Tesfaw, H. W., Virtanen, I. I., & Aikio, A. T. (2023). Characteristics of auroral electron precipitation at geomagnetic latitude 67° over Tromsø. Journal of Geophysical Research: Space Physics, 128, e2023JA031382. https://doi.org/10.1029/2023JA031382
Characteristics of auroral electron precipitation at geomagnetic latitude 67° over Tromsø
|Author:||Tesfaw, Habtamu W.1; Virtanen, Ilkka I.1; Aikio, Anita T.1|
1Space Physics and Astronomy Research Unit, University of Oulu, Oulu, Finland
|Online Access:||PDF Full Text (PDF, 3.5 MB)|
|Persistent link:|| http://urn.fi/urn:nbn:fi-fe20230901115128
American Geophysical Union,
|Publish Date:|| 2023-09-01
We use the EISCAT incoherent scatter radar data measured in years 2001–2021 to study statistical characteristics of 1–100 keV electron precipitation at 66.7° MLAT over Tromsø. Peak energies, auroral powers and number fluxes of precipitating electrons are derived from electron density altitude profiles measured along the geomagnetic field line during periods of no photoionization. The method allows us to include energetic 30–100 keV electrons, which are poorly covered in earlier satellite-based studies. Locations of the radar within the auroral oval are determined using a model with the 1-hr Hpo geomagnetic index as input. The average peak energy of precipitating electrons increases almost monotonically from evening (18 MLT) to morning hours (09 MLT). The 30–50 keV electrons dominate the energetic electron precipitation before 06 MLT, after which the 50–100 keV precipitation becomes dominant. Large auroral powers (>60 mWm-2) are observed in the 18–02 MLT sector in the main auroral oval. We obtain occurrence rate of electron precipitation in Tromsø by calculating the fraction of data points with auroral power larger than 2 mWm-2. The occurrence rate peaks during the declining phases of solar cycles (sc), in 2002–2004 for sc23 and in 2015–2017 for sc24, caused by variations in geomagnetic activity. In addition, the occurrence rate has maxima during March and September, minimum in December to January, and it increases monotonically from evening to morning hours, reaching maximum at 05–06 MLT.
Journal of geophysical research. Space physics
|Type of Publication:||
A1 Journal article – refereed
|Field of Science:||
115 Astronomy and space science
This work was supported by the Kvantum Institute of the University of Oulu, by the Academy of Finland (347796 and 24304299), and by the Vilho, Yrjö and Kalle Väisälä foundation of the Finnish Academy of Science and Letters.
|Academy of Finland Grant Number:||
347796 (Academy of Finland Funding decision)
The EISCAT data used in this study are available in the Madrigal database at https://madrigal.eiscat.se/madrigal (I. Häggström & EISCAT Scientific Association, 2021), and the Hpo geomagnetic index data can be accessed from GFZ Data Services repository at https://doi.org/10.5880/Hpo.0002 (Matzka et al., 2022). The ELSPEC software is available in the Zenodo repository at https://doi.org/10.5281/zenodo.6644454 (Virtanen & Gustavsson, 2018).
©2023. The Authors.This is an open access article under the terms of the Creative Commons Attribution License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited.