IPIM Modeling of the Ionospheric F-2 Layer Depletion at High Latitudes During a High-Speed Stream Event

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Marchaudon , A , Blelly , P -L , Grandin , M , Aikio , A , Kozlovsky , A & Virtanen , I 2018 , ' IPIM Modeling of the Ionospheric F-2 Layer Depletion at High Latitudes During a High-Speed Stream Event ' , Journal of geophysical research. Space physics , vol. 123 , no. 8 , pp. 7051-7066 . https://doi.org/10.1029/2018JA025744

Title: IPIM Modeling of the Ionospheric F-2 Layer Depletion at High Latitudes During a High-Speed Stream Event
Author: Marchaudon, A.; Blelly, P. -L.; Grandin, M.; Aikio, A.; Kozlovsky, A.; Virtanen, I.
Contributor: University of Helsinki, Department of Physics
Date: 2018-08
Language: eng
Number of pages: 16
Belongs to series: Journal of geophysical research. Space physics
ISSN: 2169-9380
URI: http://hdl.handle.net/10138/298565
Abstract: Our aim is to understand the effect of high-speed stream events on the high-latitude ionosphere and more specifically the decrease of the f(o)F(2) frequency during the entire day following the impact. First, we have selected one summertime event, for which a large data set was available: Super Dual Auroral Radar Network (SuperDARN) and European Incoherent SCATter (EISCAT) radars, Tromso and Sodankyla ionosondes, and the CHAllenging Minisatellite Payload (CHAMP) satellite. We modeled with the IPIM model (IRAP Plasmasphere Ionosphere Model) the dynamics of the ionosphere at Tromso and Sodankyla using inputs derived from the data. The simulations nicely match the measurements made by the EISCAT radar and the ionosondes, and we showed that the decrease of f(o)F(2) is associated with a transition from F-2 to F-1 layer resulting from a decrease of neutral atomic oxygen concentration. Modeling showed that electrodynamics can explain short-term behavior on the scale of a few hours, but long-term behavior on the scale of a few days results from the perturbation induced in the atmosphere. Enhancement of convection is responsible for a sharp increase of the ion temperature by Joule heating, leading through chemistry to an immediate reduction of the F-2 layer. Then, ion drag on neutrals is responsible for a rapid heating and expansion of the thermosphere. This expansion affects atomic oxygen through nonthermal upward flow, which results in a decrease of its concentration and amplifies the decrease of [O]/[N-2] ratio. This thermospheric change explains long-term extinction of the F-2 layer.
Subject: high-speed stream
SuperDARN
EISCAT
ionosondes
ELECTRON-ENERGY TRANSFER
THERMOSPHERIC COMPOSITION
GEOMAGNETIC STORM
ATOMIC OXYGEN
WIND
EXCITATION
CONVECTION
PATTERN
RATES
FLUX
115 Astronomy, Space science
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