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Pico, Azores
-VOCs-
| Observation |
| Category |
: |
Air sampling observation |
| Situation |
: |
ongoing |
| Time zone |
: |
Local time -1 |
| Sampling |
| Sampling height |
: |
7 |
| Description |
: |
continuous |
| Sampling and analysis frequency |
: |
Samples are taken up to six times a day. A series of VOC calibration standards is used for calibration. The analytical instrument as been described by
Tanner D., Helmig D., Hueber J., and Goldan P. (2006) A gas chromatography system for the automated, unattended, and cryogen-free monitoring of C2 to C6 non-methane hydrocarbons in the remote troposphere. J. Chrom. 1111, 76-88. |
| Sampling environment |
: |
VOC at the Pico Mountain Observatory primarily arise from long-range transport across the Atlantic Ocean. Interpretations of data were presented in:
Helmig D., Tanner D.M., Honrath R.E., Owen R.C., and Parrish D.D. (2008) Non-methane hydrocarbons (NMHC) at Pico Mountain, Azores. 1. Oxidation chemistry in the north-Atlantic region. J. Geophys. Res., 113, D20S91.
Honrath, R.E., Helmig, D., Owen R.C., Parrish D.D., Tanner D.M. (2008) Non-methane hydrocarbons (NMHC) at Pico Mountain, Azores. 2. Event-specific analyses of the impacts of mixing and photochemistry on hydrocarbon ratios. J. Geophys. Res., 113, D20S92. |
| Description for sampling analysis |
: |
Ozone is scrubbed in sample flow with Na2S2O3 coated glass fiber filter, sample flow is then dried to -30 deg C dewpoint, then prefocused on multi-state solid adsorbent trap, then thermal desorption with gas chromatography separation on Al2O3 PLOT column and detection by flame ionization detection. |
| Instrument and Analysis |
| Measurement method |
: |
Gas Chromatography (FID) |
| Current status and history of instrument |
: |
Custom-built inlet system.
SRI Model 8610 GC
Al2O3 PLOT column
Instrument was installed at site in 2003 and has been operated there since mostly during spring-fall. |
| Description of instrument |
: |
See:
Tanner D., Helmig D., Hueber J., and Goldan P. (2006) A gas chromatography system for the automated, unattended, and cryogen-free monitoring of C2 to C6 non-methane hydrocarbons in the remote troposphere. J. Chrom. 1111, 76-88. |
| Calibration |
| Current scale employed in the measurement |
: |
A series of compressed air gas cylinders, cross referenced against INSTAAR Atmospheric Research Laboratory VOC calibration scale which is cross referenced against World Calibration Centre for VOC.
Calibration samples are run every 2-3 days.
Blank air from a zero air generator is injected every 1-2 days.
|
| Measurement calibration |
: |
Injection of whole air standards.
Precision is 2-3% for levels > 0.1 pmol mol-1, and ~ 5% for values between the DL and 0.1 pmol mol-1. Accuracy is 2-3% for levels > 0.1 pmol mol-1, and ~ 10% for values between the DL and 0.1 pmol mol-1. Detection Limits are between ~3-10 pmol mol-1.
|
| Scale and calibration(treasability) |
: |
Multiple standards have been used over the years. Standards are rotated between our lab in Boulder and PMO. |
| Data Processing |
| Measurement unit |
: |
ppb |
| Data processing |
: |
Chromatography peak integration based on peak area. |
| Processing for averaging |
: |
Processing for Hourly Data:
Presented data are individual measurements that arise from the preconcentration of VOC from ambient air during a 20-40 min period.
|
| Data flag |
: |
In cases where a measurement was taken, but the value is below the detection limit, the data was input as half the detection limit and flagged BDL. |
| Data remarks |
: |
None |
| Other Information |
| Scientific aim |
: |
Studies of air pollution transport and atmospheric processing in the North Atlantic Regions. |
| Reference |
: |
Tanner D., Helmig D., Hueber J., and Goldan P. (2006) A gas chromatography system for the automated, unattended, and cryogen-free monitoring of C2 to C6 non-methane hydrocarbons in the remote troposphere. J. Chrom. 1111, 76-88.
Kleissl J., Honrath R. E., Dziobak M. P., Tanner D., Val Martīın M., Owen R. C., and Helmig D. (2007) Occurrence of upslope flows at the Pico mountaintop observatory: A case study of orographic flows on a small, volcanic island, J. Geophys. Res., 112, D10S35, doi:10.1029/2006JD007565.
Helmig D., Tanner D.M., Honrath R.E., Owen R.C., and Parrish D.D. (2008) Non-methane hydrocarbons (NMHC) at Pico Mountain, Azores. 1. Oxidation chemistry in the north-Atlantic region. J. Geophys. Res., 113, D20S91.
Honrath, R.E., Helmig, D., Owen R.C., Parrish D.D., Tanner D.M. (2008) Non-methane hydrocarbons (NMHC) at Pico Mountain, Azores. 2. Event-specific analyses of the impacts of mixing and photochemistry on hydrocarbon ratios. J. Geophys. Res., 113, D20S92.
http://instaar.colorado.edu/pico/ |
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| submitted by Institute of Arctic and Alpine Research, University of Colorado |
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