Prof Tim Yeoman
Professor of Magnetospheric Physics
B.Sc. (Bristol), D.Phil (York)
Tel: 0116 252 3564
Office: Room F67, Physics and Astronomy
Miscellaneous links I find useful related to teaching and research can be found on my research group homepage
Professor Yeoman graduated from the University of Bristol in 1985, and went on to the University of York, gaining a D.Phil. in the Physics of Ultra Low Frequency waves observed in the Earth's magnetosphere in 1988. He Joined the University of Leicester as a PDRA that year, and joined the Academic staff here as a Lecturer, in 1992. He was promoted to Reader in 2000, and was awarded a personal Chair in Magnetospheric Physics in 2007. He became Academic Director of the College of Science and Engineering in 2013.
My research centres on the analysis and interpretation of data from spacecraft particle and field instruments and ground-based magnetometer and ionospheric radar data. Current research activities include:
Ultra low frequency (ULF) waves are an important coupling mechanism between the magnetosphere and the ionosphere since they transfer both energy and momentum. These processes are most significant in the high-latitude ionosphere, where the magnetosphere-ionosphere interaction is strongest. The waves also act as an important diagnostic of magnetospheric morphology and dynamics. High frequency radio experiments, such as SuperDARN and spacecraft such as Cluster are providing exciting new information on ULF waves.
Dynamic spectra of ULF waves observed on Cluster. Waves generated upstream of the bow shock can be seen in the field-aligned magnetic field component. These drive a harmonic series of Alfvén waves seen in the azimuthal component (from publication (3) below).
Solar wind-magnetosphere coupling
The large scale transport of mass, momentum and energy into the Earth's magnetosphere-ionosphere system from the solar wind is mainly controlled by processes at the dayside magnetopause in the cusp region. These processes cause transient flows in the high latitude ionosphere, which can be studied with the SuperDARN radars, and auroral emissions which may be imaged from the ground, or by space-borne auroral imagers.
High spectral width backscatter from SuperDARN is used to track the equatorward motion of the footprint of the cusp region during dayside reconnection. Wave power in nearby magnetometers is strongly related to the proximity of the cusp (from publication (2) below).
Much of the energy which enters the Earth's magnetosphere through processes at the dayside magnetopause is eventually released into the nightside upper atmosphere through magnetospheric substorm processes. High frequency (HF) ionospheric radars have proved to be a powerful technique for investigating the spatial and temporal development of the ionospheric conductivities and electric fields during the three phases of the magnetospheric substorm. New, multi-instrument studies are providing a new set of opportunities for understanding the complex dynamics of the nightside magnetosphere.
Following substorm onset, waves are generated through collisionless wave-particle interactions by westward drifting energetic ions and eastward drifting energetic electrons (from publication (1) below).
Teaching activities, 2015-16:
- PA2240 Electromagnetic Fields
- Opt. 3672 Planetary Plasma Environments
I also regularly offer Pair Projects in the 3rd year, and Specialist Research Projects and Advanced Study project in the 4th year.
Details of teaching materials from past and present courses can be found here
As college Academic Director I sit on a number of University committees and working groups. These include:
- University Court and Senate
- Academic Policy Committee
- College of Science and Engineering Academic Committee (Chair)
- College of Science and Engineering Management Board
- College of Science and Engineering Business Group
- Student Experience Enhancement Group
- Fee Setting and Programme Development Committee
- QAA Higher Education Review Working Group
- Assessment Regulations Review Group
- Grade Point Average Working Group
- Distance Learning Advisory Group
- James, M. K., T. K. Yeoman, P. N. Mager, and D. Y. Klimushkin (2013), The spatio-temporal characteristics of ULF waves driven by substorm injected particles, J. Geophys. Res.: Space Physics., 118, 1737–1749, http://dx.doi.org/10.1002/jgra.50131.
- Yeoman, T. K., D. M. Wright, M. J. Engebretson, M. R. Lessard, V. A. Pilipenko, and H. Kim (2012), Upstream generated Pc3 ULF wave signatures observed near the Earth’s cusp, J. Geophys. Res., 117, A03202,http://dx.doi.org/10.1029/2011JA017327.
- Clausen, L. B. N., T. K. Yeoman, R. C. Fear, R. Behlke, E. A. Lucek, and M. J. Engebretson, (2009) First simultaneous measurements of waves generated at the bow shock in the solar wind, the magnetosphere and on the ground, Ann. Geophys., 27, 357–371, http://dx.doi.org/10.5194/angeo-27-357-2009.
- Chisham, G., T. K. Yeoman, and G. J. Sofko, (2008) Mapping ionospheric backscatter measured by the SuperDARN HF radars – Part 1: A new empirical virtual height model, Ann. Geophys., 26, 823–841, http://dx.doi.org/10.5194/angeo-26-823-2008