Space Research Institute, Austrian Academy of Sciences, Graz 8042, Austria
Abstract. A study of the characteristics of double substorm onsets in response to variations of the interplanetary magnetic field (IMF) is undertaken with magnetotail and ground observations by the Time History of Events and Macroscale Interactions during Substorms (THEMIS) mission on 18 March 2009 and 3 April 2009 (Kp ~ 0), and on 16 February 2008 and 24 February 2010 (Kp ~ 2–3). During the time of interest, THEMIS probes at −8RE > XGSM > −20RE and 5RE > YGSM > −5RE observed earth-bound flow bursts accompanied by magnetic dipolarizations varying in two stages. The keograms and all sky images close to their footprints showed two consecutive auroral breakups of which the first appeared at lower latitudes than the second. The ground-based magnetometers sensed magnetic bays and perturbations resulting from the formation of substorm current wedge. Two consecutive pulsations in the Pi2-Ps6 band period occurred simultaneously from high to low and very low latitudes. They appeared in the same cycle of growth and then decline in Kyoto-AL. The onset timing of ground pulsations mapped to the solar wind observation just in front of Earth’s magnetopause shows their occurrence under an IMF variation cycle of north-to-south and then north. Their dynamic spectrums have the spectral features of double substorm onsets triggered by northward IMF turning. Hence in response to IMF variations, double substorm onsets can be characterized with two-stage magnetic dipolarizations in the magnetotail, two auroral breakups of which the first occurring at lower latitudes than the second, and two consecutive Pi2-Ps6 band pulsations.
This preprint has been withdrawn.
How to cite. Cheng, C.-C., Russell, C. T., Mann, I. R., Donovan, E., and Baumjohann, W.: Characteristic study of double substorm onsets in response to IMF variations, Ann. Geophys. Discuss. [preprint], https://doi.org/10.5194/angeo-2018-116, 2018.
Received: 12 Oct 2018 – Discussion started: 18 Oct 2018
The comparison of geomagnetic active and quite events of double substorm onsets responsive to IMF variations shows that the occurrence sequence of all required substorm signatures looks the same and not different for small and large Kp. Double substorm onsets responsive to IMF variations can be characterized with two-stage magnetic dipolarizations in the magnetotail, two auroral breakups of which the first occurring at lower latitudes than the second, and two consecutive Pi2-Ps6 band pulsations.
The comparison of geomagnetic active and quite events of double substorm onsets responsive to...