Simultaneous observations of magnetospheric ELF/VLF emissions in Canada, Finland, and Antarctica

• Published in: Journal of Geophysical Research: Space Physics
• Main Authors: Yonezu, Yusuke, 73601, Shiokawa, Kazuo, 73602, Connors, Martin, 73603, Ozaki, Mitsunori, 73604, Manninen, Jyrki, 73605, Yamagishi, Hisao, 73606, Okada, Masaki, 73607
• Language: English
• Published: Wiley 2017
• Subjects: Syowa Station; Canada; Antarc*; Antarctica
• Online Access: http://hdl.handle.net/2237/26984; https://doi.org/10.1002/2017JA024211; https://nagoya.repo.nii.ac.jp/record/24763/files/Yonezu_et_al-2017-Journal_of_Geophysical_Research_Space_Physics.pdf

To investigate longitudinal extent of electromagnetic wave activity, we report the first simultaneous ground-based observations of magnetospheric ELF/VLF emissions at the following three longitudinally separated stations at auroral and subauroral latitudes: Athabasca, Canada (ATH; magnetic latitude: 61.3°N); Kannuslehto, Finland (KAN; 64.4°N); and Syowa Station, Antarctica (SYO; 70.5°S). The magnetic local time (MLT) separations of SYO-KAN, ATH-SYO, and ATH-KAN, are 3, 8, and 11 h, respectively. Simultaneous observation data at these stations are available for a total of 48 days in 2012–2014. The simultaneous occurrence rates of ELF/VLF emissions are 9.8%, 2.5%, and 3.6% for SYO-KAN, ATH-SYO, and ATH-KAN, respectively. We found that the simultaneous wave occurrence rate between two stations is higher in the morning-dayside sector, indicating that the longitudinal extent of the emissions exhibits MLT dependence. When emissions are simultaneously observed at two stations, the average AE and |Dst| indices tend to be higher. Similarly, if the two stations are more separated in MLT, the average |Dst| index increases. These results suggest that the longitudinal extent of ELF/VLF emissions increases with increasing geomagnetic activity. journal article