Southern Ocean CLIVARCliCSCAR Report

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Southern Ocean CLIVAR/CliC/SCARReport

• Kevin Speer, Ian Renfrew (chairs),
• Doug Martinson, Mike Sparrow (ICPO)

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Southern Ocean Panel
Topics

• 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

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5. Highlights of contributions to wider areas of
climate science
Wider areas

• 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

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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

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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
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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.

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Planned
Activities

• 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

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Southern Ocean Panel
4 Major themes

• 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

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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

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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.

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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 gt
suggests changes in the seasonality of the SAM
are inducing small (few Sv) changes in the
oceanic circumpolar transport. (Anthropogenic?)
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IPY climate studiesEx Yuan LDEO
ENSO other modes
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ENSO other modes
rClimate 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).
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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
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Decadal variability
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Southern Ocean PanelResearch Themes

• shallow overturning circulation
• deep overturning circulation
• interbasin exchange
• variability of the coupled atmosphere-ice-ocean
  system
• Process studies

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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.

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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

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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-biogeochem
  ical-ecological linkages, and teleconnections
  between polar and lower latitudes.

http//www.clivar.org/organization/southern/CASO/i
ndex.htm
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Ex CLIVAR Repeat Hydro
Lower branch of the global convection cell
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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
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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.

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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.

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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
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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
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CLIVAR Process Studies

• 18 studies http//www.clivar.org/organization/sou
  thern/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

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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.

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Diapycnal and Isopycnal Mixing Experiment in the
Southern Ocean DIMES

• A proposed USUK 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

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DIMES