1. 1)Suggested goals of this meeting 2)Why focus WMO-GAW on VOC ? 3)Calibrations Info/Options 4)Measurements Info/Options 5)Suggested Initiatives WMO VOC Experts meeting, January 2006 Geneva – Switzerland. Jonathan Williams WMO

2. Suggested Goals for this Meeting 1)Make more VOC measurements available through GAW/WMO, to public and policy makers 2)Ensure that the quality of further GAW-WMO VOC measurements is such that long term trends can be monitored. 3)Ensure that measurements made at different labs are intercomparable to get global view.

3. Why focus WMO-GAW on VOC ? 1)VOC are important for understanding tropospheric ozone (stated goal of working plan IGACO) 2)Some VOC are directly toxic and/or carcinogenic e.g. Benzene, hence direct public interest 3)Global measurements of anthropogenic VOC show extent & amount of pollution 4)Good indicators for policy makers – effects of legislation can be observed quickly (political timescales) 5)OVOCs ubiquitous, reactive, important, likely to change, but global budgets poorly understood.

4. Calibration / QC / Some thoughts Several intercomparisons have been carried out (e.g. NOMICE, AMOHA) These show research labs and government labs have very variable quality in VOC measurements. These measurements are difficult. Rigorous inter-lab QC strategy essential. A good bad example !! Fortin et al. 2005 show that the EPA-PAMS network was not run with sufficient quality control to deduce clear trends in benzene, visible in campaign data.

5. Calibration-QC / Some thoughts Chamber intercomparison for OVOC – Jülich run by Ralf Koppmann and refereed by Eric Apel has shown how instrument intercomparisons can be made. Can such exercises be performed occasionally (for different instrumentation)? To test e.g. Chrompak, Airmolec, Agilent systems Circulation of common standards must occur regularly. Involve NPL (UK) or EMPA (Swit) as quality ombudsman ???

6. Pilot Study Results Christian Plass-Dülmer – Pilot study at Hohenpeissenberg followed exactly the suggestion in WMO-GAW report 111. Very successful In-situ measurements of VOC and OVOC with GC-MS/GC-FID Detlev Helmig Measurements of alkanes from cansisters – from NOAA CO2 flask network. Piggybacks on existing resources and provides extra information for the CO2 anaylsts (Are there any new canister types from which oxygenates can be measured ???)

7. How to make more measurements ? 1) Through canisters – Detlev Helmig, Don Blake(?), Christian Plass-Dülmer(?) Pros (networks, infrastructure exists, MPI can make cans at low cost) Cons (limited VOCs possible, calibration scales must be united) 2) In-situ. Can we make use of existing networks e.g. EPA (US), German (UBA).. These are instruments maintained by government workers. Can the VOC expert group bring in quality control/standards that will ensure data can be compared. This would be a great WMO initiative Pros (instruments exists, maintained long term by nation states) Cons (methods differ, calibration scales must be united) 3) In-situ set up purpose built OVOC instruments Pros (important scientifically) Cons (expensive, methods not well established) 4) Satellites ?

8. Suggested Initiatives 1) WMO-GAW to organise meeting of governmental measurement station managers (e.g from EPA (US), UBA (D), ? (F) ? DEFRA (UK), ? China. At meeting introduce QC and calibration procedures suggested by VOC-expert group Perhaps at the 2006 IGAC meeting in South Africa? 2) Build on success of the Hohenpeissenberg (in-situ) and NOAA flask network pilot studies to make more VOC measurements available. E.g. From other flask networks, perhaps measured at Hohenpeissenberg by the same instruments as used for in-situ. 3) Agree on acceptable calibration/QC procedures for WMO-GAW VOC data. 4) WCC-VOC to co-ordinate calibration of gases and ensure long term standards for all participating stations. 5) Organise training for GAW station instrument operators and can fillers 6) Make existing data (and background information) available on internet. 7) Establish vision of what we want to have in 10 years time