TY - JOUR
T1 - Simultaneous observations of magnetospheric ELF/VLF emissions in Canada, Finland, and Antarctica
AU - Yonezu, Yusuke
AU - Shiokawa, Kazuo
AU - Connors, Martin
AU - Ozaki, Mitsunori
AU - Manninen, Jyrki
AU - Yamagishi, Hisao
AU - Okada, Masaki
N1 - Funding Information:
The ELF/VLF data at ATH are available from the Institute for Space-Earth Environmental Research (ISEE), Nagoya University. We express our gratitude to Y. Katoh, H. Hamaguchi, and Y. Yamamoto of ISEE for their continued technical support. Construction and operation of the Athabasca University Geophysical Observatory facilities is supported by the Canada Foundation for Innovation, and we thank Kyle Reiter for dedicated technical support. The OMNI data including solar wind parameters and geomagnetic indices used in this paper were obtained from the SPDF/GSFC OMNIWeb interface at http://omniweb.gsfc.nasa.gov/form/omni_min.html. The ELF/VLF wave data obtained at SYO, KAN, and ATH are available at the National Institute of Polar Research, Japan, Sodankyla Geophysical Observatory, University of Oulu, Finland, and ISEE, Nagoya University, Japan, respectively. This work was supported by the Inter-university Upper atmosphere Global Observation NETwork (IUGONET) of the Ministry of Education, Culture, Sports, Science and Technology (MEXT), Japan. We were also supported by the Grant-in-Aid for Scientific Research (20244080, 23403009, 25302006, 25247080, JP 15H05815, and JP 16H06286) from the Japan Society for the Promotion of Science.
Publisher Copyright:
©2017. American Geophysical Union. All Rights Reserved.
PY - 2017/6/1
Y1 - 2017/6/1
N2 - 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.
AB - 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.
KW - chorus
KW - hiss
KW - longitudinal extent
KW - magnetospheric ELF/VLF waves
KW - QP emission
KW - simultaneous observation
UR - http://www.scopus.com/inward/record.url?scp=85021401941&partnerID=8YFLogxK
U2 - 10.1002/2017JA024211
DO - 10.1002/2017JA024211
M3 - Journal Article
AN - SCOPUS:85021401941
SN - 2169-9380
VL - 122
SP - 6442
EP - 6454
JO - Journal of Geophysical Research: Space Physics
JF - Journal of Geophysical Research: Space Physics
IS - 6
ER -