The Southern Ocean Observing

System (SOOS)

With additional support from

Talk OutlineTalk Outline

• Why are coherent, sustained observations of the Southern Ocean needed?

• Who would use them?

• What aspects of the Southern Ocean would a monitoring system address, and how?

• What is already in place, and what are the gaps?

• Where are we in relation to planning and implementing the observing system, and what is next?

• How would a SOOS link to other international efforts?

Global reach of the Southern OceanGlobal reach of the Southern Ocean

Lumpkin and Speer (2006)

Critical part of the global thermohaline circulation

Change in zonally-integrated ocean heat content

since 1955 is largest in the southern oceans

Levitus et al., 2005

Important term in global heat budget, but Southern Ocean is still undersampled compared with rest of World Ocean

Boening et al., 2008

Boening et al., 2008

Comparison of Argo + CTD data along streamlines shows warming across the Southern Ocean, strongest on southern flank of ACC.

Southward shift of isopycnals BUT little change in tilt, hence no change in upwelling (unlike in IPCC models).

Warming in ACC, no change in overturning?

Freshening of AABWFreshening of AABW

The Weddell gyre circulation and the area of observations carried out during WECCON and CASO

Fahrbach, AWI

1985 1990 1995 2000 2005600

650

700

750

800

850Are

a (km2 )

Area of WSBW on the transect decreased by 25%from 1992 to 2008

1992

2008

Fahrbach, AWI

SCAR July 2008

Bottom melting: heat source and effect of pressure.

•Mode 1: Thermohaline circulation induced by sea ice formation and drainage of dense saline water. Melting point decreases as much as 1oC due to 0.00075 oC/dbar-1

•Mode 2: Direct inflow of intermediate-depth ‘warm’ water from the slope-front region (e.g. Circumpolar Deep Water intrusion through deep troughs).

•Mode 3: Ice-front interactions (tidal pumping, coastal currents)•Ice shelf water may refreeze to form marine ice, or sink to participate in the

formation of Antarctic bottom water, which regulates global climate.

•Mode 1 dominates for large ice shelves in the Weddell, and Ross seas.

•Mode 2 melts large volumes of ice where deep water has access to glacier grounding lines, e.g. Amundsen Sea.

Jacobs et al., 1992

CDW

AASW

ISW

SCAR July 2008

Conclusions

• Ice shelf melting controls > 50% of the ice sheet/ice shelf mass balance.

• This neglects ice-front sub-aqueous melting.

• Low melt on large ice shelves (far from CDW), Queen Maud Land, East Peninsula.

• High melt on West Peninsula (CDW), Amundsen, Bellingshausen sea (CDW), Wilkes Land (?).

• Quadratic dependence on temperature where CDW fuels high melt.

• Elsewhere, linear relationship might still hold but not enough ocean temperature data near GL.

SCAR July 2008

EAIS 1996-2006 -461 Gt/yr

WAIS 1996 -8359 Gt/yrWAIS 2000 -10660 Gt/yrWAIS 2006 -13250 Gt/yr

AP 1996-2000 -2545 Gt/yrAP 2006 -6046Gt/yr

Antarctica loss increased from-112 to -196 Gt/yr

Ocean uptake of carbon dioxide

Sabine et al., 2004

Southern Ocean a key region for uptake of anthropogenic CO2 – but is the carbon sink weakening (Le Quéré etc)?

Le Quere et al., 2007

Krill stocks in key parts of the Southern Ocean are in steep decline… need to understand why, and the implications.

19

76

19

78

19

80

19

82

19

84

19

86

19

88

19

90

19

92

19

94

19

96

19

98

20

00

20

02

Year

De

ns

ity

(n

o.

m-2

)

1

10

100

1000

0 100 200 300 400

Winter ice duration (days)

Kril

l den

sity

(no

.m-2

)

1920s and 1930s

post 1976 era

1000

100

10

1

0.1

(Atkinson et al., Nature, 2004)

Why a SOOS (continued…) ? Why a SOOS (continued…) ?

Potential users of a SOOS include …Potential users of a SOOS include …

• Research communityResearch community• Resource managers (including CCAMLR etc)Resource managers (including CCAMLR etc)• Policy makers (when is it time to act? What Policy makers (when is it time to act? What

are the consequences of not acting?)are the consequences of not acting?)• IPCCIPCC• Local planners (sea-level rise)Local planners (sea-level rise)• Antarctic tourismAntarctic tourism• Shipping operationsShipping operations• Weather and climate forecastersWeather and climate forecasters• EducationEducation• Etc.Etc.

