TY - JOUR
T1 - The 2-D Structure of Foreshock-Driven Field Line Resonances Observed by THEMIS Satellite and Ground-Based Imager Conjunctions
AU - Wang, Boyi
AU - Nishimura, Yukitoshi
AU - Zhang, Hui
AU - Shen, Xiao Chen
AU - Lyons, Larry
AU - Angelopoulos, Vassilis
AU - Ebihara, Yusuke
AU - Weatherwax, Allan
AU - Gerrard, Andrew J.
AU - Frey, Harald U.
N1 - Funding Information:
This work was supported by NASA grants NNX17AL22G and 80NSSC18K0657, NSF grants PLR-1341359 and AGS-1737823, and AFOSR FA9559-16-1-0364. The THEMIS mission is supported by NASA contract NAS5-02099. Merrimack College gratefully acknowledges support from NSF awards 1716192 and 1742693. The South Pole imager has been supported by a cooperative agreement between NSF and the National Institute of Polar Research, Japan (ANT-1643700). THEMIS, WIND/ACE, and SuperMAG data were obtained from http://themis.ssl.berkeley.edu as daily CDF files, http://spdf.gsfc.nasa.gov as daily CDF files, and http://supermag.jhuapl.edu/as daily ASCII files, respectively. Southern Hemisphere ground-based magnetometer data was obtained by British Antarctic Survey (BAS); see Rose & Kirsch, Rose & Kirsch,). H. Z. is partially supported by NSF AGS-1352669, and H. Z. is also grateful to the International Space Science Institute-Beijing for supporting the international team “Dayside Transient Phenomena and Their Impact on the Magnetosphere-Ionosphere.” This work was supported by ISSI workshop “Multiple-instrument observations and simulations of the dynamical processes associated with polar cap patches/aurora and their associated scintillations.” Data access and processing was done using SPEDAS V3.1; see Angelopoulos et al. ().
Publisher Copyright:
©2019. American Geophysical Union. All Rights Reserved.
PY - 2019/8/1
Y1 - 2019/8/1
N2 - Recent studies of Pc5-band (150–600 s) ultralow frequency waves found that foreshock disturbances can be a driver of dayside compressional waves and field line resonance, which are two typical Pc5 wave modes in the dayside magnetosphere. However, it is difficult to find spatial structure of dayside Pc5 waves using a small number of satellites or ground magnetometers. This study determines 2-D structure of dayside Pc5 waves and their driver by utilizing coordinated observations by the THEMIS satellites and the all-sky imager at South Pole during two series of Pc5 waves on 29 June 2008. These Pc5 waves were found to be field line resonances (FLRs) and driven by foreshock disturbances. The ground-based all-sky imager at South Pole shows that periodic poleward moving arcs occurred simultaneously with the FLRs near the satellite footprints over ~3° latitude and had the same frequencies as FLRs. This indicates that they are the auroral signature of the FLRs. The azimuthal distribution of the FLRs in the magnetosphere and their north-south width in the ionosphere were further determined in the 2-D images. In the first case, the FLRs distribute symmetrically in the prenoon and postnoon regions with out-of-phase oscillation as the odd toroidal mode in the equatorial plane. In the second case, the azimuthal wavelengths of the 350–500 s and 300–450 s period waves were ~8.0 and ~5.2 Re in the equatorial plane. It also shows a fine azimuthal structure embedded in the large-scale arcs, indicating that a high azimuthal wave number (m ~ 140) mode wave coupled with the low-wave number FLRs.
AB - Recent studies of Pc5-band (150–600 s) ultralow frequency waves found that foreshock disturbances can be a driver of dayside compressional waves and field line resonance, which are two typical Pc5 wave modes in the dayside magnetosphere. However, it is difficult to find spatial structure of dayside Pc5 waves using a small number of satellites or ground magnetometers. This study determines 2-D structure of dayside Pc5 waves and their driver by utilizing coordinated observations by the THEMIS satellites and the all-sky imager at South Pole during two series of Pc5 waves on 29 June 2008. These Pc5 waves were found to be field line resonances (FLRs) and driven by foreshock disturbances. The ground-based all-sky imager at South Pole shows that periodic poleward moving arcs occurred simultaneously with the FLRs near the satellite footprints over ~3° latitude and had the same frequencies as FLRs. This indicates that they are the auroral signature of the FLRs. The azimuthal distribution of the FLRs in the magnetosphere and their north-south width in the ionosphere were further determined in the 2-D images. In the first case, the FLRs distribute symmetrically in the prenoon and postnoon regions with out-of-phase oscillation as the odd toroidal mode in the equatorial plane. In the second case, the azimuthal wavelengths of the 350–500 s and 300–450 s period waves were ~8.0 and ~5.2 Re in the equatorial plane. It also shows a fine azimuthal structure embedded in the large-scale arcs, indicating that a high azimuthal wave number (m ~ 140) mode wave coupled with the low-wave number FLRs.
KW - THEMIS
KW - ULF Pc5 wave
KW - all-sky imager
KW - dayside aurora
KW - field line resonance
KW - foreshock transient
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U2 - 10.1029/2019JA026668
DO - 10.1029/2019JA026668
M3 - Article
AN - SCOPUS:85071019170
SN - 2169-9380
VL - 124
SP - 6792
EP - 6811
JO - Journal of Geophysical Research: Space Physics
JF - Journal of Geophysical Research: Space Physics
IS - 8
ER -