ACTRIS WP21/WP4 OVOC Side-by-Side Intercomparison
From: 7 October 2013
To: 18 October 2013
Place: Hohenpeissenberg, Germany

Meeting venue:  The intercomparison will take place at the Hohenpeissenberg Observatory (Deutscher Wetterdienst, Meteorologisches Observatorium), Albin-Schwaiger-Weg 10, D-82383 Hohenpeissenberg, Germany. Tel: +49 (69) 8062-9710, Fax: Tel: +49 (69) 8062-9707,

Site capabilities
Hohenpeissenberg Observatory offers a spacious guest lab (36m²) on its 3rd floor equipped with air conditioning, central gas supply, a PFA air sampling manifold/inlet line with ports to connect instruments, and several feed throughs in the wall to install sampling lines to ambient atmosphere and of course electrical and telecommunication connections (incl. W-LAN). Space, electrical and gas consumption capacity is sufficient for some 6 participating instruments. Groups should use their own data acquisition system.

Registration &
Local contact:
To apply, please contact Jennifer Englert ( or Dietmar Weyrauch ( Note that attendance is limited to 6 participants.

Deadline for application: June 1, 2013

Meeting info: 

The side-by-side experiment at Hohenpeissenberg Observatory will focus on correct OVOC measurements. For that, synthetic air mixtures as well as spiked ambient air and pure ambient air will be analyzed and compared. All participants should participate with their own equipment. The use of state-of-the-art-techniques comprising GC-MS/FID and PTR-MS techniques are envisioned. DWD will contribute with a well characterized GC-MS/FID system.

The final quality check in OVOC measurements is to demonstrate whether identical samples of simple to complex composition and of high to low mixing ratios are identically analyzed by collocated instruments. For this purpose, instruments will sample from a common manifold with either synthetic mixtures or ambient air supplied via a manifold. As in ambient air the true mixing ratios of OVOC cannot be controlled, it is essential to have best possible characterized analytical systems. These should comprise systems with different and independent measuring principles, e.g. GC and PTR-MS. A side-by-side experiment is superior to e.g. round robins as the diversity of test gases is larger and it is more challenging as complex samples can be analyzed with mole fractions varied in a wide range and in a controlled manner from the lower detection limits of the instruments to polluted conditions. This enables a full characterization of the detection limit, the linear range, and of potential artifacts due to interfering gases. Finally, the contribution of OVOC to local photochemistry can be determined based on co-located measurements of NMHC, BVOC (biogenic VOC), and total OH-reactivity operated by DWD.

Two weeks of intercomparison including set-up, initial calibration etc. are foreseen (see proposed schedule below). This activity supports the integration of European ground-based stations equipped with advanced atmospheric probing instrumentation for short-lived gas-phase species covered by the Network Activity 4 (NA4: Trace gases networking: Volatile organic carbon and nitrogen oxides) and JRA-2 (Comprehensive gas phase and aerosol chemistry) of ACTRIS.

Programme:  Proposed schedule for intercomparison is as follows:

 Date  Tasks
Mo, 7 Oct
Instrument set-up
Tu, 8 Oct Instrument set-up -> start ambient air measurements asap
We, 9 Oct Instrument set-up -> start ambient air measurements asap
Th, 10 Oct Calibration /  VOC-NPL with O3 and rH~50% / zero tests
Fr, 11 Oct Start of dilution series
Sa, 12 Oct End of diution series -> ambient air daily cylce
Su, 13 Oct Ambient air daily cylce
Mo, 14 Oct 1ppb OVOC with modulation of rH and O3=0
Tu, 15 Oct 1ppb OVOC with rH~50% and modulation of O3
We, 16 Oct Ambient air daily cylce with Addtion of OVOC and O3 (spiked air)
Th, 17 Oct Ambient air daily cylce
Fr, 18 Oct Ambient air / dismounting of instruments

Other Info:  A pdf document with the above information can be dowloaded here.

Further details will be communicated in due time.

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