Assessing the role of eddies in exchanging nutrients across the European Shelf

Lead Research Organisation: University of Liverpool
Department Name: Earth, Ocean and Ecological Sciences

Abstract

The ocean is full of time-varying, swirling circulations, called eddies. These eddies transfer heat, nutrients and carbon from one region to another, affecting the local store of each of these properties. This eddy exchange potentially becomes important across strong flows, such as boundary currents, jets and slope currents. However, while eddies are seen to occur throughout the ocean (such as remotely sensed observations), there have been very few systematic, repeated observations revealing how eddies transfer properties in the horizontal, particularly below the surface. Instead we have to rely on a combination of model and theoretical studies to understand the role of eddies in the ocean, often drawing parallels with how weather systems behave in the atmosphere.

In this study, we wish to use the new glider technology to identify how eddies transfer nutrients in the horizontal. We wish to investigate this eddy transfer on the European Shelf at three different sites, drawing on the support of an existing programme, FASTNET, examining the physical exchange across the shelf break. Our aim is to include nutrient sensors in two gliders, one supported under FASTNET and the other supported via this call. Together with nutrient data from FASTNET cruises, we aim to use the glider data to estimate the eddy flux of nutrients in these three different sites between the open ocean and shelf seas. Our hypothesis is that the eddies provide a flux of inorganic nutrients from the open ocean to the shelf seas, across the shelf break, as well as a return flux of dissolved organic nutrients from the shelf seas to the open ocean.

The eddy fluxes of nutrients onto the shelf are potentially important in sustaining biological productivity, there are particularly high rates of photosynthesis here, sustaining fishing activity and providing a biological drawdown of atmospheric carbon dioxide.

In the longer term, the glider technology has the potential to provide the repeated observations needed to quantify eddies fluxes throughout the ocean. This step is necessary to really understand how heat, nutrients and carbon are transferred throughout the ocean, as well as the wider goal of how the ocean operates in the climate system.

Planned Impact

Impact summary is not required, as that component is provided by FASTNET.

Publications

10 25 50
 
Description This is a project that supports a PhD student, Nealy Carr. Nealy is in the second year of her PhD and so the key findings of the entire project have not emerged.

Nealy has participated in 4 research cruises in the Northwest European Shelf. She has collected samples and data to assess the source, cycling and transport of dissolved organic matter in shelf seas. She presented her preliminary findings at the Challenger Society conference in September 2014 and at the ASLO Ocean Sciences meeting in New Orleans in Feb. 2016.

Nealy has now been trained to work with glider data so will use CDOM sensors on gliders to augment her findings from discrete measurements on cruises.

Main findings are starting to emerge:
There are strong spatial gradients in terrestrial organic matter across the shelf and a strong relationship with salinity.
There are strong seasonal gradients in protein like organic matter on the shelf, linked to biological productivity, especially during the spring bloom.

Nealy will prepare this for a publication for submission in summer 2016.
Exploitation Route Findings from this project could be used to help constrain the sources of DOM in shelf seas for development of budgets and presentation of terrestrially derived material in transport models.
Sectors Environment

 
Description An Alternative Framework to Assess Marine Ecosystem Functioning in Shelf Seas (AlterEco)
Amount £1,657,000 (GBP)
Funding ID NE/P013902/1 
Organisation Natural Environment Research Council 
Sector Public
Country United Kingdom
Start 05/2017 
End 05/2020
 
Description Collaboration with NOC scientists on gliders and oxygen 
Organisation National Oceanography Centre
Country United Kingdom 
Sector Academic/University 
PI Contribution Based on working with glider data, we developed ideas into a new NERC large grant called AlterEco which was funded in 2016 and led by Dr. Matthew Palmer tat NOC.
Collaborator Contribution Based on working with glider data, we developed ideas into a new NERC large grant called AlterEco which was funded in 2017 and led by Dr. Matthew Palmer tat NOC.
Impact Presentation at the ASLO Ocean Sciences meeting in 2018.
Start Year 2017