Surface Mixed Layer at Submesoscales (SMILES)

Lead Research Organisation: University of Plymouth
Department Name: Sch of Biological and Marine Sciences

Abstract

Our current understanding of the Earth's climate is largely based on the predictions of numerical models that simulate the behaviour of, and interaction between, the atmosphere and the ocean. These models are crucially limited in their resolution, however, such that processes within the ocean that have horizontal scales of less than approximately 10 km cannot be explicitly represented and need to be parameterised for their effects to be included within the models. The purpose of this project, Surface Mixed Evolution at Submesoscales (SMILES), is to identify the potentially crucial role played by one variety of these unresolved processes, referred to as submesoscales, in influencing the structure and properties of the upper ocean, and thereby the transformation of surface water masses, within the Southern Ocean. Submesoscales are flows with spatial scales of 1-10 km that occur within the upper ocean where communication and exchange between the ocean and the atmosphere occurs. Previously considered unimportant to climate-scale studies due to their small scale and the presumed insignificance of their dynamics, recent evidence from high resolution regional models and observational studies is now emerging which suggests that submesoscales are actually widespread throughout the upper ocean and play a key role within climate dynamics due to their ability to rapidly restratify the upper ocean and reduce buoyancy loss from the ocean to the atmosphere. The impact of such a process is particularly important to the surface transformation of water masses such as Subantarctic Mode Water (SAMW), which is an important component of the Meridional Overturning Circulation (MOC) that redistributes heat, freshwater and tracers around the globe. Within the MOC, dense water masses such as SAMW are formed and transformed at high latitudes by surface processes before being subducted into the ocean interior. The properties of the subducted water masses and the tracers and dissolved gases such as carbon dioxide contained within them are vitally important to the global climate and geochemical cycles as these water masses remain out of contact with the surface over decennial to centennial timescales.

In the light of the recent discoveries concerning the ability of submesoscales to substantially influence the properties of the upper ocean, we will directly study the impacts of submesoscales on SAMW properties within the Scotia Sea. Using an integrated approach, we will both observe and simulate submesoscales within the upper ocean at a range of spatial and temporal scales, spanning from turbulence up to mode water formation. The principal goal of the study is the diagnosis of the role played by submesoscales in water mass transformation so that we can accurately incorporate these effects into climate-scale models which cannot explicitly resolve them. Our methods will entail a cruise approximately 200 miles south of the Falklands Islands at the Subantarctic Front (SAF), to the north of which SAMW is transformed, and a concurrent modelling study using a state-of-the-art global circulation model. During the cruise, we will use towed instruments to measure the length scales of variability in the temperature, salinity and related fields throughout the upper 300 m of the ocean. The data will enable us to identify the intensity and distribution of submesoscales within the vicinity of the SAF, and to ascertain the forcing mechanisms that generate them. In conjunction with the modelling component of the project, which will include both high resolution and coarse-scale simulations with the MITgcm and large eddy simulations (LES), we will assess how submesoscales ultimately impact on the properties of SAMW within the region and the ultimate effect this has on the formation of SAMW.

Planned Impact

The main beneficiaries of knowledge arising from this research are anticipated to be scientists working in related disciplines and policy-makers. The overall goal of the proposal is to understand how the unresolved processes studied within the project can impact on air-sea exchange and water mass transformation, and thereby influence climate. The scientists working in related disciplines for whom the results would be of interest fall into four groups: (i) observational and physical oceanographers interested in upper ocean processes, (ii) geophysical fluid dynamicists, (iii) marine biologists and (iv) ocean biogeochemists, particularly those concerned with air-sea gas exchange. The largest group of beneficiaries is therefore from the academic sector which includes the Intergovernmental Panel on Climate Change (IPCC) community, but additional identified users include:
- the Met Office (including the Hadley Centre), the European Centre for Medium-Range Weather Forecasting (ECMWF), the National Centre for Earth Observation (NCEO) the National Centre for Ocean Forecasting (NCOF), the UK OSMOSIS consortium and US 'LatMix' and CLIMODE teams (see Letters of Support).
These groups are tasked with developing accurate models to predict changes in air-sea exchange, ocean dynamics and thereby climate change. Ultimately the results from these models inform UK policy-makers.

The UK stands to benefit from this research as the initial recipients of our enhanced understanding of upper ocean physical processes will be UK institutionsnamed above. As a competetive area of research, the substantial improvements in model fidelity to be achieved from a more accurate representation of fundamentally important atmosphere-ocean interaction will provide a competitive advantage to the UK models. The projected timescale for realising these improvements is 3-5 years following initiation of the project.

