University of Oulu

Marchaudon, A., Blelly, P.‐L., Grandin, M., Aikio, A., Kozlovsky, A., & Virtanen, I. (2018). IPIM modeling of the ionospheric F2 layer depletion at high latitudes during a high‐speed stream event. Space Physics Space Physics, 123, 7051–7066.

IPIM modeling of the ionospheric F₂ layer depletion at high latitudes during a high‐speed stream event

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Author: Marchaudon, A.1; Blelly, P.-L.1; Grandin, M.2;
Organizations: 1Institut de Recherche en Astrophysique et Planétologie, Université de Toulouse, CNRS, CNES, Toulouse, France
2Department of Physics, University of Helsinki, Helsinki, Finland
3Ionospheric Physics Research Unit, University of Oulu, Oulu, Finland
4Sodankylä Geophysical Observatory, University of Oulu, Sodankylä, Finland
Format: article
Version: published version
Access: open
Online Access: PDF Full Text (PDF, 2.7 MB)
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Language: English
Published: American Geophysical Union, 2018
Publish Date: 2019-02-28


Our aim is to understand the effect of high‐speed stream events on the high‐latitude ionosphere and more specifically the decrease of the foF₂ 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, Tromsø and Sodankylä ionosondes, and the CHAllenging Minisatellite Payload (CHAMP) satellite. We modeled with the IPIM model (IRAP Plasmasphere Ionosphere Model) the dynamics of the ionosphere at Tromsø and Sodankylä 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 foF₂ is associated with a transition from F₂ to F₁ 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 F₂ 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]/[N₂] ratio. This thermospheric change explains long‐term extinction of the F₂ layer.

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Series: Journal of geophysical research. Space physics
ISSN: 2169-9380
ISSN-E: 2169-9402
ISSN-L: 2169-9380
Volume: 123
Issue: 8
Pages: 7051 - 7066
DOI: 10.1029/2018JA025744
Type of Publication: A1 Journal article – refereed
Field of Science: 115 Astronomy and space science
114 Physical sciences
Funding: This work is supported by the Programme National Soleil Terre (PNST) from Institut des Sciences de l'Univers of Centre National de la Recherche Scientifique (INSU/CNRS) cofunded by CNES and by the Academy of Finland project 285474. M. G. is supported by the Academy of Finland (grant 312351). This work was granted access to the HPC resources of CALMIP supercomputing center under the allocation 2017‐P1520.
Academy of Finland Grant Number: 285474
Detailed Information: 285474 (Academy of Finland Funding decision)
312351 (Academy of Finland Funding decision)
Copyright information: © 2018. American Geophysical Union. All Rights Reserved.