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Hohenpeissenberg
-PAN-
| Observation |
| Category |
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Air sampling observation |
| Situation |
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ongoing |
| Time zone |
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Local time +1 |
| Sampling |
| Sampling height |
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18 |
| Description |
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continuous |
| Sampling and analysis frequency |
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Every 10 minutes a new GC cycle is started. |
| Sampling environment |
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Hohenpeissenberg is an isolated mountain at 985 m a.s.l., 40 km north of Zugspitze (Alps) in a hilly area. The mountain rises 300m above the surrounding area, which is populated to an extent typical for central Europe and partly covered with meadows (~ 70%) and forests (~ 30%). The Meteorological Observatory situated on top of Hohenpeissenberg mountain has a long history of meteorological and climatological observations (since 1781) and is well-known for its long ozone record.
Peroxiacetylnitrate (PAN) is - like ozone - a secondary trace material; i.e. it is emitted not directly, but formed from oxidation products of atmospheric hydrocarbons (VOC) and nitrogen dioxide (NO2). Main sinks are reactions at surfaces and thermal decomposition. Thus the mean life time depends strongly on temperature: At -10°C PAN has an mean life time of about 14 days, at 20°C it is only 1,7 hours.
For that PAN plays an important role in atmosphere chemical processes: It is an indicator for photochemical processes, better than ozone, since it is exclusively produced in the troposphere, while O3 is additionally produced in stratosphere. Secondly it can be transported at low temperatures (e.g. in higher air layers) over long distances into anthropogenic uninfluenced areas. There by descent of air masses and accompanied warming PAN can be a source for tropospheric ozone production. The concentration range of PAN extends from few ppt up to values of over 10 ppb in urban air masses. |
| Description for sampling analysis |
: |
Ambient air is sucked continuously through a sample loop. Every ten minutes the volume of sample loop is injected into pre-column and column with N2 as carrier gas. Detection of CCl4 and PAN after a retention time of about 5 and 7 minutes, respectively is done by an electron capture detector. |
| Instrument and Analysis |
| Measurement method |
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Gas Chromatography (ECD) |
| Current status and history of instrument |
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PAN-GC, #00437021, from "meteorologie consult", Glashtten, Germany.
Detector: ECD, # ECD80W 20037354, Thermo Electron Corporation |
| Description of instrument |
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time resolution: 10 min,
LDL: about 15 ppt
measurement range: LDL - 3 ppb
linearity tested by multi point calibration
area between PAN peak and baseline is used for calculating the PAN mixing ratio.
Peak for CCl4 serves for quality control.
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| Calibration |
| Current scale employed in the measurement |
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PAN is calibrated by use of acetone photolysis followed by gas phase titration with NO (in situ production). For that, the data refer to NO scale.
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| Measurement calibration |
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Calibration is carried out every week by photolysis of acetone (permeation source) and gas phase titration with known standard of nitrogen oxide. For that the calibration is traceable back to NO standard.
The relative CCl4 peak serves as quality control.
Informal intercomparison with two other GC systems has been undertaken, with excellent agreement in Autumn 2003.
First international PAN intercomparison took place in June 2005 with good agreement.
See also: http://acd.ucar.edu/~ffl(PIE2005.html |
| Scale and calibration(treasability) |
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The data refer to NO standard gas in cylinders |
| Data Processing |
| Measurement unit |
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ppb |
| Data processing |
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The data acquisition system provides every ten minutes PAN and CCl4 peak height, peak area and auxiliary data (flows, temperatures and other system parameters). Integration is manually checked. Zero/calibration factors and data protocols are used to convert raw data in calibrated data. Invalid data caused by local contamination, malfunction or other effects were recognized by comparison/correlation with other trace substances and meteorological data or with the aid of the station logbook and were rejected. |
| Processing for averaging |
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Processing for Hourly Data:
The arithmetic mean of data selected this way is used for generating hourly mean data with number of data more than 3.
Processing for Daily Data:
Daily data take the arithmetic mean of respective hourly data with the number of hourly data more than 16.
Processing for Monthly Data:
Monthly data take the arithmetic mean of respective hourly data with the number of daily data more than 20 (for February more than 19, respectively). |
| Data flag |
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Only validated data are sent to the WDCGG. |
| Data remarks |
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| Other Information |
| Scientific aim |
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Important trace gas for tropospheric chemistry, long range transport atmospheric pollution, oxidation capacity of the atmosphere, interpretation with respect to ozone formation/transport; climatic effects. |
| Reference |
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Stefan Gilge, Measurement of reactive Trace Gases at Hohenpeissenberg as Part of GAW, in „The German Contribution to the WMO/GAW Program: Upon the 225th anniversary of GAW Hohenpeissenberg Observatory, ed. W.Fricke, GAW Report 169, 2006
http://www.dwd.de/gaw |
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| submitted by Meteorological Observatory Hohenpeissenberg, German Meteorological Service |
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