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Dr Katy Sheen

Dr Katy Sheen

Associate Professor in Physical Geography (Marine Science)

 01326 255532

 Daphne du Maurier 3044


Daphne du Maurier Building, University of Exeter,  Penryn Campus, Penryn, Cornwall, TR10 9FE, UK


Katy is an Associate Professor of Physical Geography at the University of Exeter. An experienced sea-going oceanographer, her research explores the physics of our oceans and atmosphere. She has pioneered acoustic methods to capture ocean flows deep below the surface layers – flows that span tens of kms to microscale mixing. Such methods will help to better understand how the oceans harness energy from the winds and tides to distribute properties such as the heat, carbon and nutrients across the globe. Her expertise also spans Southern Ocean dynamics and turbulent mixing, mapping marine plastic transport, ocean-atmosphere carbon exchange, and rainfall variability in sub-saharan Africa. Through her work, she is passionate about improving our understanding of climate variability and the health of the marine environement. 

Katy is part of the Centre for Geography and Environemental Science which sits in the Department of Earth and Environmental Science, and the Exeter Marine network


2010 PhD Earth Sciences (University of Cambridge)
2005 MSci in Natural Sciences (University of Cambridge)


Katy completed her undergraduate in physics at the University of Cambridge where she continued to study for a PhD in geophysics/seismic oceanography. Before taking up her lectureship at Exeter, she worked as a researcher at the University of Southampton and the Met Office Hadley Centre for Climate Science and Services. Katy currently holds a prestigious UKRI Future Leaders Fellowship and is Principal Investigator on a NERC Exploring the Frontiers grant. To date, she has raised over £4.3 million of grant income. 

Committed to wider ocean stewardship, Katy is the UK delegate for International Association for the Physical Sciences of the Oceans and committee member of the International Union of Geodesy and Geophysics. She sits on the University NERC Funder Advisory Network (FAN). Katy has a passion for sharing her knowledge and nurturing and inspiring future ocean scientists. She leads an active team of PhD students and post-doctoral researchers and has supervised several MSc and undergraduate dissertations. She is Programme Director for Exeter’s  BSc Marine Science degree, college Widening Participation Office, an experienced Academic Tutor and has led and developed several undergraduate courses. Katy has given many public engagement talks and had her research showcased in the international media and press (iNews, Science Daily & radio interviews).

Research group links

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Research interests

Subsurface Ocean Flows: from eddies to turbulence

One of the key uncertainties in our climate system today is the future storage capacity of heat and carbon in the ocean, alongside the distribution of nutrients and oxygen, key ingredients for a healthy marine ecosystem. To address these uncertainties, improved knowledge of how the oceans move deep below the surface layers is required. In particular, a better understanding of interior ocean flows that span tens of metres to tens of kilometers (i.e. submesoscales) is critical: submesoscale flows provide a pathway to harness energy from the winds and tides and use it to stir and mix different water masses around the globe, along with the heat, carbon and nutrients that they carry. However, the intermediate size and intermittent nature of subsurface submesoscale flows make them both difficult to resolve with observations or model with computers. We are interested in addressing this challenge through the field of Seismic Oceanography. Seismic oceanography utilises acoustic reflections, as collected by the hydrocarbon industry, to image temperature and salinity changes within the water column. Similar to how bats echo-locate, a ship at the surface releases sound pulses into the water and records reflections from water layers. Seismics oceanography is unique in its ability to map out large swathes of ocean structure at unprecedented horizontal resolutions (two orders of magnitude better than other techniques), providing information about subsurface flows from mesoscale eddies (100 km) through to turbulence and mixing. 

Southern Ocean Dynamics and Carbon Uptake

The Antarctic Circumpolar Current (ACC) that encircles the Antarctic continent, plays a leading role in regulating the Earth’s climate system. Eddies, internal waves and small scale mixing processes are an important component of ACC circulation and dynamics. Better quantifying the rates and geographical distribution of the small-scale turbulent mixing in the Southern Ocean, will ultimately help to understand how the global oceans transport of heat, carbon and other important climate variables.

