|
| 
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 |
: |
high flux of real air continuosly flow through the sampling line and every 30 minutes a portion is splitted for 3 minutes to the gas-chromatograph sampling loop. |
| Sampling environment |
: |
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 |
: |
The air is sampled by a 2m long heated intake at 7 m height above
the ground. The air intake is composed by an external (outside building) steel pipe (internally covered by Teflon) and the internal (inside building) Pyrex pipe.
A Stainless steel sampling line (lenght 10m) connects the air intake with the high flux sampling pump in front of the sampling loop of the analyzer; a cracking check valve is installed downstream the pump to ensure a sligthly overpressure inside the sampling loop and discharge the excess of flow to vent. |
| Instrument and Analysis |
| Measurement method |
: |
Gas Chromatography (FID) |
| Current status and history of instrument |
: |
measurements started on Jan 2007 with a modified version of a commercial Agilent GC6890 and are still ongoing; |
| Description of instrument |
: |
time resolution: 1 measurement every 30 minutes;
sensitivity: generally below 0.3 ppbv
detection limit: theoretical LOQ (S/N = 10) 30 ppbv
measurements range: fully calibrated in the range 100 to 225 ppb (NOAA cylinders available); extrapolated for lower and higher values (assuming linearity doesn't change over the available range of std conc.)
|
| Calibration |
| Current scale employed in the measurement |
: |
WMO-CO-X2014 |
| Measurement calibration |
: |
every 15 minutes a sample is analyzed alternating between real air and reference standard in order to correct for short time instrumental drifts. molar fraction is calculated from the ratio of the peak heights;
reference standard (local working standard) is regolarly checked against NOAA cylinders |
| Scale and calibration(treasability) |
: |
reference standard from 2008 to 2012 are real air pumped in Luxfer Scott Marrin cylinders and calibrated at MPI-Jena against WMO-CH4-X2004A cylinders; from 2012 and ongoing dry are real air pumped at the station on the Luxfe ScottMarrin cylinders and calibrated on site against NOAA cylinders. a target cyclinder is measured twice per day. |
| Data Processing |
| Measurement unit |
: |
ppb |
| Data processing |
: |
reported data are single point, no average is computed; data validation is evaluated by checking the correct instrumental operation, the spread of the repeated working standard analysis; in case of anomalies, real data are flagged for a deep check and -eventually- removed form the final dataset. results from target cylinder is used to check for long term stability of the whole set up and eventually correct or remove suspect data. |
| Processing for averaging |
: |
|
| Data flag |
: |
|
| Data remarks |
: |
Each data submitted represent a real acquired concentration point, none of the post-acquisition averageing operation has been done. The precision of the measurements is then reported in the data file (REM column) as the relative standard deviation (expressed in percentage) of the repeated measure of the working standard performed in the same day of each real sample analysis (and is generally calculated over 48 working standard runs per day). |
| Other Information |
| Scientific aim |
: |
|
| Reference |
: |
|
|
| submitted by University of Urbino, Dep. of Basic Sciences and Fundamentals (DISBeF) |
|
|
