|| PH39010 |
|| IONISED ATMOSPHERE |
|| 2001/2002 |
|| Dr Eleri Pryse |
|| Semester 2 |
|| Dr James Whiteway, Professor Shadia Habbal |
|| PH29010 , Core Physics Modules at Level 2 |
| Course delivery
|| Seminars / Tutorials || 2 seminars/tutorials |
|| Lecture || 20 lectures |
|| Exam || 2 Hours end of semester examination for BSc students || 100% |
|| Exam || 3 Hours end of semester examination for MPhys students || 100% |
The presence of ionisation in the upper atmosphere was postulated to account for long distance radio wave propagation. Subsequent research established the existence of the ionised atmosphere and investigated its morphology. Active research continues to study ionospheric behaviour, in particular at high latitudes where the aurorae are a spectacular optical manifestation of incoming particles from space.
The morphology of the ionosphere is described, the production and loss processes of ionisation under normal conditions are explained, and the effects of neutral winds and electric fields are considered. An introduction is given to the influence of the ionosphere on radiowaves. The high latitude ionosphere is decribed in terms of magnetosphere processes mapped down the geomagnetic field.
After taking this module students should be able to:
understand the general behaviour of the ionosphere under normal conditions
outline the principles of propagation of radiowaves in an ionised medium
explain the behaviour of the high latitude ionosphere in terms of the mapping of magnetospheric processes
Introduction: The ionosphere at mid and low latitudes: D, E and F regions, ionisation production and loss mechanisms, Chapman layers. Observed behaviours of the mid latitude ionosphere and the equatorial ionosphere. Motions of charged particles: effects of the neutral-air wind electric field.
Radiowave Propagation: Plasma frequency, gyrofrequency, Debye length, phase velocity, group velocity, refractive index. Applications of the Appleton-Hartree equation, ionosondes, trans-ionospheric propagation.
The High-Latitude Ionosphere and the Magnetosphere: the high-latitude ionosphere as a map of processes in the magnetosphere; the precipitation of energetic particles and the aurora; magnetospheric electric fields and the eastward and westward electrojets; megnetic perturbations in the auroral zone.
** Reference Text
Radio Techniques for Probing the Terrestrial Ionosphere. Springer-Verlag ISBN 354052830X
The Solar-terrestrial Environment. Cambridge University Press ISBN 0521327482
Ionospheric Radio. Peter Peregrinus Ltd. for IEE ISBN 086341186X
M.G. Kivelson and C.T. Russell (Eds).
An Introduction to Space Physics. Cambridge University Press ISBN 0521457149