Geophysics/Meteorology Honours Projects 2014-2015 Course organiser: David Stevenson ([email protected]), Crew 314 Course secretary: Ken O’Neill ([email protected]), Grant 332 This document lists the projects on offer for senior honours (4 th year) students registered on the Geophysics/Geophysics and Geology/Geophysics and Meteorology programs. The meteorology projects (and potentially some of the others too) are also on offer to Physics with Meteorology students (if Physics with Met students are unsure whether projects are suitable, they should contact the course organiser (CO)/primary supervisor). If you are interested in a particular project, please contact the main supervisor to discuss what is involved in more detail. You need to choose a project and also a second choice (and third choice, etc., if possible), for each semester (Semester two (S2) choices can be revised later). In some cases you won’t be able to do your first choice (for example if it is chosen by multiple people, and the supervisor cannot run several variants of the same project). If you don’t get your first choice, we will try and make sure you do get your first choice in the other semester. Where projects are over- subscribed, the decision of the CO (generally in consultation with the supervisor) will be final. Any projects/combinations of projects can be taken, irrespective of whether you are a Geophysics or a Geophysics and Meteorology/Geology student. Project choices for S1 (and provisional choices for S2) should be emailed to the CO (email address above) by Tuesday in Week one (16 th Sept), and finalised allocations will be made by the end of Week one (19 th Sept) so that you have sufficient time to fully tackle projects. Students can propose their own projects, but will need to identify a suitable supervisor (normally amongst the geophysics/meteorology staff), and convince that supervisor and the CO that the project is sensible and feasible. Students should do this as soon as possible, to fit with the above timetable. Projects listed here are a mixture of one semester, 20-credit projects, and two semester, 40-credit projects. In some cases, 20-credit semester one projects can be extended to be 40-credit projects. If students wish to extend their semester one project, they will need to get the supervisor’s and the CO’s agreement, before week seven of S1. Single semester projects should typically be 20-25 pages A4 (and a maximum of 30 pages - including all diagrams, references and appendices; 12 point font, 2.5cm margins, 1.0 line spacing, space between paragraphs); Two semester projects should typically be 40-50 pages (maximum 60 pages). Projects should be spiral bound (e.g., at JCMB copy shop). Students doing 40-credit projects also need to hand in an interim report – this will be marked and you will be given feedback, as for 20-credit projects. The mark for the interim report makes up 25% of the overall mark (this is new for 2014/15). Projects are independently marked by the primary supervisor and one other staff member, using the criteria laid out on the mark sheets, see: http://xweb.geos.ed.ac.uk/~dstevens/teaching/GP_Projects_marking_protocol.pdf. Hand in S1 project reports and 40-credit interim reports by 12 noon on Tuesday January 13 th 2015. Hand in S2 project reports and 40-credit final reports by 12 noon on Friday April 4 th 2015. As part of the introduction to year four (S1, Week 0) projects will be introduced by the CO, along with examples of good (and bad) practice in how students should tackle their projects, including writing them up. It is up to students to contact potential project supervisors to discuss projects (supervisor’s contact details should be included in the project descriptions). If supervisors cannot be contacted, please let the CO know.
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In the middle of S2 (during ‘Innovative Learning Week’), students will be expected to give a short
presentation on their semester one project, or, if they are doing a single 40-credit project, on that.
This presentation will not count towards your final project mark, but does contribute 20% towards
the final mark on the ‘Transferable Skills for Geophysicists’ course.
How thick is the ionosphere? Computing density from induction coil data and
ionosonde measurements
Ciarán Beggan [[email protected]] (British Geological Survey) and Kathy Whaler (School of GeoSciences)
Induction coils measure small and very
rapid changes of the magnetic field. A set of
induction coils at the Eskdalemuir
observatory record magnetic field changes
over a frequency range of 0.1—10 Hz,
which encompasses geophysical wave
phenomena related to the conductive upper
atmosphere (called the ionosphere). The
ionosphere can act as a partial ‘barrier’
which electromagnetic (EM) waves can
bounce off, become trapped in and resonate
back and forwards for a short time. The so-
called Schumann resonances (trapped
between the Earth’s surface and the bottom
of the ionosphere) and Ionospheric Alfvén
Resonances (trapped between the bottom
and the top of the ionosphere) are two such
examples. However, to observe these
phenomena, we have to look in the frequency
domain of the measured magnetic time-series.
In spectrogram plots (i.e. a plot of the energy at a particular frequency versus time), the Ionospheric
Alfvén Resonances are observed as a set of 4-12 fringes, occurring during local night time and
disappearing during the daylight hours. Their behaviour and occurrence in frequency (f) and the
difference in frequency between fringes (∆f) varies throughout the year. Figure 1 gives an example
spectrogram showing what the resonances look like and when they occur (overlain with dotted lines).
