GEOSCAN, résultats de la recherche


TitreClimatology of GPS phase scintillation at northern high latitudes for a period from 2008 to 2013
AuteurPrikryl, P; Jayachandran, P T; Chadwick, R; Kelly, T D
SourceAnnales Geophysicae vol. 33, 2015 p. 531-545,
Séries alt.Secteur des sciences de la Terre, Contribution externe 20140373
ÉditeurCopernicus Publications
Documentpublication en série
Mediapapier; numérique; en ligne
Sujetsgéomagnétisme; champs géomagnétiques; variations géomagnétiques; levés scintillométriques; géologie extraterrestre
Illustrationslocation maps; images; plots
ProgrammeNord du Canada, risque géoscience, Géoscience pour la sécurité publique
Résumé(disponible en anglais seulement)
Global positioning system scintillation and total electron content (TEC) data have been collected by ten specialized GPS Ionospheric Scintillation and TEC Monitors (GISTMs) of the Canadian High Arctic Ionospheric Network (CHAIN). The phase scintillation index 8 is obtained from the phase of the L1 signal sampled at 50 Hz. Maps of phase scintillation occurrence as a function of the altitude-adjusted corrected geomagnetic (AACGM) latitude and magnetic local time (MLT) are computed for the period from 2008 to 2013. Enhanced phase scintillation is collocated with regions that are known as ionospheric signatures of the coupling between the solar wind and magnetosphere. The phase scintillation mainly occurs on the dayside in the cusp where ionospheric irregularities convect at high speed, in the nightside auroral oval where energetic particle precipitation causes field-aligned irregularities with steep electron density gradients and in the polar cap where electron density patches that are formed from a tongue of ionization. Dependences of scintillation occurrence on season, solar and geomagnetic activity, and the interplanetary magnetic field (IMF) orientation are investigated. The auroral phase scintillation shows semiannual variation with equinoctial maxima known to be associated with auroras, while in the cusp and polar cap the scintillation occurrence is highest in the autumn and winter months and lowest in summer. With rising solar and geomagnetic activity from the solar minimum to solar maximum, yearly maps of mean phase scintillation occurrence show gradual increase and expansion of enhanced scintillation regions both poleward and equatorward from the statistical auroral oval. The dependence of scintillation occurrence on the IMF orientation is dominated by increased scintillation in the cusp, expanded auroral oval and at subauroral latitudes for strongly southward IMF. In the polar cap, the IMF BY polarity controls dawn-dusk asymmetries in scintillation occurrence collocated with a tongue of ionization for southward IMF and with sun-aligned arcs for northward IMF. In investigating the shape of scintillation-causing irregularities, the distributions of scintillation occurrence as a function of “off-meridian” and “off-shell” angles that are computed for the receiver-satellite ray at the ionospheric pierce point are found to suggest predominantly field-aligned irregularities in the auroral oval and L-shell-aligned irregularities in the cusp.
Résumé(Résumé en langage clair et simple, non publié)
La météo spatiale fait référence aux conditions dynamiques du soleil et de l¿environnement spatial qui peuvent influer sur les infrastructures essentielles. RNCan exploite le Centre canadien de météo spatiale et étudie les effets de la météo spatiale sur les systèmes d`alimentation électrique, les pipelines, les satellites, les installations de communications radio et le FGISM pour aider l`industrie canadienne à comprendre et à atténuer les effets de la météo spatiale. Cet article examine l'occurence statistique de scintillation GNSS en haute latitude.