Data Trawler - Project details

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Project details

Title: Upper ocean biogeochemistry in the Macquarie Meander of the Antarctic Circumpolar Current
Id: 2505
Investigator(s): Peter Strutton
University of Tasmania - Institute of Marine and Antarctic Studies [details]

Description: This supplementary project will assess the biogeochemical impact of thephysical braking of the ACC, which will likely manifest in vertical mixing of nutrientsandanimpact on surface productivity.The proposed work compliments IN2016_V02, which mapped the biogeochemical impact of two eddies in almost the same region of the Southern Ocean. The work therefore adds value to the previously-awarded MNF ship timeby surveying the biogeochemistry in a meander similar to where the IN2016_V02 eddy would have formed,as well as adding a biogeochemistry dimension to IN2018_V05.The results will deepen our understanding of nutrient delivery and consumption in the Southern Ocean, with benefits for future climate models.The aims of this supplementary work are to: 1.Characterise the nutrient field in the context of the physical structure of the meander(the nutrient measurements are included in the original voyage proposal). 2.Calculate rates of nutrient delivery to the surface.3.Contrast the relative importance of upwelling and mixing with previous nearby measurements.
Years: 2018



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

Prof Nathan Bindoff (UTAS) RV Investigator research voyage in2018_v05, titled “How does a standing meander southeast of Tasmania brake the Antarctic Circumpolar Current?" The planet’s largest current, the Antarctic Circumpolar Current (ACC) distributes heat, freshwater and carbon-dioxide among the major oceans. It is a central element of the global overturning circulation that has allowed the ocean to absorb 93% of global warming. Despite Southern Ocean winds increasing for the last 2 decades, the ACC strength has not changed. A major puzzle in understanding climate variability is how the ACC responds to the additional wind energy. We will address the societally-important need to understand how the ACC and Southern Ocean’s capacity to absorb heat and carbon-dioxide will respond to climate variability and change. We will combine a full-depth CTD/LADCP and bathymetric survey of the full meander, with targeted, rapid underway sampling of smaller-scale variability using the Triaxus towed CTD, a VMP-2000 microstructure profiler and underway instruments. Multi-beam data will be important for interpreting the survey data. Water samples will be analysed for nutrients, chlorophyll and particulate organic carbon (POC). Incubation experiments will be conducted to observe phytoplankton productivity under varying physical and chemical conditions. Objectives 1. Deployment of a fleet of EM-APEX profiling floats. 2. Deployment of a tall mooring at the crest of a meander in the Polar Front of the Antarctic Circumpolar Current. 3. Full-depth hydrographic survey of the physics and biogeochemistry of the targeted ACC meander, conducting transects across the front. This will include CTD/LADCP profiles, water sample analysis, VMP-2000 microstructure profiles, bathymetry and underway instruments. 4. Triaxus transects. These will include transects across and along the front and transects around the mooring.
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