Diagnosing the role of Alfvén Waves in Magnetosphere-Ionosphere Coupling: Swarm Observations of Large Amplitude Non-Stationary Magnetic Perturbations During an Interval of Northward IMF

Publication Date:
2018-01-04
Publisher:
Wiley-Blackwell
Print ISSN:
0148-0227
Topics:
Geosciences
Physics
Published by:
http://www.wiley.com/wiley-blackwell
_version_ 1836398730235871233
autor I. P. Pakhotin, I. R. Mann, R. L. Lysak, D. J. Knudsen, J. W. Gjerloev, I. J. Rae, C. Forsyth, K. R. Murphy, D. M. Miles, L. G. Ozeke, G. Balasis
beschreibung High resolution multi-spacecraft Swarm data are used to examine magnetosphere-ionosphere coupling (MIC) during a period of northward IMF on 31 st May 2014. The observations reveal a prevalence of unexpectedly large amplitude (〉100 nT) and time-varying magnetic perturbations during the polar passes, with especially large amplitude magnetic perturbations being associated with large-scale downward field-aligned currents. Differences between the magnetic field measurements sampled at 50 Hz from Swarm A and C, approximately 10 seconds apart along-track, and the correspondence between the observed electric and magnetic fields at 16 samples per second, provide significant evidence for an important role for Alfvén waves in magnetosphere-ionosphere coupling even during northward IMF conditions. Spectral comparison between the wave E- and B-fields reveals a frequency-dependent phase difference and amplitude ratio consistent with interference between incident and reflected Alfvén waves. At low frequencies, the E/B ratio is in phase with an amplitude determined by the Pedersen conductance. At higher frequencies, the amplitude and phase change as a function of frequency in good agreement with an ionospheric Alfvén resonator model including Pedersen conductance effects. Indeed, within this Alfvén wave incidence, reflection, and interference paradigm, even quasi-static field-aligned currents might be reasonably interpreted as very low frequency (ω 0) Alfvén waves. Overall, our results not only indicate the importance of Alfvén waves for magnetosphere-ionosphere coupling, but also demonstrate a method for using Swarm data for the innovative experimental diagnosis of Pedersen conductance from low-Earth orbit satellite measurements.
citation_standardnr 6128926
datenlieferant ipn_articles
feed_copyright American Geophysical Union (AGU)
feed_copyright_url http://www.agu.org/
feed_id 7531
feed_publisher Wiley-Blackwell
feed_publisher_url http://www.wiley.com/wiley-blackwell
insertion_date 2018-01-04
journalissn 0148-0227
publikationsjahr_anzeige 2018
publikationsjahr_facette 2018
publikationsjahr_intervall 7984:2015-2019
publikationsjahr_sort 2018
publisher Wiley-Blackwell
quelle Journal of Geophysical Research JGR - Space Physics
relation http://onlinelibrary.wiley.com/resolve/doi?DOI=10.1002%2F2017JA024713
search_space articles
shingle_author_1 I. P. Pakhotin, I. R. Mann, R. L. Lysak, D. J. Knudsen, J. W. Gjerloev, I. J. Rae, C. Forsyth, K. R. Murphy, D. M. Miles, L. G. Ozeke, G. Balasis
shingle_author_2 I. P. Pakhotin, I. R. Mann, R. L. Lysak, D. J. Knudsen, J. W. Gjerloev, I. J. Rae, C. Forsyth, K. R. Murphy, D. M. Miles, L. G. Ozeke, G. Balasis
shingle_author_3 I. P. Pakhotin, I. R. Mann, R. L. Lysak, D. J. Knudsen, J. W. Gjerloev, I. J. Rae, C. Forsyth, K. R. Murphy, D. M. Miles, L. G. Ozeke, G. Balasis
shingle_author_4 I. P. Pakhotin, I. R. Mann, R. L. Lysak, D. J. Knudsen, J. W. Gjerloev, I. J. Rae, C. Forsyth, K. R. Murphy, D. M. Miles, L. G. Ozeke, G. Balasis
shingle_catch_all_1 Diagnosing the role of Alfvén Waves in Magnetosphere-Ionosphere Coupling: Swarm Observations of Large Amplitude Non-Stationary Magnetic Perturbations During an Interval of Northward IMF
High resolution multi-spacecraft Swarm data are used to examine magnetosphere-ionosphere coupling (MIC) during a period of northward IMF on 31 st May 2014. The observations reveal a prevalence of unexpectedly large amplitude (>100 nT) and time-varying magnetic perturbations during the polar passes, with especially large amplitude magnetic perturbations being associated with large-scale downward field-aligned currents. Differences between the magnetic field measurements sampled at 50 Hz from Swarm A and C, approximately 10 seconds apart along-track, and the correspondence between the observed electric and magnetic fields at 16 samples per second, provide significant evidence for an important role for Alfvén waves in magnetosphere-ionosphere coupling even during northward IMF conditions. Spectral comparison between the wave E- and B-fields reveals a frequency-dependent phase difference and amplitude ratio consistent with interference between incident and reflected Alfvén waves. At low frequencies, the E/B ratio is in phase with an amplitude determined by the Pedersen conductance. At higher frequencies, the amplitude and phase change as a function of frequency in good agreement with an ionospheric Alfvén resonator model including Pedersen conductance effects. Indeed, within this Alfvén wave incidence, reflection, and interference paradigm, even quasi-static field-aligned currents might be reasonably interpreted as very low frequency (ω 0) Alfvén waves. Overall, our results not only indicate the importance of Alfvén waves for magnetosphere-ionosphere coupling, but also demonstrate a method for using Swarm data for the innovative experimental diagnosis of Pedersen conductance from low-Earth orbit satellite measurements.
