[P-EM10] Dynamics of Magnetosphere and Ionosphere

[PEM10-P08] Pc1 pulsations simultaneously observed at the latitudinal induction magnetometer network and by the Swarm satellite

*Masahito Nose¹, Kazuo Shiokawa², Yuichi Otsuka², Liejun Wang³, Bill Jones³, Andrew Lewis³, Marck Daniel Santos⁴, Patrick Joseph Robles⁴, Viacheslav A. Pilipenko⁵ (1.School of Data Science, Nagoya City University, 2.Institute for Space-Earth Environmental Research, Nagoya University, 3.Geoscience Australia, 4.Hydrography Branch, National Mapping and Resource Information Authority (NAMRIA), 5.Space Research Institute, Moscow)

Pc1 geomagnetic pulsations are considered to be an electromagnetic ion cyclotron waves excited by the temperature anisotropy of plasmas in the magnetosphere. Previous satellite studies [Anderson et al., 1992; Usanova et al., 2012; Keika et al., 2013] reported that Pc1 pulsations are predominantly observed in the outer magnetosphere at L>7 at daytime centered around 13–18 magnetic local time (MLT). They are seldom detected in the inner magnetosphere at L<4). On the ground, MLT distribution of Pc1 pulsations at high- and mid-latitudes (L>4) is similar to those of the satellite observations [Saito et al., 1969; Plyasova-Bakounina et al., 1996]. However, Pc1 pulsations at low-latitude (L<4) show a completely different MLT distribution with the frequent occurrence at nighttime peaking at 03–06 MLT [Saito et al., 1969; Kawamura et al., 1981]. The occurrence rate of low-latitude Pc1 appears to be larger than that in the inner magnetosphere at L<4. This implies that low-latitude Pc1 pulsations are not caused by direct entry of Pc1 pulsations from the magnetosphere to the ground along the geomagnetic field line, but due to waves indirectly propagated from the magnetosphere, although the indirect propagation path is still unclear.
We have been constructing a latitudinal network of induction magnetometers in the Russian Far East-Asia-Oceania sector (Russia, Japan, Philippines, and Australia) and successfully detected Pc1 pulsations in the wide latitudinal range from −21°to 64° geomagnetic latitude at 10–15 UT on March 25, 2023. This event was observed in the premidnight sector during the recovery phase of a large magnetic storm (SYM-H minimum = −163 nT). The Swarm satellites were flying near the same MLT and provided simultaneous measurements of geomagnetic field variations that are related to the Pc1 pulsations detected at low-latitude on the ground. In this talk, results of data analysis are presented and the propagating path of EMIC waves from their excitation region to low-latitude ground stations will be discussed.