The 7Be activity concentrations measured from 1996 to 1998 at four high-altitude stations, Jungfraujoch—Switzerland, Zugspitze—Germany, Sonnblick—Austria and Mt. Cimone—Italy, were analyzed in combination with a set of, meteorological and atmospheric parameters such as the tropopause height, relative and specific humidity and also in conjunction with 3D back-trajectories in order to investigate the climatological features of 7Be. A frequency distribution analysis on 7Be activity concentrations revealed the existence of two concentration classes around 1.5 and 6 mBq m(-3) and a transition class between the two modes of the distribution at 3-4 mBq (m-3). Cross-correlation analysis performed between 7Be and a number of meteorological and atmospheric parameters at the first three stations showed a strong negative correlation with relative humidity (-0.56, -0.51,-0.41) indicating the importance of wet scavenging as a controlling mechanism. Also, the positive correlation with the height of 3-days back-trajectories and tropopause height (+0.49/+0.43, +0.59/+0.36, +0.44/+0.38) shows that downward transport from the upper or middle to lower troposphere within anticyclonic conditions plays also an important role. Trajectory statistics showed that low 7Be concentrations typically originate from lower-altitude subtropical ocean areas, while high concentrations arrive from the north and high altitudes, as is characteristic for stratospheric intrusions. Although the 7Be activity concentrations are highly episodic, the monthly means indicate an annual cycle with a late-summer maximum at all stations. The correlation coefficients calculated for monthly means of the 7Be and atmospheric data suggest that the main predictor controlling the seasonality of the 7Be concentrations is tropopause height (+0.76, +0.56, +0.60), reflecting more vertical transport from upper tropospheric levels into the lower troposphere during the warm season than during the cold season.

This paper presents studies of stratospheric intrusions in the Alps and northern Apennines, their seasonal variations, and their effect on ozone concentrations. The results are based on experimental data and on simulations with a Lagrangian tracer model. The model, employing analyzed meteorological data, advects a passive stratospheric ozone tracer through the calculation of a large number of three-dimensional trajectories. In two case studies, the model is evaluated using a comprehensive set of observation data, consisting of water vapor satellite images, total column ozone measurements, ozone soundings, and measurements of ozone, beryllium 7 and meteorological parameters at three high Alpine sites and at the highest peak in the northern Apennines. During the two episodes considered, stratospheric air was detectable in the whole Alpine area with peak ozone mixing ratios in the 70–90 ppb range and even penetrated into some valleys. During one episode, stratospheric air also reached the northern Apennines, which highlights the large extension of the affected region. At the end of this episode, as shown by the model, the air was a mixture of tropospheric air with air originating from three different stratospheric intrusions. For three high Alpine sites, the frequency of stratospheric intrusions and its seasonal variation is derived using ozone, beryllium 7 and humidity measurements. The periods covered by this climatology are 1991 to 1997 for Zugspitze, and 1996 to 1998 for Jungfraujoch and Sonnblick. Another short climatology was established from a three-year (1995–1997) model simulation. Good agreement between the two approaches is found for Zugspitze and Sonnblick: the simulated ozone tracer mixing ratios are significantly higher on “intrusion days”, identified from the observations, than on “non-intrusion days”. For Jungfraujoch, the agreement is less good, which could partly be due to the coarser time resolution of the beryllium 7 measurements at this site. The absolute frequency of stratospheric air intrusions as identified from the observations depends critically on the specification of threshold values for ozone, beryllium 7 and humidity, while the relative shape of the annual cycle is rather insensitive to threshold variations. At Zugspitze and Sonnblick, it shows a maximum in October, a secondary maximum in January and February, and a deep summer minimum. For Jungfraujoch, where the frequency of intrusions is higher than at Zugspitze and Sonnblick throughout most of the year, no clear seasonal variation is found. Simulated ozone tracer mixing ratios in the Alps are found to peak in late-winter/early-spring, when ozone concentrations are at a maximum in the stratosphere, but are almost at the same level in autumn, due to somewhat higher frequency of stratospheric intrusions in that season. Similar to the observations, there is a deep minimum in summer, when the model showed practically no intrusions with a tropospheric age of less than four days.

