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Ionospheric response to particle precipitation within aurora

Technical Report:

Abstract

The aurora is just the visible signature of a large number of processes occurring in a planetary ionosphere as a response to energetic charged particles falling in from the near-empty space far above the planetary atmosphere. This thesis, based on measurements using the EISCAT incoherent scatter radar system in northern Scandinavia, discusses ionospheric response processes and especially a mechanism leading to atmospheric gas escape from a planet. One of the most spectacular events in the high latitude atmosphere on earth are the `auroral arcs` - dynamic rayed sheets of light. An investigation of the conditions of the ionosphere surrounding auroral arcs shows that strong field-aligned bulk ion outflows appear in the topside ionosphere which account for a large fraction of the escape of atmospheric oxygen from earth. Four different additional ionospheric responses are closely related to this ion outflow; 1. enhanced electron temperatures of several thousand Kelvin above an altitude of about 250 km, 2. enhanced ionization around an altitude of 200 km corresponding to electron precipitation with energies of a few hundred eV, 3. the occurrence of naturally enhanced ion acoustic fluctuations seen in the radar spectrum, most likely produced by an ion-ion two-stream instability, and 4. upward directed  More>>
Authors:
Wahlund, J E [1] 
  1. Swedish Inst. of Space Physics, Uppsala (Sweden)
Publication Date:
Mar 01, 1992
Product Type:
Technical Report
Report Number:
IRF-208
Reference Number:
SCA: 661320; PA: AIX-24:005738; SN: 93000930876
Resource Relation:
Other Information: PBD: Mar 1992
Subject:
71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSICS; ELECTRON PRECIPITATION; AURORAE; AURORAL OVAL; EARTH MAGNETOSPHERE; ELECTRIC FIELDS; ELECTRON TEMPERATURE; EXPERIMENTAL DATA; F REGION; MAGNETIC FIELDS; PLASMA; RADAR; 661320
OSTI ID:
10118795
Research Organizations:
Swedish Inst. of Space Physics, Kiruna (Sweden)
Country of Origin:
Sweden
Language:
English
Other Identifying Numbers:
Other: ON: DE93611405; TRN: SE9200296005738
Availability:
OSTI; NTIS; INIS
Submitting Site:
SWDN
Size:
[12] p.
Announcement Date:
Jun 30, 2005

Technical Report:

Citation Formats

Wahlund, J E. Ionospheric response to particle precipitation within aurora. Sweden: N. p., 1992. Web.
Wahlund, J E. Ionospheric response to particle precipitation within aurora. Sweden.
Wahlund, J E. 1992. "Ionospheric response to particle precipitation within aurora." Sweden.
@misc{etde_10118795,
title = {Ionospheric response to particle precipitation within aurora}
author = {Wahlund, J E}
abstractNote = {The aurora is just the visible signature of a large number of processes occurring in a planetary ionosphere as a response to energetic charged particles falling in from the near-empty space far above the planetary atmosphere. This thesis, based on measurements using the EISCAT incoherent scatter radar system in northern Scandinavia, discusses ionospheric response processes and especially a mechanism leading to atmospheric gas escape from a planet. One of the most spectacular events in the high latitude atmosphere on earth are the `auroral arcs` - dynamic rayed sheets of light. An investigation of the conditions of the ionosphere surrounding auroral arcs shows that strong field-aligned bulk ion outflows appear in the topside ionosphere which account for a large fraction of the escape of atmospheric oxygen from earth. Four different additional ionospheric responses are closely related to this ion outflow; 1. enhanced electron temperatures of several thousand Kelvin above an altitude of about 250 km, 2. enhanced ionization around an altitude of 200 km corresponding to electron precipitation with energies of a few hundred eV, 3. the occurrence of naturally enhanced ion acoustic fluctuations seen in the radar spectrum, most likely produced by an ion-ion two-stream instability, and 4. upward directed field-aligned currents partly carried by the outflowing ions. From these observations, it is suggested that the energy dissipation into the background plasma through Joule heating, the production of a few hundred eV energetic run-away electrons, and strong ion outflows are partly produced by the simultaneous presence of ion acoustic turbulence and field-aligned currents above auroral arcs. (20 refs.) (au).}
place = {Sweden}
year = {1992}
month = {Mar}
}