Incoherent scatter radar studies of electron precipitation
Abstract In the studies presented in this thesis, we use the EISCAT UHF incoherent scatter radar (ISR) to study electron precipitation. A new ISR data analysis technique called BAFIM (BAyesian FIltering Module) is developed to calculate plasma parameters (electron density, electron temperature, ion...
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Oulun yliopisto
2023
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ftunivoulu:oai:oulu.fi:isbn978-952-62-3708-4 2023-07-30T04:03:15+02:00 Incoherent scatter radar studies of electron precipitation Tesfaw, H. W. (Habtamu Wubie) Virtanen, I. (Ilkka) Aikio, A. (Anita) 2023-05-31 application/pdf http://urn.fi/urn:isbn:9789526237084 eng eng Oulun yliopisto info:eu-repo/semantics/altIdentifier/pissn/1239-4327 info:eu-repo/semantics/altIdentifier/eissn/2814-967X info:eu-repo/semantics/openAccess © University of Oulu, 2023 aurora electron precipitation incoherent scatter radar info:eu-repo/semantics/doctoralThesis info:eu-repo/semantics/publishedVersion 2023 ftunivoulu 2023-07-08T20:01:54Z Abstract In the studies presented in this thesis, we use the EISCAT UHF incoherent scatter radar (ISR) to study electron precipitation. A new ISR data analysis technique called BAFIM (BAyesian FIltering Module) is developed to calculate plasma parameters (electron density, electron temperature, ion temperature and line of sight ion velocity) with high time and range resolutions from incoherent scatter radar autocorrelation function (ACF) data. BAFIM adds properties of the so-called full-profile analysis to the standard EISCAT data analysis tool, GUISDAP, and extends the concept of full-profile analysis from range direction to both range and time. BAFIM-fitted electron density is used to study a rapidly varying electron precipitation event with high time resolution (4 s). Using a method called ELSPEC, differential number fluxes of precipitating electrons are inverted from electron density altitude profiles measured along the geomagnetic field line by the EISCAT UHF incoherent scatter radar. We show that the raw electron density, that was previously used in high time resolution works, may significantly underestimate the true electron density, when auroral electron precipitation heats the electron gas. The bias affects also electron energy spectra inverted from the raw density profiles, as well as auroral powers and field-aligned currents integrated from the spectra. Temporal variations of the auroral power derived from the fitted electron density show a very good agreement with variations of auroral emission intensity at 427.8 nm. Using more than 20 years of EISCAT UHF radar data, we study statistical characteristics of 1–100 keV electron precipitation at 66.7° magnetic latitude over Tromsø, Norway. Peak energy, auroral power and number flux of electron precipitation are derived from the radar data using the ELSPEC method. We find that 1–5 keV electrons dominate the precipitation from evening until morning in magnetic local time (MLT), while 5–10 keV electrons dominate the late morning hours (06–09 MLT). The average peak energy ... Doctoral or Postdoctoral Thesis EISCAT Tromsø Jultika - University of Oulu repository Norway Tromsø |
institution |
Open Polar |
collection |
Jultika - University of Oulu repository |
op_collection_id |
ftunivoulu |
language |
English |
topic |
aurora electron precipitation incoherent scatter radar |
spellingShingle |
aurora electron precipitation incoherent scatter radar Tesfaw, H. W. (Habtamu Wubie) Incoherent scatter radar studies of electron precipitation |
topic_facet |
aurora electron precipitation incoherent scatter radar |
description |
Abstract In the studies presented in this thesis, we use the EISCAT UHF incoherent scatter radar (ISR) to study electron precipitation. A new ISR data analysis technique called BAFIM (BAyesian FIltering Module) is developed to calculate plasma parameters (electron density, electron temperature, ion temperature and line of sight ion velocity) with high time and range resolutions from incoherent scatter radar autocorrelation function (ACF) data. BAFIM adds properties of the so-called full-profile analysis to the standard EISCAT data analysis tool, GUISDAP, and extends the concept of full-profile analysis from range direction to both range and time. BAFIM-fitted electron density is used to study a rapidly varying electron precipitation event with high time resolution (4 s). Using a method called ELSPEC, differential number fluxes of precipitating electrons are inverted from electron density altitude profiles measured along the geomagnetic field line by the EISCAT UHF incoherent scatter radar. We show that the raw electron density, that was previously used in high time resolution works, may significantly underestimate the true electron density, when auroral electron precipitation heats the electron gas. The bias affects also electron energy spectra inverted from the raw density profiles, as well as auroral powers and field-aligned currents integrated from the spectra. Temporal variations of the auroral power derived from the fitted electron density show a very good agreement with variations of auroral emission intensity at 427.8 nm. Using more than 20 years of EISCAT UHF radar data, we study statistical characteristics of 1–100 keV electron precipitation at 66.7° magnetic latitude over Tromsø, Norway. Peak energy, auroral power and number flux of electron precipitation are derived from the radar data using the ELSPEC method. We find that 1–5 keV electrons dominate the precipitation from evening until morning in magnetic local time (MLT), while 5–10 keV electrons dominate the late morning hours (06–09 MLT). The average peak energy ... |
author2 |
Virtanen, I. (Ilkka) Aikio, A. (Anita) |
format |
Doctoral or Postdoctoral Thesis |
author |
Tesfaw, H. W. (Habtamu Wubie) |
author_facet |
Tesfaw, H. W. (Habtamu Wubie) |
author_sort |
Tesfaw, H. W. (Habtamu Wubie) |
title |
Incoherent scatter radar studies of electron precipitation |
title_short |
Incoherent scatter radar studies of electron precipitation |
title_full |
Incoherent scatter radar studies of electron precipitation |
title_fullStr |
Incoherent scatter radar studies of electron precipitation |
title_full_unstemmed |
Incoherent scatter radar studies of electron precipitation |
title_sort |
incoherent scatter radar studies of electron precipitation |
publisher |
Oulun yliopisto |
publishDate |
2023 |
url |
http://urn.fi/urn:isbn:9789526237084 |
geographic |
Norway Tromsø |
geographic_facet |
Norway Tromsø |
genre |
EISCAT Tromsø |
genre_facet |
EISCAT Tromsø |
op_relation |
info:eu-repo/semantics/altIdentifier/pissn/1239-4327 info:eu-repo/semantics/altIdentifier/eissn/2814-967X |
op_rights |
info:eu-repo/semantics/openAccess © University of Oulu, 2023 |
_version_ |
1772814230744989696 |