A wide range of measurements was carried out in central and southeastern Europe within the framework of the EU project STACCATO (Influence of Stratosphere-Troposphere Exchange in a Changing Climate on Atmospheric Transport and Oxidation Capacity) with the principle goal to create a comprehensive data set on stratospheric air intrusions into the troposphere along a rather frequently observed pathway over central Europe from the North Sea to the Mediterranean Sea. The measurements were based on predictions by suitable quasi-operational trajectory calculations using ECMWF forecast data. A predicted deep Stratosphere to Troposphere Transport (STT) event, encountered during the STACCATO period on 20-21 June 2001, was followed by the measurements network almost from its inception. Observations provide evidence that the intrusion affected large parts of central and southeastern Europe. Especially, the ozone lidar observations on 20-21 June 2001 at Garmisch-Partenkirchen, Germany captured the evolution of two marked tongues of high ozone with the first one descending to nearly 2 km, thus providing an excellent data set for model intercomparisons and validation. In addition, for the first time to our knowledge concurrent surface measurements of the cosmogenic radionuclides 10Be and 7Be and their ratio 10Be/7Be are presented together as stratospheric tracers in a case study of a stratospheric intrusion. The ozone tracer columns calculated with the FLEXPART model were found to be in good agreement with water vapour satellite images, capturing the evolution of the observed dry streamers of stratospheric origin. Furthermore, the time-height cross section of ozone tracer simulated with FLEXPART over Garmisch-Partenkirchen captures many details of the evolution of the two observed high-ozone filaments measured with the IFU lidar, thus demonstrating the considerable progress in model simulations. Finally, the modelled ozone (operationally available since October 1999) from the ECMWF (European Centre for Medium-Range Weather Forecasts) atmospheric model is shown to be in very good agreement with the observations during this case study, which provides the first successful validation of a chemical tracer that is derived operationally from a weather forecast model. This suggests that coupling chemistry and weather forecast models may significantly improve both weather and chemical forecasts in the future.

In order to point out and study transports of ozone rich air masses in the lower troposphere from the stratosphere/upper troposphere, continuous measurements of several parameters have been undertaken at Mt. Cimone during the European Community VOTALP project (Vertical Ozone Transport in the Alps). Several high values of surface ozone concentration due to vertical stratospheric-tropospheric exchanges have been recorded in the four mountain peak stations involved in this project (Jungfraujoch, Sonnblick, Zugspitze and Mt. Cimone) in 1996–1997. This paper presents and analyses data concerning the Mt. Cimone ground-based station, which is the highest peak of the Italian Northern Apennines and the most representative WMO-GAW site in Italy. Episodes of vertical exchange in the lower stratosphere, as tropopause folding, or in the upper troposphere, as down draft transport, have been registered at Mt. Cimone since March 1996 and subsequently studied. In fact, the comparison between the behaviours of different background trace gases at a mountain baseline station, the weather situations and the backward trajectory analyses can bring to light these events and be very useful for a better knowledge of transport phenomena. Correlation between high level of ozone concentration, chemical and meteorological parameters and three-dimensional backward trajectories relative to two particular events are herein presented.

Ground Surface Temperature (GST) is defined as the near-surface temperature of the ground (bedrock or surficial deposits), measured in the uppermost centimeters of the ground. GST is not a direct proof of permafrost existence but a proxy for estimating potential permafrost presence or absence in the subsurface and can be used for calibrating and validating numerical models. GST has to be distinguished from the Bottom Temperature of Snow cover (BTS), which is the temperature measured at the snow/ground interface in late winter. The APD does not collect raw GST data but the Mean Annual Ground Surface Temperature (MAGST) of a certain depth.

As regards glaciers, in the park 50 ice bodies are present covering about 40 km2. Among the others, Forni, at 12 km2 of area the largest Italian valley glacier. Its recent changes underlined a strong relation with regional and global climate evolution (Pelfini & Smiraglia, 1997; Smiraglia et al., 2007; Smiraglia et al., 2008); in addition this glacier was also inserted in the GOSITES list (Diolaiuti & Smiraglia, 2010), a list including all the geomorphological systems to be protected due to their high scientific, environmental and aesthetic values. On Forni Glacier since 2005 has been running the first Italian supraglacial automatic weather station (Citterio et al., 2007). The data collected were useful to model glacier energy and mass exchanges and to describe local micro-meteorology (Diolaiuti at al., 2009; Senese et al., 2010). Not only large glaciers are important for environmental studies; in fact, in the Park also smaller ones revealed important information.

The SHARE STELVIO project was developed by a group of researchers of the University of Milan, the Politecnico of Milan and CNR of Italy in the frame of the SHARE and the SHARE ITALY Projects promoted and managed by Ev-K2-CNR. The program is supported by the Lombardy Region under the umbrella of an agreement between the Lombardy Region and a regional research foundation: FLA (Lombardy Foundation for the Environment). The project aims at detecting and quantifying climate change evidences and effects on a sensible area located in the Italian Alps: The Stelvio National Park – Lombardy sector (600 km2 of area).

This Work Package of the SHARE Stelvio Project, managed by ISE-CNR research group is focus on fresh water resources (i.e.: rivers and lakes) to describe their chemical, physical and biological features and to look for relations with recent atmosphere, climate and cryosphere variability.

GM are punctual evidence of potential presence or absence of permafrost derived from geophysical methods. Electrical Resistivity/Impedance Tomography (ERT/EIT), Ground Penetrating Radar (GPR) or Seismic Refraction (SR) are suitable methods for the indirect detection of permafrost.

Temperature measured in boreholes (BH) is the most reliable evidence of permafrost presence or absence. BH data provides min/max/mean subsurface temperature at differing depth, maximum active layer thickness (ALT) and (if available) the depth of zero annual amplitude (ZAA). The APD does not collects raw borehole data but yearly synthesis data.