Semiannual variation of Pc5 ultra-low frequency (ULF) waves and relativistic electrons over two solar cycles of observations: comparison with predictions of the classical hypothese...

Autores
Poblet, Facundo Leandro; Azpilicueta, Francisco Javier; Lam, Hing-Lan
Año de publicación
2020
Idioma
inglés
Tipo de recurso
artículo
Estado
versión publicada
Descripción
Pc5 ULF (ultra-low frequency) waves can energize electrons to relativistic energies of >2  MeV in geostationary orbits. Enhanced fluxes of such electrons can induce operational anomalies in geostationary satellites. The variations of the two quantities in timescales ranging from days to solar cycles are thus of interest in gauging their space weather effects over different time frames. In this study, we present a statistical analysis of two 11-year solar cycles (cycles 22 and 23) of data comprising the daily relativistic electron fluence observed by Geostationary Environment Satellites (GOESs) and daily Pc5 ULF wave power derived from auroral zone magnetic observatories in Canada. First, an autocorrelation analysis is carried out, which indicates a 27 d periodicity in both parameters for all solar phases, and such a periodicity is most pronounced in the declining and late declining phase. Also, a 9 and 13 d periodicity are seen in some years. Then, a superposed epoch analysis is performed to scrutinize semiannual variation (SAV), which shows that fluence near the equinoxes is 1 order of magnitude higher than near solstices, and Pc5 ULF wave power is 0.5 orders of magnitude higher near the equinoxes than near the solstices. We then evaluate three possible SAV mechanisms (which are based on the axial, equinoctial, and Russell and McPherron effect) to determine which one can best explain the observations. Correlation of the profiles of the observational curves with those of the angles that control each of the SAV mechanisms suggests that the equinoctial mechanism may be responsible for the SAV of electron fluence, while both the equinoctial and the Russell and McPherron mechanisms are important for the SAV of Pc5 ULF wave power. Comparable results are obtained when using functional dependencies of the main angles instead of the angles mentioned above. Lastly, superposed curves of fluence and Pc5 ULF wave power were used to calculate least-square fits with a fixed semiannual period. Comparison of the maxima and minima of the fits with those predicted by the three mechanisms shows that the equinoctial effect better estimates the maxima and minima of the SAV in fluence while for the SAV in Pc5 ULF wave power the equinoctial and Russell and McPherron mechanisms predict one maximum and one minimum each.
Facultad de Ciencias Astronómicas y Geofísicas
Materia
Geofísica
Solar cycles
ULF
Nivel de accesibilidad
acceso abierto
Condiciones de uso
http://creativecommons.org/licenses/by/4.0/
Repositorio
SEDICI (UNLP)
Institución
Universidad Nacional de La Plata
OAI Identificador
oai:sedici.unlp.edu.ar:10915/123773

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spelling Semiannual variation of Pc5 ultra-low frequency (ULF) waves and relativistic electrons over two solar cycles of observations: comparison with predictions of the classical hypothesesPoblet, Facundo LeandroAzpilicueta, Francisco JavierLam, Hing-LanGeofísicaSolar cyclesULFPc5 ULF (ultra-low frequency) waves can energize electrons to relativistic energies of >2  MeV in geostationary orbits. Enhanced fluxes of such electrons can induce operational anomalies in geostationary satellites. The variations of the two quantities in timescales ranging from days to solar cycles are thus of interest in gauging their space weather effects over different time frames. In this study, we present a statistical analysis of two 11-year solar cycles (cycles 22 and 23) of data comprising the daily relativistic electron fluence observed by Geostationary Environment Satellites (GOESs) and daily Pc5 ULF wave power derived from auroral zone magnetic observatories in Canada. First, an autocorrelation analysis is carried out, which indicates a 27 d periodicity in both parameters for all solar phases, and such a periodicity is most pronounced in the declining and late declining phase. Also, a 9 and 13 d periodicity are seen in some years. Then, a superposed epoch analysis is performed to scrutinize semiannual variation (SAV), which shows that fluence near the equinoxes is 1 order of magnitude higher than near solstices, and Pc5 ULF wave power is 0.5 orders of magnitude higher near the equinoxes than near the solstices. We then evaluate three possible SAV mechanisms (which are based on the axial, equinoctial, and Russell and McPherron effect) to determine which one can best explain