Conferences

We present the intensive field campaign conducted from mid-June to mid-October 2025 on Monte Baldo (Italian Pre-Alps) within the TEAMx programme, aimed at improving process understanding and model representation of mountain boundary-layer exchanges. This effort was driven by the DECIPHER project, which aims at disentangling mechanisms controlling atmospheric transport and mixing processes over mountain areas at different space- and timescales. Measurements targeted a steep (~25°), east-facing, grass-covered slope in the southern Monte Baldo range, selected for its regular topography and pronounced diurnal cycle of thermally driven slope winds. The setting also enables investigation of coupling at the mountain–plain interface, linking local slope circulations to the adjacent lowland atmosphere in the Po Valley. A coordinated suite of instruments captured processes from the surface layer to the lower troposphere and their interactions across scales. Near-surface thermodynamic variability and turbulent exchange were monitored using multi-level flux towers and a slope-wide network of thermohygrometers. Variability in aerosol and particulate matter was measured using co-located mass and optical sensors. Along- and cross-slope winds were observed with multiple wind lidars, while boundary-layer and lower-tropospheric profiles were obtained with a tethered balloon system and a Raman lidar. The surface heat budget was characterized using radiation measurements together with soil temperature and moisture observations. Complementary observations included high-frequency near-surface turbulence profiling and distributed soil-moisture monitoring using a cosmic-ray neutron sensor. This contribution details the observational setup, characterizes the regional setting, and illustrates the potential of the dataset for evaluating slope-wind structure and the associated surface fluxes, boundary-layer mixing, and exchange pathways between mountains and adjacent plains.

DECIPHER (Disentangling mechanisms controlling atmospheric transport and mixing over mountains across space–time scales) investigates multi-scale exchanges of energy, momentum, and tracers between the surface and atmosphere, with a focus on thermally driven flows in the Italian Alps. We report the project’s initial observational phase, comprising two coordinated field campaigns along with an overview of topography, instrumentation, and weather during the field campaigns, and present selected case studies. The first campaign (23 July-29 October 2024) took place at Col Margherita (2543 m ASL) in the Eastern Italian Alps. Here, optical particle counter (OPC) measurements were taken to characterize the fine (diameter < 1 µm) and coarse (diameter ≥ 1 µm) fractions of aerosols over the site. Two episodes of enhanced coarse-mode aerosol at Col Margherita were identified and further investigated using Doppler and Raman lidars and standard meteorological data from Passo Valles (2032 m a.s.l.), 3 km downslope. The second field campaign (2 October-10 November 2024) was carried out in the Monte Baldo mountain range on a steep east-facing slope. A two-level eddy covariance tower, complemented by a four-way net radiometer, soil sensors, and thermohygrometers distributed along the slope, was deployed to investigate surface-layer processes and turbulent fluxes associated with slope-wind systems. A typical day with fully developed thermally-driven slope winds was highlighted using eddy covariance tower measurements. Together, the two campaigns represent preparatory efforts aimed at informing and supporting a larger observational initiative scheduled for summer 2025 at the Monte Baldo site under the international cooperation initiative TEAMx (Multi-scale transport and exchange processes in the atmosphere over mountains - programme and experiment).

Oral Presentation

Atmospheric transport processes over mountainous terrains are intrinsically affected by a variety of landforms, surface covers, atmospheric stability situations and interactions among different airflows, typical occurring on multiple space and time scales. Our understanding of the interplay of such factors is still far from being fully understood. In particular, the peculiar properties of atmospheric turbulence controlling the exchanges of momentum, heat and mass between the land surface, the atmospheric boundary layer and upper levels are still largely unexplored. As a contribution to filling these gaps, the research project DECIPHER implemented observational and modelling actions aimed at disentangling mechanisms controlling atmospheric transport and mixing processes over mountain areas at different space- and timescales, in the framework of the larger international research effort TEAMx (Serafin et al. 2018, Rotach et al. 2021). As part of the project, field measurements were performed at selected areas to investigate transport and exchange processes associated with thermally-driven slope winds and other local winds, and their connections with various ambient and weather conditions. In particular, an intensive field campaign was organised over an east-facing steep slope of Monte Baldo (45°39'56.0"N, 10°49'10.9"E), an approximately north-south oriented mountain range in the Southern Alps. Several different instruments were operated from mid-June to mid-October 2025 to cover atmospheric processes at different scales. Turbulent processes were monitored through multi-level flux towers installed at different elevations, along with thermohygrometers distributed along the slope to capture the vertical structure of the ambient atmosphere. Mass and optical sensors monitored concentrations and properties of particulate matter. The 3-D structures of local along- and cross-slope winds and vertical temperature profiles were also observed with multiple wind lidars based at different points. Moreover, tropospheric profiles were obtained from a tethered balloon and a Raman lidar. Further non-conventional measurements included high-frequency profiling of turbulence near the surface and distributed soil moisture monitoring using a cosmic-ray neutron sensor. Preliminary outcomes from the analysis of the resulting huge dataset allow for identifying interesting patterns of local circulations and their connections with turbulence structure, as well as with the surrounding flow and stability conditions, under different weather situations. Besides research achievements, DECIPHER was also a remarkable and unique opportunity to consolidate relationships of scientific cooperation among the numerous partners involved, and to successfully test new observational techniques and logistic solutions for the nontrivial deployment of such a major field campaign. Hence it contributed to build-up It was a great opportunity for growing a scientific community characterised by complementary expertise, a remarkable amount of personnel involved, and the numerosity and diversity of instruments enabled to plan and perform the unusual effort adequate for phenomena, whose complexity would not be captured with any fewer instruments. Buildup of a scientific community

