Linking valley flow and vertical exchange in complex terrain – the LIVAVERT(EX)2 project

Quantifying the exchange of mass, momentum and energy between the earth’s surface and the atmosphere is pivotal for the understanding and prediction of weather and climate processes. Due to the superposition of horizontal and vertical transport, exchange processes in complex terrain are especially efficient and important.

This contribution presents a new project embedded in the international TEAMx campaign. The LIVAVERT(EX)² project - linking valley flow and vertical exchange in complex terrain - focuses on observing exchange processes in the Sarntal Alps region, a local hotspot of convection initiation in the Alps. As part of the project, a novel airborne Doppler lidar (ADL) is deployed for the first extended measurements in complex terrain. Thereby, 3D wind observations are available at 100 m along-track and vertical resolution, providing spatially resolved insight into valley wind systems and vertical exchange. The variability observed across repeated flights enables the differentiation between recurring and transient features.

TEAMx also encompasses a KITcube deployment in the Sarntal Alps region, which establishes an extensive meso-scale ground-based Doppler lidar (GDL) network. Through the comparison of ADL and GDL observations of valley flow, the Doppler lidar wind profiling accuracy and representativeness can be validated. Additionally, new ways to validate existing GDL-based volume flux estimation methods are created. Combining volume flux budget and direct vertical exchange observations allows a more quantitative insight into valley flow and its relation to convective initiation over the surrounding mountains than ever before. Overall, the LIVAVERT(EX)² project aims to improve our understanding and the prediction of atmospheric processes in complex terrain.