The Occurrence of Embedded Region 1 and 2 Currents Depends on Geomagnetic Activity Level

The geospace plume, referring to the combined processes of the plasmaspheric and the ionospheric storm‐enhanced density (SED)/total electron content (TEC) plumes, is one of the unique features of geomagnetic storms. The apparent spatial overlap and joint temporal evolution between the plasmaspheric plume and the equatorial mapping of the SED/TEC plume indicate strong magnetospheric‐ionospheric coupling. However, a systematic modeling study of the factors contributing to geospace plume development has not yet been performed due to the lack of a sufficiently comprehensive model including all the relevant physical processes. In this paper, we present a numerical simulation of the geospace plume in the 31 March 2001 storm using the Multiscale Atmosphere‐Geospace Environment model. The simulation reproduces the observed linkage of the two plumes, which, we interpret as a result of both being driven by the electric field that maps between the magnetosphere and the ionosphere. The model predicts two velocity channels of sunward plasma drift at different latitudes in the dusk sector during the storm main phase, which are identified as the sub‐auroral polarization stream (subauroral polarization streams (SAPS)) and the convection return flow, respectively. The SAPS is responsible for the erosion of the plasmasphere plume and contributes to the ionospheric TEC depletion in the midlatitude trough region. We further find the spatial distributions of the magnetospheric ring current ions and electrons, determined by a delicate balance of the energy‐dependent gradient/curvature drifts and the E × B drifts, are crucial to sustain the SAPS electric field that shapes the geospace plume throughout the storm main phase.

Section: Discussionmentioning

confidence: 99%

“…Figures 9a1-9d1 and 9a2-9d2 are DMSP F13 and F15 measurements during 06:57-07:09UT and 08:26-08:41UT, 03-31-2001 respectively. Ranges of the Region-1 and the Region-2 currents can be derived from the magnetic field perturbation following the method from J Liu et al (2022),. which are divided by the back dashed line in Figure9a1and a2.…”

mentioning

confidence: 99%

The Relation Among the Ring Current, Subauroral Polarization Stream, and the Geospace Plume: MAGE Simulation of the 31 March 2001 Super Storm

Bao,

Wang,

Sorathia

et al. 2023

“…This correlation was consistently observed in the 28 events that have good FGM magnetic field measurements (these events are collected after March 2021). This correlation is expected because the flux dropouts are within the plasma sheet region, where part of the R1 FAC is known to be connected with cross‐tail currents and is likely to be driven by pressure gradients there (Birn et al., 1999; Liu et al., 2021, 2022; Vasyliunas, 1970; Xing et al., 2009). We also note that most flux dropout events are located close to the R1/R2 interface.…”

Section: Observationsmentioning

confidence: 99%

Energetic Electron Flux Dropouts Measured by ELFIN in the Ionospheric Projection of the Plasma Sheet

Shen,

Artemyev,

Runov

et al. 2023

Self Cite

Low‐altitude observations of magnetospheric particles provide a unique opportunity for remote probing of the magnetospheric and plasma states during active times. We present the first statistical analysis of a specific pattern in such observations, energetic electron flux dropouts in the low‐altitude projection of the plasma sheet. Using 3.5 years of data from the ELFIN CubeSats we report the occurrence distribution of 145 energetic electron flux dropout events and identify characteristics, including their prevalence in the dusk and premidnight sectors, their association with substorms and enhanced auroral activities, and their correlation with the region‐1 (R1) field‐aligned current region. We also investigate three representative dropout events which benefit from satellite conjunctions between ELFIN, GOES, and THEMIS, to better understand the magnetospheric drivers and magnetic field conditions that lead to such dropouts as viewed by ELFIN. One class of dropouts may be associated with magnetic field mapping distortions due to local enhancements and thinning of cross‐tail current sheets and amplification of R1 field‐aligned currents. The other class may be associated with the increase in perpendicular anisotropy of magnetospheric electrons due to magnetic field dipolarizations near premidnight. These plasma sheet flux dropouts at ELFIN provide a valuable tool for refining magnetospheric models, thereby improving the accuracy of field‐line mapping during substorms.

“…The other data set we use is boundaries of R1 and R2 currents identified from DMSP transects of the auroral zone. Liu et al (2022) determined these boundaries using a fully-automated algorithm based on the perturbation magnetic field. This algorithm has been applied to all DMSP auroral zone transects with the available Poynting flux data (Knipp et al, 2021), which provide 14,796 transects with R1 and R2 boundaries thus identified for our statistical studies (as illustrated in Figure 1).…”

Section: Data Setsmentioning

confidence: 99%

“…Our investigation is based on a recently assembled S p database (Knipp et al., 2021) and a recent method for determining boundaries of Region 1 and 2 currents (Liu et al., 2022), both using data from the DMSP mission. All DMSP spacecraft are polar orbiting with a low‐earth orbit of ∼850 km altitude.…”

Section: Data Setsmentioning

confidence: 99%

Poynting Flux Input to the Auroral Ionosphere: The Impact of Subauroral Polarization Streams and Dawnside Auroral Polarization Streams

Liu,

Lyons,

Knipp

et al. 2024

Self Cite

The Poynting vector (Poynting flux) from Earth's magnetosphere downward toward its ionosphere carries the energy that powers the Joule heating in the ionosphere and thermosphere. The Joule heating controls fundamental ionospheric properties affecting the entire magnetosphere‐ionosphere‐thermosphere system, so it is necessary to understand when and where the Poynting flux is significant. Taking advantage of new data sets generated from DMSP (Defense Meteorological Satellite Program) observations, we investigate the Poynting flux distribution within and around the auroral zone, where most magnetosphere‐ionosphere (M‐I) dynamics and thus Joule heating occurs. We find that the Poynting flux, which is generally larger under more active conditions, is concentrated in the sunlit cusp and near the interface between Region 1 and 2 currents. The former concentration suggests voltage generators drive the cusp dynamics. The latter concentration shows asymmetries with respect to the interface between the Region 1 and 2 currents. We show that these reflect the controlling impact of subauroral polarization streams and dawnside auroral polarization streams on the Poynting flux.