Dr Katy Sheen
Senior Lecturer in Physical Geography
Peter Lanyon A090
Peter Lanyon Building, University of Exeter, Penryn Campus, Treliever Road, Penryn, Cornwall, TR10 9FE, UK
Office hours: Monday 3-4 pm Tuesday 4-5 pm
Monday 3-4 pm
Tuesday 4-5 pm
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.
2010 PhD Earth Sciences (University of Cambridge)
2005 MSci in Natural Sciences (University of Cambridge)
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 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. 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 a to the Southern Ocean and Antarctica:
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.
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.
Using Seismic and Satellite Data to Characterize Oceanic Submesoscale Processes in a Boundary Region of High Eddy Kinetic Energy (NASA funding)
This project will investigate the role of small-scale processes (1-100 km) on mixing and distributing water masses in the Mozambique Channel. Thess scale dynamics are currently poorly understood or characterised in climate models, despite their potential importanct to ocean physics and biology. We will used a unqiue seismic acoustic dataset provided by Schlumberger Cambridge Research. This project is led by Dr. Kathy Gunn from the University of Miami.
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.
- 2020 NASA - National Aeronautics and Space Administration
Investigating submesoscale dynamics in cross-slope exchanges in the Mozambique channel using sesimic acoustic data. (Co-I)
- 2019 Met Office Hadley Centre
Met Office Hadley Centre funding grant: AMMA-2050 Expert Judgement of CMIP5 projected change in summer mean Sahel rainfall
Publications by category
Publications by year
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. These include:
GEO2475 (module convenor) - Physical Ocean Proceses. Second 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.
Isles of Scilly Field Trip (team taught)
Dissertation in Geography/Marine Science/Environmental Science
Widening Participation Officer for CGES
Supervision / Group
- Tobias Friedrich Ehmen PhD student in Seismic Oceanography
- Daniel Ford (biological control of net community production and atmosphere-ocean gas exchange)
- Andrea Rochner
- Daniel Wilson PhD student in modelling microplastic pathways in the Southern Ocean
- Wuxin Xiao Xiao PhD student in Seismic Oceanography