Research has shown that the frequency interval (∆f) between the fringes is related to the density of the
upper atmosphere – a ‘thinner’ atmosphere allows the EM waves to propagate more quickly, leading
to wider frequency intervals. As an added bonus, it turns out that if we measure another property of
the ionosphere (from an instrument called an ionosonde1) we can quantify these relationships exactly
and infer the density (e.g. Hebden et al., 2005). A new method of automatic detection based on signal
and image processing techniques has been developed to identify the fringes and to quantify the values
of ∆f. Previously, this required manual identification of the fringes every day. Figure 1 shows an
example of the detected fringes in the spectrogram (Beggan, 2014).
The project will look at two years of induction coil data from Eskdalemuir and use the automatic
detection code to produce hourly values of ∆f, which will be combined with hourly values of the
Chiltern ionosonde data, to compute various ionospheric parameters such as density, cavity length and
wave velocity and see how they vary seasonally and annually. The student will be required to process
time-series data from a number of different data sets, to produce a small piece of comparison code and
to plot the data in a suitable format. The project will use Matlab to process and plot the data.
References:
[1] Beggan, C., Automatic detection of Ionospheric Alfvén Resonances using signal and image processing techniques, Annales
Geophysicae, in press, 2014
[2] Hebden, S. R., Robinson, T. R., Wright, D. M., Yeoman, T., Raita, T., and Bosinger, T.: A quantitative analysis of the diurnal evolution
of Ionospheric Alfvén resonator magnetic resonance features and calculation of changing IAR parameters, Annales Geophysicae, 23, 1711–
1721, 2005
1Ionosondes are essentially radio transmitters that record values related to the reflectance of the mid-ionosphere at the 5.4MHz radio or foF2 frequency – in the UK there is an instrument at Chiltern. http://www.ukssdc.ac.uk/ionosondes/ionosondes.html
Figure 1: A spectrogram (energy at each frequency over
time) of induction coil data for 14 Feb 2014. The width
between the black dotted lines (∆f) gives information
about the density of the ionosphere (from Beggan, 2014).
Seismicity is an important tool for understanding the physical processes occurring at
depth within the Earth. In northern Iceland, large numbers of earthquakes are recorded
on the local seismic monitoring network, and provide an opportunity to study the
complex interactions between magmatism and faulting in this rift-transform system.
The earthquake catalogue is influenced both by natural processes and those associated
with the monitoring network. Winters are harsh in this part of the world, and storms
can reduce the magnitude detection threshold – unpicking these monitoring effects
from natural processes is important to avoid artefacts. This project will look at the
seasonal properties of the earthquake catalogue in northern Iceland, using established
Python routines to determine magnitude completeness thresholds and seismic “b-
values”. It will develop a “best-practice” methodology for managing these effects
when undertaking more complex analyses.
.
Figure 2: Locations of earthquakes in N Iceland (left) and magnitudes of earthquakes in this
region 2012-2014 (right).
References:
Woessner, J., and S. Wiemer, 2005, Assessing the Quality of Earthquake Catalogues: Estimating the Magnitude of Completeness and Its Uncertainty: Bulletin of the Seismological Society of America, v. 95, p. 684-698.
Weimer, S., and M. Wyss, 2000, Minimum Magnitude of Completeness in Earthquake Catalogs: Examples from Alaska, the Western United States, and Japan: Bulletin of the Seismological Society of America, v. 90, p. 859-869.
Footprint of the South Asian monsoon on African climate
Supervisors: Massimo Bollasina ([email protected]), Simon Tett, and Gabi Hegerl
20 credits semester 1 or 2, or extendable to 40 credits across 2 semesters
South Asia is home to the immense South Asian monsoon, a key component of the global water and
energy cycles with profound worldwide influences. Its remarkable seasonal shift of precipitation is
the life-blood of more than 30% of the world’s population and their agrarian societies.
A link between the S. Asian monsoon and African climate is expected based on the underlying
dynamics: at lower levels, the African southwesterlies over the S. Atlantic reach the Horn of Africa
converging with the Somali jet in the western Indian Ocean. At upper levels, the tropical easterly jet
resulting from regional heating is one of the main characteristics of the African monsoon.
Many features of the above link are however still unclear, especially at subseasonal time scale. How
the link works in current and future climate, with rapidly varying emissions of greenhouse gases and
aerosols, has important implications for regional climate projections over Africa. In tackling this
question, a significant source of uncertainty is represented by internal climate variability, which is
the unforced component arising from internal processes.
This project will use data from the novel NCAR CESM Large Ensemble (LE) project to explicitly
identify the role of internal climate variability in the link between the S. Asian monsoon and African
climate for the recent past and the near future. The data consists of a 30-member ensemble of
1920-2080 experiments with a state-of-the-art global climate model.
