A statistical study of plasmaspheric plumes and ionospheric outflows observed at the dayside magnetopause

Although the effects of magnetic reconnection in magnetospheres can be observed at planetary scales, reconnection is initiated at electron scales in a plasma. Surrounding the electron diffusion region, there is an Ion‐Decoupling Region (IDR) of the size of the ion length scales (inertial length and gyroradius). Reconnection at the Earth's magnetopause often includes cold magnetospheric (few tens of eV), hot magnetospheric (10 keV), and magnetosheath (1 keV) ions, with different gyroradius length scales. We report observations of a subregion inside the IDR of the size of the cold ion population gyroradius (∼15 km) where the cold ions are demagnetized and accelerated parallel to the Hall electric field. Outside the subregion, cold ions follow the E × B motion together with electrons, while hot ions are demagnetized. We observe a sharp cold ion density gradient separating the two regions, which we identify as the cold and hot IDRs.

Section: Citationmentioning

confidence: 99%

Cold ion demagnetization near the X‐line of magnetic reconnection

Toledo‐Redondo

André

Khotyaintsev

et al. 2016

“…Sometimes, a plume of dense plasma will extend from the main body of the plasmasphere (e.g., Sandel et al, 2003) and can be observed near the dayside magnetopause (e.g., Lee et al, 2016). The plume ions are characterized by being perpendicular to magnetic fields, in contrast to the generally field-aligned ionospheric outflow ions (e.g., Lee et al, 2016).…”

Section: Introductionmentioning

confidence: 99%

ULF Waves Modulating and Acting as Mass Spectrometer for Dayside Ionospheric Outflow Ions

Liu

Zong

Zhou

et al. 2019

Self Cite

Ionospheric outflow has been shown to be a dominant ion source of Earth's magnetosphere. However, most studies in the literature are about ionospheric outflow injected into the nightside magnetosphere. We still know little about ionospheric outflow injected into the dayside magnetosphere and its further energization after it enters the magnetosphere. Here, with data from Magnetospheric Multiscale mission, we report direct observations of the modulation of dayside ionospheric outflow ions by ultralow frequency (ULF) waves. The observations indicate that the modulation is mass dependent, which demonstrates the possibility of using ULF waves as a mass spectrometer to identify ion species. Moreover, the measurement suggests that polarization drift may play a role in O+ modulation, which may lead to a true acceleration and even nonadiabatic behavior of O+. This interaction scenario can work throughout the whole magnetosphere and impact upon the plasma environment and dynamics.

“…The plasmapause locations are marked by the vertical red curves, on basis of the method of Moldwin et al (2002), with the outbound one at L~3.7 and the inbound one at L~4.0. These two plume crossings were on the postmidnight to dawnside, which is rare according to the statistics of plasmaspheric plume (e.g., Darrouzet et al, 2008;Lee et al, 2016;Moldwin et al, 2004). As shown as shaded regions, one occurred at 1610-1800 UT Zoom-in plots of these two time intervals are shown in Figures 1b and 1c to provide detailed information of the ambient electron density and the spatial location defined by L-shell, MLT, and magnetic latitude (MLAT) for the plume.…”

Section: Observations Of a Nightside Plume And Hiss Emissionsmentioning

confidence: 99%

“…• Moderately strong hiss emissions can occur to peak at~100 Hz within the two crossings of a pronounced post-midnight-to-dawn plume • Plasmaspheric hiss in the nightside plume is efficient to pitch angle scatter~10-100 keV electrons • With the resultant electron loss timescales varying over 3 orders of magnitude, hiss emissions in the nightside plume can account for the fast loss of ≲100 keV electrons and for the slow decay of higher energy electrons occurrence rate increasing with the solar wind dynamic pressure (e.g., Darrouzet et al, 2008;Lee et al, 2016;Moldwin et al, 2004). In addition to hiss-induced electron scattering in the plasmasphere, hiss in plumes can also resonate with radiation belt electrons.…”

Section: 1029/2018gl077212mentioning

confidence: 99%

“…Plasmaspheric plumes are a continuous outward extension of the plasmasphere and may extend far from the Earth, as a result of the interaction between inward moving solar wind-driven convection electric fields and corotational forces after geomagnetically periods (e.g., Goldstein et al, 2014;Moldwin et al, 2004). Plumes preferentially occur during moderate geomagnetic activities at the 14-24 magnetic local time ( occurrence rate increasing with the solar wind dynamic pressure (e.g., Darrouzet et al, 2008;Lee et al, 2016;Moldwin et al, 2004). In addition to hiss-induced electron scattering in the plasmasphere, hiss in plumes can also resonate with radiation belt electrons.…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Electron Scattering by Plasmaspheric Hiss in a Nightside Plume

Zhang

et al. 2018

Plasmaspheric hiss is known to play an important role in radiation belt electron dynamics in high plasma density regions. We present observations of two crossings of a plasmaspheric plume by the Van Allen Probes on 26 December 2012, which occurred unusually at the post‐midnight‐to‐dawn sector between L ~ 4–6 during a geomagnetically quiet period. This plume exhibited pronounced electron densities higher than those of the average plume level. Moderate hiss emissions accompanied the two plume crossings with the peak power at about 100 Hz. Quantification of quasi‐linear bounce‐averaged electron scattering rates by hiss in the plume demonstrates that the waves are efficient to pitch angle scatter ~10–100 keV electrons at rates up to ~10−4 s−1 near the loss cone but become gradually insignificant to scatter the higher energy electron population. The resultant timescales of electron loss due to hiss in the nightside plume vary largely with electron kinetic energy over 3 orders of magnitude, that is, from several hours for tens of keV electrons to a few days for hundreds of keV electrons to well above 100 days for >1 MeV electrons. Changing slightly with L‐shell and the multiquartile profile of hiss spectral intensity, these electron loss timescales suggest that hiss emissions in the nightside plume act as a viable candidate for the fast loss of the ≲100 keV electrons and the slow decay of higher energy electrons.