Large‐scale current systems and ground magnetic disturbance during deep substorm injections

Yang, Jian; Toffoletto, F.; Wolf, R. A.; Sazykin, S.; Ontiveros, P. A.; Weygand, J. M.

doi:10.1029/2011ja017415

Cited by 66 publications

(120 citation statements)

References 62 publications

Supporting

Mentioning

110

Contrasting

Order By: Relevance

“…The BBFs in the braking phase are expected to add to the partial ring current and contribute to strengthening the R2 FAC and the ionospheric Pedersen current closure in the ionosphere (and thereby enhancing the EEJ) in Harang region-south, as we document in our ground-satellite observations at dusk. The magnetospheric part of this phenomenon has been predicted by Yang et al (2012) and Birn and Hesse (2013).…”

Section: Discussionmentioning

confidence: 99%

“…Henderson et al, 2006, andBurke et al, 2007). According to the modeling work of Yang et al (2012) and Birn and Hesse (2013) and the experimental study of Frissell et al (2011) such deep inward penetration of the plasma-depleted flux tubes may contribute to the partial ring current and associated R2 FAC coupling to the ionosphere. In MHD studies it has been shown that shears in the azimuthal flows near the plasma sheet-partial ring current interface can give rise to R1 and R2 polarity FACs at the outer and inner edges of the intruding plasma bubbles (Birn and Hesse, 2013).…”

Section: P E Sandholt Et Al: Repetitive Substorm Activity Driven Bmentioning

confidence: 99%

See 1 more Smart Citation

M–I coupling across the auroral oval at dusk and midnight: repetitive substorm activity driven by interplanetary coronal mass ejections (CMEs)

2014

View full text Add to dashboard Cite

Abstract. We study substorms from two perspectives, i.e., magnetosphere-ionosphere coupling across the auroral oval at dusk and at midnight magnetic local times. By this approach we monitor the activations/expansions of basic elements of the substorm current system (Bostrøm type I centered at midnight and Bostrøm type II maximizing at dawn and dusk) during the evolution of the substorm activity. Emphasis is placed on the R1 and R2 types of field-aligned current (FAC) coupling across the Harang reversal at dusk. We distinguish between two distinct activity levels in the substorm expansion phase, i.e., an initial transient phase and a persistent phase. These activities/phases are discussed in relation to polar cap convection which is continuously monitored by the polar cap north (PCN) index. The substorm activity we selected occurred during a long interval of continuously strong solar wind forcing at the interplanetary coronal mass ejection passage on 18 August 2003. The advantage of our scientific approach lies in the combination of (i) continuous ground observations of the ionospheric signatures within wide latitude ranges across the auroral oval at dusk and midnight by meridian chain magnetometer data, (ii) "snapshot" satellite (DMSP F13) observations of FAC/precipitation/ion drift profiles, and (iii) observations of current disruption/near-Earth magnetic field dipolarizations at geostationary altitude. Under the prevailing fortunate circumstances we are able to discriminate between the roles of the dayside and nightside sources of polar cap convection. For the nightside source we distinguish between the roles of inductive and potential electric fields in the two substages of the substorm expansion phase. According to our estimates the observed dipolarization rate (δB z /δt) and the inferred large spatial scales (in radial and azimuthal dimensions) of the dipolarization process in these strong substorm expansions may lead to 50-100 kV enhancements of the cross-polar-cap potential due to inductive electric field coupling.

show abstract

Section: Discussionmentioning

confidence: 99%

Section: P E Sandholt Et Al: Repetitive Substorm Activity Driven Bmentioning

confidence: 99%

M–I coupling across the auroral oval at dusk and midnight: repetitive substorm activity driven by interplanetary coronal mass ejections (CMEs)

2014

View full text Add to dashboard Cite

show abstract

“…The role of Earthward-propagating dipolarisation front flow bursts within X = −20 to −10 R E as a basic element (substructure) in the substorm process in the magnetotail is emphasized by Lyons et al (2012). On the association between dipolarization of flux tubes, inward transport of flux from the tail, and the generation of twin-cell flow in the ionosphere we refer to the review paper by Cowley (2000) and the recent simulation results of Yang et al (2012).…”

Section: Discussionmentioning

confidence: 99%

The pulsed nature of the nightside contribution to polar cap convection: repetitive substorm activity under steady interplanetary driving

