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Monte Cimone
-CO-
| Observation |
| Category |
: |
Air sampling observation |
| Situation |
: |
ongoing |
| Time zone |
: |
Local time +1 |
| Sampling |
| Sampling height |
: |
7 |
| Description |
: |
continuous |
| Sampling and analysis frequency |
: |
Continuously on a 1-minute time basis. Every 15 minutes a zero check is performed for 15 minutes. |
| Sampling environment |
: |
Mountain peak with completly free horizon.
No local sources of contamination. No access by road.
Timberline about 300m below the measurement site. |
| Description for sampling analysis |
: |
Ambient air is drawn in the instrument using the internal pump at 1.0 l/min and the instrument (Thermo Tei48C) is connect to a glass manifold with approx. 1.5 m of Teflon tube. The glass manifold is part of the trace gases glass inlet (main flux: 40 l/s), extending 1.5 m above the roof of the station.
With the aim of minimizing possible influence of water vapor in the NDIR detection, the ambient air pass through a drying system (Nafion© Dryer) and is then injected in the measurement cell. The exhaust from the measurement cell is used as drying flow of the Nafion© Dryer exchange system. The system is also equipped with a purge air unit (constituted of a Parker drying system and steel tube filled with Sofnocat 423). |
| Instrument and Analysis |
| Measurement method |
: |
NDIR |
| Current status and history of instrument |
: |
From June 2012: Thermo Scientific TEI 48C-TL #0517111935 |
| Description of instrument |
: |
Intruments performance are available on http://gaw.empa.ch/audits/CMN_2012.pdf |
| Calibration |
| Current scale employed in the measurement |
: |
|
| Measurement calibration |
: |
To minimize the influence of temperature on the measurements a specific software was designed and used to control the zero calibration, forcing the instrument to execute this calibration every 15 minutes.
The zero air necessary for the zero calibration is obtained using a steel tube containing Sofnocat 423. Due to the switching in the instrument internal valves during the zero cycle, the ambient air is forced to pass through Sofnocat ©. The zero air is then injected in the cell for 15 minutes and only the final 5 minutes are averaged to produce the zero value that is the applied to the instrument using our self-built software.
The span calibration is performed once a day, starting at 00:30 AM and ending at 00:45 AM. The span value is 500 nmol/mol and this concentration is obtained from the dilution of a 10 ppm CO standard cylinder (CO synthetic air, Messer Switzerland, 2% (k=2) uncertainty) with zero air produced by the zero air unit, which is constituted by carbonate cylinder filled with silica gel (to dry the ambient air) and a steel tube containing Sofnocat© 423. The standard and zero air flows are regulated using two Mass Flow Controller (MFC) (Producer: Brook Instrument Ltd) with different operative range: the one regulating zero air flow works between 0 and 5000 l/min, while the one regulating the standard flow works between 0 and 500 l/min.
Two valves electronically controlled are installed before the two MFCs, so that the system could be completely controlled in the case of failures; moreover, in this way, the two MFCs (as are the valves) are normally closed and are opened only when there is the need for the span calibration. This increase the stability of the MFCs calibration as well as the MCF life time.
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| Scale and calibration(treasability) |
: |
10 ppm CO standards produced by esser Switzerland with 2% (k=2) uncertainty. |
| Data Processing |
| Measurement unit |
: |
ppb |
| Data processing |
: |
Row (1-min) data from the monitoring device are acquired every minute and processed to 1-hour mean values. Data is evaluated by the station staff using Excel (visual inspection, consistency checks using
additional parameter such as zero/span checks, meteorological data, and statistical checks) |
| Processing for averaging |
: |
Processing for Hourly Data:
Hourly data are obtained averaging 1 minutes mean O3 values
Processing for Daily Data:
Daily data are obtained by averaging hourly data
Processing for Monthly Data:
Monthly data are obtained by averaging daily data |
| Data flag |
: |
No flags |
| Data remarks |
: |
No remarks |
| Other Information |
| Scientific aim |
: |
Investigation of background troposphere conditions
Investigation of regional and long-range pollution
Investigation of stratospheric intrusion events
Model validations
Near-real time data delivery |
| Reference |
: |
Zellweger, Christoph, et al. 2012. System and Performance Audit of Surface Ozone, Methane, Carbon Dioxide, Nitrous Oxide and Carbon Monoxide at the Global GAW Station Mt. Cimone, Italy, September 2012. |
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| submitted by National Research Council, Institute of Atmospheric Sciences and Climate |
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