Lorenzo Giovannini

This paper presents the rationale, experimental design and preliminary outcomes of two field campaigns undertaken as part of the project DECIPHER at two mountain sites in the Italian Alps to investigate surface-layer processes and turbulent fluxes associated with slope-wind systems. The first campaign (23 July-29 October 2024) was concentrated at Col Margherita (2543 m above sea level (ASL) )and nearby Passo Valles. The second field campaign (2 October-10 November 2024) was carried out in the Monte Baldo mountain range on a steep east-facing slope. Deployed instruments included an optical particle counter (OPC) for aerosol measurements, a Doppler wind Lidar, a Raman Lidar, a disdrometer, a two-level eddy covariance tower, complemented by a four-way net radiometer, soil sensors and thermohygrometers distributed along the slope. Results showed that at Col Margherita, OPC measurements identified coarse-mode aerosol enhancement episodes on 30 July–1 August (Episode 1) and 15–17 August (Episode 2), both were linked to long-range dust transport, as supported by Copernicus Atmosphere Monitoring Service (CAMS) analyses and lidar observations. During non-episodic periods, variability in fine- and coarse-mode aerosols appeared to be strongly influenced by local moisture conditions, with specific humidity values greater than 10 g kg− 1 over the site. At the Monte Baldo site, the last 12 days of the field campaign (30 October–10 November) were characterized by meteorological conditions favorable for the development of slope winds. A representative case of a fully developed thermally driven slope-wind system on 7 November clearly highlighted the role of slope orientation and topographic geometry in controlling the timing, persistence, and intensity of transitions between upslope and downslope flow regimes. This occurred even during November, a period generally considered less favorable for thermally driven circulations than summer conditions. Further in-depth analyses will be the subject of forthcoming publications.

We analyse 17 Mediterranean cyclones with tropical‐like characteristics using European Centre for Medium‐Range Weather Forecasts (ECMWF) Reanalysis Version 5 (ERA5) reanalysis data to investigate the role of upper‐tropospheric processes and their seasonal variations in cyclone development. Our results show that cyclones occurring in September exhibit the most intense convection, with Ianos , one of the strongest medicanes on record, representing an extreme case. Using correlation coefficients between and upper‐level relative humidity () and potential vorticity (), we find that warm‐core strengthening is systematically linked to upper‐tropospheric moistening. While is generally negative, consistent with diabatic erosion/decoupling of the upper‐level PV anomaly during warm‐core growth, both its magnitude and the level of maximum anticorrelation vary across cyclones. Using back‐trajectory analyses, we investigate the presence of dry intrusions in the early and mature cyclone phases. We show that one or more dry intrusions are common in medicanes, with an intensity that is case‐dependent. Consistently, 700‐hPa equivalent potential temperature () fields show that descending trajectories correspond to low‐ filaments wrapping around the cyclone, and that a warm‐seclusion‐like structure is visible during warm‐core onset. While dry intrusions can accelerate warm‐core formation by favouring convection, the eventual warm‐core intensity depends critically on diabatic processes near the cyclone centre, as exemplified by Ianos . In fact, despite only marginally descending flows before the main tropical‐like phase, this cyclone develops the strongest warm core among the cyclones analysed. This motivates us to examine Ianos in detail using ERA5 and a Weather Research and Forecasting (WRF) simulation with a grid spacing of 3 km, which confirms the need for high resolution to represent the cyclone intensity correctly, highlights the dominant contribution of diabatic heating to cyclone deepening, and suggests a secondary role of the weak descending branch of the PV streamer.

Although the definition of medicanes has been recently provided (Miglietta et al., 2025), the characteristics of the most intense among these cyclones have yet to be determined. This latter subcategory of medicanes includes cyclones that, during their mature phase, are driven almost exclusively by air-sea interaction and are responsible for the greatest damage.In this context, we analyze 17 medicanes using ERA5 reanalysis data to study the role of upper-tropospheric processes in cyclone development. Using back-trajectory analysis, we investigated the presence of dry intrusions in the early and mature phases of cyclones. We found that the standard definition of a dry intrusion, characterized by a descent of 400 hPa in 48 hours, is rarely met. In contrast, weaker and shallower descents associated with PV streamers are more common. Although dry intrusions can accelerate warm core formation by promoting convection, the final intensity of the warm core depends critically on diabatic processes near the cyclone's center, as exemplified by Ianos.In fact, in Ianos only marginal descending flows occur before the main tropical phase, yet this cyclone develops the most intense warm core among the analyzed cyclones. This prompted us to examine Ianos in detail using a WRF model simulation with a 3 km grid spacing. This simulation highlights the dominant contribution of diabatic heating to the cyclone's intensification already in the early stages and suggests a secondary role for the baroclinic forcing, indicating a different pathway in the cyclone's evolution. However, in the mature phase, a weak upper-level PV streamer contributes to the rapid deepening of the cyclone.