During my post-doc which was part of the Diapycnal and Isopycnal Mixing Experiment in the Southern Ocean (DIMES) project, we made some of the first dedicated measurements of abyssal turbulent mixing and variability in the Southern Ocean, and how they relate to the larger scale flow. This work has provided unprecedented insights into the mechanisms by which the deep waters of the global oceans are ultimately driven back to the surface, where they can interact with the atmosphere.

Here is a link to a film which we made during a field campaign to the Southern Ocean and Antarctica: A Drop in the Southern Ocean - Fereday Films

Sahel Summer Rainfall Variability

The Sahel region of Africa is particularly vulnerable to climate variability. Exhibiting some of the largest rainfall changes worldwide and with a community reliant on agricultural productivity, droughts are major natural disasters for the region. Given that our Earth’s climate is in a state of rapid change, accurate forecasting and a better understanding of the Sahel summer rainy season is of fundamental importance for implementing successful adaptation strategies to ensure the future food security and economic wealth of sub-Saharan Africa.

Working with the inter-annual and decadal climate prediction team at the Met Office, we have utilized state of the art climate models to show that both inter-annual rainfall fluctuations and prolonged drought periods can be successfully predicted across the Sahel. Key to our confidence in the observed statistical skill is the ability to also predict the dominant physical processes that modulate Sahel rainfall. This work has shed new light on the character of Sahel rainfall change on different timescales, particularly in relation to how the different ocean basins impact both the moisture advected into the Sahel and the dynamics that promote ascent of locally sourced moisture. Here is a short film about the work and a visit to Senegal and Ghana to build research collaborations and talk with schools.

Research projects

Current projects include:

COSSMoSS: Capturing Oceanic Submesoscales, Stirring, and Mixing with Sound and Simulations​ (UKRI funded Future Leaders Fellowship). Project partners Prof. Jim McWilliams University of Californa Los Angeles, in collaboration with Dr. Jonathan Gula of Universite de Bretagne Occidentale and Prof. Zhijin Li of Fudan University.

COSSMoSS will employ observational technologies that use sound, alongside developing state-of-the-art simulations, to capture yet unresolved interior flows at a key region of inter-ocean basin exchange, the Brazil-Malvinas Confluence.  A targeted sea-going programme using active acoustics will capture the full range of current flows that exist beneath the surface ocean layers, alongside the mixing and stirring that they generate.  Acoustic measurements will be combined for the first time with cutting-edge robotics, vessel-mounted and moored instrumentation. In parallel, state-of- the-art model simulations will be both validated and improved using our new ocean observation data.  The experiment will take place at a global hotspot of ocean activity: the Brazil-Malvinas Confluence off the coast of Argentina. Here sub-tropical waters from the Atlantic collide with polar waters from the Southern Ocean. Water mass exchanges at this confluence, which are likely driven by submesoscale currents, play a key role in the distribution of heat, salt, carbon and life sustaining nutrients and oxygen throughout the global oceans. These data and simulations will be used to quantify interior submesoscale initiation, ubiquity and interactions, and assess their impact on ocean energy budgets, vertical mixing, water mass transformations and property distributions. By revealing interior ocean dynamics in unparalleled detail at the Brazil-Malvinas Confluence, COSSMoSS will shed light on a significant missing piece of the scientific ocean puzzle helping us to better understand our future biosphere and climate.

