Scheel, H.E.

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Scheel, H. E.

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KIT – University of the State of Baden-Wuerttemberg and National Research Center of the Helmholtz AssociationMonitoring in the GAW Network(GAW = Global Atmosphere Watch)H.E. Scheel(hans-eckhart.scheel@kit.edu)Karlsruhe Institute of Technology (KIT)Institute for Meteorology and Climate Research (IMK-IFU)GAW World Calibration Centre for Nitrous Oxide (WCC-N2O)DEA Workshop "Establishment and Implementation of the National Reference Laboratory"Pretoria, 17 February 2011Monitoring in the GAW Network1. About GAW2. Role of Guidelines within GAW3. Concepts of Quality Assurance and Quality Control (QA/QC) in GAW4. Calibration scales and traceability5. AuditingOutline of TalkKeywords to be addressed:guidelines, operational monitoring procedures, calibration, reference traceability, technical auditing 3What is GAW?• GAW focuses on global networks for GHGs, ozone, UV, aerosols, selected reactive gases, and precipitation chemistry.• GAW is a partnership involving contributors from 80 countries.• GAW is coordinated by the Environment Division of WMO/AREP under the purview of WMO Commission for Atmospheric Science (CAS)• Currently GAW coordinates activities and data from 27 Global stations, 413 Regional stations, and 164Contributing stations (http://gaw.empa.ch/gawsis/)The 2nd International Workshop on Atmosphere Watch in Asia “Greenhouse Gases Monitoring Activities”, Oct.  21 - 22,  201 0Source: http://www.wmo.int/pages/prog/arep/gaw 5Global GAW stationsThe 2nd International Workshop on Atmosphere Watch in Asia “Greenhouse Gases Monitoring Activities”, Oct.  21 - 22,  201 0Within WMO/GAW, work is guided by a series of Strategic Implementation Plans:WMO/GAW Reports No.142. Strategy for the Implementation of the Global Atmosphere Watch Programme (2001-2007), A Contribution to the Implementation of the Long-Term Plan (WMO TD No.1077).156. Addendum for the Period 2005-2007 to the Strategy for the Implementation of the Global Atmosphere Watch Programme (2001-2007), GAW Report No. 142 (WMO TD No. 1209)172. WMO Global Atmosphere Watch (GAW) Strategic Plan: 2008 – 2015 (WMO TD No. 1384), 108 pp, August 2008Currently being edited:WMO Global Atmosphere Watch (GAW) Strategic Plan: 2008 – 2015, Update for the Period 2012 – 2015.Most of the recent GAW Reports are available for download as PDF files athttp://www.wmo.int/pages/prog/arep/gaw/gaw-reports.htmlSeveral Measurement Guidelines (MG) or equivalent documents have been prepared in recent  years.143. Global Atmosphere Watch Measurements Guide (WMO TD No. 1073).146. Quality Assurance in monitoring solar ultraviolet radiation: the state of the art. (WMO TD No. 1180), 2003.153. WMO/GAW Aerosol Measurement Procedures: Guidelines and Recommendations. (WMO TD No. 1178)160. Manual for the GAW Precipitation Chemistry Programme (Guidelines, Data Quality Objectives and Standard Operating Procedures) (WMO TD No. 1251), 186 pp, November 2004..183. Operations Handbook – Ozone Observations with a Dobson Spectrophotometer (WMO TD No. 1469), 91 pp, March 2009.185. Guidelines for the Measurement of Methane and Nitrous Oxide and their Quality Assurance (WMO TD No. 1478), 49 pp, September 2009.190. Instruments to Measure Solar Ultraviolet Radiation Part 3: Multi-channel filter instruments (lead author: G. Seckmeyer) (WMO TD No. 1537).191. Instruments to Measure Solar Ultraviolet Radiation Part 4: Array spectroradiometers (lead author: G. Seckmeyer) (WMO TD No. 1538).192. Guidelines for the Measurement of Atmospheric Carbon Monoxide( WMO/TD-No. 1551), July 2010.In general, Measurement Guidelines (MG) leave more flexibility than Standard Operating Procedures (SOP).Depending on the measurement technique(s), SOPs may be less appropriate than MGs for the work at GAW Global Stations.Data Quality Objectives (DQO) for GAW Global Stations are driven by scientific needs. Examples:For a detailed description of DQOs for CH4 and N2O along with guidance for the measurements see:GAW Report No. 185:Guidelines for the Measurement of Methane and Nitrous Oxide and their Quality AssuranceSimilarly, for CO see:GAW Report No. 192. Guidelines for the Measurement of Atmospheric Carbon MonoxideGAW Reports at: http://www.wmo.int/pages/prog/arep/gaw/gaw-reports.html11Need for quality control•Detect small trends (through DQO)•Detect small spatial gradients•Ensure long-term stability of observations•Data comparability (on the same scale)The 2nd International Workshop on Atmosphere Watch in Asia “Greenhouse Gases Monitoring Activities”, Oct.  21 - 22,  201 0comparability: comparability of measurement results that are metrologically traceable to the same referencecompatibility: difference of any pair of values from different measurement results (should be) smaller than some chosen uncertainty of that difference12Conceptual framework of the GAW quality systemThe 2nd International Workshop on Atmosphere Watch in Asia “Greenhouse Gases Monitoring Activities”, Oct.  21 - 22,  201 0BIPM / NMIBureau International des Poids et Mesures / National Metrology Institutes13Conceptual framework of the GAW quality systemThe 2nd International Workshop on Atmosphere Watch in Asia “Greenhouse Gases Monitoring Activities”, Oct.  21 - 22,  201 0BIPM / NMIBureau International des Poids et Mesures / National Metrology InstitutesCCQM: Consultative Committee for Amount of Substance – Metrology in ChemistryCalibration scales:Historically, individual institutes maintained their scale for trace gas measurements, notably GHGs.In recent years comparisons with CIPM-related institutions(International Committee for Weights and Measures)April 2010: CIPM Mutual Recognition ArrangementThe World Meteorological Organization (WMO) has become the second intergovernmental organization to join the CIPM MRA.Source of information: http://www.bipm.org/en/cipm-mra/Global Atmosphere Watch (GAW)GAW Central Facilities:Quality Assurance/Science Activity Centres(QA/SAC)WorldCalibrationCentres(WCC)Central Calibration Laboratories(CCL)World Data Centres (WDC)& GAWSISCO2, CH4, N2OGAW CCLs are essential for network-wide comparability of measurement dataWCCs serve for improving the data quality in various waysGAWGLOBALSTATIONSCentral Calibration Laboratory (CCL)WCC-N2OGAW StationsOther Stations, LaboratoriesTransfer of scaleQA/QC:Audits & Round-Robin Exper.HarmonisationTraceability of Calibrations and Audits, Example N2OPrimary Standards Secondary StandardsLaboratory Standards Laboratory StandardsWorking StandardsHarmonisationTransfer / Travelling StandardsTransfer of scaleRound-robinManufacturers,LaboratoriesSupply with gas cylindersNMI orCCLNCL (Network Calibration Lab)StationsLaboratoriesTransfer of scaleQA/QC:Audits & Round-Robin Exper.HarmonisationTraceability of Calibrations and Audits – more generalPrimary Standards Secondary StandardsLaboratory Standards Laboratory StandardsWorking StandardsHarmonisationTransfer / Travelling StandardsTransfer of scaleRound-robinManufacturers,LaboratoriesSupply with gas cylindersTasks of CCLsTerms of Reference, GAW Report No. 172, p.15 Host in the long term (many decades) the GAW primary standard and scale for a particular variable. Serve the needs of the other quality assurance facilities and activities of GAW. Prepare or commission laboratory standards required by the GAW network members for calibration purposes. Supply well-calibrated air to GAW analytical laboratories as needed for conducting inter-comparisons (in collaboration with the World or Regional Calibration Centres). Development of quality control procedures Maintaining laboratory and transfer standards that are traceable to the standard scale Conducting performance and system audits at stations Conducting round-robin experiments (intercomparisons)and participation in international intercomparisons Providing training and long-term technical help for station scientists and technicians To assist members operating GAW stations to link their observations to the GAW primary standardTasks of WCCsTerms of Reference, GAW Report No. 172, p.16Audits: DefinitionsSystem audit: generally defined as a check of the overall conformity of a station with the principles of the GAW QA system. It involves an assessment of the station siting, infrastructure, organization, operation, etc.Performance  audit: voluntary check for conformity of a measurement where the audit criteria are the Data Quality Objectives (DQOs) for the specific parameter. The audit involves ensuring the traceability of measurements to the Standard Scale.Adopted from GAW Report No. 172, p. 28.In particular, for trace gases (GHG, CO, VOC), travelling standards in high-pressure cylinders are used.Depending on the parameter(s), instruments for on-site comparisons are employed. • A too small concentration range was covered by the standard(s) available at the site.• Differences between station calibration scale and WCC ⇒ Further intercomparisons necessary.• Insufficient separation between peaks CO2, N2O and SF6 in the gas chromatogram: Rather complex issue due to wide variety of GC configurations.• Laboratory safety: High-pressure cylinders not securedIN SUMMARY: The more recent N2O audits show better results than the earlier ones.  An overall progress towards the goals of GAW is evident. Audits (N2O): Summary of findingsExamplesThe GAW QA system recommends the adoption and use of internationally accepted methods and vocabulary to describe uncertainty in measurements(GAW Report No. 172).To promote the use of common terminology, a web-based glossary has been developed.http://gaw.empa.ch/glossary/glossary.htmlA special word of thanks to DEAfor the invitation to the workshopAcknowledgement: WMO GAW for a number of slidesused in this presentation(Authors: Oksana Tarasova, Liisa Jalkanen and Leonard Barrie, Atmospheric Environment Research Department)

Monitoring in the GAW network. (GAW = Global Atmosphere Watch)

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Monitoring in the GAW network. (GAW = Global Atmosphere Watch)

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