What Happens Before a Southward IMF Turning Reaches the Magnetopause?

Samsonov, A. A.; Sibeck, D. G.; Dmitrieva, N. P.; Semenov, V. S.

doi:10.1002/2017gl075020

Cited by 10 publications

(25 citation statements)

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“…Samsonov et al () recently used an MHD simulation to study a DD accompanied by a southward turning and showed that the DD propagation time through the magnetosheath was 14 min in good agreement with the ground response seen in changes of the Polar Cap North (PCN) index (Troshichev et al, ). Samsonov et al () noted a significant deceleration of the DD as it approached the magnetopause. The IMF was northward before the DD, and a magnetic barrier (Pudovkin, ) formed near the magnetopause.…”

Section: Introductionmentioning

confidence: 79%

“…Finally, it takes only about 1 min from the contact of the DD with the subsolar magnetopause to the first ground (ionospheric) response. During the same event, Samsonov et al () noted a sunward motion of the subsolar magnetopause for ∼10 min before the DD had reached the magnetopause. Their MHD simulation showed that the dissipation of the magnetic barrier caused by magnetosheath reconnection gradually decreases the total pressures applied to the magnetopause thus resulting in the sunward magnetopause motion.…”

Section: Introductionmentioning

confidence: 84%

“…This paper builds upon the work of Samsonov et al () and investigates which parameters affect the magnetosheath propagation time. We will use MHD simulations with the solar wind conditions similar to the ones in Samsonov et al () but also simulated several artificial events and finally compare the numerical results with observed time delays in the ground response to solar wind DDs.…”

Section: Introductionmentioning

confidence: 98%

“…Previous studies (e.g., Bhaskar & Vichare, ; Ridley et al, ; Ruohoniemi & Greenwald, ; Saunders et al, ; Taylor et al, ; see more references in Samsonov et al, ) determined that the delay from a solar wind DD reaching the subsolar bow shock to the first response in ground magnetometers or radars is on the order of 10–16 min. Samsonov et al () recently used an MHD simulation to study a DD accompanied by a southward turning and showed that the DD propagation time through the magnetosheath was 14 min in good agreement with the ground response seen in changes of the Polar Cap North (PCN) index (Troshichev et al, ). Samsonov et al () noted a significant deceleration of the DD as it approached the magnetopause.…”

Section: Introductionmentioning

confidence: 99%

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Magnetosheath Propagation Time of Solar Wind Directional Discontinuities

et al. 2018

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Observed delays in the ground response to solar wind directional discontinuities have been explained as the result of larger than expected magnetosheath propagation times. Recently, Samsonov et al. (2017, https://doi.org/10.1002/2017GL075020) showed that the typical time for a southward interplanetary magnetic field (IMF) turning to propagate across the magnetosheath is 14 min. Here by using a combination of magnetohydrodynamic simulations, spacecraft observations, and analytic calculations, we study the dependence of the propagation time on solar wind parameters and near-magnetopause cutoff speed. Increases in the solar wind speed result in greater magnetosheath plasma flow velocities, decreases in the magnetosheath thickness and, as a result, decreases in the propagation time. Increases in the IMF strength result in increases in the magnetosheath thickness and increases in the propagation time. Both magnetohydrodynamic simulations and observations suggest that propagation times are slightly smaller for northward IMF turnings. Magnetosheath flow deceleration must be taken into account when predicting the arrival times of solar wind structures at the dayside magnetopause.

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Section: Introductionmentioning

confidence: 79%

Section: Introductionmentioning

confidence: 84%

Section: Introductionmentioning

confidence: 98%

Section: Introductionmentioning

confidence: 99%

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Magnetosheath Propagation Time of Solar Wind Directional Discontinuities

et al. 2018

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“…Assuming the nose of the bow shock at 14 R E , we get the propagation time from THC to the bow shock about 6 minutes. The propagation time through the magnetosheath can be estimated as 14 min (Samsonov et al, 2017). Thus, the southward turning of IMF Bz could reach the magnetopause 20 min after registration onboard THC, and the ionospheric convection is expected to respond in ~ 20 min after that (Hairson and Heelis, 1995).…”

Section: Pre-onset Phenomena In the Interplanetary Spacementioning

confidence: 99%

Polar substorm on 7 December 2015: pre-onset phenomena and features of auroral breakup

Safargaleev¹,

Kozlovsky²,

Mitrofanov³

2019

Preprint

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Abstract. Comprehensive analysis of a moderate 600-nT substorm was performed with using simultaneous optical observations inside the auroral oval and in the polar cap, combined with data from satellites, radars, and ground magnetometers. The onset took place near the poleward boundary of the auroral oval that is not typical for classical substorms. The substorm onset was preceded by two negative excursions of the IMF Bz component with 15-min interval between them, two enhancements of the antisunward convection in the polar cap with the same repetition period, and 15-minute oscillations in geomagnetic H-component in the auroral zone. The distribution of the pulsation intensity along meridian has two local maxima – at equatorial and poleward boundaries of the auroral oval where pulsations occurred in the out-of-phase mode resembling the field-line resonance. At initial stage, the auroral breakup developed as auroral torch stretching and expanding poleward along the meridian. Some later it took a form of the large-scale coiling structure that also distinguishes the considered substorm from classical one. Magnetic, radar and AMPERE satellite data show that before the collapse the coiling structure was located between two field-aligned currents: downward at poleward boundary of structure and upward at equatorial boundary. The set of GEOTAIL satellite and ground data fits to the near-tail current disruption scenario of the substorm onset. We suggest that the 15-min oscillations might play a role in the substorm initiation.

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Exploring solar-terrestrial interactions via multiple imaging observers

et al. 2021

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How does solar wind energy flow through the Earth’s magnetosphere, how is it converted and distributed? is the question we want to address. We need to understand how geomagnetic storms and substorms start and grow, not just as a matter of scientific curiosity, but to address a clear and pressing practical problem: space weather, which can influence the performance and reliability of our technological systems, in space and on the ground, and can endanger human life and health. Much knowledge has already been acquired over the past decades, particularly by making use of multiple spacecraft measuring conditions in situ, but the infant stage of space weather forecasting demonstrates that we still have a vast amount of learning to do. A novel global approach is now being taken by a number of space imaging missions which are under development and the first tantalising results of their exploration will be available in the next decade. In this White Paper, submitted to ESA in response to the Voyage 2050 Call, we propose the next step in the quest for a complete understanding of how the Sun controls the Earth’s plasma environment: a tomographic imaging approach comprising two spacecraft in highly inclined polar orbits, enabling global imaging of magnetopause and cusps in soft X-rays, of auroral regions in FUV, of plasmasphere and ring current in EUV and ENA (Energetic Neutral Atoms), alongside in situ measurements. Such a mission, encompassing the variety of physical processes determining the conditions of geospace, will be crucial on the way to achieving scientific closure on the question of solar-terrestrial interactions.

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What Happens Before a Southward IMF Turning Reaches the Magnetopause?

Cited by 10 publications

References 42 publications

Magnetosheath Propagation Time of Solar Wind Directional Discontinuities

Magnetosheath Propagation Time of Solar Wind Directional Discontinuities

Polar substorm on 7 December 2015: pre-onset phenomena and features of auroral breakup

Exploring solar-terrestrial interactions via multiple imaging observers

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