References

1. Rotach, M.W., Serafin, S., Ward, H.C., Arpagaus, M., Colfescu, I., Cuxart, J., De Wekker, S.F.J., Grubišic, V., Kalthoff, N., Karl, T., Kirshbaum, D.J., Lehner, M., Mobbs, S., Paci, A., Palazzi, E., Bailey, A., Schmidli, J., Wittmann, C., Wohlfahrt, G. and Zardi, D. (2022): A collaborative effort to better understand, measure and model atmospheric exchange processes over mountains. Bulletin of the American Meteorological Society. https://doi.org/10.1175/BAMS-D-21-0232.1

2. Serafin, S., Adler, B., Cuxart, J., De Wekker, S.F.J., Gohm, A., Grisogono, B., Kalthoff, N., Kirshbaum, D.J., Rotach, M.W., Schmidli, J., Stiperski, I., Večenaj, Ž. and Zardi D. (2018): Exchange Processes in the Atmospheric Boundary Layer Over Mountainous Terrain. Atmosphere, 9, 102. https://doi.org/10.3390/atmos9030102

Invited Talk

Two major field campaigns were performed in the summer of 2024 at two selected sites in the eastern Italian Alps under the project DECIPHER (Disentangling mechanisms controlling atmospheric transport and mixing processes over mountain areas at different space- and timescales). The project was ancillary and preliminary to the intensive observing period envisaged by the international research initiative TEAMx (Multi-scale transport and exchange processes in the atmosphere over mountains – programme and experiment). The first site was near the peak of Col Margherita, in the area of the eastern Dolomites, where a permanent monitoring station is operated by the Institute of Polar Sciences for monitoring atmospheric pollutants, and in particular particulate matter and mercury, besides a conventional weather station for standard meteorological variables. The second site was the east-facing sidewall of Monte Baldo, a 70-km long north-south oriented mountain range east of Lake Garda in the southern Prealps, on a slope spanning an altitude that ranges from the slope foot at 1400 m ASL to the top at 1670 m ASL. The results of these campaigns were a useful preliminary exercise for the full campaigns to be held under the TEAMx Special Observing Period in the Summer of 2025. For the latter, all instruments were concentrated at the Monte Baldo site at three different levels: a) at the top crest, b) at mid-slope, as for 2024 campaign, and c) at the slope feet. Preliminary results from all the above campaigns will be presented as well.

Oral Presentation

Two major field campaigns were performed in the summer of 2024 at two selected sites in the eastern Italian Alps under the project DECIPHER (Disentangling mechanisms controlling atmospheric transport and mixing processes over mountain areas at different space- and timescales). The project was ancillary and preliminary to the intensive observing period envisaged by the international research initiative TEAMx (Multi-scale transport and exchange processes in the atmosphere over mountains – programme and experiment).The first site was near the peak of Col Margherita, in the area of the eastern Dolomites, where a permanent monitoring station is operated by the Institute of Polar Sciences for monitoring atmospheric pollutants, and in particular particulate matter and mercury, besides a conventional weather station for standard meteorological variables. Additional instruments were installed at Passo Valles, a lower pass nearby, where two permanent weather stations are also operated by the Regional Weather Services of the Veneto Region and the Province of Trento, respectively. The additional instruments included a wind LIDAR, a thermodinamic Raman LIDAR and a disdrometer. Instruments were operated from 23 July to 29 October 2024. Measurements from remote sensing instruments allowed retrieval of both thermal and dynamical vertical structures of the atmosphere under various weather conditions, including both horizontal and vertical mean wind components. The simultaneous monitoring procedure of the two LIDARs offers a rare opportunity to explore innovative methodologies to compute turbulent fluxes of latent and sensible heat, mass, and momentum through a remote sensing approach. These structures were then analysed in connection with a time series of concentrations of particulate matter observed at Col Margherita to identify patterns of the transport process, through the analysis of back trajectories derived from various Lagrangian tracer dispersion models.The second site was the east-facing sidewall of Monte Baldo, a 70-km long north-south oriented mountain range east of Lake Garda in the southern Prealps, on a slope spanning an altitude that ranges from the slope foot at 1400 m ASL to the top at 1670 m ASL. A 6-m tower was installed at the mid-altitude with two sonic anemometers at 3 m and 6 m AGL, one water vapour analyser at the lower level, a net radiometer on top and a heat-flux plate and soil moisture and temperature sondes in the ground. Furthermore, 6 stand-alone temperature and humidity sensors (HOBOs) were installed at various altitudes, from 1400 m ASL to the mountain crest, to document the virtual thermal structure of the ambient atmosphere. Instruments were operated from 1 October to 11 November 2024. These measurements allowed us to characterise the wind and thermal regimes associated with slope winds under various weather conditions, synoptic and local forcings. The results of these campaigns were a useful preliminary exercise for the full campaigns to be held under the TEAMx Special Observing Period in the Summer of 2025.

