Association of consecutive Pi2‐Ps6 band pulsations with earthward fast flows in the plasma sheet in response to IMF variations

Cheng, C.; Mann, I. R.; Baumjohann, W.

doi:10.1002/2013ja019275

Cited by 5 publications

(5 citation statements)

References 52 publications

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“…Moreover, two consecutive pulsations in the Pi2-Ps6 band period occurred simultaneously from high latitudes down to very low latitudes (see . These observational results support the suggestion by Shiokawa et al (1998) that braking of earth-bound 20 flow bursts leads to Pi2 onset and the earlier finding that Ps6 can occur right after the Pi2 onset in a time sequence (Cheng et al, 2014 and references of therein).…”

Section: Discussion and Summarysupporting

confidence: 90%

Characteristic study of double substorm onsets in response to IMF variations

Cheng

Russell

Mann

et al. 2018

Preprint

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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.

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Section: Discussion and Summarysupporting

confidence: 90%

Characteristic study of double substorm onsets in response to IMF variations

Cheng

Russell

Mann

et al. 2018

Preprint

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“…Regular long-period oscillations in the B field field over widespread regions in the midnight sector are reminiscent of the low-frequency (4-40 min period) Ps6 disturbances that usually occur in conjunction with omega band auroral structures (Amm et al, 2005;Apatenkov et al, 2020;Lühr & Schlegel, 1994;Saito, 1978) near substorm onset (Connors et al, 2003;Wild et al, 2011) or recovery (Amm et al, 2005;Saito, 1978) phases. When the magnetotail snaps back to Earth, the Earthward fast flow may drive Ps6-type disturbances (Cheng et al, 2014;Henderson et al, 2002). Some authors prefer the term disturbance because these are not pulsations in the sense that they are rather the ground signatures of FAC systems (Amm et al, 2005;Lühr & Schlegel, 1994).…”

Section: Event 2: June 2015 Stormmentioning

confidence: 99%

Geomagnetic Pulsations Driving Geomagnetically Induced Currents

2021

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Geomagnetically induced currents (GICs) are driven by the geoelectric field induced by fluctuations of Earth's magnetic field. Drivers of intense GICs are often associated with large impulsive events such as coronal mass ejections. To a lesser extent fluctuations from regular oscillations of the geomagnetic field, or geomagnetic pulsations, have also been identified as possible drivers of GICs. In this work we show that these low‐frequency pulsations are directly observed in measured GIC data from power networks. Due to the low‐pass nature of GICs, Pc5 and lower‐frequency pulsations drive significant GICs for an extended duration even at midlatitudes. Longer‐period Ps6‐type disturbances apparently not typical of midlatitudes are seen with GIC amplitudes comparable to the peak GIC at storm sudden commencement. The quasi‐ac (alternating current) nature of the sustained pulsation driving affects the power system response and cannot be properly modeled using only direct current (dc) models. A further consideration is that the often used dB/dt GIC proxy is biased to the sampling rate of the geomagnetic field measurements used. The dB/dt metric does not adequately characterize GIC activity at frequencies in the low ultralow‐frequency (ULF) range, and a frequency‐weighted proxy akin to geoelectric field should be used instead.

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“…Like mid-latitude Pi2 pulsations can result from a plasmaspheric cavity resonance, Pi3 pulsations may be associated with some MHD cavity response [Cheng et al, 2014]. For example, a MHD cavity resonator may be formed in a nightside region with decreased Alfvén velocity [Leonovich and Mazur, 2005].…”

Section: Discussionmentioning

confidence: 99%

Conjugate properties of Pi3/Ps6 pulsations according to Antarctica-Greenland observations

Martines-Bedenko¹,

Hartinger²,

Partamies³

et al. 2022

Russian Journal of Earth Sciences

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We consider interhemispheric properties of fine structure of substorm – quasi-periodic geomagnetic fluctuations, Pi3 pulsations, using data from conjugate magnetometers in Antarctica and Greenland. Pi3 pulsations are found to accompany both the substorm expansion/recovery phases and the steady magnetospheric convection (SMC) events. The epicenter of Pi3 power is at the same latitude as maximal amplitude of magnetic bays. The interhemispheric properties of Pi3 pulsations are not consistent: in some events, coherent in-phase magnetic oscillations are observed in both hemispheres, in others, periodic variations are observed in one hemisphere only. When Pi3 pulsations are observed in both conjugate sites, their H-components are in-phase, which corresponds to the fundamental mode of field line oscillations between high-conductive ionospheres. Conjugate observations have provided an additional information on an elusive mechanism of Pi3 pulsations.

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Association of consecutive Pi2‐Ps6 band pulsations with earthward fast flows in the plasma sheet in response to IMF variations

Cited by 5 publications

References 52 publications

Characteristic study of double substorm onsets in response to IMF variations

Characteristic study of double substorm onsets in response to IMF variations

Geomagnetic Pulsations Driving Geomagnetically Induced Currents

Conjugate properties of Pi3/Ps6 pulsations according to Antarctica-Greenland observations

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