I. P. Pakhotin, I. R. Mann, R. L. Lysak, D. J. Knudsen, J. W. Gjerloev, I. J. Rae, C. Forsyth, K. R. Murphy, D. M. Miles, L. G. Ozeke, G. Balasis
Wiley-Blackwell
0148-0227
01480227
shingle_catch_all_2 Diagnosing the role of Alfvén Waves in Magnetosphere-Ionosphere Coupling: Swarm Observations of Large Amplitude Non-Stationary Magnetic Perturbations During an Interval of Northward IMF
High resolution multi-spacecraft Swarm data are used to examine magnetosphere-ionosphere coupling (MIC) during a period of northward IMF on 31 st May 2014. The observations reveal a prevalence of unexpectedly large amplitude (>100 nT) and time-varying magnetic perturbations during the polar passes, with especially large amplitude magnetic perturbations being associated with large-scale downward field-aligned currents. Differences between the magnetic field measurements sampled at 50 Hz from Swarm A and C, approximately 10 seconds apart along-track, and the correspondence between the observed electric and magnetic fields at 16 samples per second, provide significant evidence for an important role for Alfvén waves in magnetosphere-ionosphere coupling even during northward IMF conditions. Spectral comparison between the wave E- and B-fields reveals a frequency-dependent phase difference and amplitude ratio consistent with interference between incident and reflected Alfvén waves. At low frequencies, the E/B ratio is in phase with an amplitude determined by the Pedersen conductance. At higher frequencies, the amplitude and phase change as a function of frequency in good agreement with an ionospheric Alfvén resonator model including Pedersen conductance effects. Indeed, within this Alfvén wave incidence, reflection, and interference paradigm, even quasi-static field-aligned currents might be reasonably interpreted as very low frequency (ω 0) Alfvén waves. Overall, our results not only indicate the importance of Alfvén waves for magnetosphere-ionosphere coupling, but also demonstrate a method for using Swarm data for the innovative experimental diagnosis of Pedersen conductance from low-Earth orbit satellite measurements.
I. P. Pakhotin, I. R. Mann, R. L. Lysak, D. J. Knudsen, J. W. Gjerloev, I. J. Rae, C. Forsyth, K. R. Murphy, D. M. Miles, L. G. Ozeke, G. Balasis
Wiley-Blackwell
0148-0227
01480227
shingle_catch_all_3 Diagnosing the role of Alfvén Waves in Magnetosphere-Ionosphere Coupling: Swarm Observations of Large Amplitude Non-Stationary Magnetic Perturbations During an Interval of Northward IMF
High resolution multi-spacecraft Swarm data are used to examine magnetosphere-ionosphere coupling (MIC) during a period of northward IMF on 31 st May 2014. The observations reveal a prevalence of unexpectedly large amplitude (>100 nT) and time-varying magnetic perturbations during the polar passes, with especially large amplitude magnetic perturbations being associated with large-scale downward field-aligned currents. Differences between the magnetic field measurements sampled at 50 Hz from Swarm A and C, approximately 10 seconds apart along-track, and the correspondence between the observed electric and magnetic fields at 16 samples per second, provide significant evidence for an important role for Alfvén waves in magnetosphere-ionosphere coupling even during northward IMF conditions. Spectral comparison between the wave E- and B-fields reveals a frequency-dependent phase difference and amplitude ratio consistent with interference between incident and reflected Alfvén waves. At low frequencies, the E/B ratio is in phase with an amplitude determined by the Pedersen conductance. At higher frequencies, the amplitude and phase change as a function of frequency in good agreement with an ionospheric Alfvén resonator model including Pedersen conductance effects. Indeed, within this Alfvén wave incidence, reflection, and interference paradigm, even quasi-static field-aligned currents might be reasonably interpreted as very low frequency (ω 0) Alfvén waves. Overall, our results not only indicate the importance of Alfvén waves for magnetosphere-ionosphere coupling, but also demonstrate a method for using Swarm data for the innovative experimental diagnosis of Pedersen conductance from low-Earth orbit satellite measurements.
