Spatio-temporal development of cosmic noise absorption at subauroral latitudes using multipoint ground-based observations
Abstract
Electron density enhancements in the ionospheric D-region due to the precipitation of high-energy electrons (> 30 keV), have been measured as increases in cosmic radio noise absorption (CNA) using ground-based riometers. However, there have been few studies of CNA observations at multi-point ground stations distributed in longitudes at subauroral latitudes. Thus, the spatio-temporal development of CNA along subauroral latitudes has not been well understood. In this study, we analyzed the longitudinal development of CNA using simultaneous riometer observations at six stations at subauroral latitudes in Canada, Alaska, Russia, and Iceland over 3 years from 2017 to 2020. These stations are located encircling the earth at ~60 degree magnetic latitudes. To study CNA produced by substorm particle injections, we focused on the steep enhancements of CAN defined as dCNA/dt larger than 0.04 dB/min at the CNA onset with maximum amplitudes larger than 0.4 dB within 30 min. In this presentation, the substorm events during the geomagnetic storm of 25-28 August 2018 and statistical results over the 3 years will be reported. We will discuss the expansion direction and velocity of CNA enhancements and energy ranges of source electrons, based on the timing differences of the CNA onsets between two neighboring stations, as well as their dependence on solar wind and substorm indices and magnetospheric ELF/VLF waves through superposed epoch analysis.
- Publication:
-
AGU Fall Meeting Abstracts
- Pub Date:
- December 2022
- Bibcode:
- 2022AGUFMSM14A..07K