ratio (Chen et al., 2001); or radiation feedbacks through snow cover (Betts and Ball, 1997). On the seasonal time scale vegetation phenology (Bounoua et al., 2000; Buermann et al., 2001) and the soil moisture stor- age (Sch€ ar et al., 1999; Koster and Suarez, 2001) can play a role in the land surface hydro- logical cycle, especially through control of the boundary layer development and radiation- cloud-precipitation feedbacks. Soil heat storage and soil freezing in cold climates can play an important role in the land surface energy parti- tioning, as was found by McCaughey et al. (1997) and Viterbo et al. (1999). On the interan- nual or longer time scale feedbacks include pro- cesses like land use changes (Heck et al., 1999; Pielke, 2001) and nutrient cycling (Dickinson