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Southern Ocean CLIVAR/CliC/SCAR Report

Southern Ocean CLIVAR/CliC/SCAR Report. Kevin Speer, Ian Renfrew (chairs), Doug Martinson , Mike Sparrow (ICPO). Topics. Southern Ocean Panel. 2. Contributions to CLIVAR's 4 Major Themes (covered last; workshop) 3.–5. Annual workshops; ocean's role in climate; wider areas of climate science

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Southern Ocean CLIVAR/CliC/SCAR Report

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  1. Southern Ocean CLIVAR/CliC/SCARReport Kevin Speer, Ian Renfrew (chairs), Doug Martinson, Mike Sparrow (ICPO)

  2. Topics Southern Ocean Panel 2. Contributions to CLIVAR's 4 Major Themes (covered last; workshop) 3.–5. Annual workshops; ocean's role in climate; wider areas of climate science 6. New Activities • Cross Panel and Working Group links • Cross WCRP links • Data management • Review ToRs (next panel meeting) 11. Issues for SSG

  3. Wider areas 5. Highlights of contributions to wider areas of climate science • Workshop on Modes of Southern Hemisphere climate variability • June, 2005, Scott Polar Research Institute, Cambridge • S.O. Panel meeting held following workshop • Organized papers for CLIVAR Exchanges 35 on "Antarctic circumpolar ice-ocean modeling" • Panel members attended relevant meetings such as CliC SSG and WGOMD • Observations kept updated (online) for use by community

  4. New activities A change of direction • Half of panel were due to rotate off • Replaced to reflect more climate system and less physical oceanography • Aiming to become more relevant to: • Climate of southern hemisphere • IPCC process • Coupled models

  5. New activities Panel members 1. Ian Renfrew, co-chair UK atmospheric processes 2. Kevin Speer, co-chair USA ocean obs and processes 3. Steve Rintou Aus ocean obs and processes 4. Doug Martinson USA ocean-ice interaction 5. Aike Beckmann Finland ocean-ice modelling New members: 6. Christian Haas Germany sea ice and remote sensing 7. Alberto Naveirra-Garabato UK ocean circulation 8. Dave Thompson USA large-scale atmospheric dynamics 9. Yasu Fukamachi Japan ocean/ice observations 10. Sabrina Speich France ocean modelling 11. Hughes Goosse Belgium coupled modelling, incl. paleoclimate 12. Michiel Van den Broeke Holland atmospheric dynamics & processes 13. Niki Gruber Switzerland ecosystems, geochemistry, carbon Ex Officio: Alex Orsi (iAnZone) Eberhard Fahrbach (SCAR/SCOR Expert Group) ICPO: Mike Sparrow

  6. Activities Activities • Co-sponsorship with SCAR. • Presentations to JSC, CLIVAR and CliC SSGs, 8th International Conference on S. H. Meteorology and Oceanography, etc. • Workshop on Modes of Variability, Cambridge, June 2005. • Numerical models of the Southern Ocean workshop held in Tasmania, Nov 2005. • IPY input via CASO • Upgraded web site including: • ‘The Observing System in the SO Region’ • ESA Google consumer portal: visualisations of sea ice drift, concentration, icebergs, etc. • Next meeting: Buenos Aires, Nov 2006.

  7. Activities Planned • Review/assessment of IPCC models, GCM coupled models, etc. in S.O. region • Focus on S.O. region indices for OOPC/GSOP: • Identify role of subsurface ocean (e.g., upwelling, dense water formation, polynyas, etc.) from atmos/ocean/ice observations • Discuss role of eddies and storms • Expose surface and deep circulation anomalies • Focus on observational themes: • Meteorological observations • Sustained time series, etc. • Effect of S.O. on regional climate in Latin America may be a theme of our next panel meeting (in B.A.) • Co-chair will attend IPY-Thorpex meeting in Oslo in June

  8. 4 Major themes Southern Ocean Panel • Contributions to CLIVAR'S 4 Major Themes • Specific science contributions clear through June 2005 workshop on Modes of Southern Hemisphere climate variability • Scott Polar Research Institute, Cambridge, UK • Have not developed S.O. connection to monsoons • Ocean's role in climate no separate coverage

  9. CLIVAR Exchanges 35 • Focus on Modes of Southern Hemisphere Variability, building on June workshop • 34 articles • The following shows just a few of examples highlighting the 4 CLIVAR themes

  10. 40% of total oceanic accumulation of anthropogenic CO2 is located south of 35S. ACC Sabine et al., 2002 • Ocean carbon models suggest SO uptake is sensitive to climate change. • Ocean carbon models show greatest discrepancy in SO, largely due to differences in circulation + mixing. • New observations support lower range of model estimates.

  11. ACC SAM and “Seasonal” timescales (left) Monthly trends in the SAM index during the 1990s (plotted inverted and with mean removed for comparison with bottom pressure data) (right) Monthly trends in bottom pressure data from southern Drake Passage during the 1990s => suggests changes in the seasonality of the SAM are inducing small (few Sv) changes in the oceanic circumpolar transport. (Anthropogenic?)

