Atmosphere, Wave and Ocean observations at the Southern Ocean Flux Station

Eric SchulzCAWCR BoM

2nd wind-waves Symposium 4-5 June, Melbourne

Introducing the IMOS Southern Ocean Flux Station

• IMOS facility• Multiple moorings• Freely available data• Platform for other

instruments• Annual visits• Located 47S, 142E in Sub-

Antarctic zone, north of AAC

SOFS, 47S, 142E in Sub-Antarctic zone

Southern Ocean Time Series(SOTS), including SOFS

•Located 47oS, 140oE in the Sub-Antarctic Zone, southwest of Tasmania•Comprises:

• SAZ Sediment Trap mooring• Pulse bio-geo-chemical mooring • Southern Ocean Flux Station mooring• Profiling drifters & Glider (ANFOG)

Southern Ocean Flux Station

SAZ Sediment trap

Pulse Bio-geo-chemical mooring

SOTS & SOFS Data Holdings•Multidisciplinary •Multiplatform•Redundancy•Builds on 10-year SAZ record

Example of data holdings related to SOTS

Filled= data in hand, open=collection underway, dashed=planned collection

SOFS in Action

Vital Stats

The Centre for Australian Weather and Climate Research A partnership between CSIRO and the Bureau of Meteorology

Buoy weight: 1270 kg

2.7m

1.6m

2.7m

SOFS Tower and instruments

The Centre for Australian Weather and Climate Research A partnership between CSIRO and the Bureau of Meteorology

Short- & Long-wave radiationWind

Temperature & Humidity

Precipitation

Air pressure

Buoy well

The Centre for Australian Weather and Climate Research A partnership between CSIRO and the Bureau of Meteorology

Loading the Anchor

The Centre for Australian Weather and Climate Research A partnership between CSIRO and the Bureau of Meteorology

Anchor weight: 3900 kg

The Centre for Australian Weather and Climate Research A partnership between CSIRO and the Bureau of Meteorology

Chain 8m

Wire 1.9km

Rope 4.1km

Depth 4.5km

Mooring Diagram

Oceanographic instrumentation

The Centre for Australian Weather and Climate Research A partnership between CSIRO and the Bureau of Meteorology

Measurements on SOFS• Atmospheric

– Wind, temperature, humidity, pressure, radiation, rain (bulk fluxes of mass, heat, momentum)

• Wave – Motion Reference Unit (CSIRO design)– Captures 3-D buoy motion and orientation at 5 Hz– Proxy for waves– Measures last 10 minutes of each hour

• Ocean– Temperature (to 500m)– Salinity, pressure, PAR, sparse array– Currents (ADCP to 500m)– BGC at surface and 30-50m

SOFS & NCEP (Josey)

SOFS data & Results •World first 12-month flux record in SO •First time SO in situ fluxes used to validate atmospheric models•Wave from SOFS and Pulse

Net Heat flux and SST from SOFS-1

SOFS1 & 2 WavesSea Temperature

SOFS data & Results

Fluxes and SST from SOFS-1

24-months of wave & wind observations

SOFS 1Mar 2010-Jan 2011

SOFS 2Nov 2012-July 2013

SOFS 3July 2013-Dec 2014

SWH & U10N

• SWH peaks at 22 m (September 2010)• More typical (believable) SWH max are 10-15 m• U10 average = 10 ms-1, max = 29 ms-1

24-months of wave & wind observations

SOFS 1Mar 2010-Jan 2011

SOFS 2Nov 2012-July 2013

SOFS 3July 2013-Dec 2014

SWH & Tau

• Tau mean = 0.2 Nm-2

• Tau peak = 2.8 Nm-2

MRU-Triaxis comparison

MRU and Triaxis wave package deployed on SOFS-2

• MRU is 0.15m larger than Triaxis • MRU is 3% larger than Triaxis• MRU overestimates the peaks

New Observations for wave-ocean mixing and currents

• Program to understand wave induced mixing in upper ocean (Babanin, Hemer, Ghantous, Schulz, Rapizo)

• New instruments on SOFS-4 (CSIRO & Swinburne)

• Vert. profile ~cm of u & v down ~1m, ADCP (Nortek Aquadopp 1 Mhz profiler) in buoy hull

• u & v point currents @30m (Nortek Aquadopp HR)

• 3-D currents @30 m (Nortek Vector)

• Frontier observations – what will we get?

Evidence for big breaking waves… 3m up

The Centre for Australian Weather and Climate Research A partnership between CSIRO and the Bureau of Meteorology

Sonic Arms out of alignment

Rain Gauge funnels missing

SOFS-1

Rain Gauge supports bent

SOFS-3