The characteristics of the nocturnal drainage wind flowing from the tributary Isarco Valley into the Bolzano basin, in the Italian Alps, during wintertime are investigated. Analyses are performed by combining measurements from an intensive field campaign and the output of four high‐resolution numerical simulations, run with the Weather Research and Forecasting (WRF) model using different planetary boundary‐layer (PBL) schemes. Two episodes are identified, based on the vertical temperature stratification in the basin and the evolution of the drainage flow at the valley exit. Numerical results show that the drainage flow behaves as a valley‐exit wind, the main structure of which at the exit of the valley is captured well by the model independently of the PBL scheme. However, the model struggles to reproduce the temperature stratification in the basin correctly, with better results when a PBL scheme including, among others, a prognostic equation for the temperature variance and a counter‐gradient term is used. This has an impact on the simulation of the onset and duration of the valley‐exit wind, which are sensitive to the temperature contrasts between the valley and the basin. Overall, the model is able to reproduce the different behavior of the drainage wind at the exit of the valley in the two case studies. It is found that the presence of a cold‐air pool in the basin favors an upward trajectory of the flow at the exit of the valley, resulting in unperturbed calm wind conditions in the lower levels. On the other hand, with weak temperature stratification, the drainage flow follows the topography closely, also resulting in strong winds near the surface.

This study investigates the sensitivity of numerical simulations of atmospheric processes over complex terrain to land surface model (LSM) parameters, focusing on thermally driven circulations in an idealized valley. The sensitivity analysis is performed using the Weather Research and Forecasting model coupled with the Noah‐MP LSM, for forest and grassland land cover classes. An ensemble of 400 simulations for mixed forest and grassland is emulated with a suite of machine‐learning regressors, and variance‐based global sensitivity indices are computed from the surrogates. Sensitivity is evaluated for near‐surface wind, potential temperature, turbulent kinetic energy (TKE), and surface heat fluxes at representative valley locations. Results clearly discriminate influential and non‐influential parameters, providing guidance in identifying those that most affect model results and therefore should be treated with the most care. Over forests, stomatal minimum resistance ( RS ) is the most influential parameter overall, followed by canopy height ( HVT ), with importances intensifying during the night. Near‐infrared leaf reflectivity ( RHOL_NIR ), leaf area index, and optimal transpiration temperature ( TOPT ) also result as important parameters. Over grasslands, by contrast, both leaf and stem ( SAI ) area indices dominate, followed by RHOL_NIR . The roughness length ( Z0MVT ) is the most important parameter affecting turbulent kinetic energy during daytime, while RS and HVT are largely non‐influential. The results highlight that the proposed approach, integrating variance‐based global sensitivity analysis with machine learning, represents a reliable framework to perform sensitivity analyses for complex numerical models, providing valuable insights into the dynamic interactions between land surface parameters and atmospheric conditions over complex terrain.

This contribution presents an overview of the activities and results of the INTERFACE project, which aims to quantify the non-closure of the surface energy balance across various Alpine sites, where processes related to the lack of closure, i.e., advection due to the development of thermally-driven circulations, are expected to be particularly significant. This objective is addressed by combining flux station and unmanned aerial system (UAS) measurements. The UAS provides spatially distributed observations around eddy-covariance sites, which are essential for estimating advection.The analysis of eddy-covariance data from various sites representing diverse Alpine contexts (e.g., valley floor, slope, and mountain top) and climatic settings (North vs. South of the main Alpine crest) allows a systematic quantification and comparison of the characteristics of the surface energy balance, including the lack of closure. Particular emphasis is placed on the evaluation of the role of thermally-driven circulations in the non-closure of the surface energy balance, utilizing objective criteria to select days with well-developed slope and valley winds.The INTERFACE project contributes to the TEAMx international research programme, which aims to improve our understanding of exchange processes in the atmosphere over mountains.

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.

