Sandhu, JK;
Yeoman, TK;
Rae, IJ;
Fear, RC;
Dandouras, I;
(2017)
The Dependence of Magnetospheric Plasma Mass Loading on Geomagnetic Activity Using Cluster.
Journal of Geophysical Research: Space Physics
, 122
(9)
pp. 9371-9395.
10.1002/2017JA024171.
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Abstract
Understanding changes in the magnetospheric mass density during disturbed geomagnetic conditions provides valuable insight into the dynamics and structure of the environment. The mass density plays a significant role in a variety of magnetospheric processes, such as wave propagation, magnetic reconnection rates and radiation belt dynamics. In this study, the spatial variations of total plasma mass density are explored through the analysis of Cluster observations. Data from the WHISPER (Waves of High frequency and Sounder for Probing of Electron density by Relaxation) and CODIF (ion Composition and Distribution Function analyser) instruments, on board the four Cluster spacecraft for a time interval spanning 2001 - 2012, are used to determine empirical models describing the distribution of the total plasma mass density along closed geomagnetic field lines. The region considered covers field lines within 5.9≤L < 9.5, corresponding to the outer plasmasphere, plasmatrough, and near-Earth plasma sheet. This study extends previous work to examine and quantify spatial variations in the electron density, average ion mass, and total plasma mass density with Dst index. The results indicate that during periods of enhanced ring current strength, electron density is observed to decrease and average ion mass is observed to increase, compared with quiet geomagnetic conditions. The combination of these variations show that although heavy ion concentration is enhanced, the decrease in plasma number density results in a general decrease in total plasma mass density during disturbed geomagnetic conditions. The observed decrease in mass density is in contrast to prevailing understanding and, due to the dependence of the Alfvén speed on mass density, has important implications for a range of plasma processes during storm time conditions (e.g. propagation of wave modes).
| Type: | Article |
|---|---|
| Title: | The Dependence of Magnetospheric Plasma Mass Loading on Geomagnetic Activity Using Cluster |
| Open access status: | An open access version is available from UCL Discovery |
| DOI: | 10.1002/2017JA024171 |
| Publisher version: | http://dx.doi.org/10.1002/2017JA024171 |
| Language: | English |
| Additional information: | ©2017. The Authors. This is an open access article under the terms of the Creative Commons Attribution License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited. |
| Keywords: | Mass Density; Ion Composition; Cluster; Geomagnetic Storms; CODIF; WHISPER |
| UCL classification: | UCL UCL > Provost and Vice Provost Offices > UCL BEAMS UCL > Provost and Vice Provost Offices > UCL BEAMS > Faculty of Maths and Physical Sciences UCL > Provost and Vice Provost Offices > UCL BEAMS > Faculty of Maths and Physical Sciences > Dept of Space and Climate Physics |
| URI: | https://discovery.ucl.ac.uk/id/eprint/1572225 |
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