2012

View full text Add to dashboard Cite

Abstract. The aim of this study is to investigate the relative contributions of dayside and nightside processes to the spatial and temporal structure of polar cap plasma convection. The central parameter is the cross-polar cap potential (CPCP). Selecting a 10-h-long interval of stable interplanetary driving by an interplanetary CME (ICME), we are able to distinguish between the dayside and nightside sources of the convection. The event was initiated by an abrupt enhancement of the magnetopause (MP) reconnection rate triggered by a southward turning of the ICME magnetic field. This was followed by a long interval (10 h) of steady and strong driving. Under the latter condition a long series of electrojet intensifications was observed which recurred at 50 min intervals. The detailed temporal structure of polar cap convection in relation to polar cap contraction events is obtained by combining continuous ground observations of convection-related magnetic deflections (including polar cap magnetic indices in the Northern and Southern Hemispheres, PCN and PCS) and the more direct, but lower-resolution ion drift data obtained from a satellite (DMSP F13) in polar orbit. The observed PCN enhancements combined with DMSP satellite observations (F13 and F15 data) of polar cap contractions during the evolution of selected substorm expansions allowed us to estimate the CPCP enhancements (25 %) associated with individual events in the series. Ground-satellite conjunctions are further used to investigate the spatial structure of polar cap convection, i.e., the homogeneous plasma flow in the centre (V i ≤ 1 km s −1 ) versus channels of enhanced antisunward flows (V i ≥ 1 km s −1 ) along the periphery of the polar cap. We emphasise the temporal structure of these polar cap flow phenomena in relation to the prevailing solar wind forcing and the repetitive substorm activity.

show abstract

“…In recent years, the Rice Convection Model (RCM) and the Rice Convection Model-Equilibrium (RCM-E) have been extensively used to investigate how the plasma inside depleted flux tubes is transported in the nearEarth region [Lemon et al, 2004;Zhang et al, 2008;Zhang et al, 2009aZhang et al, , 2009bYang et al, 2008Yang et al, , 2011Yang et al, , 2012Yang et al, , 2014aYang et al, , 2014b. The model uses the slow-flow approximation and assumes an isotropic pressure distribution along magnetic field lines.…”

Section: Introductionmentioning

confidence: 99%

On the contribution of plasma sheet bubbles to the storm time ring current

et al. 2015

View full text Add to dashboard Cite

Particle injections occur frequently inside 10 Re during geomagnetic storms. They are commonly associated with bursty bulk flows or plasma sheet bubbles transported from the tail to the inner magnetosphere. Although observations and theoretical arguments have suggested that they may have an important role in storm time dynamics, this assertion has not been addressed quantitatively. In this paper, we investigate which process is dominant for the storm time ring current buildup: large‐scale enhanced convection or localized bubble injections. We use the Rice Convection Model‐Equilibrium (RCM‐E) to model a series of idealized storm main phases. The boundary conditions at 14–15 Re on the nightside are adjusted to randomly inject bubbles to a degree roughly consistent with observed statistical properties. A test particle tracing technique is then used to identify the source of the ring current plasma. We find that the contribution of plasma sheet bubbles to the ring current energy increases from ~20% for weak storms to ~50% for moderate storms and levels off at ~61% for intense storms, while the contribution of trapped particles decreases from ~60% for weak storms to ~30% for moderate and ~21% for intense storms. The contribution of nonbubble plasma sheet flux tubes remains ~20% on average regardless of the storm intensity. Consistent with previous RCM and RCM‐E simulations, our results show that the mechanisms for plasma sheet bubbles enhancing the ring current energy are (1) the deep penetration of bubbles and (2) the bulk plasma pushed ahead of bubbles. Both the bubbles and the plasma pushed ahead typically contain larger distribution functions than those in the inner magnetosphere at quiet times. An integrated effect of those individual bubble injections is the gradual enhancement of the storm time ring current. We also make two predictions testable against observations. First, fluctuations over a time scale of 5–20 min in the plasma distributions and electric field can be seen in the central ring current region for the storm main phase. We find that the plasma pressure and the electric field EY there vary over about 10%–30% and 50%–300% of the background values, respectively. Second, the maximum plasma pressure and magnetic field depression in the central ring current region during the main phase are well correlated with the Dst index.

show abstract

Large‐scale current systems and ground magnetic disturbance during deep substorm injections

Cited by 66 publications

References 62 publications

M–I coupling across the auroral oval at dusk and midnight: repetitive substorm activity driven by interplanetary coronal mass ejections (CMEs)

M–I coupling across the auroral oval at dusk and midnight: repetitive substorm activity driven by interplanetary coronal mass ejections (CMEs)

The pulsed nature of the nightside contribution to polar cap convection: repetitive substorm activity under steady interplanetary driving

On the contribution of plasma sheet bubbles to the storm time ring current

Contact Info

Product

Resources

About