Climatic drivers of elevation-dependent warming (EDW): A concerted field and modeling assessment for an alpine national park

Mountain regions, such as the Alps, play a crucial role in providing ecosystem services, e.g., by acting as water towers and substantially contributing to the discharge of the main European rivers. However, global warming is causing significant changes to the cryosphere, biodiversity and ecosystems in these regions.Hence, understanding the microclimatic changes in mountainous areas is essential, particularly the phenomenon of elevation-dependent warming (EDW), describing an amplified warming trend predominantly at higher elevations compared to adjacent lowlands. In the scientific community multiple drivers of EDW are being discussed, among them snow-albedo feedback, changes in cloud properties, and aerosols. The contribution of the individual drivers varies regionally and the role of surface energy balance components, especially ground heat flux, is rarely examined. Therefore, this study focuses on investigating the elevation-dependency of temperature trends and surface energy balance components, as well as its driving mechanisms in the Berchtesgaden National Park, Germany. This area in the northern limestone Alps is characterized by a highly variable topography, diverse landscapes and numerous ecosystems. Preliminary results from this ongoing study are presented, emphasizing the methodological approach and initial insights gained: Extensive data from the meteorological measuring station network, covering elevations from 600 to 2700 m.a.s.l., is analyzed to identify EDW patterns in the national park and its surroundings. Additionally, from fall 2023 to 2025, a transect of three meteorological stations is established at different elevations (600 to 2000 m.a.s.l.) for a detailed investigation of land surface energy balance. Besides measuring the radiative components in highly variable terrain, the field observations focus especially on ground heat flux, obtained at multiple positions within each station site to capture the small-scale variance and aspect dependency of ground heat flux. Additionally, at one of the stations the turbulent heat fluxes are assessed, using the Modified Bowen Ratio Method. To gain a holistic picture of the processes within the national park, the land surface model Noah-MP is employed to simulate the surface energy exchange processes at a high spatial resolution of 100 m. To improve the understanding of the development over time, model runs covering several decades in the past and a run during the measurement period (20232025) are performed, with results validated against the observational data.