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Project details

Title: Eddy: Linking eddy physics and biogeochemistry in the Antarctic Circumpolar Current south of Tasmania
Id: 2442
Acronym: Eddy Project
Investigator(s): Peter Strutton
University of Tasmania - Hobart [details]

Description: Our ultimate goal is to understand how eddy circulation impacts elemental cycling, and how this scales up to the eddy field of the Southern Ocean. We will conduct a process study of two contrasting eddies, one cyclonic and one anti-cyclonic, during the MNF voyage and expand our results to the Southern Ocean more broadly through data analysis and modelling efforts.
Years: 2016



Journal Article


List of surveys that this project was on.

Use [details] link to view survey details (map, reports, metadata etc) including links to download data.

Survey InvestigatorDescription

Tom Trull (CSIRO, ACE-CRC) RV Investigator research voyage in2016_v02. Titled SOTS: Southern Ocean Time Series automated moorings for climate and carbon cycle studies southwest of Tasmania. This voyage combines work from three projects. SOTS, CAPRICORN and Eddy Voyage objectives: SOTS The primary objective is to first deploy a reduced set (SAZ and FluxPulse) and then recover a full set of SOTS moorings (SOFS, Pulse, and SAZ). Additional work will obtain ancillary information on the atmospheric and oceanographic conditions using CTD casts, underway measurements, the Triaxus towed body, and autonomous profiling "Bio-Argo" floats. Each of the SOTS moorings delivers to specific aspects of the atmosphere-ocean exchanges, with some redundancy: * the SAZ sediment trap mooring focuses on quantifying the transfer of carbon and other nutrients to the ocean interior by sinking particles, and collecting samples to investigate their ecological controls * the Southern Ocean Flux Station (SOFS) focuses on air properties, ocean stratification, waves, and currents. * the Pulse biogeochemistry mooring focuses on processes important to biological CO2 consumption, including net community production from oxygen measurements and nitrate depletion, biomass concentrations from bio-optics and bio-acoustics, and collection of water samples for nutrient and plankton quantification. * the FluxPulse mooring combines some elements of Pulse onto the SOFS platform to create a combined mooring, which will be deployed for the first time in 2016. This combination meets financial constraints while still measuring almost all planned parameters CAPRICORN * The primary objective is to collect cloud, aerosol, precipitation, radiation and atmospheric composition measurements over the Southern Ocean over 30 days, and to capture the latitudinal variability of these properties from the latitude of Hobart down to 55-60S if time allows. The Investigator will be equipped with a state-of the art suite of instruments for that purpose (see list in voyage plan). * In order to address the "satellite validation" objectives, we need to locate the research vessel under the track of the CloudSat-CALIPSO instrument and within the larger swath of the NASA GPM and A-Train radars and radiometers. This will be achieved in coordination with the requirement to sample a mesoscale oceanic eddy using a dedicated pattern that will include satellite track following and mesoscale eddy sampling using radial transects, after the SOTS moorings are deployed and recovered. * In order to address the "ACCESS model validation" objectives, we need to sample the sub-grid scale variability of the atmospheric properties, therefore we will undertake some periods of intensive sampling of 12*12 km2 grids with small-scale lawnmower patterns, ensuring that the aerosol measurements are not perturbed by the ship exhaust. The timing and location of these grids will be determined during the voyage. Eddy * Deploy a suite of floats, two different models per eddy, to obtain profiles of temperature, salinity, velocity, oxygen, nitrate, pH and bio-optics near the eddy centre while we perform spatial surveys. * Measure the velocities and mixing in the two eddies. * Quantify the elemental fluxes associated with the eddy circulation, including nutrient transport and air-sea CO2 flux. * Measure the biological response to the circulation and nutrient transport, including primary productivity, trace metal biogeochemistry, new production and the respiration of downward carbon flux (using free-drifting sediment traps). Our combined ship-satellite-float observations will provide the most comprehensive view thus far of Southern Ocean eddies. Our work also contributes to emerging international programs in the Southern Ocean that are combining expanded autonomous observations with large scale modelling efforts. Full details are in the in2016_v02 voyage plan.
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