status and plans for a southern ocean observing system for climate

Establishing a coordinated Southern Ocean Observing System (SOOS) Hobart, 15 July 2006

Status and plans for a Southern Ocean observing system for

climate

Steve Rintoul, Kevin Speer and

Eberhard FahrbachAlfred-Wegener-Institut für Polar- und Meeresforschung

Bremerhaven, Germany

Establishing a coordinated Southern Ocean Observing System (SOOS) Hobart, 15 July 2006

Schmitz (1996)

Establishing a coordinated Southern Ocean Observing System (SOOS) Hobart, 15 July 2006

Heat and freshwater budget

Gas exchange

Sea ice biota

Technical challenge

Sea ice

Establishing a coordinated Southern Ocean Observing System (SOOS) Hobart, 15 July 2006

Establishing a coordinated Southern Ocean Observing System (SOOS) Hobart, 15 July 2006

Rintoul 2001

Establishing a coordinated Southern Ocean Observing System (SOOS) Hobart, 15 July 2006

Mean temperature in the Weddell gyre at the Greenwich Meridian Warm Deep Water

temperature increased until the mid 1990’s and isdecreasing since

Weddell Sea Bottom Water temperature is still increasing

pot.

Tem

pera

ture

[°

C]

pot.

Tem

pera

ture

[°C

] HOWEVER:

Cooling and freshening in the East Antarctic sector

Establishing a coordinated Southern Ocean Observing System (SOOS) Hobart, 15 July 2006

Time series of salinity in Winter Water

1985 1990 1995 2000 2005

34.16

34.2

34.24

34.28

34.32

34.36

Sal

inity

S(Tm in)S(Tm in) corrected

Salinity increase in the Winter Water

HOWEVER

Freshening of mode and intermediate waters

Establishing a coordinated Southern Ocean Observing System (SOOS) Hobart, 15 July 2006

Wide range of time scales:Aliasing!?

Increase of temperature and salinity in the bottom water of the Weddell Sea from moored instruments and CTD profiles

Establishing a coordinated Southern Ocean Observing System (SOOS) Hobart, 15 July 2006

Relevant time scales (ACW, SAM, ENSO, AADP) exceed duration research projects

Thompson and Solomon 2002

Recent trends in surface temperature and wind (Dec-May 1969-2000).

Total trends Congruent with SAM

Establishing a coordinated Southern Ocean Observing System (SOOS) Hobart, 15 July 2006

Carbon uptake

Sabine et al., 2004

Establishing a coordinated Southern Ocean Observing System (SOOS) Hobart, 15 July 2006

IPABWCRP/SCAR International Programme for

Antarctic Buoys

Problems to maintain it due to seasonal sea ice

Committments are needed

Establishing a coordinated Southern Ocean Observing System (SOOS) Hobart, 15 July 2006

Sea ice

Altimeter

Scatterometer

Gravimeter

SST

SSS

Establishing a coordinated Southern Ocean Observing System (SOOS) Hobart, 15 July 2006

CLIVAR/CliC/SCAR Southern Ocean Region Implementation Panel

Establishing a coordinated Southern Ocean Observing System (SOOS) Hobart, 15 July 2006

CLIVAR/CliC/SCAR Southern Ocean Region Implementation Panel

Establishing a coordinated Southern Ocean Observing System (SOOS) Hobart, 15 July 2006

Calibration by means of

Climate of Antarctica and the Southern

Ocean

CASO – IPY

CLIVAR/CliC/SCAR Southern Ocean

Region Implementation

Panel

Establishing a coordinated Southern Ocean Observing System (SOOS) Hobart, 15 July 2006

Joint sponsorship of GOSS/GCOS (OOPC), research (CLIVAR OOP, JGOFS, …) and the DEOS

A Time Series Science Team for the development of sustained time series stations

Establishing a coordinated Southern Ocean Observing System (SOOS) Hobart, 15 July 2006

Recent ARGO float distribution

http://argo.ocean.fsu.edu/images/big-so-map.pdf

Establishing a coordinated Southern Ocean Observing System (SOOS) Hobart, 15 July 2006

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

Establishing a coordinated Southern Ocean Observing System (SOOS) Hobart, 15 July 2006

Range of RAFOS signals in the Weddell Sea

Establishing a coordinated Southern Ocean Observing System (SOOS) Hobart, 15 July 2006

Establishing a coordinated Southern Ocean Observing System (SOOS) Hobart, 15 July 2006

Establishing a coordinated Southern Ocean Observing System (SOOS) Hobart, 15 July 2006

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)

Establishing a coordinated Southern Ocean Observing System (SOOS) Hobart, 15 July 2006

Establishing a coordinated Southern Ocean Observing System (SOOS) Hobart, 15 July 2006

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

Establishing a coordinated Southern Ocean Observing System (SOOS) Hobart, 15 July 2006

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

Establishing a coordinated Southern Ocean Observing System (SOOS) Hobart, 15 July 2006

SCAR/SCOR Oceanography expert group