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THE CANADIAN BREWER SPECTROPHOTOMETER NETWORK (CBSN)

THE CANADIAN BREWER SPECTROPHOTOMETER NETWORK (CBSN). by: Tom Grajnar Ozone and UV Network Manager. The Brewer Spectrophotometer: A Canadian Contribution to the Global Ozone and UV Monitoring Programme.

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THE CANADIAN BREWER SPECTROPHOTOMETER NETWORK (CBSN)

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  1. THE CANADIAN BREWER SPECTROPHOTOMETER NETWORK(CBSN) by: Tom Grajnar Ozone and UV Network Manager

  2. The Brewer Spectrophotometer: A Canadian Contribution to the Global Ozone and UV Monitoring Programme • Developed to replace Dobson spectrophotometer as prime standard for ground-based ozone monitoring • Is a modified Ebert spectrophotometer that can be used to measure total column ozone, SO2, NO2, ozone profile, aerosol optical depth and temperature of the ozone layer • 1979-Development began at MSC • 1980-Working prototype displayed at QOS in Boulder • 1980-Initiation of Commercial production at SCI-TEC (now Kipp & Zonen) • 1982-First foreign MKII delivered to Greece • 1985-First MKIV • 1987-Patented by Kerr et al. • 1992-First MKIII • 1997-First MSC MKV • 2000-Over 165 Brewers in 43 countries and Antarctica

  3. CBSN: History • 1957 to 1962 - Implementation of Dobson Network – 5 stations • 1982 to 1994 – Implementation of Brewer Network – 13 stations

  4. CBSN: Present State • Canada: • 13 stations • 28 Brewer spectrophotometers (+31 computers) • 1 Dobson spectrophotometer • United States: • 1 station (Mauna Loa Observatory, Hawaii) • 2 Brewer spectrophotometers (+3 computers)

  5. CBSN: Station Location and Instrumentation

  6. CBSN: Station Map

  7. CBSN Management and Maintenance: Purpose • Long-term monitoring of total column ozone and solar spectral ultraviolet radiation • Provision of near real-time data for use in CMC ozone and UV forecasts • Submission of data to WOUDC for long-term archival (trends studies) • Ozone transfer calibrations— for other organizations

  8. CBSN Management and Maintenance: Staff • Direct • Network Manager • Network Technologist • Three Interns (9 months each) • One intern supporting network operations • Two interns writing software • Indirect • Station employees • Station contractors

  9. CBSN Management and Maintenance:Key Operational Tools • Budget spreadsheets • Brewer parts inventory database • Electronic station Log Forms • Various other databases

  10. CBSN Management and Maintenance:Key Operational Tools – Parts Inventory Database • Microsoft Access Database • Over 800 entries • Information: • Product ID# • Product Name • Product Description • Kipp & Zonen or Supplier Part #’s and Prices • Storage Location • Quantity in stock • Quantity required in stock • Quantity to order

  11. CBSN Management and Maintenance:Key Operational Tools – Log Form • Excel workbook • One sheet per month • One Log File per year • Sections: • Contact information • Daily checks • Notes for proper Brewer operation and maintenance • Frequency of non-daily checks • Table to log non-daily checks • Table to log other maintenance notes

  12. CBSN Management and Maintenance:Station Visits -- Overview • For: calibrations, maintenance, repairs, training • Visit frequency: every 2 years • Ideal staff complement: 2 • Duration: about 6 days incl. travel time • Equipment: about 450 kg • Completed so far this year • Alert • Additional station visits this year: • Goose Bay, Dartmouth, Montreal, Mauna Loa?

  13. CBSN Management and Maintenance:Station Visits -- Agenda • Calibration reference + details • Preliminary diagnostics examination • Initial Calibrations (Dispersion, UV, Ozone, etc.) • Maintenance + repairs (260 checks) • New equipment installation + upgrades • Final Calibrations (Dispersion, UV, Ozone, etc.) • Calibration data processing • Installation of new constants • Computer maintenance (15 checks) • Station inventory (50 checks) • Station photos + panorama • GPS station coordinates check • Training • Report finalization

  14. CBSN Management and Maintenance:Station Visits – New Activities • Pressure test all Brewers • Installation of a sky cameras • Installation of a land cameras

  15. CBSN Management and Maintenance:Station Visits – Future Upgrades • Humidity sensors • External desiccant system (closed cases) • Sky and land cameras • Proportionally controlled heaters with fans • Umkehr measurements at all stations • NO2 measurements where possible • Insulated covers for Arctic and northern stations

  16. CBSN Management and Maintenance: Arctic Strategy • Historically the most problematic • Network Brewers range in age from 6 to 21 years -> average = 18 years • Arctic challenges: • High employee/contractor turnover (or no staff) • High cost of non-scheduled station visit • High cost of shipping parts back and forth for testing • Time lag due to infrequent flights, wx conditions employee/contractor time available to test/diagnose • Two Brewers each with one computer • Alert: red + single, Eureka: red + double, Resolute: red + single • Benefits: • Dramatic reduction in data record gaps • Red vs regular Brewer ozone measurement studies • Spare + diagnostic equipment already there • Data comparison

  17. Software Tools: Calibration Software • Ozone calibration: intcom3a/BfilePro • Dispersion calibration: DisPro • UV calibration: LampsPro • Temperature coefficients: TempCoef • GS scan analysis: GraSPro • Mirror positioning: Et.rtn • Neutral density filter test: Testfw2 • Sunscans: IdealStepNumber • Zenith sky coefficients: FullZen

