Research Article

Comparison of geomagnetic storm and non-storm periods mid-latitude Pc1 pulsations characteristics

¹ Division of Space Science, Korea Astronomy and Space Science Institute, 776, Daedeok-daero, Yuseong-gu, 34055 Daejeon, Republic of Korea
² Department of Astronomy and Space Science, University of Science and Technology, 217, Gajeong-ro, Yuseong-gu, 34113 Daejeon, Republic of Korea
³ Department of Atmospheric Science, Yonsei University, 50, Yonsei-ro, Seodaemun-gu, 03722 Seoul, Republic of Korea
⁴ Space Research Institute, Austrian Academy of Sciences, Dr. Ignaz Seipel-Platz 2, 1010 Vienna, Austria

^* Corresponding author: jykwak@kasi.re.kr

Received: 26 August 2023
Accepted: 29 July 2024

Abstract

Pc1 pulsations are infrequently observed at mid-latitude ground stations. Previous studies have shown that these pulsations near the ground are commonly observed during dawn and geomagnetic storms, particularly in the storm recovery phase. However, few studies have directly compared the characteristics of Pc1 pulsations during storm and non-storm times using long-term ground-based data. In this study, we conducted a comparative analysis of storm-related and non-storm-related Pc1 pulsations detected at a mid-latitude ground station located at Bohyun mountain in Korea (BOH, L~1.34). Our findings reveal notable distinctions between the two groups. Pc1 pulsations during the non-storm period exhibit a sharper peak in the local time distribution of the occurrence, relatively well indicating daytime wave power attenuation during propagation. Additionally, during the non-storm period, Pc1 pulsations show relatively lower frequencies (0.6~1 Hz) with predominantly linear polarization. In contrast, storm-related Pc1 pulsations exhibit higher and broader frequencies (up to 3 Hz) with more frequent left-handed polarization. These results suggest that storm-related Pc1 pulsations might originate from a more diverse range of spatial sources.