Research in this area will develop skills (computation, numerical analysis,
modelling, visualisation, data analysis, statistical techniques) which
are highly transferrable and attractive to employers.
Candidates will have the
opportunity to collaborate with experts at world class institutions with
whom I maintain ongoing research partnerships,
including Lockheed Martin and Stanford University.
My research is published in high-impact peer reviewed journals
such as the Astrophysical Journal, the premier US journal in the field.
You can achieve research at this level!
Bayesian prediction of solar flares
The largest solar flares produce hazardous "space weather" conditions near the
Earth. They appear to occur at random, but there are many indicators that
flares might occur. Can we combine these indicators to make a more accurate
forecast? What limits the predictability of flares? This project will apply
state-of-the-art techniques from Bayesian inference to these key problems.
Skills learnt: Markov chain Monte Carlo methods, Bayesian inference,
prediction methods, numerical methods, data
analysis, visualization techniques
References: Wheatland, M.S. 2005, A statistical solar flare forecast
method, Space Weather Vol. 3, No. 7, S07003 doi:10.1029/2004SW000131
(past work)
Computational modelling of quantum plasmas
Quantum plasmas may be modelled using a fluid description, based in
the simplest case on the Schrodinger and Poisson equations. The
quantum plasma model is applicable to ultrasmall electronic devices,
in which the de Broglie wavelength of the charge carriers is comparable
to the dimensions of the system. This has motivated recent intense
interest in this field in the literature. Although it is possible to
solve some simple quantum plasma problems analytically, in general
the fluid equations are intractable, and a numerical approach is
required. This project will investigate numerical solution of a number
of quantum plasma models. The initial focus will be on the solution
of a specific model for nonlinear waves (solitons) in a magnetised
quantum plasma. The project will involve computation and visualisation,
as well as analytical investigation.
Skills learnt: Programming, numerical methods, analytical
skills, visualization techniques
How well can we determine sunspot magnetic fields?
Intense magnetic fields in the vicinity of sunspots produce solar
flares. All three components of the magnetic field at the Sun's
surface may be determined from polarisation measurements of spectral
lines, leading to a map of the vector field across the surface (a
vector magnetogram). Recent data are provided by the Solar Optical
Telescope (SOT) on the satellite Hinode, and by the Vector
SpectroMagnetograph (VSM) at the US National Solar Observatory's
Synoptic Optical Long-term Investigations of the Sun (SOLIS)
facility. This project involves comparing vector magnetograms from
Hinode/SOT and SOLIS/VSM for the same sunspots.
Skills learnt: Programming, data analysis, numerical methods,
visualisation techniques
Megaflares!
In 1859 a gigantic solar flare erupted on the Sun, disabling telegraph
communications on the Earth (an entertaining account is given in
Stuart Clark's book The Sun Kings). Solar flares are magnetic
explosions in the solar atmosphere that affect our local
"space weather," producing dangerous energetic particle populations
and disruptive electrical current systems in our local space
environment. The "Carrington
flare" of 1859 is believed to have been the largest solar flare of
the last 150 years -- but how likely is another megaflare, and what
are the consequences? On the second question, a recent study
(Odenwald, Green, and Taylor 2006) suggests that a Carrington event
at the next solar maximum could incur US$70 billion in lost revenue.
Flare statistics can address the first question. In this project
techniques from Extreme Value Theory (Coles 2001) will be brought to
bear on historical satellite data, to assess the risk of another
Carrington event... or worse! The project involves programming, data
analysis, numerical methods, and the application of statistical
procedures including Bayesian methods.
Skills learnt: Programming, data analysis, numerical methods,
Bayesian methods, statistics
Revisiting the Aly-Sturrock conjecture
The Aly-Sturrock conjecture (Aly 1984, 1991; Sturrock 1991) states
that the maximum energy of a magnetic field configuration with
a given boundary flux distribution is the open field state. This
has consequences for our understanding of how coronal mass
ejections (large-scale expulsions of material from the Sun, which
appear to open the Sun's coronal magnetic field) operate, and has
been the subject of intense study. However, the question of the
validity of the conjecture remains open. In this project the
Aly-Sturrock conjecture will be revisited using a powerful nonlinear
force-free code, which allows calculation of test magnetic field
configurations with fixed boundary flux distributions but different
energies. A preliminary investigation suggests that nonlinear
force-free equilibria are obtained with the code up to energies
approaching the Aly-Sturrock limit. For greater energies, equilibria
are not obtained. This suggests that the conjecture is correct.
However, the question will be examined in detail in this project.
There is scope for theory, computation, and scientific visualisation.
Skills learnt: Programming, numerical methods, visualisation
techniques, analytical skills
Self-consistent force-free modelling of the magnetic field in
the Sun's corona
The magnetic field in the solar corona (the outer atmosphere
of the Sun) is the source of energy for solar flares, so there
is considerable interest in accurate numerical modelling of
this field from observations. The magnetic field at the
Sun's surface, the solar photosphere, may be determined based
on polarisation measurements of spectral lines, and in
principle this data provides boundary values for computational
modelling of the field in the corona. We also have an accurate
and simple model for the coronal field, the "nonlinear
force-free model." But, there is a complication! The boundary data
originate at a level in the atmosphere where the force-free model
does not strictly apply, and this has prevented accurate and robust
modelling. Recently, a new approach to solving this problem has
been developed. This project involves involve applying the new
approach to state-of-the-art solar data, to infer physical
parameters of solar active regions - for the first time!
Skills learnt: Plasma physics, parallel programming,
high-performance computing, numerical methods, spectral methods,
data analysis, visualization techniques
References: DeRosa et al. 2009, A critical assessment of
nonlinear force-free modelling of the solar corona for active
region 10953, Astrophysical Journal 696, 1780-1791
(past work)
Feel free to discuss these and other research opportunities
with me, in person or via e-mail.
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