Conjugate Observations of Dayside and Nightside VLF Chorus and QP Emissions Between Arase (ERG) and Kannuslehto, Finland. Issue 1 (9th January 2020)

• Record Type: Journal Article
• Authors: Martinez‐Calderon, Claudia; Katoh, Yuto; Manninen, Jyrki; Kasahara, Yoshiya; Matsuda, Shoya; Kumamoto, Atsushi; Tsuchiya, Fuminori; Matsuoka, Ayako; Shoji, Masafumi; Teramoto, Mariko; Shinohara, Iku; Shiokawa, Kazuo; Miyoshi, Yoshizumi
• Is Part Of: Journal of geophysical research. Volume 125:Issue 1(2020)
• Page Start: n/a
• Page End: n/a
• Publication Date: 2020-01-09
• Subjects: ELF/VLF -- conjugated events -- QP -- chorus -- ERG; Magnetospheric physics -- Periodicals; Space environment -- Periodicals; Cosmic physics -- Periodicals; Planets -- Atmospheres -- Periodicals; Heliosphere (Astrophysics) -- Periodicals; Geophysics -- Periodicals; 523.01
• DOI: 10.1029/2019JA026663
• Languages: English
• ISSNs: 2169-9380

Abstract

Abstract: We compare for the first time two conjugate events showing simultaneous very low frequency (VLF) wave observations between the same ground station and spacecraft, at different geomagnetic conditions and on opposite sides of the magnetosphere. Waves were observed at Kannuslehto (MLAT = 64.4°N, L =5.46), Finland, and on board Arase (Exploration of energization and Radiation in Geospace, ERG) in the inner magnetosphere. Case 1 on 28 March 2017 shows quasiperiodic (QP) emissions and chorus simultaneously observed on the postmidnight side during the recovery phase of a storm, with sustained high solar wind speed and A E index. Case 2 on 30 November 2017 shows clear one‐to‐one correspondence of QP elements on the noonside during geomagnetic quiet time ( D s t >10 nT and A E <100 nT). We present the characteristics of both cases, focusing on coherence and spatial extent of the waves, electron density, and magnetic field variations. We report that the magnetic field gradient plays a role in the changes of spectral features of the waves. Key Points: We report observations of ELF/VLF conjugated emissions between ground and space at opposite sides of the magnetosphere We present Y‐shaped features with frequency drift, likely generated by high intensity source Spatial gradient of magnetic field affects spectral features of emissions