Pycnocline Mixing in Shelf Seas

Lead Research Organisation: National Oceanography Centre
Department Name: Science and Technology

Abstract

The continental shelf seas provide a transition zone between estuaries and the ocean across which carbon, nutrients, sediments and contaminants are exchanged. The currents and mixing on the NW European continental shelf are dominated by the tide interacting with the sea bed, with density stratification occurring during summer months across ~80% of the region. Significant levels of biological primary production occur in these regions. However, the exchange of nutrients and carbon across these critical interfaces of stratified fluid is poorly understood and so is poorly represented in numerical models.
This project aims to compile the world's largest observational data base of shelf sea pycnocline turbulence and hydrographic measurements and to exploit state-of-the-art computer modelling and new observational technology to investigate, quantify, and parameterise the physical mechanisms and processes responsible for the fluxes across this critical interface. In particular we will develop improved understanding of pycnocline turbulence and mixing promoted by shear instability. We will test the hypothesis that these mechanisms, or interaction between mechanisms, drives pycnocline shear to levels which exceed a critical threshold beyond which there is a catastrophic loss of stability resulting in episodic mixing. Parameterisations for this mixing will be developed and tested.

Planned Impact

This project has potentially a wide range of beneficiaries. As well as the benefits to the academic community in synthesising the world's largest shelf sea microstructure data base; developing an LES tool that would work like a 1D mixing model; and delivering a parameterisation to a key aspect of shelf sea modelling, namely the ability to simulate vertical mixing in stratified waters, there are some significant indirect benefits:

Science into Policy: Marine turbulence is an underlying control of many ecosystem processes (e.g. primary production and plankton community structure, so up the food chain through fish to piscivorous fish, sea birds and marine mammals). Modelling is a crucial tool in developing an ecosystem approach to marine management, since it can take a 'whole-systems' approach and has the potential for predictive capability. Hence the model development proposed here directly benefits several areas of marine policy, specifically the Marine Strategy Framework Directive and our understanding of the descriptors of Good Environmental Status1 therein, and their vulnerability to change (Descriptor 3: Population of commercial fish / shell fish; Descriptor 4: Elements of marine food webs; Descriptor 5: Eutrophication; Descriptor 7: Alteration of hydrographical conditions). The potential beneficiaries are UK and European policy makers: DEFRA, European Environment Agency, OSPAR. These issues are generic and faced outside Europe, so there are many potential international beneficiaries, although engagement will be less direct.

Wealth creation for UK and the Green Economy:
Improving shelf sea modeling capability has wider implications for many areas of the economy. Improved ecosystem predictions provide benefits for environmental impact assessments of marine renewable energy installations, and predictions of impacts of marine carbon capture and storage programmes. Improved bottom temperature predictions have potential benefits to demersal fisheries and gas pipeline planning criteria - both act within specific temperature tolerances. The move towards ocean-atmosphere coupled weather forecasting at the UK Met Office (UKMO) means this work potentially benefits UK weather forecasts, with agricultural, defense and tourism implications.

Media Relations and Public Engagement:
As opportunities arise, we will seek to present our research to UK and international audiences. We will publish at least one popular science article in Planet Earth and have an outward looking project website. In this way the general public will also have appropriate access to our research.

Publications

10 25 50
 
Description A new fine resolution NW European shelf configuration simulates internal tides which help us better simulate the stratification of UK waters.
Exploitation Route More accurate simulation of time and space varying stratification. The UK Met Office is now adopting this fine scale regional model for its operational forecast.
Sectors Aerospace, Defence and Marine,Energy,Leisure Activities, including Sports, Recreation and Tourism

 
Description Analysis of the mixing parameterisations is feeding into the design of Met Office ocean forcast simulations
First Year Of Impact 2017
Sector Aerospace, Defence and Marine,Environment
Impact Types Societal

 
Description PycnMix_collab 
Organisation Bangor University
Department School of Ocean Sciences
Country United Kingdom 
Sector Academic/University 
PI Contribution This collaboration is part of a jointly funded NERC standard grant. NOC brings, among other things numerical modelling expertise to the collaboration.
Collaborator Contribution Met Office - yet to commence - we will jointly implement recommendations from the project Bangor - 3yr postdoc - postdoc left before objective were met SAMS - 2yr postdoc - in the process of writing a manuscript (including picking up where Bangor postdoc left)
Impact Really too early, though we have two manuscripts that were facilitated by the collaboration (Guihou 2017, Graham 2018) and a one about to be submitted (Luneva, in prep.) and other in prep (Toberman, in prep)
Start Year 2014
 