Oral Presentation

Two major field campaigns were performed in the summer of 2024 at two selected sites in the eastern Italian Alps under the project DECIPHER (Disentangling mechanisms controlling atmospheric transport and mixing processes over mountain areas at different space- and timescales). The project was ancillary and preliminary to the intensive observing period envisaged by the international research initiative TEAMx (Multi-scale transport and exchange processes in the atmosphere over mountains – programme and experiment).

The first site was near the peak of Col Margherita, in the area of the eastern Dolomites, where a permanent monitoring station is operated by the Institute of Polar Sciences for monitoring atmospheric pollutants, and in particular particulate matter and mercury, besides a conventional weather station for standard meteorological variables. Additional instruments were installed at Passo Valles, a lower pass nearby, where two permanent weather stations are also operated by the Regional Weather Services of the Veneto Region and the Province of Trento, respectively. The additional instruments included a wind LIDAR, a Raman LIDAR and a disdrometer. Instruments were operated from 23 July to 29 October 2024. Measurements from remote sensing instruments allowed retrieval of both thermal and dynamical vertical structures of the atmosphere under various weather conditions, including both horizontal and vertical mean wind components. The simultaneous monitoring procedure of the two LIDARs offers a rare opportunity to explore innovative methodologies to compute turbulent fluxes of heat, mass, and momentum through a remote sensing approach. These structures were then analysed in connection with a time series of concentrations of particulate matter observed at Col Margherita to identify patterns of the transport process, through the analysis of back trajectories derived from various Lagrangian tracer dispersion models.

The second site was the east-facing sidewall of Monte Baldo, a 70-km long north-south oriented mountain range east of Lake Garda in the southern Prealps, on a slope spanning an altitude that ranges from the slope foot at 1400 m ASL to the top at 1670 m ASL. A 6-m tower was installed at the mid-altitude with two sonic anemometers at 3 m and 6 m AGL, one water vapour analyser at the lower level, a net radiometer on top and a heat-flux plate and soil moisture and temperature sondes in the ground. Furthermore, 6 stand-alone temperature and humidity sensors (HOBOs) were installed at various altitudes, from 1400 m ASL to the mountain crest, to document the virtual thermal structure of the ambient atmosphere. Instruments were operated from 1 October to 11 November 2024. These measurements allowed us to characterise the wind and thermal regimes associated with slope winds under various weather conditions, synoptic and local forcings.

The results of these campaigns were a useful preliminary exercise for the full campaigns to be held under the TEAMx Special Observing Period in the Summer of 2025.

Oral Presentation

The atmospheric boundary layer (ABL) in mountainous regions is characterised by various airflows, originating from complex landform forcing. In particular daily-periodic thermally-driven circulations develop over inclines under clear sky and in the absence of major synoptic forcing. These airflows, as well as the turbulence associated with them, affect a variety of processes, including surface-atmosphere exchanges of momentum, energy and mass, and transport across a variety of scales. They may also contribute to the initiation of orographic convection.  Here, we focus on the simplest of these flows, namely slope winds. In particular, the slope-normal structure of turbulence is investigated, over diverse slope configurations and properties, analyzing data from measurement campaigns performed under the projects METCRAX, MATERHORN, and MAP-RIVIERA. The near-surface structure of the first- and second-order moments of velocity and temperature are examined. Despite the diversity of situations covered by the field measurements, results reveal intercomparable structures.  After their onset, anabatic winds rarely reach a really steady state, but rather continuously evolve in time with increasing intensity. The height of the wind speed maximum turns out to be challenging to determine, due to the scarce data at upper levels, however it increases with time until the evening transition. Furthermore, small but nonnegligible negative slope-normal velocity components are often detected. Unlike what is usually found in katabatic winds, the turbulent kinetic energy (TKE) increases in the first meters above ground before reaching an asymptotic value at higher levels. A clear linear relationship emerges between surface turbulent fluxes of heat and momentum, as well as between the jet height, the slope angle, the buoyancy frequency of the ambient atmosphere and the friction velocity. Finally, the normalized standard deviations of temperature exhibit a fairly good scaling with Obukhov length, albeit with a structure different from the one which is commonly found over flat terrain. Preliminary results from ongoing efforts to investigate these flows within the current initiative TEAMx - Multi-scale transport and exchange processes in the atmosphere over mountains – programme and experiment (http://www.teamxprogramme.org/)  are also presented.