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Hohenpeissenberg
-SO2-
| 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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Continuous, measuring interval is 10 seconds. The maximum time resolution provided by the data acquisition system is 1 minute. |
| 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.
SO2 is the most important source for sulfate aerosol and for that also important for cloud formation processes and climatic effects (e.g. anti-greenhouse effect). SO2/sulfuric acid affects the aerosol mass, aerosol chemistry, radiation effects of aerosol, formation of cloud condensation nuclei, is the most important trace gas for the particle new formation and is involved in acid rain formation. SO2 originates mainly from anthropogenen sources, i.e. from industrial combustion processes. In addition, it is emitted by volcanic eruptions. Major sinks are reaction by OH radicals and by wet deposition, i.e. by solution in cloud drops, in which it is converted to sulfurous acid and sulfuric acid. The mean life time in the atmosphere is around 3-4 days (life span against OH 5-20 days). SO2 can be used as tracer for European-wide air mass transport. |
| Description for sampling analysis |
: |
Teflon PFA inlet line: about 18m above ground; 1/2 inch diameter, 4 m length, together with other trace gases, residence time < 2 seconds. Inlet line is heated 3°C above ambient air temperature to avoid condensation.
Continuous SO2 UV pulsed fluorescence analyzer, model: Thermo Instruments 43 CTL, #43CTL-56118-306.
The experimentally identified LDL with this set-up is about 50 pptv. |
| Instrument and Analysis |
| Measurement method |
: |
Fluorometry |
| Current status and history of instrument |
: |
Jan.1995 - Jan.2002 : Thermo Instruments 43 BS, #43BS-51632-288
Jan.2002 - ongoing : Thermo Instruments 43 CTL, #43CTL-56118-306
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| Description of instrument |
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Time resolution is one minute (limited by data acquisition system), LDL and resolution is about 50 ppt. The instrument is linear from LDL up to at least 50 ppb.
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| Calibration |
| Current scale employed in the measurement |
: |
Certified SO2 in N2 in cylinders and dynamic dilution with synthetic air is used for calibration.
From time to time inter-comparisons between Hohenpeissenberg and Schneefernerhaus site. |
| Measurement calibration |
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1/95-10/97 : Calibration and zero check twice a week.
Since 10/97: Calibration and zero check once a week.
Certified SO2 in N2 in cylinders and dynamic dilution with synthetic air is used for calibration. For zero measurement ambient air after removal of SO2 by activated charcoal and alternatively synthetic air is used (with same results).
Twice a year a multi point calibration (0, 5, 10, 15, 20 ppb) and a check of the efficiency of the activated charcoal cartridge is undertaken.
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| Scale and calibration(treasability) |
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Certified SO2 concentrations in cylinders and dynamic dilution were used for calibration.
Comparisons with a wet chemical method was undertaken in summer 1995 and 2005. The analyzers showed an excellent agreement. The SO2 calibration gas was compared to newly diluted sulfite standards. |
| Data Processing |
| Measurement unit |
: |
ppb |
| Data processing |
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The data acquisition system provides one minute mean raw data. Zero/calibration factors and data protocols are used to convert raw data into calibrated data. Invalid data caused by local impacts, malfunction or other effects were recognised by comparison/correlation with other trace substances and meteorological data or with information from the station logbook and were rejected.
10 minute mean values are generated by calculating the arithmetic mean of the remaining data with number of data being more than 6.
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| Processing for averaging |
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Processing for Hourly Data:
Hourly data take the arithmetic mean of respective one minute mean validated data with the number of data more than 40.
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).
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| Data flag |
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Only validated data are sent to WDCGG. |
| Data remarks |
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| Other Information |
| Scientific aim |
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Aerosol formation from gas phase, tracer for anthropogenic impact. |
| 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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