FILLING THE OBSERVING GAP OVER COMPLEX TERRAIN: CHARACTERIZE WATER VAPOR AND CLOUDS OVER SARNTAL ALPS USING GROUND-BASED REMOTE SENSING OBSERVATIONS AT DIFFERENT ALTITUDES

C. Acquistapace¹, B. Pospichal¹, D. Corradini¹, A. Oertel², A. Wieser²

¹Institute of Geophysics and Meteorology, University of Cologne, ²Institute of Meteorology and Climate Research Troposphere Research (IMKTRO), Karlsruhe Institute of Technology (KIT)

The World Climate Research Programme highlights gaps in observing, understanding, and modeling precipitation, particularly over mountainous terrain. To achieve such a goal, it is key to characterize environmental conditions before the rain onset.

With this contribution, we want to introduce and promote a field campaign initiative supported by the IDEA-S4S network under the umbrella of the GPEX working group. As part of the TEAMx observational summer extensive observation period, two identical measurement sites formed by one scanning microwave radiometer (MWR), one micro rain radar, and one disdrometer were deployed along an altitudinal transect in the Alps at approximately 1200 m and 2100 m altitude along the slope of the Corno del Renon, Bolzano, Italy. They are nested in a network of further ground-based remote sensing sites of KITcube that surround the mountain and can monitor the valley and mountain flows on a larger scale. One of these sites at the valley floor (~250 m altitude) was also equipped with a MWR.

Here, we would like to present some first results describing the distribution of water vapor and clouds in thermally driven days over the study area collected between May and September 2025, using MWR observations at three different altitudes. We analyze products like cloud liquid water path (LWP) and integrated water vapor (IWV) as well as MWR scans obtaining temperature and water vapor distribution conducted at these sites. Observations will be compared with ICON high resolution runs over the area, and we will use additional available datasets from the campaign as well as from satellite to characterize the flow circulation patterns in this precise atmospheric regime.

The overarching aim of the work is to 1) characterize moist convection initiation by monitoring the variability of temperature and humidity, 2) statistically characterize cloud distributions, 3) evaluate the model representation of moist convection initiation over complex terrain and 4) discuss the potential of MWR observations to capture these processes.