Accurate quantification of the Surface Energy Balance (SEB) in complex terrains remains an open challenge due to high spatial heterogeneity and scale mismatches between surface fluxes and atmospheric observations. Eddy Covariance Towers (ECT) provide continuous flux monitoring, but their spatial representativeness is limited in environments where atmospheric conditions vary over short distances, particularly in Alpine regions. Uncrewed Aircraft Vehicles (UAV) represent a complementary observation strategy by enabling distributed measurements of the near-surface variables that affect turbulent and radiative exchanges in sub-mesoscale ranges.This work reports on the development, validation, and field deployment of a UAV-based measurement platform and data aggregation workflow for the spatial acquisition of wind, air temperature, relative humidity, and shortwave radiation in proximity to ECTs, to estimate the role of local circulations and advection on the SEB closure.At first, computational fluid dynamics (CFD) simulations using the k–ε turbulence model were performed to assess propeller-induced aerodynamic distortions and to guide sensor onboarding on a multirotor UAV. Then, wind-tunnel experiments were executed at the WindShape facility (Switzerland), using a dedicated UAV testing setup comprising a 6-degree-of-freedom robotic arm for controlling UAV attitude and orientation. Lastly, a field campaign including repeated flights and hovering stops at predefined locations was carried out in Mezzolombardo (Italy) within the framework of the TEAMx international research programme.By comparing ECT and UAV data, some general remarks can be made. In the case of temperature (T) and relative humidity (RH) measurements, sensors with fast response time are crucial for exploiting at best the limited UAV flight endurance. Our field tests highlighted T and RH maximum differences between the ECT HMP155A Vaisala sensor and UAV Galltech PM15P sensor measurements of 1.0 °C and 7%, respectively in a range of 100 m from the tower. However, this data is very fragmented due to the long acquisition time needed to get to steady-state values. In the case of wind measurements, no issues with sensor response time were noticed. Horizontal wind gusts up to 3 m/s were recorded by a TriSonica Mini LI-550 mounted on the UAV, while wind gusts up to 2 m/s were recorded by the Gill HS-100 anemometer of the ECT. Our preliminary results aim at demonstrating that multirotor UAV platforms have the capability of capturing information that ECT observations alone cannot resolve, provided that high-res. / high-freq. sensors are onboarded and conditioned according to the aforementioned procedure. This strategy (possibly empowered by UAV swarms) is expected to greatly contribute to the interpretation of flux footprints and assessment of horizontal heterogeneity in ongoing and future SEB closure studies.

Italy has long played a pivotal role in the development of meteorology, from the invention of key instruments to the establishment of some of the earliest international observational networks. Over the past three centuries, this legacy has resulted in a vast and valuable archive of meteorological data preserved in Italian repositories. Although numerous initiatives have contributed to safeguarding parts of this heritage, a substantial fraction of the records remains available only in paper format. These collections are particularly vulnerable to physical deterioration, putting at risk data of considerable scientific value for meteorology, climate science, and climate change assessments.This study presents a recent project developed by the Italian Association of Atmospheric Sciences and Meteorology (AISAM) within the framework of Climate Data Rescue (Cli-DaRe) initiatives. In particular, the Cli-DaRe@Images project, launched in 2024 and close to its end, integrates education and climate change awareness with the recovery of historical meteorological data. The project actively involves high school students in the Trentino region in the digitization of meteorological records preserved at the San Bernardino Library in Trento.Following the photographic acquisition of the original documents, the data will be transcribed into digital spreadsheets, thereby recovering and making accessible a priceless scientific heritage. The project adopts a Citizen Science approach, moving beyond a traditional educational model, in which students are passive recipients of knowledge, toward one in which they become active contributors to scientific research. Through this process, participating students gain firsthand experience in the digital retrieval of historical meteorological data and manuscripts in addition to the subsequent processing.

The surface energy balance (SEB), which defines the partitioning of energy exchange between the Earth’s surface and the atmosphere, is crucial for characterizing the development and evolution of the atmospheric boundary layer. While an accurate assessment of SEB components is essential for numerous applications, eddy-covariance measurements remain affected by significant uncertainties. Specifically, turbulent heat fluxes typically fail to balance the available energy at the surface. Research suggests that this energy balance closure problem stems primarily from advection driven by secondary circulations, which are prevalent over heterogeneous and complex terrain due to differential heating.This study assesses the relationship between SEB non-closure, surface heterogeneity, and the subsequent development of local and mesoscale thermally driven circulations. The analysis utilizes data from seven flux sites across diverse Alpine environments (both on flat and sloped terrain) - including vineyards, pastures, pre-alpine and continental forests - incorporating at least two years of data per site, with many exceeding four years. The results provide a systematic and robust quantification of SEB non-closure across several typical Alpine contexts, highlighting key similarities and differences between sites based on their topographic features, land cover, and prevailing meteorological conditions.The present work is part of the INTERFACE project (INvestigating ThE suRFACe Energy balance over mountain areas), which is performed in the framework of the TEAMx research programme.