Status and plans for a Southern Ocean observing system for climate

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Status and plans for a Southern Ocean observing
system for climate

• Steve Rintoul, Kevin Speer and
• Eberhard Fahrbach
• Alfred-Wegener-Institut für Polar- und
  MeeresforschungBremerhaven, Germany

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Schmitz (1996)
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Heat and freshwater budget Gas exchange Sea ice
biota Technical challenge
Sea ice
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Rintoul 2001
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Mean temperature in the Weddell gyre at the
Greenwich Meridian
Warm Deep Water temperature increased until the
mid 1990s and is decreasing since
HOWEVER Cooling and freshening in the East
Antarctic sector
Weddell Sea Bottom Water temperature is still
increasing
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Time series of salinity in Winter Water
Salinity increase in the Winter
Water HOWEVER Freshening of mode and intermediate
waters
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Wide range of time scalesAliasing!? Increase
of temperature and salinity in the bottom water
of the Weddell Sea from moored instruments and
CTD profiles
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Relevant time scales (ACW, SAM, ENSO, AADP)
exceed duration research projects
Total trends
Congruent with SAM
Recent trends in surface temperature and wind
(Dec-May 1969-2000).
Thompson and Solomon 2002
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Carbon uptake
Sabine et al., 2004
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IPAB WCRP/SCAR International Programme for
Antarctic Buoys
Problems to maintain it due to seasonal sea
ice Committments are needed
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Sea ice Altimeter Scatterometer Gravimeter SST SSS
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CLIVAR/CliC/SCAR Southern Ocean Region
Implementation Panel
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CLIVAR/CliC/SCAR Southern Ocean Region
Implementation Panel
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Calibration by means of Climate of Antarctica and
the Southern Ocean CASO IPY CLIVAR/CliC/SCAR
Southern Ocean Region Implementation Panel
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A Time Series Science Team for the development of
sustained time series stations
Joint sponsorship of GOSS/GCOS (OOPC), research
(CLIVAR OOP, JGOFS, ) and the DEOS
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Recent ARGO float distribution
http//argo.ocean.fsu.edu/images/big-so-map.pdf
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Ice compatibility of ARGO floats a 3 step process
Ice sensing algorithm (ISA) Interim storage (iStore) RAFOS
Checks temperature in the upper 50 m, ascent aborted if near freezing point Provides delayed mode profile when surfacing impossible Provides subsurface profile position when surfacing impossible
Tested successfully about 80 survival rate additional modifications are planed 8 NEMO floats are currently under test and delivered first results Tested in 2003/4 with 5 RAFOS floats tracking range is at least 600 km throughout season.
Now standard for all AWI float orders (APEX and NEMO) Ordered for all further NEMO floats Ordered for further NEMO floats (APEX and NEMO)
? ISA/iSore/RAFOS Float fully ice compatible
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Range of RAFOS signals in the Weddell Sea
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Sound sources (red to be deployed by Keith
Nichols, BAS, black in the water, blue in plan)
and floats (green floats)in the Weddell Sea west
of the Greenwich Meridian. The extension of the
network will occur in cooperation with Svein
Osterhus frorm the Bjerknes centre in Bergen
(Norway)
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Forecasting Ocean Assimilation Model Data from
all Argo floats are assimilated in to the
Forecasting Ocean Assimilation Model (FOAM) run
at the Met Office. Images of potential
temperature, salinity and velocity at five metres
and 995.5 m supplied by the Met Office at monthly
intervals are provided
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Enhancements needed

• Sea ice zone
• Sea ice thickness/volume
• Ocean properties under sea ice
• Expanded met buoy network
• Coastal margin onshore-offshore exchange
• Meteorology
• High quality ship obs (IMET on supply vessels)
• Air-sea flux reference stations
• Argo
• Maintaining and re-seeding array
• Under sea ice
• Repeat hydrography tracers time series
  stations
• Good plans, but not all funded
• Satellite data streams must be maintained.
• Altimeter gravity ice SST SSS, wind

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SCAR/SCOR Oceanography expert group