Scope of the SOOSScope of the SOOS• Space:

– circumpolar– Subtropical Front to coast / ice shelf grounding line

• Time: – days to decades (longer-term proxies from ice and sediment

cores are critical, but lie outside of SOOS)• Domain:

– sea surface to sea floor (including bathymetry)– ocean + sea ice– include air-sea flux, not upper atmosphere– include sub-ice shelf cavity, not glacial ice itself

• Feasibility/readiness:– consider READY NOW, 5-10 YEAR VISION and BY 2030– consider both MINIMAL and IDEAL

Scope of the SOOSScope of the SOOS

• Discipline:– physics (ocean circulation and sea ice)– biology and ecology (microbes to whales...)– biogeochemistry– bathymetry– surface meteorology

• Models: Emphasis is on sustained observations, but modelling plays a key role in – system design– interpolation and interpretation of sparse observations– demonstrating utility of SOOS (eg initialisation of climate

models)

Some examples of observing system Some examples of observing system elements already in placeelements already in place……

http://argo.ocean.fsu.edu/

Argo

Sound sources deployed in Weddell Sea to track modified Argo floats under ice

Temperature and current field in the area of Maud Rise derived from floats – Olaf Klatt

5oW 0o 5oE 10oE 15oE 72oS

70oS

68oS

66oS

64oS

62oS

5oW 0o 5oE 10oE 15oE 72oS

70oS

68oS

66oS

64oS

62oS

0.1

0.2

0.3

0.4

0.5

0.6

0.7

Tagging of marine mammals (SEaOS etc)

Elephant seal oceanography

Mapping the ocean underneath the sea ice for the first time (Charassin et al., PNAS, 2008).

SEaOS: Number of profiles

http://biology.st-andrews.ac.uk/seaos/index.html

SODB: 10513

Argo: 19463

SEaOS: 22230

Courtesy L. Boehme

Mapping high latitude fronts

Charassin et al., PNAS, 2008

Sea ice formation from salinity change

The Survey covers>70 % of theSouthern OceanOctober to April

135,000 nauticalmiles of data havebeen collected since1991

This represents morethan 27,000 samples,200+ taxa +environmental data

Approximately40-50 tows each year>4,000 samples p.a.5 n-mile resolution

Australia, Japan, NZ,Germany, UK, USA,Russia

Continuous Plankton Recorder Tows 1991-2008

Hosie et al

What observing system elements are already in place?

• Above plus:-

• Satellites (e.g. SeaWiFS, Cryosat)

• Current meter arrays

• Tide gauge network

• Sediment trap moorings

• Underway measurements (e.g. CO2 ,

Salinity…)

• Sea ice thickness; snow cover; drift

• Etc….

Gaps in the observing system in the Southern Ocean region

• Ice-covered regions still poorly sampled, despite progress

• Deep ocean below depth of Argo

• Ocean in ice shelf cavities

• Seabed is poorly observed (benthic communities etc)

• Non-physical measurements rarely routinely made (need other sensors for Argo etc)

• etc

SOOS TimelineSOOS Timeline

• August 2006: Initial scoping workshop, Hobart

• October 2007: Workshop in Bremen. Planning and writing tasks assigned

• July 2008: St. Petersburg progress review meeting

• January 2009: Make draft SOOS planning document available to community for comment

• February 2009: Comments received

• March 2009: Publish report

• April 2009: Commence implementation...

SOOS designed to address six key SOOS designed to address six key challengeschallenges

• Role of Southern Ocean in global freshwater balance

• Stability of Southern Ocean overturning

• Stability of Antarctic ice sheet and future contribution to sea-level rise

• Future of Southern Ocean carbon uptake

• Future of Antarctic sea ice

• Impacts of climate change on Antarctic ecosystems

(*draft*)

(*draft*)

Strawman Southern Ocean Observing System

Initial SOOS consists of coordination/enhancement of extant elements, as discussed, including:-

• Repeat full-depth hydro/tracer sections along WOCE lines

• Profiling floats, open ocean and under sea ice

• Sensors on marine mammals• Sea ice observations• Ocean-ice shelf interaction• Surface meteorology observations• Surface and sea-ice drifters• Ecological monitoring• …

Orsi et al., 1999

CFC-11

Strawman Southern Ocean Observing System

5-10 years and 2030 vision (see planning document for details) as previous, but including:

• Enhanced profiling floats with additional sensors, depth range and longevity.

• Cost-effective time series stations, using data capsule technology and expendable moorings.

• Supply/research ships doing routine surveys/sections on way into Antarctic bases

• Network of integrated fast ice “mass balance” stations

• A network of ice-capable gliders• etc

Strawman Southern Ocean Observing System

SOOS coordination group to oversee the implementation of the observing system, plus:-

• Relevant data archaeology• Delivery of Southern Ocean climate

information• Modeling• Identification of remote sensing needs• Identification of key gaps requiring

enhanced process understanding• Array design studies• Technology development requirements• …

A final word…

““Many more voyages of discovery are also Many more voyages of discovery are also needed, especially in the vast expanses of the needed, especially in the vast expanses of the southern seas that remain relatively unexplored”southern seas that remain relatively unexplored”

““Troubled Waters”Troubled Waters”The Economist, Jan 3The Economist, Jan 3rdrd 2009 2009