I. P. Pakhotin, I. R. Mann, R. L. Lysak, D. J. Knudsen, J. W. Gjerloev, I. J. Rae, C. Forsyth, K. R. Murphy, D. M. Miles, L. G. Ozeke, G. Balasis
Wiley-Blackwell
0148-0227
01480227
shingle_catch_all_4 Diagnosing the role of Alfvén Waves in Magnetosphere-Ionosphere Coupling: Swarm Observations of Large Amplitude Non-Stationary Magnetic Perturbations During an Interval of Northward IMF
High resolution multi-spacecraft Swarm data are used to examine magnetosphere-ionosphere coupling (MIC) during a period of northward IMF on 31 st May 2014. The observations reveal a prevalence of unexpectedly large amplitude (>100 nT) and time-varying magnetic perturbations during the polar passes, with especially large amplitude magnetic perturbations being associated with large-scale downward field-aligned currents. Differences between the magnetic field measurements sampled at 50 Hz from Swarm A and C, approximately 10 seconds apart along-track, and the correspondence between the observed electric and magnetic fields at 16 samples per second, provide significant evidence for an important role for Alfvén waves in magnetosphere-ionosphere coupling even during northward IMF conditions. Spectral comparison between the wave E- and B-fields reveals a frequency-dependent phase difference and amplitude ratio consistent with interference between incident and reflected Alfvén waves. At low frequencies, the E/B ratio is in phase with an amplitude determined by the Pedersen conductance. At higher frequencies, the amplitude and phase change as a function of frequency in good agreement with an ionospheric Alfvén resonator model including Pedersen conductance effects. Indeed, within this Alfvén wave incidence, reflection, and interference paradigm, even quasi-static field-aligned currents might be reasonably interpreted as very low frequency (ω 0) Alfvén waves. Overall, our results not only indicate the importance of Alfvén waves for magnetosphere-ionosphere coupling, but also demonstrate a method for using Swarm data for the innovative experimental diagnosis of Pedersen conductance from low-Earth orbit satellite measurements.
I. P. Pakhotin, I. R. Mann, R. L. Lysak, D. J. Knudsen, J. W. Gjerloev, I. J. Rae, C. Forsyth, K. R. Murphy, D. M. Miles, L. G. Ozeke, G. Balasis
Wiley-Blackwell
0148-0227
01480227
shingle_title_1 Diagnosing the role of Alfvén Waves in Magnetosphere-Ionosphere Coupling: Swarm Observations of Large Amplitude Non-Stationary Magnetic Perturbations During an Interval of Northward IMF
shingle_title_2 Diagnosing the role of Alfvén Waves in Magnetosphere-Ionosphere Coupling: Swarm Observations of Large Amplitude Non-Stationary Magnetic Perturbations During an Interval of Northward IMF
shingle_title_3 Diagnosing the role of Alfvén Waves in Magnetosphere-Ionosphere Coupling: Swarm Observations of Large Amplitude Non-Stationary Magnetic Perturbations During an Interval of Northward IMF
shingle_title_4 Diagnosing the role of Alfvén Waves in Magnetosphere-Ionosphere Coupling: Swarm Observations of Large Amplitude Non-Stationary Magnetic Perturbations During an Interval of Northward IMF
timestamp 2025-06-30T23:31:43.536Z
titel Diagnosing the role of Alfvén Waves in Magnetosphere-Ionosphere Coupling: Swarm Observations of Large Amplitude Non-Stationary Magnetic Perturbations During an Interval of Northward IMF
titel_suche Diagnosing the role of Alfvén Waves in Magnetosphere-Ionosphere Coupling: Swarm Observations of Large Amplitude Non-Stationary Magnetic Perturbations During an Interval of Northward IMF
topic TE-TZ
U
uid ipn_articles_6128926