The benefits to the wider community will be realised through the development of a project website (set-up and maintained by the UoP PDRA) and the hosting of an international workshop on 'Submesoscale impacts on upper ocean exchange: Physical, biological and chemical consequences'. The website will also host a blog that is updated daily during the cruise and will inform interested members of the general public of the project progress. This workshop, hosted at BAS in recognition of the polar emphasis of this project, will bring together leading scientists from the academic sector and stakeholder groups to present results and discuss issues related to the influence of submesoscales on water properties, biological processes and gas uptake. A key aspect of the workshop will be the interdisciplinary nature; it will bring together scientists who may not ordinarily collaborate, but whose research is linked by a common theme of requiring a detailed understanding of intermediate-scale upper ocean processes and their implications for climate impacts. It will have two key goals: (i) to act as a conduit to pass on the results of the project to the user community and (ii) to provide a forum for the discussion and exchange of ideas of an interdisciplinary nature, with the possibility of inducing new collaborative activities.

In addition to the website, the general public will be engaged through an interactive, computer based exhibit at the National Marine Aquarium (NMA) in Plymouth that details the fundamental aims and importance of the project and enables members of the public to change various parameters within a range of relevant simulations to visualise ocean behaviour. The exhibit, which will also emphasise the operational elements of the project that are anticipated to capture the pubic's imagination, will benefit from the high footfall passing through the NMA. School visits at NMA will be hosted by members of the project team to educate and enthuse school children about the role played by the oceans in influencing climate.
 
Description Mesoscale eddies in the Southern Ocean host small-scale instabilities on their periphery that enhance subduction throughout the Southern Ocean. The instabilities have been identified in numerical modelling studies as submesoscale Rossby waves and are a new mechanism operating at submesoscales identified in the ocean. Furthermore, three-dimensional surveys of the eddy in question revealed a host of submesoscale instabilities that were the focus of investigation during the project and have been invoked a mechanism promoting the degeneration of the mesoscale feature and reducing its lifespan. The day also propagated through a gap in the Scotia Ridge that has until now been considered a barrier to zonal transport in the Southern Ocean; the escape of such a significant feature from the ACC has implications for our view of zonal heat flux and water properties int eh Southern Ocean, with potential climate implications and certainly for the Falklands basin. Finally, numerical modelling studies have revealed the preponderance of submesoscales to regions of high strain, providing significant insight into the locations in which submesoscales may be expected.
Exploitation Route Our insight into the dominant controls on the generation of submesoscales, and our success in measuring such features in the ocean, can be readily applied by climate scientist investigating similar features. in particular, the identification of such features in promoting subduction will have potentially crucial ramifications to those studying water subduction at ocean fronts, which includes the globally important role of the Southern ocean in the climate system.
Sectors Aerospace, Defence and Marine,Environment

URL http://www.smiles-project.org
 
Title SMILES oceanographic dataset 
Description Data obtained during the SMILES research cruise to the Scotia Sea during April/May 2015. Data include extensive towed CTD data, drifter based observations, microstructure and remote sensing. 
Type Of Material Database/Collection of data 
Provided To Others? No  
Impact Four oral presentations were presented at the AGU Ocean Sciences Meeting in New Orleans in February 2016 as a direct result of the data collected during the cruise. The data have already been archived with BODC and will be available to other researchers in 2 years. 
 
Description Challenger conference talk 
Form Of Engagement Activity A talk or presentation
Part Of Official Scheme? No
Geographic Reach International
Primary Audience Professional Practitioners
Results and Impact A talk by Dr. Kate Adams presenting results form the SMILES cruise.
Year(s) Of Engagement Activity 2016
 
Description John Taylor AGU Ocean Sciences presentation 
Form Of Engagement Activity A talk or presentation
Part Of Official Scheme? No
Geographic Reach International
Primary Audience Professional Practitioners
Results and Impact Oral presentation by John taylor entitled 'Submesoscale Wrinkles in the Antarctic Circumpolar Current' to an international conference attended by oceanographers, the AGU Ocean Sciences Biannual meeting, New Orleans, Feb. 2016
Year(s) Of Engagement Activity 2016
URL http://www.smiles-project.org/news.html
 
Description Kate Adams AGU Ocean Sciences presentation 
Form Of Engagement Activity A talk or presentation
Part Of Official Scheme? No
Geographic Reach International
Primary Audience Professional Practitioners
Results and Impact Presentation given by Kate Adams to AGU Ocean Sciences, New Orleans, Feb. 2016 entitled, 'Submesoscale In-Situ Observations Across the ACC during the Formation of a Mesoscale Eddy during SMILES..' More than 200 scientists were in the audience and provided the first opportunity to disseminate our cruise findings to the wider scientific community.
Year(s) Of Engagement Activity 2016
URL http://www.smiles-project.org/news.html
 
