Bibliography

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Found 27 entries in the Bibliography.

Showing entries from 1 through 27

2022

Transpolar Arcs: Seasonal Dependence Identified by an Automated Detection Algorithm

Transpolar arcs (TPAs) are auroral features that occur polewards of the main auroral oval suggesting that the magnetosphere has acquired a complicated magnetic topology. They are primarily a northward interplanetary magnetic field (IMF) auroral phenomenon, and their formation and evolution have no single explanation that is unanimously agreed upon. An automated detection algorithm has been developed to detect the occurrence of TPAs in UV images captured from the Special Sensor Ultraviolet Spectrographic Imager (SSUSI) instrument onboard the Defense Meteorological Satellite Program (DMSP) spacecraft, in order to further study their occurrence. Via this detection algorithm TPAs are identified as a peak in the average radiance intensity poleward of 12.5° colatitude, in two or more of the wavelengths/bands sensed by SSUSI. Using the detection algorithm for the years 2010 to 2016, over 5000 images containing TPAs are identified. The occurrence of these TPAs shows a seasonal dependence, with more arcs being visible in the winter hemisphere. The orbital plane of DMSP has been investigated as a possible explanation of the dependences in the results of the detection algorithm. For the spacecraft of interest this leads to a preferential observation of the northern hemisphere with the detection algorithm missing TPAs in the southern hemisphere around 01–06 UT. No seasonal bias has been found for these spacecraft. We discuss the ramifications of these findings in terms of proposed TPA generation mechanisms and suggest reasons for the seasonal dependence including it being a reflection of probability of seeing TPAs due to visibility.

Bower, G.; Milan, S.; Paxton, L.; Imber, S.;

Published by: Journal of Geophysical Research: Space Physics Published on:

YEAR: 2022 DOI: 10.1029/2021JA029743

auroras; magnetosphere; transpolar arc

Occurrence statistics of horse collar aurora

Bower, Gemma; Milan, Stephen; Paxton, Larry; Anderson, Brian;

Published by: Journal of Geophysical Research: Space Physics Published on:

YEAR: 2022 DOI:

Statistics of transpolar arcs identified by an automated detection algorithm

Bower, Gemma; Milan, Steve; Paxton, Larry; Imber, Suzie;

Published by: Published on:

YEAR: 2022 DOI:

Height-integrated polar cap conductances during an average substorm

Carter, Jennifer; Milan, Steven; Lester, Mark; Forsyth, Colin; Paxton, Larry; Gjerloev, Jesper; Anderson, Brian;

Published by: Published on:

YEAR: 2022 DOI:

Lobe Reconnection and Cusp-Aligned Auroral Arcs

Abstract Following the St. Patrick s Day (17 March) geomagnetic storm of 2013, the interplanetary magnetic field had near-zero clock angle for almost two days. Throughout this period multiple cusp-aligned auroral arcs formed in the polar regions; we present observations of, and provide a new explanation for, this poorly understood phenomenon. The arcs were observed by auroral imagers onboard satellites of the Defense Meteorological Satellite Program. Ionospheric flow measurements and observations of energetic particles from the same satellites show that the arcs were produced by inverted-V precipitation associated with upward field-aligned currents (FACs) at shears in the convection pattern. The large-scale convection pattern revealed by the Super Dual Auroral Radar Network and the corresponding FAC pattern observed by the Active Magnetosphere and Planetary Electrodynamics Response Experiment suggest that dual-lobe reconnection was ongoing to produce significant closure of the magnetosphere. However, we propose that once the magnetosphere became nearly closed complicated lobe reconnection geometries arose that produced interleaving of regions of open and closed magnetic flux and spatial and temporal structure in the convection pattern that evolved on timescales shorter than the orbital period of the DMSP spacecraft. This new model naturally explains many features of cusp-aligned arcs, including why they focus in from the nightside toward the cusp region.

Milan, S.; Bower, G.; Carter, J.; Paxton, L.; Anderson, B.; Hairston, M.;

Published by: Journal of Geophysical Research: Space Physics Published on:

YEAR: 2022 DOI: https://doi.org/10.1029/2021JA030089

2021

Field-Aligned Current During an Interval of BY-Dominated Interplanetary-Field; Modeled-to-Observed Comparisons

Carter, Jennifer; Samsonov, AA; Milan, Stephen; Branduardi-Raymont, Graziella; Ridley, Aaron; Paxton, Larry; Anderson, Brian; Waters, Colin; Edwards, Thomas;

Published by: Journal of Geophysical Research: Space Physics Published on:

YEAR: 2021 DOI:

Field-aligned current during an interval of $$\backslash$rm B\_ $\$Y$\$ $-dominated interplanetary-field; modeled-to-observed comparisons

Carter, Jennifer; Samsonov, Andrey; Milan, Stephen; Branduardi-Raymont, Graziella; Ridley, Aaron; Paxton, Larry; Anderson, Brian; Waters, Colin; Edwards, Thomas;

Published by: Earth and Space Science Open Archive ESSOAr Published on:

YEAR: 2021 DOI:

Transpolar arcs: Seasonal dependence identified by an automated detection algorithm

Bower, Gemma; Milan, Stephen; Paxton, Larry;

Published by: Earth and Space Science Open Archive ESSOAr Published on:

YEAR: 2021 DOI:

Dual-lobe reconnection and cusp-aligned auroral arcs

Milan, Stephen; Bower, Gemma; Carter, Jennifer; Paxton, Larry; Anderson, Brian; Hairston, Marc;

Published by: Published on:

YEAR: 2021 DOI:

2020

Aurora in the Polar Cap: A Review

This paper reviews our current understanding of auroral features that appear poleward of the main auroral oval within the polar cap, especially those that are known as Sun-aligned arcs, transpolar arcs, or theta auroras. They tend to appear predominantly during periods of quiet geomagnetic activity or northwards directed interplanetary magnetic field (IMF). We also introduce polar rain aurora which has been considered as a phenomenon on open field lines. We describe the morphology of such auroras, their development and dynamics in response to solar wind-magnetosphere coupling processes, and the models that have been developed to explain them.

Hosokawa, Keisuke; Kullen, Anita; Milan, Steve; Reidy, Jade; Zou, Ying; Frey, Harald; Maggiolo, Romain; Fear, Robert;

Published by: Space Science Reviews Published on: 02/2020

YEAR: 2020 DOI: 10.1007/s11214-020-0637-3

Bifurcated Region 2 Field-Aligned Currents Associated With Substorms

Sangha, H; Milan, SE; Carter, JA; Fogg, AR; Anderson, BJ; Korth, H; Paxton, LJ;

Published by: Journal of Geophysical Research: Space Physics Published on:

YEAR: 2020 DOI:

Height-Integrated Ionospheric Conductances Parameterized By Interplanetary Magnetic Field and Substorm Phase

Carter, JA; Milan, SE; Paxton, LJ; Anderson, BJ; Gjerloev, J;

Published by: Journal of Geophysical Research: Space Physics Published on:

YEAR: 2020 DOI:

Bifurcated region 2 field-aligned currents associated with substorms

Sangha, H; Milan, SE; Carter, JA; Fogg, AR; Anderson, BJ; Korth, H; Paxton, LJ;

Published by: Journal of Geophysical Research: Space Physics Published on:

YEAR: 2020 DOI:

The evolution of long-duration cusp spot emission during lobe reconnection with respect to field-aligned currents

Carter, Jennifer; Milan, Stephen; Fogg, Alexandra; Sangha, Harneet; Lester, Mark; Paxton, Larry; Anderson, Brian;

Published by: Journal of Geophysical Research: Space Physics Published on:

YEAR: 2020 DOI:

Dual-lobe reconnection and horse-collar auroras

Milan, Stephen; Carter, Jennifer; Bower, Gemma; Imber, Suzanne; Paxton, Larry; Anderson, Brian; Hairston, Marc; Hubert, Benoit;

Published by: Journal of Geophysical Research: Space Physics Published on:

YEAR: 2020 DOI:

2019

Dayside Aurora

Dayside aurora is related to processes in the dayside magnetosphere and especially at the dayside magnetopause. A number of dayside aurora phenomena are driven by reconnection between the solar wind interplanetary magnetic field and the Earth\textquoterights internal magnetic field at the magnetopause. We summarize the properties and origin of aurora at the cusp foot point, High Latitude Dayside Aurora (HiLDA), Poleward Moving Auroral Forms (PMAFs), aurora related to traveling convection vortices (TCV), and throat aurora. Furthermore we discuss dayside diffuse aurora, morning side diffuse aurora spots, and shock aurora.