Description PycnMix_collab 
Organisation Meteorological Office UK
Country United Kingdom 
Sector Public 
PI Contribution This collaboration is part of a jointly funded NERC standard grant. NOC brings, among other things numerical modelling expertise to the collaboration.
Collaborator Contribution Met Office - yet to commence - we will jointly implement recommendations from the project Bangor - 3yr postdoc - postdoc left before objective were met SAMS - 2yr postdoc - in the process of writing a manuscript (including picking up where Bangor postdoc left)
Impact Really too early, though we have two manuscripts that were facilitated by the collaboration (Guihou 2017, Graham 2018) and a one about to be submitted (Luneva, in prep.) and other in prep (Toberman, in prep)
Start Year 2014
 
Description PycnMix_collab 
Organisation Scottish Association For Marine Science
Country United Kingdom 
Sector Charity/Non Profit 
PI Contribution This collaboration is part of a jointly funded NERC standard grant. NOC brings, among other things numerical modelling expertise to the collaboration.
Collaborator Contribution Met Office - yet to commence - we will jointly implement recommendations from the project Bangor - 3yr postdoc - postdoc left before objective were met SAMS - 2yr postdoc - in the process of writing a manuscript (including picking up where Bangor postdoc left)
Impact Really too early, though we have two manuscripts that were facilitated by the collaboration (Guihou 2017, Graham 2018) and a one about to be submitted (Luneva, in prep.) and other in prep (Toberman, in prep)
Start Year 2014
 
Description PycnMix_collab 
Organisation University of South Florida
Country United States 
Sector Academic/University 
PI Contribution This collaboration is part of a jointly funded NERC standard grant. NOC brings, among other things numerical modelling expertise to the collaboration.
Collaborator Contribution Met Office - yet to commence - we will jointly implement recommendations from the project Bangor - 3yr postdoc - postdoc left before objective were met SAMS - 2yr postdoc - in the process of writing a manuscript (including picking up where Bangor postdoc left)
Impact Really too early, though we have two manuscripts that were facilitated by the collaboration (Guihou 2017, Graham 2018) and a one about to be submitted (Luneva, in prep.) and other in prep (Toberman, in prep)
Start Year 2014
 
Description Into the Blue. NERC Showcase. RRS Discovery, Pier Head, Liverpool 
Form Of Engagement Activity Participation in an open day or visit at my research institution
Part Of Official Scheme? No
Geographic Reach Regional
Primary Audience Schools
Results and Impact I presented an overview of UK tides using a range of animations and graphics and the interactive tablet app (anyTide). I spoke to a range of groups from secondary school children, undergraduate engineers, maritime industry professionals and a radio journalist. Obviously nuancing the material appropriate too what the recipients understood.
Year(s) Of Engagement Activity 2016
 
Description Into the Blue. NERC Showcase. The Runway visitor park, Manchester Airport 
Form Of Engagement Activity Participation in an open day or visit at my research institution
Part Of Official Scheme? No
Geographic Reach Regional
Primary Audience Public/other audiences
Results and Impact NERC had a science showcase event and the NOC had a stand. Following the open day on the Discovery I put together an educational exhibit demonstrating sensor development and deployment using simple off the shelf electronics that an enthusiastic secondary school child could relate to. The point was to demonstrate that marine science is interesting and do-able. A few bright kids engaged well with the demonstration. The adults, less so...
Year(s) Of Engagement Activity 2016
 
Description Public lecture - Ethics and the Oceans 
Form Of Engagement Activity A talk or presentation
Part Of Official Scheme? No
Geographic Reach Local
Primary Audience Public/other audiences
Results and Impact Public talk about the Ethics of the Ocean. Presented material on climate change to a lay audience from a local church. The audience were self selected as interested in the subject, and with predisposed to be conservation minded. Audience: ~50
Year(s) Of Engagement Activity 2019
 
Description School Visit (St Mary's Runcorn Primary) 
Form Of Engagement Activity A talk or presentation
Part Of Official Scheme? No
Geographic Reach Local
Primary Audience Schools
Results and Impact I gave 4 presentations, pitched slightly differently to different year groups, at a local primary school during their careers week. I talked about "What do oceanographers do? Octonauts for real". In total about 170 children attended and we had questions and answer sessions afterward. One class did homework on the talk writing about what sort of oceanographer they would be and what they would discover.
Year(s) Of Engagement Activity 2016