Description Kate Adams research seminar at Scripps 
Form Of Engagement Activity A talk or presentation
Part Of Official Scheme? No
Geographic Reach International
Primary Audience Professional Practitioners
Results and Impact Kate Adams presented the results from the SMILES cruise to researchers at the Scripps Institute for Oceanography. The seminar provided the opportunity to not only disseminate our findings to one of the top oceanographic institutes in the country but also to obtain advice from leading practitioners in the field.
Year(s) Of Engagement Activity 2016
 
Description Megan Stamper presentation at AGU Ocean Sciences 
Form Of Engagement Activity A talk or presentation
Part Of Official Scheme? No
Geographic Reach International
Primary Audience Professional Practitioners
Results and Impact Oral presentation by Megan Stamper entitled 'Numerical Simulations of the Competition Between Restratification and Mixing Induced by Submesoscale Instabilities' to an international conference attended by oceanographers, the AGU Ocean Sciences Biannual meeting, New Orleans, Feb. 2016
Year(s) Of Engagement Activity 2016
URL http://www.smiles-project.org/news.html
 
Description Phil Hosegood AGU Ocean Sciences Conference presentation 
Form Of Engagement Activity A talk or presentation
Part Of Official Scheme? No
Geographic Reach International
Primary Audience Professional Practitioners
Results and Impact Presentation given by Phil Hosegood to AGU Ocean Sciences, New Orleans, Feb. 2016 entitled, 'Submesoscale dynamics at the Subantarctic Front in the Scotia Sea: Implications for vertical exchange and water mass transformation.' More than 200 scientists were in the audience and provided the first opportunity to disseminate our cruise findings to the wider scientific community.
Year(s) Of Engagement Activity 2016
URL http://www.smiles-project.org/news.html
 
Description Poster by Ricardo Torres given at AGU Ocean Sciences 
Form Of Engagement Activity A talk or presentation
Part Of Official Scheme? No
Geographic Reach International
Primary Audience Professional Practitioners
Results and Impact Poster given by Dr. Ricardo Torres sat AGU Ocean Sciences, Feb. 2016 in New Orleans entitled, 'Birth, life and death of an Anticyclonic eddy in the Southern Ocean.'
Year(s) Of Engagement Activity 2016
URL http://www.smiles-project.org/news.html
 
Description Presentation at Liege colloquia 
Form Of Engagement Activity A talk or presentation
Part Of Official Scheme? No
Geographic Reach International
Primary Audience Professional Practitioners
Results and Impact A talk by Dr. Kate Adams presenting results form the SMILES cruise.
Year(s) Of Engagement Activity 2016
 
Description Scott Bachman presentation to AGU Ocean Sciences 
Form Of Engagement Activity A talk or presentation
Part Of Official Scheme? No
Geographic Reach International
Primary Audience Professional Practitioners
Results and Impact Oral presentation by Scott Bachman entitled 'Modelling Submesoscale Dynamics: A New Parameterization for Symmetric Instability.' to an international conference attended by oceanographers, the AGU Ocean Sciences Biannual meeting, New Orleans, Feb. 2016
Year(s) Of Engagement Activity 2016
URL http://www.smiles-project.org/news.html
 
Description Scripps CASPO seminar 
Form Of Engagement Activity A talk or presentation
Part Of Official Scheme? No
Geographic Reach National
Primary Audience Professional Practitioners
Results and Impact A talk by Dr. Kate Adams presenting results form the SMILES cruise.
Year(s) Of Engagement Activity 2016
 
Description Scripps SOCCOM seminar 
Form Of Engagement Activity A talk or presentation
Part Of Official Scheme? No
Geographic Reach National
Primary Audience Professional Practitioners
Results and Impact A talk by Dr. Kate Adams presenting results form the SMILES cruise.
Year(s) Of Engagement Activity 2016
 
Description Talk at Oregon State POA 
Form Of Engagement Activity A talk or presentation
Part Of Official Scheme? No
Geographic Reach National
Primary Audience Professional Practitioners
Results and Impact A talk by Dr. Kate Adams presenting results form the SMILES cruise.
Year(s) Of Engagement Activity 2016
 
Description Talk at UoP MPRG seminar 
Form Of Engagement Activity A talk or presentation
Part Of Official Scheme? No
Geographic Reach Local
Primary Audience Professional Practitioners
Results and Impact A talk by Dr. Kate Adams presenting results form the SMILES cruise.
Year(s) Of Engagement Activity 2016