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Atmospheric Chemistry Sub-group Report

Atmospheric Chemistry Sub-group Report. Bojan R. Bojkov. Overview. Sub-group meeting summaries Current AC cal/val issues Recommendations to WGCV. Sub-group meeting report. Two meetings held ACSG-6 December 2006, Frascati (in conjunction with Envisat ACVE-3)

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Atmospheric Chemistry Sub-group Report

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  1. Atmospheric ChemistrySub-group Report Bojan R. Bojkov

  2. Overview • Sub-group meeting summaries • Current AC cal/val issues • Recommendations to WGCV WGCV Plenary, NPL, June 12-15, 2007

  3. Sub-group meeting report • Two meetings held • ACSG-6 December 2006, Frascati (in conjunction with Envisat ACVE-3) • Topical meeting April 2007, Montreux (in conjunction with Envisat Symposium) • Good attendance by sub-group members • Guests: • Envisat Cal/Val team (ESA/ESRIN, both meetings) • GOSAT team representative (JAXA, Montreux) WGCV Plenary, NPL, June 12-15, 2007

  4. Sub-group meeting report (2) • December 2006: ACSG-6 at Frascati • E. Hilsenrath stepped-down as Chairman • Overview of AC missions cal/val status • Coordination of and discussions on pressing cal/val issues (X-sections, Air quality, aerosols, etc.) • Discussions on sub-group mission: Atmospheric Chemistry vs. Atmospheric Composition WGCV Plenary, NPL, June 12-15, 2007

  5. Sub-group meeting report (3) • April 2007: at Montreux • Preparations for the upcoming Cal/Val Workshop • Main discussion on “methodology”, “quality issues” and “site accreditation” • Discussions regarding contributions to the Atmospheric Composition Constellation (ACC) • ACC presentation by E. Hilsenrath • Cal/val integral to ACC • ESA/NASA collaboration on cal/val data sharing and SAUNA campaigns identified as example contributions WGCV Plenary, NPL, June 12-15, 2007

  6. Sub-group meeting report (4) • Next ACSG meeting • Darmstadt, September 12, 2007 (in conjunction with 2nd AC Constellation meeting) • Final cal/val WS preparations • Invite atmospheric composition teams: • Aerosols: • B. Holben (Aeronet, NASA) • O. Torres (advanced aerosol retrievals, NASA) • GHG: • OCO (JPL) and GOSAT (JAXA) val team leads • M. de Maziere (NDACC IR working group Chair, IASB) WGCV Plenary, NPL, June 12-15, 2007

  7. “Hot” cal/val items • Ozone column measurement discrepancies (from the ground and from space) • Air quality validation capabilities • Data assimilation • Cal/val data issues WGCV Plenary, NPL, June 12-15, 2007

  8. Ozone column issues • Driving questions: • Total column trends (i.e. detection of the turnaround and recovery) • Development of new tropospheric ozone products • Input to satellite UV products and studies • Currently: • Satellite measurements agree within 2-3% globally • Differences at low sun, high column amounts, high reflectivities, etc. • Similar issues for ground-based measurements WGCV Plenary, NPL, June 12-15, 2007

  9. Ozone column issues (2) • In an attempt to better understand the column issues, NASA, ESA and FMI conducted two field campaigns • Focus during high column, low sun periods in Northern Finland • SAUNA: March-April 2006 • SAUNA 2: February-April 2007 • Combined network instruments: Dobsons, Brewers, DOAS, sondes and LIDAR • Included World and European standard instruments • Involved more than 30 Scientists from 12 institutes in 10 countries WGCV Plenary, NPL, June 12-15, 2007

  10. WGCV Plenary, NPL, June 12-15, 2007

  11. WGCV Plenary, NPL, June 12-15, 2007

  12. WGCV Plenary, NPL, June 12-15, 2007

  13. SAUNA (column) summary • SAUNA behavior seen at other high and mid-latitude sites • The state of the network calibration (Brewer and Dobson) are uncertain (at best) and require improvements • Updated and systematic calibration transfers required • Especially when considering tropospheric ozone products • Identify key players to implement this across networks • With improved GB calibration, differences most probably due to ozone X-sections uncertainties • High spectral resolved X-section required which can be used by both satellites and ground-based instruments WGCV Plenary, NPL, June 12-15, 2007

