nerc.ac.uk

Climatology of the Auroral Electrojets derived from the Along-Track Gradient of Magnetic Field Intensity measured by POGO, Magsat, CHAMP, and Swarm

Smith, A.R.A.; Beggan, C.D.; Macmillan, S.; Whaler, K.A.. 2017 Climatology of the Auroral Electrojets derived from the Along-Track Gradient of Magnetic Field Intensity measured by POGO, Magsat, CHAMP, and Swarm. Space Weather. 10.1002/2017SW001675

Before downloading, please read NORA policies.
[img]
Preview
Text (Open Access Paper)
Smith_et_al-2017-Space_Weather.pdf - Published Version
Available under License Creative Commons Attribution 4.0.

Download (5MB) | Preview

Abstract/Summary

The auroral electrojets (AEJs) are complex and dynamic horizontal ionospheric electric currents which form ovals around Earth’s poles, being controlled by the morphology of the main magnetic field and the energy input from the solar wind interaction with the magnetosphere. The strength and location of the AEJ varies with solar wind conditions and the solar cycle but should also be controlled on decadal timescales by main field secular variation. To determine the AEJ climatology, we use data from four polar Low Earth Orbit magnetic satellite missions: POGO, Magsat, CHAMP, and Swarm. A simple estimation of the AEJ strength and latitude is made from each pass of the satellites, from peaks in the along-track gradient of the magnetic field intensity after subtracting a core and crustal magnetic field model. This measure of the AEJ activity is used to study the response in different sectors of magnetic local time (MLT) during different seasons and directions of the interplanetary magnetic field (IMF). We find a season-dependent hemispherical asymmetry in the AEJ response to IMF By, with a tendency toward stronger (weaker) AEJ currents in the north than the south during By>0 (By<0) around local winter. This effect disappears during local summer when we find a tendency toward stronger currents in the south than the north. The solar cycle modulation of the AEJ and the long-term shifting of its position and strength due to the core field variation are presented as challenges to internal field modelling.

Item Type: Publication - Article
Digital Object Identifier (DOI): 10.1002/2017SW001675
NORA Subject Terms: Earth Sciences
Date made live: 23 Oct 2017 12:02 +0 (UTC)
URI: http://nora.nerc.ac.uk/id/eprint/518079

Actions (login required)

View Item View Item

Document Downloads

Downloads for past 30 days

Downloads per month over past year

More statistics for this item...