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Dr Katy Sheen

Dr Katy Sheen

Lecturer in Physical Geography

 01326 255532

 Peter Lanyon A090

 

Peter Lanyon Building, University of Exeter, Penryn Campus, Treliever Road, Penryn, Cornwall, TR10 9FE, UK

 Office hours:

Tuesday 2-3 pm

Thursday 10-11 am

Overview

I completed an MSci in physics at the University of Cambridge, where I continued to study for a PhD in geophysics. My PhD thesis focused on developing an acoustic method of mapping out oceanic structure, known as seismic oceanography. This work sparked off my interest in physical oceanography, and I subsequently joined the National Oceanography Centre in Southampton as a post-doctoral researcher in Southern Ocean physics. Following this, I worked as a senior scientist in the inter-annual and decadal climate prediction team at the Met Office Hadley Centre. I joined the University of Exeter in 2016 as a lecturer in physical geography.

Broad research specialisms:

My research explores the physics of our oceans and atmosphere. Using both observations and models, I am interested in how the physical processes within our Earths climate system work, and how they may respond to a changing climate.

To date, my work has largely been focused on the remote Southern Ocean, where I have spent many months in the field collecting information about abyssal turbulent mixing processes. These measurements are important because they ultimately influence the uptake of heat and carbon by the oceans. I am also developing an autonomous acoustic method of sampling temperature and salinity horizons in the oceans. Because these measurements have high spatial resolutions, they will help to answer fundamental questions about important smaller-scale oceanic processes, otherwise very difficult to capture.

More recently, I have expanded my research to atmospheric physics and climate modeling. I have been looking at how well climate models can predict summer rainfall levels in the Sahel region of Africa, an area particularly vulnerable to persistent and devastating droughts. I’m particularly interested in the mechanisms that drive Sahel rainfall variability on different timescales, and how they are modulated by changes in the global oceans.

Qualifications

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

Research

Research interests

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.

Seismic Oceanography

Seismic oceanography, in a novel technique that utilises acoustic reflections, as

collected by the hydrocarbon industry, to image temperature and salinity changes within the water column. It is unique in its ability to map out large swathes of ocean structure at unprecedented horizontal resolutions. I believe that seismic

oceanography is likely to have a profound impact on our quantitative understanding of four-dimensional ocean dynamics, key to parameterizing global climate models. Based on my previous work in the field, I am currently engaged in developing an autonomous system for collecting acoustic reflection data from the ocean.

Southern Ocean Dynamics

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. I’m interested in better quantifying the rates and geographical distribution of the small-scale turbulent mixing in the Southern Ocean, which ultimately control the global oceans transport of heat, carbon and other important climate variables.

Through the Diapycnal and Isopycnal Mixing Experiment in the Southern Ocean (DIMES) project, we have made 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 my last trip to the Southern Ocean and Antarctica:

A Drop in the Southern Ocean

 

Research projects

OCTONAUT: Ocean impacts of Cryospheric TransformatiON by Antarctic Underwater Turbulence (NERC CASS through the British Antarctic Surbey funded)

The glaciers and ice shelves of the Western Antarctic Peninsula (WAP) 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 WAP coastline.

 

ACOUSTIC IMAGING OF SOUTHERN OCEAN FRONTS (SDF funding):

We will be supplementing a geophysical seismic research survey with oceanographic measuements in early 2018 in the Southern Ocean to investigate the physics of Southern Ocean fronts using acoustic and oceanographic data.

 

RAINFALL: Rainfall in Africa INitiative: Forecasting at Longer-Leadtimes (SDF funding):

A succesful field trip to Senegal and Ghana highlighted the need for improved early warning systems for drought and flooding in the Sahel region of Africa. We are currently working with colleagues in these regions to improve forecasting summer rain variability from the previous winter to many years in advance.

 

Publications

Key publications | Publications by category | Publications by year

Key publications


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.  Full text.
Sheen KL, Smith D, Dunstone N, Eade R, Rowell D, Vellinga M (2017). Skilful prediction of Sahel summer rainfall on inter-annual and multi-year timescales. Nature Communications, 8 Full text.
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.  Full text.
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. Full text.
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.  Full text.

Publications by category


Journal articles

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.  Full text.
Sheen KL, Smith D, Dunstone N, Eade R, Rowell D, Vellinga M (2017). Skilful prediction of Sahel summer rainfall on inter-annual and multi-year timescales. Nature Communications, 8 Full text.
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.  Full text.
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.  Full text.
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. Full text.
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.
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.
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.  Full text.
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.
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.
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.
Sheen KL, White NJ, Hobbs RW (2009). Estimating mixing rates from seismic images of oceanic structure. Geophysical Research Letters, 36

Publications by year


2018

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.  Full text.

2017

Sheen KL, Smith D, Dunstone N, Eade R, Rowell D, Vellinga M (2017). Skilful prediction of Sahel summer rainfall on inter-annual and multi-year timescales. Nature Communications, 8 Full text.

2016

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.  Full text.
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.

2015

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.  Full text.
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. Full text.
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.

2014

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.
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.  Full text.
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.

2013

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.
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.

2012

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.

2011

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.

2009

Sheen KL, White NJ, Hobbs RW (2009). Estimating mixing rates from seismic images of oceanic structure. Geophysical Research Letters, 36

Refresh publications

Teaching

I currently teach on several modules in Geography and Environmental Science at the Penryn Campus. These include:

GEO1408b (module convenor) - Global Issues in Environmental Science. First year module.

GEO2451 (team taught) - Ice Sheets: Glaciology, Climate and the Oceans. Second year module.

GEO3454 (module convenor) - Antarctica: Science from a Frozen Continent. Third year module.

West Penwith Field Course

Azores Field Trip

North Wales Field Trip

Dissertation in Geography

Tutorials

Admissions Tutor (Academic lead for open days fro prospective students)

Widening Participation Officer for CGES

Office Hours:

Tuesdays 4pm-5pm

Thursdays 10am-11am

Modules

2018/19


Supervision / Group

Postgraduate researchers

  • John Bruun
  • Tobias Friedrich Ehmen PhD student in Seismic Oceanography
  • Daniel Ford (biological control of net community production and atmosphere-ocean gas exchange)
  • Hannah Green (satellite observations of Ocean Acidification in the Arctic)
  • Andrea Rochner
  • Wuxin Xiao Xiao PhD student in Seismic Oceanography

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