Magnetic Local Time and Latitude Distribution of Ionospheric Large‐Spatial‐Scale EMIC Wave Events: Swarm Observations. Issue 3 (14th March 2022)

• Record Type: Journal Article
• Authors: Wang, Hui; Sun, Luyuan; Lühr, Hermann; Liu, Yiwen; He, Yangfan
• Is Part Of: Journal of geophysical research. Volume 127:Issue 3(2022)
• Page Start: n/a
• Page End: n/a
• Publication Date: 2022-03-14
• Subjects: electromagnetic ion cyclotron waves -- ionospheric ducting -- electron density -- mid‐latitude trough -- dipole tilt angle; Magnetospheric physics -- Periodicals; Space environment -- Periodicals; Cosmic physics -- Periodicals; Planets -- Atmospheres -- Periodicals; Heliosphere (Astrophysics) -- Periodicals; Geophysics -- Periodicals; 523.01
• DOI: 10.1029/2022JA030276
• Languages: English
• ISSNs: 2169-9380

Abstract

Abstract: In the present work, the magnetic local time and latitude (MLT and MLat) distributions of ionospheric large‐spatial‐scale (>20° MLat) electromagnetic ion cyclotron waves were investigated using high‐resolution 50‐Hz geomagnetic field data from Swarm A and B satellites. Both parallel and transverse waves were studied in a comparative manner for different geomagnetic activities and seasons. Frequent occurrences of large‐spatial‐scale waves in the South Atlantic Anomaly and North America, where the parallel waves propagate over the longest distance, were observed. Waves appear mostly in the 02–10 MLT sector wherein the pre‐noon parallel waves propagate farthest in latitudinal range. With the enhancement of geomagnetic activity, both transverse and parallel waves increase in occurrence. The dayside occurrence rate is higher during weak geomagnetic activity, whereas the situation is reversed on the nightside and duskside. The dayside waves are located outside the mid‐latitude trough, and the nightside waves are located near (inside) the equatorward boundary of the mid‐latitude trough. Large‐spatial‐scale waves tend to occur at the equinoxes when the absolute value of the dipole tilt angle is less than 10°, while the long‐distance transmission in the waveguide occurs in the pre‐noon in summer. Parallel waves propagate in the region where the electron density is higher than that of the transverse waves. There is a close relationship between EMIC wave and electron density oscillation. Key Points: The spatial distribution of large‐spatial‐scale transverse and longitudinal electromagnetic ion cyclotron (EMIC) waves are compared with electron density The relative latitudinal position of large‐spatial‐scale EMIC waves with the mid‐latitude trough in different magnetic local time sectors are revealed The effect of Earth's dipole tilt angle on the occurrence rate of large‐spatial‐scale EMIC waves are presented