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Timescales of Birkeland Currents Driven by the IMF
Author(s) -
Coxon John C.,
Shore Robert M.,
Freeman Mervyn P.,
Fear Robert C.,
Browett Stephen D.,
Smith Andrew W.,
Whiter Daniel K.,
Anderson Brian J.
Publication year - 2019
Publication title -
geophysical research letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.007
H-Index - 273
eISSN - 1944-8007
pISSN - 0094-8276
DOI - 10.1029/2018gl081658
Subject(s) - magnetosphere , physics , ionosphere , interplanetary magnetic field , latitude , geophysics , current (fluid) , ampere , solar wind , magnetic field , interplanetary spaceflight , astrophysics , computational physics , atmospheric sciences , astronomy , quantum mechanics , thermodynamics
We obtain current densities from the Active Magnetosphere and Planetary Electrodynamics Response Experiment (AMPERE), alongside B y and B z from the Interplanetary Magnetic Field (IMF) for March 2010. For each AMPERE spatial coordinate, we cross‐correlate current density with B y and B z , finding the maximum correlation for lags up to 360 min. The patterns of maximum correlation contain large‐scale structures consistent with the literature. For the correlation with B y , the lags on the dayside are 10 min at high latitudes but up to 240 min at lower latitudes. Lags on the nightside are 90–150 min. For B z , the shortest lags on the dayside are 10–20 min; on the equatorward edge of the current oval, 60–90 min; and on the nightside, predominantly 90–150 min. This novel approach enables us to see statistically the timescales on which information is electrodynamically communicated to the ionosphere after magnetic field lines reconnect on the dayside and nightside.