Diurnal variations in global Joule heating morphology and magnitude due to neutral winds

Billett, D. D. and Grocott, A. and Wild, J. A. and Walach, M.-t. and Kosch, M. J. (2018) Diurnal variations in global Joule heating morphology and magnitude due to neutral winds. Journal of Geophysical Research: Space Physics, 123 (3). pp. 2398-2411. ISSN 2169-9402

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Abstract

In the polar ionosphere, variations in Joule heating are significantly controlled by changes in plasma convection, such as that brought about by changes in the interplanetary magnetic field (IMF). However, another important consideration when calculating Joule heating is the velocity difference between this plasma and the neutral thermosphere co-located with the ionosphere. Neutral wind data is often difficult to obtain on a global scale, thus Joule heating has often previously been calculated assuming that neutral velocities are small and can therefore be neglected. Previous work has shown the effect of neutral winds on Joule heating estimations to be more significant than originally thought, however, the diurnal variations of the neutrals due to changes in solar pressure gradients and Coriolis forces have yet to have their impact on Joule heating assessed. We show this universal time (UT) effect to be significant in calculating Joule heating, and thus can differ significantly from that calculated by neglecting the neutrals. In this study, we use empirical models for the neutral wind, conductivities and magnetic field to create northern hemispheric patterns of Joule heating for approximately 800,000 individual plasma convection patterns generated using data from the Super Dual Auroral Radar Network (SuperDARN). From this, a statistical analysis of how Joule heating varies in morphology and magnitude with UT is shown for differing seasons and levels of geomagnetic activity. We find that neutral winds do play a significant role in the morphology and total energy output of Joule heating.

Item Type: Journal Article
Journal or Publication Title: Journal of Geophysical Research: Space Physics
Subjects:
Departments: Faculty of Science and Technology > Physics
ID Code: 123882
Deposited By: ep_importer_pure
Deposited On: 07 Mar 2018 10:20
Refereed?: Yes
Published?: Published
Last Modified: 21 Feb 2020 04:03
URI: https://eprints.lancs.ac.uk/id/eprint/123882

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