the observations. Correlation of the profiles of the observational curves with those of the angles that control each of the SAV mechanisms suggests that the equinoctial mechanism may be responsible for the SAV of electron fluence, while both the equinoctial and the Russell and McPherron mechanisms are important for the SAV of Pc5 ULF wave power. Comparable results are obtained when using functional dependencies of the main angles instead of the angles mentioned above. Lastly, superposed curves of fluence and Pc5 ULF wave power were used to calculate least-square fits with a fixed semiannual period. Comparison of the maxima and minima of the fits with those predicted by the three mechanisms shows that the equinoctial effect better estimates the maxima and minima of the SAV in fluence while for the SAV in Pc5 ULF wave power the equinoctial and Russell and McPherron mechanisms predict one maximum and one minimum each.Facultad de Ciencias Astronómicas y Geofísicas2020-09-04info:eu-repo/semantics/articleinfo:eu-repo/semantics/publishedVersionArticulohttp://purl.org/coar/resource_type/c_6501info:ar-repo/semantics/articuloapplication/pdf953-968http://sedici.unlp.edu.ar/handle/10915/123773enginfo:eu-repo/semantics/altIdentifier/issn/1432-0576info:eu-repo/semantics/altIdentifier/issn/0992-7689info:eu-repo/semantics/altIdentifier/doi/10.5194/angeo-38-953-2020info:eu-repo/semantics/openAccesshttp://creativecommons.org/licenses/by/4.0/Creative Commons Attribution 4.0 International (CC BY 4.0)reponame:SEDICI (UNLP)instname:Universidad Nacional de La Platainstacron:UNLP2025-09-29T11:29:28Zoai:sedici.unlp.edu.ar:10915/123773Institucionalhttp://sedici.unlp.edu.ar/Universidad públicaNo correspondehttp://sedici.unlp.edu.ar/oai/snrdalira@sedici.unlp.edu.arArgentinaNo correspondeNo correspondeNo correspondeopendoar:13292025-09-29 11:29:28.847SEDICI (UNLP) - Universidad Nacional de La Platafalse
dc.title.none.fl_str_mv Semiannual variation of Pc5 ultra-low frequency (ULF) waves and relativistic electrons over two solar cycles of observations: comparison with predictions of the classical hypotheses
title Semiannual variation of Pc5 ultra-low frequency (ULF) waves and relativistic electrons over two solar cycles of observations: comparison with predictions of the classical hypotheses
spellingShingle Semiannual variation of Pc5 ultra-low frequency (ULF) waves and relativistic electrons over two solar cycles of observations: comparison with predictions of the classical hypotheses
Poblet, Facundo Leandro
Geofísica
Solar cycles
ULF
title_short Semiannual variation of Pc5 ultra-low frequency (ULF) waves and relativistic electrons over two solar cycles of observations: comparison with predictions of the classical hypotheses
title_full Semiannual variation of Pc5 ultra-low frequency (ULF) waves and relativistic electrons over two solar cycles of observations: comparison with predictions of the classical hypotheses
title_fullStr Semiannual variation of Pc5 ultra-low frequency (ULF) waves and relativistic electrons over two solar cycles of observations: comparison with predictions of the classical hypotheses
title_full_unstemmed Semiannual variation of Pc5 ultra-low frequency (ULF) waves and relativistic electrons over two solar cycles of observations: comparison with predictions of the classical hypotheses
title_sort Semiannual variation of Pc5 ultra-low frequency (ULF) waves and relativistic electrons over two solar cycles of observations: comparison with predictions of the classical hypotheses
dc.creator.none.fl_str_mv Poblet, Facundo Leandro
Azpilicueta, Francisco Javier
Lam, Hing-Lan
author Poblet, Facundo Leandro
author_facet Poblet, Facundo Leandro
Azpilicueta, Francisco Javier
Lam, Hing-Lan
author_role author
author2 Azpilicueta, Francisco Javier
Lam, Hing-Lan
author2_role author
author
dc.subject.none.fl_str_mv Geofísica
Solar cycles
ULF
topic Geofísica
Solar cycles
ULF
dc.description.none.fl_txt_mv Pc5 ULF (ultra-low frequency) waves can energize electrons to relativistic energies of >2  MeV in geostationary orbits. Enhanced fluxes of such electrons can induce operational anomalies in geostationary satellites. The variations of the two quantities in timescales ranging from days to solar cycles are thus of interest in gauging their space weather effects over different time frames. In this study, we present a statistical analysis of two 11-year solar cycles (cycles 22 and 23) of data comprising the daily relativistic electron fluence observed by Geostationary Environment Satellites (GOESs) and daily Pc5 ULF wave power derived from auroral zone magnetic observatories in Canada. First, an autocorrelation analysis is carried out, which indicates a 27 d periodicity in both parameters