An observational study of the Inn Valley exit jet

<p>Previous studies have found a pronounced nocturnal low-level jet at the exit of the Inn Valley north of the valley contraction near Schwaigen which reaches into the Alpine foreland for several tenth of kilometers (e.g. Pamperin and Stilke, 1985 as part of the MERKUR experiment or a model study by Z&#228;ngl, 2004). The exit jet forms under nocturnal stably stratified atmospheric conditions and is interpreted as a transition from subcritical to supercritical hydraulic flow.</p><p>As part of the pre-experiment of the TEAMx programme in June to August 2022, we will conduct measurements to corroborate and extend the previous findings on the formation and maintenance of the Inn Valley exit jet. For this, a wind lidar will be deployed north of the valley contraction. Further, during selected days, radiosondes will be launched at the site of the wind lidar, accompanied by drone measurements. Additionally, the operational network of the German Meteorological Service (DWD) will be supplemented by ground station measurements of wind, temperature and humidity along the valley and at one higher elevated station between Kufstein and the wind lidar site. At selected stations, pressure, radiation and precipitation measurements will be conducted additionally. These will run until the completion of the main TEAMx campaign in 2024/2025.</p><p>&#160;This contribution will show some preliminary results of the measurement campaign.</p><p>&#160;</p><p><em>References:</em></p><p><em>Z&#228;ngl, G. "A reexamination of the valley wind system in the Alpine Inn Valley with numerical simulations."&#160;</em><em>Meteorology and Atmospheric Physics</em><em>&#160;87.4 (2004): 241-256.</em></p><p><em>Pamperin, H., and G. Stilke. "N&#228;chtliche Grenzschicht und LLJ im Alpenvorland nahe dem Inntalausgang."&#160;Meteorologische Rundschau&#160;38.5 (1985): 145-156.</em></p>