Hostname: page-component-78c5997874-4rdpn Total loading time: 0 Render date: 2024-11-19T07:35:41.876Z Has data issue: false hasContentIssue false

MHD mode conversion in a stratified atmosphere

Published online by Cambridge University Press:  01 September 2007

A. M. Dee McDougall
Affiliation:
School of Mathematics and Statistics, University of St Andrews, St Andrews, KY16 9SS, UK email: [email protected]
Alan W. Hood
Affiliation:
School of Mathematics and Statistics, University of St Andrews, St Andrews, KY16 9SS, UK email: [email protected]
Rights & Permissions [Opens in a new window]

Abstract

Core share and HTML view are not available for this content. However, as you have access to this content, a full PDF is available via the ‘Save PDF’ action button.

Mode conversion in the region where the sound and Alfvén speeds are equal is a complex process, which has been studied both analytically and numerically, and has been seen in observations. In order to further the understanding of this process we set up a simple, one-dimensional model, and examine wave propagation through this system using a combination of analytical and numerical techniques. Simulations are carried out in a gravitationally stratified atmosphere with a uniform, vertical magnetic field for both isothermal and non-isothermal cases. For the non-isothermal case a temperature profile is chosen to mimic the steep temperature gradient encountered at the transition region. In all simulations, a slow wave is driven on the upper boundary, thus propagating down from low-β to high-β plasma across the mode-conversion region. In addition, a detailed analytical study is carried out where we predict the amplitude and phase of the transmitted and converted components of the incident wave as it passes through the mode-conversion region. A comparison of these analytical predictions with the numerical results shows good agreement, giving us confidence in both techniques. This knowledge may be used to help determine wave types observed and give insight into which modes may be involved in coronal heating.

Type
Contributed Papers
Copyright
Copyright © International Astronomical Union 2008

References

Cairns, R.A. & Lashmore-Davies, C.N. 1983, Phys. Fluids 26, 1268CrossRefGoogle Scholar
Cally, P.S. 2001, ApJ 548, 473Google Scholar
Ferraro, V.C.A. & Plumpton, C. 1958, ApJ 127, 459CrossRefGoogle Scholar
McDougall, A.M.D. & Hood, A.W. 2007, Solar Phys. in pressGoogle Scholar
McLaughlin, J.A. & Hood, A.W. 2006, A&A 459, 641Google Scholar
Zhugzhda, Y.D. 1979, Soviet Astron. 23, 42Google Scholar
Zhugzhda, Y.D. & Dzhalilov, N.S. 1981, Soviet Astron. 25, 477Google Scholar
Zhugzhda, Y.D. & Dzhalilov, N.S. 1982, A&A 112, 16Google Scholar