for all solar phases, and such a periodicity is most pronounced in the declining and late declining phase. Also, a 9 and 13 d periodicity are seen in some years. Then, a superposed epoch analysis is performed to scrutinize semiannual variation (SAV), which shows that fluence near the equinoxes is 1 order of magnitude higher than near solstices, and Pc5 ULF wave power is 0.5 orders of magnitude higher near the equinoxes than near the solstices. We then evaluate three possible SAV mechanisms (which are based on the axial, equinoctial, and Russell and McPherron effect) to determine which one can best explain the observations. Correlation of the profiles of the observational curves with those of the angles that control each of the SAV mechanisms suggests that the equinoctial mechanism may be responsible for the SAV of electron fluence, while both the equinoctial and the Russell and McPherron mechanisms are important for the SAV of Pc5 ULF wave power. Comparable results are obtained when using functional dependencies of the main angles instead of the angles mentioned above. Lastly, superposed curves of fluence and Pc5 ULF wave power were used to calculate least-square fits with a fixed semiannual period. Comparison of the maxima and minima of the fits with those predicted by the three mechanisms shows that the equinoctial effect better estimates the maxima and minima of the SAV in fluence while for the SAV in Pc5 ULF wave power the equinoctial and Russell and McPherron mechanisms predict one maximum and one minimum each.
Facultad de Ciencias Astronómicas y Geofísicas
description Pc5 ULF (ultra-low frequency) waves can energize electrons to relativistic energies of >2  MeV in geostationary orbits. Enhanced fluxes of such electrons can induce operational anomalies in geostationary satellites. The variations of the two quantities in timescales ranging from days to solar cycles are thus of interest in gauging their space weather effects over different time frames. In this study, we present a statistical analysis of two 11-year solar cycles (cycles 22 and 23) of data comprising the daily relativistic electron fluence observed by Geostationary Environment Satellites (GOESs) and daily Pc5 ULF wave power derived from auroral zone magnetic observatories in Canada. First, an autocorrelation analysis is carried out, which indicates a 27 d periodicity in both parameters for all solar phases, and such a periodicity is most pronounced in the declining and late declining phase. Also, a 9 and 13 d periodicity are seen in some years. Then, a superposed epoch analysis is performed to scrutinize semiannual variation (SAV), which shows that fluence near the equinoxes is 1 order of magnitude higher than near solstices, and Pc5 ULF wave power is 0.5 orders of magnitude higher near the equinoxes than near the solstices. We then evaluate three possible SAV mechanisms (which are based on the axial, equinoctial, and Russell and McPherron effect) to determine which one can best explain the observations. Correlation of the profiles of the observational curves with those of the angles that control each of the SAV mechanisms suggests that the equinoctial mechanism may be responsible for the SAV of electron fluence, while both the equinoctial and the Russell and McPherron mechanisms are important for the SAV of Pc5 ULF wave power. Comparable results are obtained when using functional dependencies of the main angles instead of the angles mentioned above. Lastly, superposed curves of fluence and Pc5 ULF wave power were used to calculate least-square fits with a fixed semiannual period. Comparison of the maxima and minima of the fits with those predicted by the three mechanisms shows that the equinoctial effect better estimates the maxima and minima of the SAV in fluence while for the SAV in Pc5 ULF wave power the equinoctial and Russell and McPherron mechanisms predict one maximum and one minimum each.
publishDate 2020
dc.date.none.fl_str_mv 2020-09-04
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info:eu-repo/semantics/publishedVersion
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dc.identifier.none.fl_str_mv http://sedici.unlp.edu.ar/handle/10915/123773
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info:eu-repo/semantics/altIdentifier/issn/0992-7689
info:eu-repo/semantics/altIdentifier/doi/10.5194/angeo-38-953-2020
dc.rights.none.fl_str_mv info:eu-repo/semantics/openAccess
http://creativecommons.org/licenses/by/4.0/
Creative Commons Attribution 4.0 International (CC BY 4.0)
eu_rights_str_mv openAccess
rights_invalid_str_mv http://creativecommons.org/licenses/by/4.0/
Creative Commons Attribution 4.0 International (CC BY 4.0)
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