Here is public talk I gave about the research: Curiosity Captivated the Cat: the ocean and me (Speak You) 

Can you hear marine snow falling? (NERC Exploring the Frontiers Grant) PI, in collaboration with the National Oceanography Center (Dr Sarah Giering) and the British Antarcic Survey (Dr. Sophie Fielding and Dr. Clara Manno)

The global ocean plays a key role in our climate system by extracting and storing much of the carbon released by humans into the atmosphere, thereby buffering the effects of global warming. However, there are uncertainties as to how this important ocean-carbon sink may change in future, and critically a better understanding of the ocean-carbon system is needed to accurately predict the Earth's climate. A key driver of ocean carbon uptake is marine life: plants that live in the surface ocean convert the atmospheric carbon that is absorbed into the ocean into their body organic matter through photosynthesis. This organic matter eventually sinks to the deep ocean in the form of 'marine snow' where it can be locked up for thousands of years in seafloor sediments. Oceanographers typically use sediment-traps to capture and measure marine snow, however sediment traps can only collect data in one place on typically monthly timescales. The result is a severe lack of information about the shorter time and space scale variability of marine snow, making it difficult to understand the processes that mediate ocean carbon storage.

In this project we will develop a novel method to repurposestandard oceanographic acoustic current meter data, typically collected alongside sedi ment traps, to estimate carbon fluxes at much higher temporal resolutions (hours). We will use backscatter data, also recorded by the acoustic current meter but normally disregarded as a bi-product. To test the method, we will analyse an exemplar data set collected in the Southern Ocean which consists of both sediment-trap and acoustic backscatter data. As well as providing carbon flux data at yet unresolved temporal scales, output from this project can be applied to a wealth of legacy acoustic data (e.g. current data records collected across the world oceans over past decades), greatly improving the global coverage of past and present carbon flux estimates. Ultimately, we will improve the ability to understand and predict the future carbon storage capacity of the ocean and hence the Earth's climate.

Reducing Uncertaining in Rainfall Projections in the Central and East Sahel (funded under AMMA-2050 through UK Met Office). In collaboration with Dr. Dave Rowell, UK Met Office

The future of precipitation in the Sahel region of Africa is highly uncertain with models showing a divergence of projections. Which model projections are most credible? In this work, we aim to quantify the validity of different Coupled Model Intercomparison Project (CMIP6) Sahel rainfall projections through better understanding the physical mechanisms responsible for intermodel variability. This work will help to improve resilience and timely adaptation to future climate changes in the vulnerable Sahel.

OCTONAUT: Ocean impacts of Cryospheric TransformatiON by Antarctic Underwater Turbulence (NERC CASS through the British Antarctic Surbey funded). In collaboration with Dr. Ben Lincoln, University of Bangor.

The glaciers and ice shelves of the Western Antarctic Peninsula are undergoing major changes. Strong glacier retreat rates are observed in many regions, primarily driven by enhanced delivery of warm ocean water at depth. This project will investigate the processes that modulate both the outflow of melt water and the inflow of deep warm along the Western Antarctic Peninsula coastline.

Here is public talk I gave about the research: Polar expeditions, Börgen Bay, and what Antarctic research can teach us about our effect on climate change - ExeTalks

See also PhD projects under Supervision/Group tab

Research grants

  • 2023 UKRI (ESRC)
    Future Leader Fellowship: Capturing Oceanic Submesoscales, Stirring, and Mixing with Sound and Simulations MR/X035611/1
  • 2023 ERC Consolidators Grant
    Capturing Oceanic Submesoscales, Stirring, and Mixing with Sound and Simulations, Grant awarded but I chose to accept the FLF instead as for a similar project
  • 2022 NERC
    Can you hear marine snow falling? NE/X009483/1
  • 2019 Met Office Hadley Centre
    Met Office Hadley Centre funding grant: AMMA-2050 Expert Judgement of CMIP5 projected change in summer mean Sahel rainfall
  • 2018 UKRI (ESRC)
    UK Research Council funded Models To Decisions Pilot Project Award: Enhancing Earth System decisions with Dominant Frequency State Analysis.