  14. Air quality • Air quality is an increasing priority with space agencies and has clear Societal Benefits • Envisat-Sciamachy, Aura-OMI, MetOp-GOME/2 are already measuring many key tropospheric air quality constituents (NO2, HCHO, CHOCHO, SO2, etc.) and with other species retrievals under development • There are however limited and/or limiting validation capabilities • In-situ measurements (from established networks) are not necessarily suitable for validation and/or are very difficult to interpret • New (and modified existing) ground-based remote sensing methods under development • SAUNA-style intercomparison needed ASAP to quantify instruments and algorithms WGCV Plenary, NPL, June 12-15, 2007

  15. Data assimilation • An overview of the current and future data assimilation capabilities as related to atmospheric chemistry/composition cal/val is needed • ACSG initiated a workshop on “Use of data assimilation in satellite validation” • Organized by W. Lahoz (U. reading) and B. Bojkov (NASA) • Co-sponsored by NASA, ESA and U. Maryland (Baltimore County) • Baltimore, June 3-5, 2008 • ~35 invited participants, with five keynote speakers/themes • Reviewed proceedings to be published Summer 2008 WGCV Plenary, NPL, June 12-15, 2007

  16. Cal/val data • Data sharing essential to enhance validation • Envisat/Aura sharing enabled the use of ~7,000 sondes for OMI tropospheric column validation (instead of only 2,000 available through WOUDC and NASA field experiments) • Envisat/Aura model to continue with GMES, but also encouraged for other missions M. Schoeberl, NASA/GSFC WGCV Plenary, NPL, June 12-15, 2007

  17. Cal/val data (2) • Essential to have homogeneity in data content reporting • Key (and mandatory) variables must be reported to facilitate interpretation of the validation measurements • Close coordination with NDACC (through Aura Validation Data Center) • Profiling instruments (MWR, LIDAR, sondes) reporting synchronized • Other network instrumentation homogenization ongoing • Concern with new WMO data initiative for “2015” • “Replacement” for the World Weather Watch to include ground-based and satellite datasets • “Homogenous” data formatting proposed • Clarifications of WMO objectives required WGCV Plenary, NPL, June 12-15, 2007

  18. ACSG recommendations 4 proposals to WGCV 1 proposal to CEOS

  19. Recommendation # 1 • Improve TOZ calibration of Brewer and Dobson networks • Essential for trends and new tropospheric ozone products development • Side by side Dobson and Brewer (incl. reference instruments) operation and calibration transfer resulting in a “homogeneous” network • Timeline ASAP (preferably Sept. 2007 for European campaign at Huelva, Spain) WGCV Plenary, NPL, June 12-15, 2007

  20. Recommendation # 2 • Ozone X-sections • X-sections thought to be remaining uncertainty in ozone retrievals • Goal is to have a common X-section reference baseline • Support on-going activities at U. Bremen for highly resolved GOME/GOME-2 X-section work on O3, NO2 and SO2 • Timeline ASAP WGCV Plenary, NPL, June 12-15, 2007

  21. Recommendation # 3 • Air quality ground intercomparison • Quantify state of validation assets • SAUNA-like deployment to include classical instrumentation, plus DOAS/SAOZ, direct-sun CCD and complimentary measurements (ultra-light gas sampling) and LIDAR (NO2 + aerosol) • Timeline Summer 2008 WGCV Plenary, NPL, June 12-15, 2007

  22. Recommendation # 4 • Cal/Val data sharing across missions… • Extend WGCV-26, Recommendation 2 • Encourage new missions: • To follow Envisat/Aura data exchange across existing and future AC missions (incl. GHG missions) • To follow homogeneous data reporting by leveraging on existing efforts such as undertaken by NDACC • Timeline: ASAP WGCV Plenary, NPL, June 12-15, 2007

  23. Recommendation # 5 (CEOS) • Validation requires use of “overlapping” information to meet actual product quantification (for example effect of NO2 on aerosol retrievals) • Propose to extend ACSG mission/mandate to encompass atmospheric composition (atmospheric chemistry, air quality, aerosols, GHG) • Timeline: formal change during WGCV-28 (after next ACSG meeting) WGCV Plenary, NPL, June 12-15, 2007

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