TY - JOUR
T1 - SECS Analysis of Nighttime Magnetic Perturbation Events Observed in Arctic Canada
AU - Weygand, James M.
AU - Engebretson, Mark J.
AU - Pilipenko, Viacheslav A.
AU - Steinmetz, Erik S.
AU - Moldwin, Mark B.
AU - Connors, Martin G.
AU - Nishimura, Yukitoshi
AU - Lyons, Larry R.
AU - Russell, Christopher T.
AU - Ohtani, Shin Ichi
AU - Gjerloev, Jesper
N1 - Funding Information:
This research was also supported by NSF grants AGS‐1651263 and AGS‐2013648 to Augsburg University, AGS‐1654044 and AGS‐2013433 to the University of Michigan, AGS‐1502700 to JHU/APL, and at UCLA by the MMS project. Martin Connors thanks NSERC for research support and the Canadian Space Agency for support of AUTUMNX. The spherical elementary currents produced by J.M. Weygand were made possible by NASA grants 80NSSC18K1220, 80NSSC18K1227, 80NSSC20K1364, 80NSSC18K0570, and NASA Contract 80GSFC17C0018. The work of Dr. Y. Nishimura was supported by NASA grant 80NSSC18K0657, 80NSSC20K0604 and 80NSSC20K0725, NSF grant AGS‐1907698, and AFOSR grant FA9559‐16‐1‐0364. The THEMIS ASIs are supported by Canadian Space Agency. The work by Dr. L.R. Lyons was supported by NSF grant 20191955.
Publisher Copyright:
© 2021. American Geophysical Union. All Rights Reserved.
PY - 2021/11
Y1 - 2021/11
N2 - Large changes of the magnetic field associated with magnetic perturbation events (MPEs) with amplitudes |ΔB| of hundreds of nT and 5–10 min duration have been frequently observed within a few hours of midnight. This study compares the statistical location of nighttime MPEs with |dB/dt| ≥ 6 nT/s within the auroral current system observed during 2015 and 2017 at two stations, Cape Dorset and Kuujjuarapik, in Eastern Canada. Maps of the two dimensional nightside auroral current system were derived using the Spherical Elementary Current Systems (SECS) technique. Analyses were produced at each station for all events, and for premidnight and postmidnight subsets. We examine four MPE intervals in detail, two accompanied by auroral images, and show the varying associations between MPEs and overhead ionospheric current systems including electrojets and the field-aligned like currents. We find 225 of 279 MPEs occurred within the westward electrojet and only 3 within the eastward electrojet. For the premidnight MPEs 100 of 230 events occurred within the Harang current system while many of the remainder occurred within either the downward region 1 current system or the upward region 2 current system. Many of the 49 postmidnight MPEs occurred in either the downward region 1 (11 events) or upward region 2 current system (27 events). These result suggest that the source of MPEs in the premidnight sector is somewhere between the inner to mid plasma sheet and the source for the MPEs in the postmidnight sector is somewhere between the inner magnetosphere and the inner plasma sheet.
AB - Large changes of the magnetic field associated with magnetic perturbation events (MPEs) with amplitudes |ΔB| of hundreds of nT and 5–10 min duration have been frequently observed within a few hours of midnight. This study compares the statistical location of nighttime MPEs with |dB/dt| ≥ 6 nT/s within the auroral current system observed during 2015 and 2017 at two stations, Cape Dorset and Kuujjuarapik, in Eastern Canada. Maps of the two dimensional nightside auroral current system were derived using the Spherical Elementary Current Systems (SECS) technique. Analyses were produced at each station for all events, and for premidnight and postmidnight subsets. We examine four MPE intervals in detail, two accompanied by auroral images, and show the varying associations between MPEs and overhead ionospheric current systems including electrojets and the field-aligned like currents. We find 225 of 279 MPEs occurred within the westward electrojet and only 3 within the eastward electrojet. For the premidnight MPEs 100 of 230 events occurred within the Harang current system while many of the remainder occurred within either the downward region 1 current system or the upward region 2 current system. Many of the 49 postmidnight MPEs occurred in either the downward region 1 (11 events) or upward region 2 current system (27 events). These result suggest that the source of MPEs in the premidnight sector is somewhere between the inner to mid plasma sheet and the source for the MPEs in the postmidnight sector is somewhere between the inner magnetosphere and the inner plasma sheet.
KW - ground magnetometer data
KW - ionospheric currents
KW - magnetic perturbation events
KW - spherical elementary currents
KW - substorms
UR - http://www.scopus.com/inward/record.url?scp=85119826931&partnerID=8YFLogxK
U2 - 10.1029/2021JA029839
DO - 10.1029/2021JA029839
M3 - Journal Article
AN - SCOPUS:85119826931
SN - 2169-9380
VL - 126
JO - Journal of Geophysical Research: Space Physics
JF - Journal of Geophysical Research: Space Physics
IS - 11
M1 - e2021JA029839
ER -