  18. Calibration Procedures: UV Calibration • Irradiance source: 1,000 Watt DXW NIST traceable lamps • Lamps operated at 8.0 amps DC in horizontal position • 40 cm distance from middle of lamp filament to teflon diffuser • Lamp system components: • Power supply: Xantrex model XHR 150-7 • 8.3 amp current limit and 16-bit resolution with RS232 interface • Digital Voltmeter: HP Model 34420A nono-volt/micro-Ohm meter • 7.5 digits resolution • Shunt: Isotek model RUG-Z-R100-0.1 • 0.1 ohm resistor (0.1% tolerance, 1ppm/degree C TCR) • Reference precision standard resistor: Guildline model 9222/0.05 Resistor s/n 33635 • Computer: IBM compatible with RS232 interface for instrument control

  19. Calibration Procedures: UV Calibration • Computer controls power supply and DVM via a single serial port • The current is set to 8.0 amps • Every 10 seconds voltage across shunt is measured and checked to be within 0.0014% of 8.0 amp target • Adjustments are made as required to satisfy this criteria

  20. The Brewer Reference Triad • Established in 1984 • Consists of Brewers 008, 014 and 015 • Each Brewer is calibrated absolutely and independently • Each of the triad goes to MLO for a two week period at least every 8 years to collect data for an absolute calibration • Any refurbishment or changes to the instrument are done at this time • Not a requirement that the same instruments remain part of the triad even though this has been the case • The long-term mean standard deviation among the 3 instruments is < 1%

  21. Implementation and Maintenance of the CBSN Traveling Standard Brewer • Primary and backup traveling standards • Instruments must demonstrate high quality diagnostics and good stability • SL ratios and other diagnostics are checked before leave MSC, on arrival at station and on return to MSC • Calibrated against the triad at least annually, more frequently if concerns exist

  22. Software Tools: Remote Control Software • PCAnywhere 9.2 • Used for: • Diagnostics • Testing • File upload/download • Connections: • 5 stations with TCP inside MSC firewall • 2 stations with TCP outside MSC firewall • 6 stations with modem outside MSC firewall

  23. Software Tools: Brewer Control Software • Network Brewer software: v3.75e/3.75f • VB6.0 Brewer software in development: • Temporary setback—loss of programmer • Two intern programmers for 9 months • About 85 of the 100 routines completed • Will support all Brewer models and all 3 electronic board configurations • Completion of Stage II could be as soon as September 2003 followed by submission to interested parties for Beta testing and comment

  24. Data Transfer from Stations • Ozone and uv bulletins (and some images several times per hour from each Brewer to CMC (and GTS) and to MSC website • All new Brewer data, program, constants, log and image files on a daily basis to CBSN server • WOUDC downloads files from CBSN server daily

  25. Data Quality Assurance Procedures • First level Q/A—Real-time Bulletins • Automatically displayed to desktop computer screens • Compare ds ozone with uv ozone • Note time of last bulletin to ensure continuous operation • Second level Q/A • Monthly diagnostics checks—action as required • Monthly Log Form checks—Feedback to station operators • Final Data Q/A • Data processing and submission to WOUDC by Vitali Fioletov

  26. Final Processing of Observations from Individual Stations: New BDMS Software • Processes B- and UV-files at the same time • Calculates ozone and UV from raw counts • Works directly with ICF and DCF files • “Flexible” SL test correction • Allows specification of time window and weighting function • Typically use median value which works well with spikes and calibrations • HG test-based quality control • Rejection of data if hg after data changes by more than 3 to 5 steps or if low correlation coefficient • If before hg is bad then data acceptance constraints are tougher • If before and after hg are bad then data is rejected • Outputs daily ozone values and individual measurements in ExtCSV format

  27. Final Processing of Observations from Individual Stations: New UV Algorithm • Linear responsivity interpolation • Stray light correction • Using laser scan data (if available) • Otherwise use parameterization • Total ozone and SO2 calculation • “Spikes” correction • HG control • Use same process describe above for total ozone • Angular response correction

  28. Application of New BDMS Software • Currently only Canadian data is processed every 4 to 6 months • Looking into processing UV data for other countries • Not currently available for public use due to lack of good user interface and installation package • Intention exists to make it widely available

  29. CBSN as an Example for the Regional Networking of Brewer Stations in the GAW Network • CBSN is an example of how a Brewer Network might be operated with minimal resources • Best to get input from other Brewer networks and scientists and recommend a set of “minimal requirements” for proper Brewer operation and a set of “optimal requirements” • These recommendations may then be forwarded to the Brewer Ad-Hoc Committee and the WMO to act as a guide for others and be tailored to their own resource situation

  30. New Developments for WOUDC • New Web Address: http:///www.woudc.org • New Web Form: http://www.woudc.org/data/MetaQuery/metaquery_e.cfm • Allows users to sub search on what data are available from the WOUDC archive • Calibrations • It has become an important issue to have data originators include calibration information, inter-comparison details and summaries and any reports dealing with the status of instruments • It is important to have this information sent to the WOUDC • The archive is designed to accommodate and report on this information • WOUDC News • The Czech Dobson and Brewer analysis programs are being successfully used by several data originators (contributors) to the WOUDC archive

  31. New Developments for WOUDC/BDMS • New Web site • WOUDC web site has undergone recent changes and so will the BDMS portion of the site • Changes are expected to be completed by late summer 2003. • Meeting reports • Will continue to post meeting reports from Biennial Brewer meetings • Hopefully can add reports from inter-comparisons. • Bulletin board for Brewer community • BDMS web site may also used as a Brewer community “bulletin board” for information such as standard operating procedures, best practises, lessons learned, even FAQs about networks and operations. • Ad hoc reports • Reports from the Brewer Sub-committee will be posted at this site

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