Linking valley flow and vertical exchange in complex terrain

• Applicant: Dr. Philipp Gasch
• Subject Area: Atmospheric Science
• Term: since 2025
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 563995063

Quantifying the exchange of mass, momentum and energy between the earth’s surface and the atmosphere is pivotal for the understanding and prediction of many weather and climate processes. Exchange processes in the mountain boundary layer are particularly important since they are more effective than in flat and homogeneous terrain. The effectiveness is due to diurnal multi-scale circulations, such as valley and slope winds, which are superimposed on local turbulence, the principal mechanism dominating vertical exchange in flat and homogeneous terrain. Thus, understanding exchange in complex terrain requires knowledge of multi-scale flow processes and their interaction. The most prominent manifestation of vertical exchange is the initiation of deep convection. So far, however, our capabilities to observe the spatial variability of flow and exchange, especially in relation to convection, are limited. The proposed project will create a breakthrough in observing multi-scale flow and exchange processes through airborne Doppler lidar measurements of unprecedented high resolution. In linking the airborne measurements with a meso-scale network of ground-based Doppler lidars provided through the TEAMx campaign, a flux budget estimation method will be validated. Combining flux budget and direct vertical exchange observations will allow a more quantitative insight into valley flow and its relation to convective initiation over surrounding mountains than ever before. Overall, the expected results will be crucial to improve our understanding and the prediction of atmospheric processes in complex terrain.

• DFG Programme: Research Grants