The study concerning carbon dioxide measurements taken during the 1997, 1998 and 1999 summer campaigns at two different altitude stations and biospheric conditions are presented. The higher station (Mt. Cimone, 2165 m a.s.l.) is characterised by 360° free horizon and is located on a rocky mountain while the lower (Ninfa lake, 1550 m a.s.l.) is located inside the red spruce and beech forest. The different behaviour of CO2 at the two mountain stations has been registered. It shows the strong effect of nighttime soil emission and vegetation respiration on CO2 mixing ratio increases and of diurnal vegetative activity on CO2 concentration decreases at the lower measurement site. The baseline character of the higher measurement site has been confirmed by comparison of CO2 diurnal amplitudes recorded at the two stations.

Le concentrazioni di anidride carbonica sono misurate utilizzando l’analizzatore PICARRO G2401; tale strumento si basa sulla tecnologia Cavity-Ring-Down Spectroscopy (CRDS) che, dall’analisi dell’attenuazione di un segnale laser su un cammino ottico di 20 km, permette di valutare in modo accurato e selettivo le concentrazione dei gas. Lo strumento è stato tarato sulla base di miscele di taratura fornite dal World Calibration Center (NOAA-GMDL) della rete WMO/GAW. Ogni 48 ore vengono eseguite tarature di routine utilizzando working standard commerciali Instrument (Picarro G2401) is used to determine atmospheric carbon dioxide. The instrument is connected by a Synflex 1300 (OD: ¼”) to the air intake manifold. Antiparticulate filter (Svagelock) are present at the instrument inlet. Scale and calibration: WMO-CO2-X2007. Once the implementation phase will be ended (end of summer 2015), two working standards will be used for automatic calibration every 48h. These working standard will be calibrated every month against two travelling/secondary standards which, on turn, will be calibrated, every six months against NOAA – GMDL reference cylinders (CB11039, CB11164, CB10928) hosted at the twin station “Lamezia Terme” and representing the laboratory primary standard. The working and secondary standards have CO2 mole fractions representing upper and lower ranges of the expected ambient variability. Working standards (50 lt, Alluminum tanks at 150bar) and travelling standards (10 lt, Aluminum tanks at 150 bar) are provided by RIVOIRA (Praxair). Two-stage stainless steel pressure regulators for high purity gas are used (Praxiar RSD2SX). Currently and until the end of the implementation phase, manual calibration against the two working standard is carried out every 14days/1month by ISAC-CNR operators. The link to the NOAA-GMDL standard at Lamezia Terme is still not effective, thus currently the instrument is running with factory calibration parameter. Data are recorded on a 5 sec basis by the Picarro internal PC and mirrored to a station server , then delivered in NRT mode to ISAC-CNR HQs in Bologna, where 1-minute average were calculated. Final aggregation to hourly average will be executed by using validated 1-min data. On hourly basis data will be flagged to identify “background” observations. This can be done both by considering wind sector (with the aim of selecting observations under sea breeze conditions, thus neglecting influence from in-land contributions) as well as by using de-spiking procedures as proposed by Thoning et al. [1989] . Information about instrument functioning and intervention are stored within an e-logbook. Instrument manual are present at the station. SOP are extracted by the: GAW Report No. 185 “Guidelines for the Measurement of Methane and Nitrous Oxide and their Quality Assurance”, GAW Report No. 192 “Guidelines for the Measurement of Atmospheric Carbon Monoxide”; GAW Report No. 213 “17th WMO/IAEA Meeting on Carbon Dioxide, Other Greenhouse Gases and Related Tracers Measurement Techniques”.

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.

Le concentrazioni di CO, CO2, CH4 e la percentuale di H2O sono misurate utilizzando l’analizzatore PICARRO G2401; tale strumento si basa sulla tecnologia Cavity-Ring-Down Spectroscopy (CRDS) che, dall’analisi dell’attenuazione di un segnale laser su un cammino ottico di 20 km, permette di valutare in modo accurato e selettivo le concentrazione dei gas. Lo strumento è stato tarato sulla base di miscele di taratura fornite dal World Calibration Center (NOAA-GMDL) della rete WMO/GAW. Ogni 48 ore vengono eseguite tarature di routine utilizzando working standard commerciali. Instrument (Picarro G2401) is connected by a Synflex 1300 (OD: ¼”) to the air intake manifold. Antiparticulate filter (Svagelock) are present at the instrument inlet. Scale and calibration: WMO-CH4-X2004, WMO-CO-X2014, WMO-CO2-X2007. CALIBRATION STANDARDS: A set composed by n.3 calibration standards from NOAA-GMDL is available at the Lamezia Terme station: CB11039, CB11164, CB10928. They represent the I-AMICA network laboratory primary standards. These calibration standards will be compared every 6 months against the station working standards for evaluating possible working standard drifts and directly to the instrument to evaluate the stability of calibration factors. WORKING STANDARD: For each gas, two working standards (6 cylinders in total) with CO2,CH4 and CO representing upper and lower ranges of the expected ambient variability are used to perform automatic calibration every 48 h. Working standard are provided by SOL S.p.A. 48h calibration are performed at different time from one day to another. Avoiding to perform routinely calibrations at the same hour of day, helps in increasing the representativeness of the measurements at daily scales and allows to determine possible problems occurring at different time of day (e.g. related with laboratory ambient conditions). Two-stage stainless steel pressure regulators for high purity gas are used (HARRIS Calorific mod. LHP 742 N2). Data are recorded on a 5sec basis by the Picarro internal PC and mirrored to a station server, then delivered in NRT mode to ISAC-CNR HQs in Lamezia Terme, where 1-minute averages are calculated. Final aggregation to hourly average will be executed by using validated 1-min data. On hourly basis data will be flagged to identify “background” observations. This can be done both by considering wind sector (with the aim of selecting observations under sea breeze conditions, thus neglecting influence from in-land contributions) as well as by using de-spiking procedures as proposed by Thoning et al. [1989] Information about instrument functioning and intervention are stored within an e-logbook. Instrument manual are present at the station. SOP are extracted by the: GAW Report No. 185 “Guidelines for the Measurement of Methane and Nitrous Oxide and their Quality Assurance”, GAW Report No. 192 “Guidelines for the Measurement of Atmospheric Carbon Monoxide”; GAW Report No. 213 “17th WMO/IAEA Meeting on Carbon Dioxide, Other Greenhouse Gases and Related Tracers Measurement Techniques”.