This project involves data analyses and plotting, hence knowledge of programming in IDL, Matlab or
Python is highly desirable. More sophisticated utilities for reading, analysing and plotting the data
will be provided.
Figure 1: Difference in standardized rainfall anomalies between post- and pre- S. Asian monsoon onset
pentads. Positive anomalies are shaded. Figure from Camberlin et al. (2010).
Background reading:
Camberlin, P., B. Fontaine, S. Louvet, P. Oettli, and P. Valimba, 2010: Climate adjustments over Africa
accompanying the Indian monsoon onset. J. Climate, 23, 2047–2064.
Kay, J. E., and coauthors, 2014: The Community Earth System Model (CESM) Large Ensemble Project: A
Community Resource for Studying Climate Change in the Presence of Internal Climate Variability. Bull. Amer.
Capturing and injecting CO2 in depleted oil/gas reservoirs has been recognised as a poten-tially significant contribution to reducing carbon emissions. CCS projects have been runningfor some time but they have yet to be implemented at larger scales. Before they are, oneneeds to establish the safety and feasibility of such projects.
To that end, seismic imaging has being used extensively to monitor the mobility of CO2 ininjection fields. One of the most well-studied fields is the Sleipner filed in the North Sea andthis project will utilise time-lapse data from this field to deduce correlations between seismicattenuation and CO2 saturation.
In rock physics theory, such a correlation should be observed and indeed some of thepreliminary results from the Sleipner field are encouraging (Figure 1).
For this project you will be using an appropriate spectral method implemented in MAT-LAB (or a language of your choice) to estimate seismic attenuation. You will apply thismethod to estimate Q from pre-stack data for two di↵erent year vintages obtained in theSleipner field and, finally, you will use appropriate rock physics models to interpret your re-sults.
SuperBin 1
SuperBin 2
3800 3850 3900
3100
3200
3300
Inline
Crossline
1994
SuperBin 1
SuperBin 2
3800 3850 3900
3100
3200
3300
Inline
Crossline
2010
AVO Intercept
0 20 40 60 80 100
Figure 1: Q estimation has been done for the two superbins for each of the years shown. Thepicture on the left shows AVO attributes pre CO2 injection while the one on the right after.The estimated Q for each superbin di↵ers greatly for the superbin within the CO2 saturatedarea whereas the Q estimate for superbin 1 remains unchanged.
Does the jet stream position strongly influence our weather?
Supervisors: Ruth Doherty ([email protected]), Simon Tett, 20 credits semester 1 or 2.
The jet stream is a narrow, variable band of very strong, predominantly westerly air currents
encircling the globe several miles above the earth. The location of the jet-stream determines
whether storms track over the UK or to the North or South and hence exerts a major role on
the weather we experience. Typically the jet-stream moves with the annual cycle of heating
northward in the summer1. However, the summer of 2010 was characterised by the “frozen
Jetstream” 2 which was in turn related to extreme weather events worldwide most notably
flooding in Pakistan and a heatwave in Russia. This year over the UK, the position of the jet-
stream has also received attention as its northward location led to heatwave conditions across
the UK3.
This project will use meteorological reanalyses data4 to define the jet stream and determine
its position and its variability over recent summers, and subsequently to examine its impact
on UK and European weather. This study will hence determine how strong the relationship is
between the variation in jet-stream position and temperature and rainfall across the UK and
Europe.
This project involves data analyses and plotting maps, hence some knowledge of
programming in IDL, Matlab or Python is desirable.
Figure 1: Description of the "Frozen Jetstream" in July 2010 and its effect on global weather2
The subduction of oceanic lithosphere transports water into the mantle (Fig. 1). The
concentration of water has significant effects on mantle properties such as melting
temperature, rheology, and electrical conductivities. Understanding of the mechanisms of
water circulation in the mantle will therefore provide vital information about how water is
related to the dynamics and evolution of the solid Earth. For water subduction, stability
relations of hydrous phases in subducting slabs are essential because they carry water
into the deep mantle. Such phase relations to the mantle transition zone (410-660 km
depth) were extensively studied while those in the lower mantle have been poorly
understood.
This project is aimed at elucidating the stability relations of the hydrous minerals and fluids
under lower mantle conditions. You will employ analyses of published experimental papers
and construct a phase diagram which is applicable to the lower mantle conditions. Results
of this project will contribute to our understanding of behaviour of water transported in the
deep Earth. Basic knowledge of petrology and chemical thermodynamics is beneficial.
References
Komabayashi, T. et al., (2004) Petrogenetic Grid in the System MgO-SiO2-H2O up to 30 GPa,
1600°C: Applications to Hydrous Peridotite Subducting Into the Earth’s Deep Interior.
