High-Mountain Atmospheric Research

The Mediterranean basin represents a global hotspot for climate change, air quality, and anthropogenic contributions to these issues. Since the early 1990s at Mt. Cimone, the highest peak of Italian northern Apennines, an observatory is performing continuous measurements of atmospheric composition. The Italian climate observatory “O. Vittori” is a research infrastructure managed by the Institute for Atmospheric Sciences and Climate (ISAC) of the National Research Council of Italy (CNR) and hosted by the Italian Air Force. It is part of the WMO/GAW global station “Mt. Cimone” (GAW id: CMN). Due to the completely free horizon, high altitude, and great distance from major pollution sources, CMN represents a strategic platform to study the chemical–physical characteristics and climatology of the free troposphere in the South Europe and Mediterranean basin. At this observatory, continuous monitoring of climate-altering compounds (trace gases and aerosol), solar radiation, as well as meteorological parameters is carried out. Besides providing a historical perspective of scientific research at CMN, we characterize the measurement site, and we describe the current observatory technical facilities, including the e-access to data and the services for near-real-time data delivery. Good practices for educational and outreach activities are also presented.

In the past decades, accurate and precise atmospheric measurements of radiatively active gases have been crucial in revealing the rapid and unceasing growth of their global concentrations that has been long recognized as the main driver of climate change. Even if carbon dioxide is the major anthropogenic contributor to radiative forcing, other gases such as methane, nitrous oxide, and halogenated gases are extremely relevant in climate issues because of their very high global warming potential. Continuous measurement programs of these gases are carried out at CMN in the frame of important international programs. This chapter reports an overview of the scientific results obtained based on 15 years of atmospheric measurements. These results have been achieved combining atmospheric data with different modeling approaches, with the aim of understanding the budget of these radiatively active gases and providing emission estimates at the regional scale. Such estimates constitute an important support to improve bottom-up emission data that each country is required to submit every year in the frame of the most important international global protocols aimed at combatting climate change.

The Mediterranean basin represents a global hot spot for climate change, air quality, and anthropogenic contributions to these issues. In this region, a relevant role is played by reactive gases (RGs), i.e., O₃, CO, SO₂, NO_x, and VOCs. At the “O. Vittori” observatory at Mt. Cimone, a number of RGs are observed since more than 20 years. These observations are carried out within the framework of international program (e.g., WMO/GAW, ACTRIS) representing a valuable resource of information for quantifying the variability of these atmospheric key compounds and for investigating the influence of specific atmospheric processes to this variability (e.g., polluted air mass transport, open fire emissions, mineral dust outbreaks, stratospheric intrusion events). These observations were used to experimental applications like near-real-time data delivery services or model verification and satellite data ground-truthing.

Naturally-occurring and artificial radionuclides in PM₁₀ aerosol samples have been systematically measured for more than 12 years at the “O. Vittori” observatory, a baseline station located in a crucial position in the middle of the Mediterranean basin under the influence of relevant atmospheric streamers crossing in this area. The database collected and herein described covers PM₁₀ mass load, ⁷Be and ²¹⁰Pb, while sporadic samples showed the occurrence of artificial radionuclides as a result of accidents such as the tsunami induced Fukushima nuclear accident or the Algeciras non-nuclear ¹³⁷Cs release. The principal scope of radioactivity monitoring at CMN has been the study of Stratosphere to Troposphere Exchange, mainly based on the variation of cosmogenic ⁷Be, while the availability of ²¹⁰Pb as well of the mass load of PM₁₀ allowed to extend the efficiency of radiotracer data to the identification of continental aerosol sources such as Saharan dust and the Balkan region. Extensive work has been and is still in progress based on the collected dataset concerning the application of global circulation models which rely on the support of objective tracers for their validation.

The aerosol chemical composition at Mt. Cimone has been investigated since 2000 during a series of field campaigns. Starting from 2009, systematic measurements on PM₁ filters was conducted as a contribution to the EUSAAR/ACTRIS network. Moreover, first online chemical measurements were conducted at Mt. Cimone (CMN) in summer 2012 using a high-resolution aerosol mass spectrometer (AMS). The analyses show that the concentrations of mineral elements, associated to coarse particles, are largely influenced by long-range transport of desert dust from Africa. The submicron aerosol composition is dominated by sulfate, carbonaceous material and, to a lesser extent, by nitrate. The concentrations of all PM₁ major components followed a yearly cycle with maxima in the summer when the station prevalently resides in the planetary boundary layer (PBL). The organic-to-sulfate ratio is smaller in summer then in winter. A meta-analysis of the whole dataset shows evidence of a decrease of sulfate concentrations in PM₁ from 2000 to 2010. The sources of organic matter at CMN are still subject of investigation, although biogenic secondary organic aerosol seems to play a role in summertime while biomass burning becomes prevalent in winter.

By this appendix, we provide a set of statistical information about long-term observations of Essential Climate Variables at CMN. We provide a short description of the statistical methods, together with tables and plots describing typical ECV average values and variabilities as a function of seasons and years.