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TitleCharacterizing auroral-zone absorption based on global Kp and regional geomagnetic hourly range indices
AuthorFiori, R A DORCID logo; Trichtchenko, LORCID logo; Balch, C; Spanswick, E; Groleau, S
SourceSpace Weather vol. 18, issue 12, 2020 p. 1-23,
Alt SeriesNatural Resources Canada, Contribution Series 20200465
PublisherSpace Weather
Mediapaper; on-line; digital
File formatpdf
Subjectsgeophysics; mathematical and computational geology; Science and Technology; auroral zone; absorption; magnetic interpretations; geomagnetism
Illustrationslocation maps; tables; models; graphs; histograms; plots
ProgramPublic Safety Geoscience Assessing space weather hazards
Released2020 10 19
AbstractIncreased ionization in the auroral oval leads to the absorption of high-frequency radio waves in the auroral zone, or auroral absorption. Auroral absorption is typically characterized by global geomagnetic activity indices, such as the Kp index. In this paper the hourly range of the magnetic field (HR) is examined as an alternative to the 3-hr Kp index for describing the dynamic and localized features of auroral absorption represented by the hourly range of absorption (HRA). Kp, magnetometer, and riometer data were examined for a 3-year period for stations spread across typical auroral latitudes. A general linear relationship was shown to exist between Kp and LOG10(HRA) for Kp < 4; for Kp > 4 the correlation was weaker. A stronger linear correlation was demonstrated between LOG10(HRA) and LOG10(HR) for HR > 50 nT, characterized by a correlation coefficient of R = 0.63. Increased variability in the relationship between HRA and Kp was attributed to the following factors: the variability of the magnetic field within the 3?hr window characterized by the Kp index, which was better represented by a 1-hr HR; the dependence of the Kp index on subauroral magnetic data, which is not subject to the geomagnetic variations typically experienced within the auroral region; and reduced statistics for Kp > 6.
Summary(Plain Language Summary, not published)
High frequency radio wave propagation, used for communication, military surveillance, and research, is subject to disturbances caused by space weather. This paper studies auroral absorption which is a disturbance associated with the precipitation of energetic electrons into the ionosphere within the auroral oval. Auroral absorption is typically characterized by a global geomagnetic activity index called the Kp index. In this paper, a alternative index based on the hourly range of the magnetic field is examined as an alternative to the Kp index. This is done by examining the relationship between Kp, the hourly range of the magnetic field, and the hourly range of absorption using data from a collection of instruments located within the auroral zone. Hourly range of absorption was shown to agree well with the Kp index for lower levels of activity (Kp<4); the relationship deteriorated for higher levels of activity. A stronger agreement was shown been the hourly range of absorption and the hourly range of the magnetic field.

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