Frey, Harald; Han, Desheng; Kataoka, Ryuho; Lessard, Marc; Milan, Stephen; Nishimura, Yukitoshi; Strangeway, Robert; Zou, Ying;

Published by: Space Science Reviews Published on: 11/2019

YEAR: 2019 DOI: 10.1007/s11214-019-0617-7

Understanding the global dynamics of the equatorial ionosphere in Africa for space weather capabilities: A science case for AfrequaMARN

Lawal, Hammed; Lester, Mark; Cowley, Stanley; Milan, S.E.; Yeoman, T.K.; Provan, Gabby; Imber, Suzie; Rabiu, A.Babatunde;

Published by: Journal of Atmospheric and Solar-Terrestrial Physics Published on: 10/2019

YEAR: 2019 DOI: 10.1016/j.jastp.2018.01.008

2018

The association of high-latitude dayside aurora with NBZ field-aligned currents

Carter, JA; Milan, SE; Fogg, AR; Paxton, LJ; Anderson, BJ;

Published by: Journal of Geophysical Research: Space Physics Published on:

YEAR: 2018 DOI:

Interhemispheric survey of polar cap aurora

Reidy, Jade; Fear, RC; Whiter, DK; Lanchester, B; Kavanagh, Andrew; Milan, SE; Carter, JA; Paxton, LJ; Zhang, Y;

Published by: Journal of Geophysical Research: Space Physics Published on:

YEAR: 2018 DOI:

2017

Transpolar arcs observed simultaneously in both hemispheres

Carter, Jennifer; Milan, Stephen; Fear, RC; Walach, M-T; Harrison, ZA; Paxton, LJ; Hubert, Beno\^\it;

Published by: Journal of Geophysical Research: Space Physics Published on:

YEAR: 2017 DOI:

North—south asymmetries in earth’s magnetic field

The solar-wind magnetosphere interaction primarily occurs at altitudes where the dipole component of Earth’s magnetic field is dominating. The disturbances that are created in this interaction propagate along magnetic field lines and interact with the ionosphere–thermosphere system. At ionospheric altitudes, the Earth’s field deviates significantly from a dipole. North–South asymmetries in the magnetic field imply that the magnetosphere–ionosphere–thermosphere (M–I–T) coupling is different in the two hemispheres. In this paper we review the primary differences in the magnetic field at polar latitudes, and the consequences that these have for the M–I–T coupling. We focus on two interhemispheric differences which are thought to have the strongest effects: 1) A difference in the offset between magnetic and geographic poles in the Northern and Southern Hemispheres, and 2) differences in the magnetic field strength at magnetically conjugate regions. These asymmetries lead to differences in plasma convection, neutral winds, total electron content, ion outflow, ionospheric currents and auroral precipitation.

Laundal, Karl; Cnossen, Ingrid; Milan, Stephen; Haaland, SE; Coxon, John; Pedatella, NM; Förster, Matthias; Reistad, Jone;

Published by: Space Science Reviews Published on:

YEAR: 2017 DOI: 10.1007/s11214-016-0273-0

Two mechanisms for dayside polar cap auroral emissions under northward IMF

Carter, Jennifer; Milan, Steve; Paxton, Larry; Fogg, A;

Published by: Published on:

YEAR: 2017 DOI:

2016

Average field-aligned current configuration parameterised by solar wind conditions

We present the first large-scale comparison of the spatial distribution of field-aligned currents as measured by the Active Magnetosphere and Planetary Electrodynamics Response Experiment, with the location and brightness of the average auroral oval, determined from the Imager for Magnetopause-to-Aurora Global Exploration far ultraviolet instrument. These distributions are compared under the same interplanetary magnetic field magnitude and clock angle conditions. The field-aligned currents and auroral oval drop to lower latitudes, as the interplanetary magnetic field becomes both increasingly stronger in magnitude and increasingly southward. We find that the region 2 currents are more closely aligned with the distribution of auroral UV emission, whether that be in the discrete auroral zone about dusk or in the postmidnight diffuse aurora sector. The lack of coincidence between the region 1 field-aligned currents with the auroral oval in the dusk sector is contrary to expectation.

Carter, J.; Milan, S.; Coxon, J.; Walach, M.-T.; Anderson, B.;

Published by: Journal of Geophysical Research: Space Physics Published on: 01/2016

YEAR: 2016 DOI: 10.1002/2015JA021567

auroral oval; field-aligned currents

Average field-aligned current configuration parameterized by solar wind conditions

Carter, JA; Milan, Stephen; Coxon, JC; Walach, M-T; Anderson, BJ;

Published by: Journal of Geophysical Research: Space Physics Published on:

YEAR: 2016 DOI:

2014

Connection between high-latitude arcs and the low-latitude boundary layer during periods of northward IMF

Maggiolo, Romain; Fontaine, Dominique; Hosokawa, Keisuke; Maes, Lukas; Zhang, Yongliang; Fear, Robert; Cumnock, Judy; Kozlovsky, Alexander; Kullen, Anita; Milan, Steve; , others;