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Journal articles

Sheen KL, Smith DM, Dunstone NJ, Eade R, Rowell DP, Vellinga M (In Press). Skilful prediction of Sahel summer rainfall on inter-annual and multi-year timescales. Nature Communications
Wilson DR, Godley BJ, Haggar GL, Santillo D, Sheen KL (2024). Corrigendum to "The influence of depositional environment on the abundance of microplastic pollution on beaches in the Bristol Channel, UK" [Mar. Pollut. Bull. 164 (2021) 111997]. Mar Pollut Bull, 202  Author URL.
Cox I, Brewin RJW, Dall'Olmo G, Sheen K, Sathyendranath S, Rasse R, Ulloa O (2023). Distinct habitat and biogeochemical properties of low‐oxygen‐adapted tropical oceanic phytoplankton. Limnology and Oceanography, 68(9), 2022-2039. Abstract.
Ford DJ, Tilstone GH, Shutler JD, Kitidis V, Sheen KL, Dall’Olmo G, Orselli IBM (2023). Mesoscale Eddies Enhance the Air‐Sea CO<sub>2</sub> Sink in the South Atlantic Ocean. Geophysical Research Letters, 50(9). Abstract.
Wilson DR, Sheen KL, Clark JR, Thorpe SE, Young EF (2023). Modelling the transport of microplastic pollution across the Antarctic Circumpolar Current.
Gunn KL, Sheen KL, Tang Q (2022). Editorial: Acoustically Mapping the Ocean. Frontiers in Marine Science, 9
Ehmen T, Sheen K, Watson A, Brearley A, Palmer M, Roper D (2022). High resolution acoustic imaging of frontal dynamics and thermohaline finestructure in the Southwest Atlantic sector of the Southern Ocean.
Meredith M, Inall M, Brearley A, Munday D, Ehmen T, Sheen K, Retallick K, Annett A, Jones R, Carvalho F, et al (2022). Internal tsunamigenesis and mixing driven by glacier calving in Antarctica.
Meredith MP, Inall ME, Brearley JA, Ehmen T, Sheen K, Munday D, Cook A, Retallick K, Van Landeghem K, Gerrish L, et al (2022). Internal tsunamigenesis and ocean mixing driven by glacier calving in Antarctica. Sci Adv, 8(47). Abstract.  Author URL.
Mitchell DM, Stone EJ, Andrews OD, Bamber JL, Bingham RJ, Browse J, Henry M, MacLeod DM, Morten JM, Sauter CA, et al (2022). The Bristol <scp>CMIP6</scp> Data Hackathon. Weather, 77(6), 218-221.
Waterman S, Meyer A, Polzin KL, Naveira Garabato AC, Sheen KL (2021). Antarctic Circumpolar Current Impacts on Internal Wave Life Cycles. Geophysical Research Letters, 48(8). Abstract.
Munoz-Ramirez CP, Beltran-Concha M, Perez-Araneda K, Sands CJ, Barnes DKA, Roman-Gonzalez A, de Lecea AM, Retallick K, van Landeghem K, Sheen K, et al (2021). Genetic variation in the small bivalve Nuculana inaequisculpta along a retreating glacier fjord, King George Island, Antarctica. REVISTA DE BIOLOGIA MARINA Y OCEANOGRAFIA, 56(2), 151-156.  Author URL.
Fortnam M, Atkins M, Brown K, Chaigneau T, Frouws A, Gwaro K, Huxham M, Kairo J, Kimeli A, Kirui B, et al (2021). Multiple impact pathways of the 2015-2016 El Niño in coastal Kenya. Ambio, 50(1), 174-189. Abstract.  Author URL.
Xiao W, Sheen KL, Tang Q, Shutler J, Hobbs R, Ehmen T (2021). Temperature and Salinity Inverted for a Mediterranean Eddy Captured with Seismic Data, Using a Spatially Iterative Markov Chain Monte Carlo Approach. Frontiers in Marine Science, 8
Wilson DR, Godley BJ, Haggar GL, Santillo D, Sheen KL (2021). The influence of depositional environment on the abundance of microplastic pollution on beaches in the Bristol Channel, UK. Mar Pollut Bull, 164 Abstract.  Author URL.
Whalen CB, de Lavergne C, Naveira Garabato AC, Klymak JM, MacKinnon JA, Sheen KL (2020). Internal wave-driven mixing: governing processes and consequences for climate. Nature Reviews Earth & Environment, 1(11), 606-621.
Bascur M, Muñoz-Ramírez C, Román-González A, Sheen K, Barnes DKA, Sands CJ, Brante A, Urzúa Á (2020). The influence of glacial melt and retreat on the nutritional condition of the bivalve Nuculana inaequisculpta (Protobranchia: Nuculanidae) in the West Antarctic Peninsula. PLOS ONE, 15(5), e0233513-e0233513.
