TY - JOUR
T1 - Study of Pc1 pearl structures observed at multi-point ground stations in Russia, Japan, and Canada
AU - Jun, Chae Woo
AU - Shiokawa, Kazuo
AU - Connors, Martin
AU - Schofield, Ian
AU - Poddelsky, Igor
AU - Shevtsov, Boris
N1 - Funding Information:
We thank M. Sera and Y. Ikegami at the Moshiri observatory of the Solar-Terrestrial Environment Laboratory, Nagoya University, all the staff of the Institute of Cosmophysical Research and Radiowave Propagation (IKIR), and Y. Katoh, H. Hamaguchi, and Y. Yamamoto of STEL, Nagoya University, for their help and support in the operation of the induction magnetometers. The Dst and AE indices were provided by the WDC-C2 for geomagnetism at Kyoto University. This work was supported by Grants-in-Aid for Scientific Research (16403007, 18403011, 19403010, and 20244080), the 21th Century COE Program (Dynamics of the Sun-Earth-Life Interactive System, No. G-4), the Global COE Program of Nagoya University ‘Quest for Fundamental Principles in the Universe (QFPU)’, the Special Funds for Education and Research (Energy Transport Processes in Geospace), and the IUGONET Project from MEXT, Japan, as well as the Leadership Development Program for Space Exploration and Research from Nagoya University for Leading Graduate Schools.
Publisher Copyright:
© 2014 Jun et al.; licensee Springer.
PY - 2014
Y1 - 2014
N2 - We investigate possible generation mechanisms of Pc1 pearl structures using multi-point induction magnetometers in Athabasca in Canada, Magadan in Russia, and Moshiri in Japan. We selected two Pc1 pulsations that were simultaneously observed at the three stations and applied a polarization analysis. In case 1, on 8 April 2010, Pc1 pearl structures were slightly different in some time intervals at different stations, and their polarization angles varied depending on the frequencies at the three stations. Case 2, on 11 April 2010, showed Pc1 pearl structures that were similar at different stations, and their polarization angle was independent of frequency at all three stations. In order to understand these differences, we performed two simple model calculations of Pc1 pearl structures under different conditions. The first model assumes that Pc1 waves propagated from a latitudinally extended source with different frequencies at different latitudes to the observation points, representing beating of these waves in the ionosphere. The second model considers Pc1 waves for which different frequencies are mixed at a point source to cause the beating at the source point, indicating that the Pc1 pearl structures are generated in the magnetosphere. The first model shows slightly different waveforms at different stations. In contrast, the second model shows identical waveforms at different stations. From these results, we conclude that, in case 1, Pc1 pearl structures were caused by beating in the ionosphere. On the other hand, in case 2, they were the result of magnetospheric effects. We suggest that beating processes in the ionosphere could be one of the generation mechanisms of Pc1 pearl structures.
AB - We investigate possible generation mechanisms of Pc1 pearl structures using multi-point induction magnetometers in Athabasca in Canada, Magadan in Russia, and Moshiri in Japan. We selected two Pc1 pulsations that were simultaneously observed at the three stations and applied a polarization analysis. In case 1, on 8 April 2010, Pc1 pearl structures were slightly different in some time intervals at different stations, and their polarization angles varied depending on the frequencies at the three stations. Case 2, on 11 April 2010, showed Pc1 pearl structures that were similar at different stations, and their polarization angle was independent of frequency at all three stations. In order to understand these differences, we performed two simple model calculations of Pc1 pearl structures under different conditions. The first model assumes that Pc1 waves propagated from a latitudinally extended source with different frequencies at different latitudes to the observation points, representing beating of these waves in the ionosphere. The second model considers Pc1 waves for which different frequencies are mixed at a point source to cause the beating at the source point, indicating that the Pc1 pearl structures are generated in the magnetosphere. The first model shows slightly different waveforms at different stations. In contrast, the second model shows identical waveforms at different stations. From these results, we conclude that, in case 1, Pc1 pearl structures were caused by beating in the ionosphere. On the other hand, in case 2, they were the result of magnetospheric effects. We suggest that beating processes in the ionosphere could be one of the generation mechanisms of Pc1 pearl structures.
KW - Multi-point ground-based observation
KW - Pc1 pulsations
KW - Pearl structures
UR - http://www.scopus.com/inward/record.url?scp=84983532602&partnerID=8YFLogxK
U2 - 10.1186/s40623-014-0140-8
DO - 10.1186/s40623-014-0140-8
M3 - Journal Article
AN - SCOPUS:84983532602
SN - 1343-8832
VL - 66
JO - Earth, Planets and Space
JF - Earth, Planets and Space
IS - 1
M1 - 140
ER -