  12. IPY climate studiesEx: Yuan LDEO ENSO & other modes

  13. ENSO & other modes r[Climate Modes, Sea Ice Concentration anomalies] The impacts of different climate modes on sea ice extent are examined by correlations shown in this figure. Apparently, PSA and Wave-3 patterns are strongly correlated with the Antarctic Dipole in sea ice in the western Hemisphere and generally have higher correlations than SAM and SAO. The influences of SAM and SAO on sea ice are more evenly distributed around Antarctica. Since all climate indices and sea ice concentration anomalies were filtered prior to the correlation by a Gaussian filter with filter length of 13 months, these correlations represent shared variance on interannual and longer time scales. Correlation coefficients between Antarctic sea ice concentration anomalies (lag of 2 months) and time series of the Pacific South American Pattern (PSA), Wave-3 pattern, Southern Annular Mode (SAM) and Semi-Annual Oscillation (SAO).

  14. 0.107˚ C/year Significant at 0.05 ~5.4x global average Decadal variability • Western Antarctic Peninsula • Most rapid recent regional winter warming on Earth • Major loss of perennial sea ice • 83% of glaciers are in retreat Perennial Ice

  15. Ocean heat flux (FT) to atmosphere over wAP shelf • shows considerable change in latter part of 1900s • (coinciding with increased Tair and glacial melt): • Large step increase in 1990 (+4 Wm-2) • Qshelf & Qslope are proxies for FT • FT jumps in 1998 by 3 Wm-2 followed by same jump each year thereafter Decadal variability

  16. Southern Ocean PanelResearch Themes • shallow overturning circulation • deep overturning circulation • interbasin exchange • variability of the coupled atmosphere-ice-ocean system • Process studies

  17. Implementation • IPY: CASO, an International Polar Year program • Development of Southern Ocean Argo web site. • Implementation of Southern Ocean Argo has grown strongly, but still lack broad coverage due to sea-ice. • WECCON mooring, float and CTD programme in the Weddell Sea continued; Ross Sea underway… • Mooring array recovered Kerguelen deep western boundary current in 2005. • Repeat XBT lines at 30S Atlantic, Indian, Africa-AA. • Most repeat hydrography/carbon/tracer sections are committed, but ice-breaker problems limit access.

  18. Argo status • Successful under-ice deployments in Weddell (Germany) and acoustic tracking of drifting RAFOS floats. Need to recover profiles from under ice. • SO deployments planned in next year • Deployment opportunities still can be problematic

  19. The International Polar Year CASO (Climate of Antarctica and the Southern Ocean) Project • Panel-led project • Lead project in the Southern Ocean (SO) Circulation cluster • Main aims: - To obtain a synoptic circumpolar snapshot of the physical environment of the SO (with SASSI) - To enhance understanding of the role of the SO in past, present and future climate, including connections between the zonal and meridional circulation of the Southern Ocean, water mass transformation, atmospheric variability, ocean-cryosphere interactions, physical-biogeochemical-ecological linkages, and teleconnections between polar and lower latitudes. http://www.clivar.org/organization/southern/CASO/index.htm

  20. Ex: CLIVAR Repeat Hydro Lower branch of the global convection cell

  21. Ex: WECCON Weddell Sea I/O Vertical section along the meridian of Greenwich with the moored instruments. Mooring 227 to 239 are the moorings which have been replaced. In addition sound sources were attached in mooring 229, 231, and in 240 which is a newly deployed one at 10° E

  22. Issues and Challenges • Need to maintain push for SO Argo, Met, ice buoys, and other sustained observations in southern hemisphere • Resources and champions for time series sites (some progress on subsurface physics – biogeochemistry sites; unclear progress on SO air-sea flux sites - ORION?) • Need to push for enhanced air-sea flux observations from resupply and other ships. • Coordination of atmospheric and oceanographic communities improving; new panel reflects this. • Concept of “Climate Process Teams” in US may hold promise as approach to enhancing model-obs interaction.

  23. Issues for the SSG • Role of the Panel for climate model evaluation, anything to offer regarding a framework ? • Panel needs to continue to work to identify CLIVAR/CliC relevant data sets and interact with GSOP on ocean model evaluation. • Biggest holes are sustained obs in the seasonal sea-ice zone and meteorological initiatives.

  24. Ex: Kerguelen Plateau Deep Western Boundary Current Australia, USA, Japan 8 tall moorings; CTD/LADCP - recovered in 2005 Goal: quantify transport of a major AABW pathway Plateau ADCP data

  25. Ex: AnSlope - the Ross Sea AABW sourceRelatively salty shelf water plume, 150 to 250-m thick, Froude numbers range from 0.7 to 1.2, speeds 0.5-1.0 m/sec

  26. CLIVAR Process Studies • 18 studies: http://www.clivar.org/organization/southern/process.htm Examples: • GOODHOPE : Interbasin exchange south of Africa (France, South Africa, Germany, Russia, USA) - elements underway • OISO (France) - ongoing program • Diapycnal and Isopycnal Mixing Experiment in the Southern Ocean (DIMES). - proposed J Ledwell (for US), A N-Garabato (for UK); 2007 to 2012

  27. Goodhope Objectives 1. Variability in the Indo-Atlantic interocean exchanges and impact on the global thermohaline circulation and present day climate. OISO Objectives Observational network to observe air-sea exchange of CO2 and hydrography 2+ occupations per year.

  28. Diapycnal and Isopycnal Mixing Experiment in the Southern Ocean “DIMES” • A proposed US+UK experiment • diapycnal diffusivity and isopycnal mixing • stirring and eddy fluxes of potential vorticity and heat in a large sector of the Southern Ocean in the region of the ACC • parameterizations of how these fluxes depend on variables accessible to numerical models will be tested and refined

  29. DIMES

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