Journal of Geophysical Research, 109, B03206, doi:10.1029/2003JB002651.
Nishi, M. et al., (2014) Stability of hydrous silicate at high pressures and water transport to the
deep lower mantle. Nature Geoscience, doi: 10.1038/NGEO02074
Observed variations in greenhouse gases and reactive trace gases in the background troposphere Paul Palmer ([email protected]) Single semester project The Global Atmosphere Watch (GAW) programme of the World Meteorological Organization is a partnership involving 80 countries, which provides reliable scientific data and information on the chemical composition of the atmosphere, its natural and anthropogenic change, and helps to improve the understanding of interactions between the atmosphere, the oceans and the biosphere. It collects data on greenhouse gases (CO2, CH4, CFCs, N2O, surface ozone, etc.) and related gases (CO, NOx, SO2, VOC, etc.). The GAW measurement stations tend to be located in remote geographical regions away from urban environments. The student will develop a set of robust statistical metrics that describe observed variations in gases at the GAW stations, and provide a scientific interpretation of results by understanding the sources, sinks, and resulting atmospheric lifetimes of the gases. The student will be responsible for selecting a collection of, possibly interrelated, gases from the available measurement suite. Ideal candidates will have knowledge of IDL or Python.
Title: The composition of the mesosphere using ground-based mm-wave remote sensing
The mesosphere, lying at altitudes between 50 and 80 km, is one of the least-understood regions of the
atmosphere. One way to study its composition is to use a millimetre-wave receiver (essentially a radio
telescope) sited on the ground (preferably on a high mountain). The spectra from such an instrument
can provide information on the mixing ratio of a variety of chemical species of interest. Recent
improvements in technology are permitting easier access to higher frequencies.
This, then, poses these questions: which species might one usefully measure with this technique? What
characteristics (bandwidth, resolution, noise level) would a spectrometer require in order to make the
measurement? How badly affected would the measurement be by a wet troposphere (and hence, how
high a mountain would you need)? The basic technique of the project is to simulate a measurement
using a readily-available radiative-transfer model (ARTS: see http://www.sat.ltu.se/arts) and apply the
standard techniques of inverse theory[1] to the simulation to determine what information the
measurements would contain. Several projects along these lines would be possible, to answer such
questions as:
Which of the various absorption lines of HCN is most suitable for sounding the mesosphere?
Is it possible to use ground-based sensing of HCl to track the chlorine loading of the middle
atmosphere?
Two years of measurements of the 230GHz carbon monoxide spectral line taken from the Norwegian Antarctic base using
the British Antarctic Survey’s microwave radiometer. The project was run in 2011-12 to study CO. If run again, it would
target different species.
These projects would probably be 20-point projects available in either semester. It would be suitable for
students on any physics or geophysics-based degree programme. The ARTS output would be analysed
using a data analysis language such as R, MATLAB, Octave or python/matplotlib. [1] Inverse Methods for Atmospheric Sounding: Theory and practice by Clive D. Rodgers (World Scientific, ISBN 981-02-
Single semester project, potentially extendible to two semesters.
The University of Edinburgh’s weather station, located on the top of the James Clerk Maxwell
Building, has been recording several meteorological variables near continuously at 1-minute
resolution since May 2006. One of these variables is the direct flux of solar radiation (Figure 1). This
flux follows an annual and diurnal variation due to the Earth’s rotation and orbit around the Sun that
is well understood, albeit with numerous subtleties2. However, deviations from this predictable
sinusoidally-varying behaviour occur due to atmospheric scattering, mainly from clouds (and also to
a lesser extent by aerosols). Scattering can either decrease or increase the measured direct solar flux
compared to the theoretical ‘clear-sky’ value.
Figure 1: Solar flux data from the JCMB weather station (August 6-13, 2013)1
The data can be analysed in several ways. The predicted clear-sky annual and diurnal variations can
be calculated and compared to the actual measurements. Daily measurements nearly always show
some cloud cover (this is Edinburgh after all!), but there are occasional completely clear days in the
record, and many almost clear days. These allow a direct comparison to the theoretical clear-sky
predictions. The scattering behaviour on cloudy days is also interesting, and can be expected to vary
with zenith angle (i.e. height of the Sun in the sky), and may also show some coherent diurnal
variation, and/or relationships with other measured variables. For example, we would expect to find
more cloud in afternoons, as convective cloud should peak when surface temperatures reach a
maximum. The student would be expected to test various hypotheses using the data.
This is a data analysis project, and will require high-level programming (e.g., MatLab, IDL, R or
similar).
References
1http://www.geos.ed.ac.uk/abs/Weathercam/station/latestweek.html [Accessed 13th August 2013] 2http://www.esrl.noaa.gov/gmd/grad/solcalc/calcdetails.html [Accessed 13th August 2013]