Xiao W, Sheen K, Tang Q, Hobbs R, Shutler J, Browse J (2020). Uncertainty quantification during seismic oceanography inversion with start Temperature-Salinity models of different lateral resolutions.
Abrahamsen EP, Meijers AJS, Polzin KL, Naveira Garabato AC, King BA, Firing YL, Sallée J-B, Sheen KL, Gordon AL, Huber BA, et al (2019). Stabilization of dense Antarctic water supply to the Atlantic Ocean overturning circulation. Nature Climate Change, 9(10), 742-746.
Dunstone N, Smith D, Scaife A, Hermanson L, Fereday D, O'Reilly C, Stirling A, Eade R, Gordon M, MacLachlan C, et al (2018). Skilful Seasonal Predictions of Summer European Rainfall. Geophysical Research Letters, 45(7), 3246-3254. Abstract.
Clement L, Frajka-Williams E, Sheen KL, Brearley JA, Garabato ACN (2016). Generation of Internal Waves by Eddies Impinging on the Western Boundary of the North Atlantic. JOURNAL OF PHYSICAL OCEANOGRAPHY, 46(4), 1067-1079.  Author URL.
Smith DM, Booth BBB, Dunstone NJ, Eade R, Hermanson L, Jones GS, Scaife AA, Sheen KL, Thompson V (2016). Role of volcanic and anthropogenic aerosols in the recent global surface warming slowdown. Nature Climate Change, 6(10), 936-940.
Trossman DS, Waterman S, Polzin KL, Arbic BK, Garner ST, Naveira-Garabato AC, Sheen KL (2015). Internal lee wave closures: Parameter sensitivity and comparison to observations. JOURNAL OF GEOPHYSICAL RESEARCH-OCEANS, 120(12), 7997-8019.  Author URL.
Sheen KL, Brearley JA, Naveira Garabato AC, Smeed DA, Laurent LS, Meredith MP, Thurnherr AM, Waterman SN (2015). Modification of turbulent dissipation rates by a deep Southern Ocean eddy. Geophysical Research Letters, 42(9), 3450-3457. Abstract.
Sarkar S, Sheen KL, Klaeschen D, Brearley JA, Minshull TA, Berndt C, Hobbs RW, Garabato ACN (2015). Seismic reflection imaging of mixing processes in Fram Strait. JOURNAL OF GEOPHYSICAL RESEARCH-OCEANS, 120(10), 6884-6896.  Author URL.
Sévellec F, Naveira Garabato AC, Brearley JA, Sheen KL (2015). Vertical Flow in the Southern Ocean Estimated from Individual Moorings. Journal of Physical Oceanography, 45(9), 2209-2220. Abstract.
Brearley JA, Sheen KL, Naveira Garabato AC, Smeed DA, Speer KG, Thurnherr AM, Meredith MP, Waterman S (2014). Deep boundary current disintegration in Drake Passage. Geophysical Research Letters, 41(1), 121-127. Abstract.
Sheen KL, Garabato ACN, Brearley JA, Meredith MP, Polzin KL, Smeed DA, Forryan A, King BA, Sallée JB, St. Laurent L, et al (2014). Eddy-induced variability in Southern Ocean abyssal mixing on climatic timescales. Nature Geoscience, 7(8), 577-582. Abstract.
Waterman S, Polzin KL, Naveira Garabato AC, Sheen KL, Forryan A (2014). Suppression of Internal Wave Breaking in the Antarctic Circumpolar Current near Topography. Journal of Physical Oceanography, 44(5), 1466-1492. Abstract.
Brearley JA, Sheen KL, Naveira Garabato AC, Smeed DA, Waterman S (2013). Eddy-Induced Modulation of Turbulent Dissipation over Rough Topography in the Southern Ocean. Journal of Physical Oceanography, 43(11), 2288-2308. Abstract.
Sheen KL, Brearley JA, Naveira Garabato AC, Smeed DA, Waterman S, Ledwell JR, Meredith MP, St. Laurent L, Thurnherr AM, Toole JM, et al (2013). Rates and mechanisms of turbulent dissipation and mixing in the Southern Ocean: Results from the Diapycnal and Isopycnal Mixing Experiment in the Southern Ocean (DIMES). Journal of Geophysical Research: Oceans, 118(6), 2774-2792. Abstract.
Sheen KL, White NJ, Caulfield CP, Hobbs RW (2012). Seismic imaging of a large horizontal vortex at abyssal depths beneath the Sub-Antarctic Front. Nature Geoscience, 5(8), 542-546.
Sheen KL, White N, Caulfield CP, Hobbs RW (2011). Estimating Geostrophic Shear from Seismic Images of Oceanic Structure. Journal of Atmospheric and Oceanic Technology, 28(9), 1149-1154. Abstract.
Sheen KL, White NJ, Hobbs RW (2009). Estimating mixing rates from seismic images of oceanic structure. Geophysical Research Letters, 36(24). Abstract.


