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Ruth Mugford

Research Associate

Ruth's research is numerical modelling of permafrost in the Arctic with the aim to understand the spatial and temporal changes that have been occurring due to climate warming.

Previously, Ruth worked as a Postdoc at the Environmental Systems Science Centre, University of Reading on the International Polar Year (IPY) Programme Arctic Synoptic Basin-wide Oceanography (ASBO), which aims to determine the origin of the excess freshwater observed in the North Atlantic and Nordic seas over the last five decades.

Biography

Ruth studied for her PhD at the Scott Polar Research Institute, University of Cambridge from January 2004-2008, which involved developing a computer model of sediment delivery from tidewater glaciers to the marine environment, where iceberg-rafting and glacial meltwater plumes are the two main processes of sediment transport.

Ruth studied Physics with Astrophysics from 1999-2003 at the University of Leeds. Here she discovered and developed her interest in environmental and geophysical applications of physics.

She went on a six month ERASMUS exchange to Aarhus in Denmark during her third year, where she completed a research project "Simulating the surface of Mars". This involved a number of experiments, such as using a low-pressure wind tunnel to simulate dust storms on Mars in order to study the electrical properties of Mars analogue dust, and studying the effect of the Martian low atmospheric pressure and Solar UV radiation on water versus heat diffusion through Mars analogue soil.

When she returned to Leeds in her fourth year, her final year extended project was "Modelling the Cosmic Ray Flux at the International Space Station" and involved writing a computer program to trace the movement of cosmic rays in the Earth's magnetic field in order to calculate their flux at the orbit of the ISS.

During her gap year from 1998-9, and during her summer holidays from 2000-2002, Ruth worked in the Space Department at QinetiQ (formerly DERA), in Farnborough. She was involved in a number of projects during this time including: processing and analysing data from the CREAM (Cosmic Radiation Environment and Activation Monitor) passive detectors and CREDO (Cosmic Radiation Environment Dosimetry) experiments, which measure inner belt proton, cosmic ray and solar particle activity in the near Earth environment; micrometeoroids and whether they could be responsible for electrical discharges and subsequent anomalies on spacecraft; and characterising Hall-Effect thruster cathodes in the Ion Propulsion group.

Qualifications

Research

Modelling

Ruth's current research is numerical modelling of permafrost in the Arctic with the aim to understand the spatial and temporal changes that have been occurring due to climate warming.

From February 2008 to May 2009, Ruth worked as a Postdoc at the Environmental Systems Science Centre, University of Reading on the International Polar Year (IPY) Programme Arctic Synoptic Basin-wide Oceanography (ASBO), which aims to determine the origin of the excess freshwater observed in the North Atlantic and Nordic seas over the last five decades, with the specific objectives to:

She was using the NEMO 1/4 degree global ice-ocean model to investigate the seasonal and interannual variability of ocean temperature, salinity and circulation and sea ice properties in the Arctic Ocean, as well as to quantify the heat and freshwater exchanges around the Arctic basin. The NEMO 1/4 degree model has eddy-permitting resolution and in the Arctic the grid is approximately 12 km. The version of NEMO that is run at ESSC includes a data assimilation scheme, which is implemented on depth, temperature and salinity surfaces in the Arctic. The model incorporates in-situ oceanographic observations and Ruth studied how assimilation improves the accuracy of the model.

During Ruth's PhD research, she wrote computer programs to simulate sediment delivery by glacial processes to the marine environment. This type of computer program is termed a stratigraphic simulation model (SSM) and they are able to predict the impact of sedimentary processes with time. SSMs are useful to better understand the behaviour of the Earth system and for testing the effect of different environmental conditions. One of the current leading SSMs is Sedflux, developed by The Delta Force at the Institute of Arctic and Alpine Research (INSTAAR), University of Colorado. SEDFLUX combines individual process-response models into one fully interactive model, to deliver a range of sediment grain sizes onto and across a continental margin. At present it solely considers sediment delivered by rivers and does not include routines for glaciated margins. One aim of Ruth's PhD was to integrate additional routines into Sedflux to simulate the processes that occur in a glaciated fjord leading to sediment accumulation. This is now happening as part of the Community Surface Dynamics Modeling System (CSDMS).

Ruth developed numerical models of the two dominant sediment transport processes from tidewater glaciers to the marine environment: iceberg-rafting and glacial meltwater plumes. In particular, the numerical methods she applied were:

  1. Monte Carlo based techniques to simulate deposition from icebergs.
  2. Numerical solution to a system of non-linear ordinary differential equations to model deposition from glacial meltwater plumes.

The SedBerg model simulates the formation, drift and melt of a population of icebergs. Underlying the model are a number of parametric probability distributions to describe the stochastic behaviour of iceberg formation and dynamics. Parametric values of the probability density functions are found using maximum likelihood estimation from field observations.

The SedPlume model utilises an integral model formulation for the conservation of volume, momentum, buoyancy and sediment mass along the path of the plume, which results in a set of coupled first-order differential equations. When the plume reaches the surface, it is treated as a radially spreading surface gravity current, for which exact solutions exist for the mass flux of sediment deposited.

The programs were tested against field observations of sedimentation rates. One of the case studies for the iceberg model was Kangerdlugssuaq Fjord in South East Greenland, where a major outlet glacier draining the Greenland ice sheet terminates, which has undergone dramatic acceleration and thinning in recent years. Ruth took part in a fieldwork cruise to the area in 2004 on R.R.S. James Clark Ross collecting a suite of geophysical and oceanographic data. The sedimentation rate due to iceberg rafting has been modelled for Kangerdlugssuaq fjord over the last 1500 years. Climatic, oceanographic and glacial conditions were estimated from a combination of the data collected in 2004, other present day measurements and values inferred from the sedimentary and foraminiferal records.

Fieldwork

Ruth has taken part in the following ship-based field work in the Arctic during her PhD and Postdoc:

Publications

Selected publications

External activities