Module Identifier PH39010  
Module Title IONISED ATMOSPHERE  
Academic Year 2002/2003  
Co-ordinator Dr Eleri Pryse  
Semester Semester 2  
Other staff Professor Shadia R Habbal  
Pre-Requisite PH29010 , Core Physics Modules at Level 2  
Course delivery Seminars / Tutorials   2 seminars/tutorials  
  Lecture   20 lectures  
Assessment Semester Exam   2 Hours end of semester examination for BSc students   100%  
  Semester Exam   3 Hours end of semester examination for MPhys students   100%  

Learning outcomes

After taking this module students should be able to:

Brief description

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.

Content

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.

Reading Lists

Books
** Reference Text
R.D. Hunsucker. Radio Techniques for Probing the Terrestrial Ionosphere. Springer-Verlag
J.K. Hargreaves. The Solar-terrestrial Environment. Cambridge University Press
K. Davies. Ionospheric Radio. Peter Peregrinus Ltd. for IEE
M.G. Kivelson and C.T. Russell (Eds). An Introduction to Space Physics. Cambridge University Press