Transcript schulz_SO_flux_schulz_nov2012x

Southern Ocean Air-Sea Flux
Observations
Eric Schulz, CAWCR, BoM
Motivation
• The Southern Ocean is large (22% of world
ocean) and is expected to play a significant role in
the global climate system
• Role in the carbon, heat and mass cycle?
• Very few in situ observations due to harsh and
remote nature
• Poorly constrained for these air-sea fluxes
– How much carbon is trapped in the deep ocean?
– How much heat absorbed, transported and released?
• The Sub-Antarctic Zone occupies half of the
Southern Ocean and is a region of extensive
surface water subduction
The Centre for Australian Weather
and Climate Research
A partnership between CSIRO and the
Bureau of Meteorology
Observation Programs
• IMOS funded, lead by the Bureau
– Data freely available
– 3 research vessels, broad spatial coverage but
patchy in time and space
– 1 mooring, 1 location, continuous presence
– Collaboration and piggybacking (mooring)
encouraged
– Mooring program uses MNF vessel for annual
visits
Southern Ocean
Time Series
Sustained Ocean observatory
• Multidisciplinary (met ,ocean, biogeo-chemical (BGC)
• Multiple platforms
– SAZ mooring (sediment traps) –
transfer of carbon to deep ocean
– Pulse mooring (BGC) –
consumption of CO2 in mixed
layer
– SOFS mooring (weather, fluxes,
CO2 physical ocean) – physical
fluxes through ocean surface
– Gliders (physical and BCG) –
spatial context & vertical profiles
– Drifting Profilers (physical and
BGC) – spatial context & vertical
profiles
SOTS
Location
Southern Ocean Time Series Observatory
Funded by IMOS
Operated by Bureau, CSIRO & UTAS
3 Moorings
Gliders & Profiling Floats
46.75oS, 142oE
350 NM SW of Tasmania
Sub-Arctic Zone with strong
biological activity
SOTS
47S 142E
Situated centrally in the Sub Antartic Zone,
Australian sector of the Southern Ocean
Pilot deployment flux buoy at 60S 140E,
2012, JAMSTEC
SOFS and JAMSTEC 60S mooring locations in
Australian sector of the Southern Ocean.
The Centre for Australian Weather
and Climate Research
A partnership between CSIRO and the
Bureau of Meteorology
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SOFS Observations
Wind
Air Temperature & Humidity
Long- & Short-wave Radiation
Rain
Pressure
PAR,
Wind
pCO2
Waves
SST & salinity
BGC
• Oxygen
• Fluorescence
• Sub-surface 10-500m
• Temperature
• Salinity
• PAR
• Pressure
• Currents
• Particle size Air pressure
The Centre for Australian Weather
and Climate Research
A partnership between CSIRO and the
Bureau of Meteorology
Short- & Long-wave radiation
Temperature
& Humidity
Precipitation
Tower and instruments
Data availability 1998-2012
Started with SAZ sediment traps in 1997
Added Pulse BGC in 2009 – summer only,
annual since 2011
Added SOFS in 2010
Dedicated profilers (2005) & gliders (2010)
halted in 2011 with technical issues
Gaps in SAZ are due to
Instrument and mooring
failures
The Centre for Australian
Weather and Climate Research
A partnership between CSIRO and the Bureau
of Meteorology
SOFS example observations:
Wind speed and Solar Radiation
9-month refurbishment gap
Between SOFS 1 & 2, now
back-to-back deployments
Winds peaking ~50kts
Distinct solar radiation annual
cycle
SOFS3 data is hourly
real-time, so less variability
than SOFS1&2
The Centre for Australian
Weather and Climate Research
A partnership between CSIRO and the Bureau
of Meteorology
Buoy Refurbishment
SOFS applications: Air-Sea Fluxes
Bulk Fluxes from SOFS-1, March
2010- March 2011
Net deployment ocean cooling of 10
Wm-2
Asymmetric seasonal signal in Net
Incoming SW dominates seasonal
signal
Severe short-term ocean turbulent
cooling events (>400 Wm-2) with cold,
dry southerly winds.
Frequent ocean heating events from Hs
Ocean heat content shows trend
agreement with air-sea flux on seasonal
scale.
The Centre for Australian
Weather and Climate Research
A partnership between CSIRO and the Bureau
of Meteorology
See: Schulz et al. 2012, GRL.
Ship Observations
• IMOS Underway ship flux facility
• Provides instruments to complete existing
sensor suite, data telemetry & processing,
routine calibration and real-time quality
controlled data delivery
• Recruited
– Southern Surveyor, April 2008
– Aurora Australis, September 2010
– Tangaroa, April 2011
Ship Instrumentation
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Rain
Wind
Air Temperature & Humidity
Pressure
PAR
pCO2
SST & salinity
Currents
Long- & Short-wave Radiation
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The Centre for Australian Weather
and Climate Research
A partnership between CSIRO and the
Bureau of Meteorology
1-minute averages
telemeterd every 1-3 hours.
Automated QC of
observations and generate
flux products and delivered
to IMOS ocean portal
Equipment will be
transferred from Surveyor to
Investigator
RV Southern Surveyor
Data coverage 2008-2012
4ox4o Gridded net heat flux 2008-2012
Summer: Oct-April
Winter: May-Sept
(+ve = ocean cooling)