Gille ST, Sheen KL, Swart S, Thompson AF (2022). Chapter 12 Mixing in the Southern Ocean. In  (Ed) Ocean Mixing, Elsevier, 301-327.
Sheen K, Gille S, Thompson A, Swart S (2021). Mixing in the Southern Ocean. In Garabato A, Meredith M (Eds.) Ocean Mixing Drivers, Mechanisms and Impacts, Elsevier, 301-327. Abstract.

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External Engagement and Impact

Committee/panel activities

UK delegate for International Association for the Physical Sciences of the Oceans and committee member of the International Union of Geodesy and Geophysics

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I am Programme Director of our Marine Science degree programme

I currently teach on several modules in Marine Science, Geography, Environmental Science at the Penryn Campus (see below). I am also the Widening Participation Officer for Centre of Geography and Environmental Science

Here is a short video about some of the aspects that I teach


  • GEO2457 - Physical Ocean Processes (Module Convenor)
  • GEO3473 - Antarctica & the Southern Ocean (Module Convenor)
  • GEO2460 - Environment and Sustainability on the Isles of Scilly
  • GEO2451 - Ice Sheets: Glaciology, Climate and the Oceans
  • BIO1433 - Marine Biology
  • GEO1422 - Marine Science Tutotials
  • GEO2461 - Second Year Tutorials
  • GEO3462 - Dissertation in Marine Science



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Supervision / Group

Postdoctoral researchers

  • Tobias Ehmen

Postgraduate researchers

  • Laura Byrne PhD student in modelling Antarctic ice sheet evolution
  • Isabelle Cox PhD student investigating low-oxygen zone biogeochemistry
  • Yao Meng PhD student in seismic oceanography (Mozambique Channel)
  • Andrea Rochner PhD student in modelling carbon uptake in the Southern Ocean
  • Daniel Wilson PhD student in modelling microplastic pathways in the Southern Ocean
  • Wuyi Zhao PhD looking at the impact of eddies on ocean biogeochemistry


  • John Bruun Research Fellow investigating the role of sea surface temperatures and variability in sub-Saharan rainfall
  • Tobias Ehmen PhD student in seismic oceanography (Southern Ocean)
  • Daniel Ford PhD student in ocean-atmosphere carbon fluxes

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Office Hours:

Monday 3-4 pm

Tuesday 4-5 pm

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