Cold Plasma Redistribution in the Coupled Ionosphere-Magnetosphere
Location
Yosemite National Park
Start Date
2-10-2014 11:50 AM
End Date
2-10-2014 12:20 PM
Description
Large-scale cold plasma redistribution is a multi-step geospace system-wide processes involving the equatorial, low, mid, auroral, and polar-latitude regions. Penetration electric fields enhance the equatorial ionization anomaly peaks, while polarization electric field effects at the dusk terminator redistribute the low-latitude TEC in both longitude and latitude to create a preferred longitude for the enhancement total electron content (TEC) in the American sector. This TEC enhancement forms a localized source for the intense storm enhanced density (SED) erosion plumes that are observed over the Americas during major storms. Ring current enhancements generate strong poleward-directed subauroral polarization stream (SAPS) electric fields in the evening sector as field-aligned currents close through the low-conductivity ionosphere. The SAPS electric field overlaps the outer plasmasphere, drawing out SED / plasmasphere erosion plumes. These enhanced cold plasma fluxes traverse the cusp and enter the polar cap forming the polar tongue of ionization (TOI). Antisunward flow in the TOI carries the eroded material into the midnight auroral oval, providing a rich source of heavy ions for magnetospheric injection and acceleration mechanisms which operate both at the cusp and on the nightside. We describe the redistribution process with multi-instrument observations at both ionospheric and magnetospheric altitudes. GPS TEC mapping reveals a continuous plume of storm enhanced density (SED) extending from the dusk sector into and through the cusp region and back across polar latitudes. Incoherent scatter radar and overflights with the DMSP satellites give details of plasma convection velocities and altitude/spatial distributions. The Themis spacecraft observe the erosion plume at the dayside magnetopause, and the Van Allen Probes daily provide multiple crossings of the plasmasphere boundary layer. We examine dusk sector (18 MLT) plasmasphere erosion with simultaneous direct observations of the sunward ion flux at high altitude by the Van Allen Probes RBSP-A (at ~3.5 Re) and at ionospheric heights by DMSP F-18. On March 17, 2013 RBSP-A observed ~6000 m/s high altitude erosion velocity and ~1.2e12 m-2 s-1 sunward ion flux in the erosion plume, while DMSP F-18 measured ~1750 m/s SAPS velocity and sunward flux of ~2.e13 m-2 s-1 in the underlying ionosphere. There was high correspondence between the location, spatial extent, and characteristics of both the SAPS flow and the erosion plume at high and low altitudes. The intermittent transfer of dayside SED plasma across cusp field lines is seen to be a low altitude signature of dayside merging activity at the magnetopause. Significant ion fluxes are involved in the plasma redistribution. For the March 17th storm, we estimate the total fluence of eroded ionospheric / plasmaspheric ions carried antisunward in the polar TOI to be ~5.e25 ions s-1. Concurrently, the RBSP A & B spacecraft observed the redistribution plasma near the magnetic equator at ~ 6 Re altitude in the midnight sector at the point where the TOI exits the polar cap. The observations made during the March 17th event provide quantitative, simultaneous evidence at multiple points within this redistribution chain that significant plasma erosion fluxes are involved both at ionospheric and magnetospheric altitudes.
Cold Plasma Redistribution in the Coupled Ionosphere-Magnetosphere
Yosemite National Park
Large-scale cold plasma redistribution is a multi-step geospace system-wide processes involving the equatorial, low, mid, auroral, and polar-latitude regions. Penetration electric fields enhance the equatorial ionization anomaly peaks, while polarization electric field effects at the dusk terminator redistribute the low-latitude TEC in both longitude and latitude to create a preferred longitude for the enhancement total electron content (TEC) in the American sector. This TEC enhancement forms a localized source for the intense storm enhanced density (SED) erosion plumes that are observed over the Americas during major storms. Ring current enhancements generate strong poleward-directed subauroral polarization stream (SAPS) electric fields in the evening sector as field-aligned currents close through the low-conductivity ionosphere. The SAPS electric field overlaps the outer plasmasphere, drawing out SED / plasmasphere erosion plumes. These enhanced cold plasma fluxes traverse the cusp and enter the polar cap forming the polar tongue of ionization (TOI). Antisunward flow in the TOI carries the eroded material into the midnight auroral oval, providing a rich source of heavy ions for magnetospheric injection and acceleration mechanisms which operate both at the cusp and on the nightside. We describe the redistribution process with multi-instrument observations at both ionospheric and magnetospheric altitudes. GPS TEC mapping reveals a continuous plume of storm enhanced density (SED) extending from the dusk sector into and through the cusp region and back across polar latitudes. Incoherent scatter radar and overflights with the DMSP satellites give details of plasma convection velocities and altitude/spatial distributions. The Themis spacecraft observe the erosion plume at the dayside magnetopause, and the Van Allen Probes daily provide multiple crossings of the plasmasphere boundary layer. We examine dusk sector (18 MLT) plasmasphere erosion with simultaneous direct observations of the sunward ion flux at high altitude by the Van Allen Probes RBSP-A (at ~3.5 Re) and at ionospheric heights by DMSP F-18. On March 17, 2013 RBSP-A observed ~6000 m/s high altitude erosion velocity and ~1.2e12 m-2 s-1 sunward ion flux in the erosion plume, while DMSP F-18 measured ~1750 m/s SAPS velocity and sunward flux of ~2.e13 m-2 s-1 in the underlying ionosphere. There was high correspondence between the location, spatial extent, and characteristics of both the SAPS flow and the erosion plume at high and low altitudes. The intermittent transfer of dayside SED plasma across cusp field lines is seen to be a low altitude signature of dayside merging activity at the magnetopause. Significant ion fluxes are involved in the plasma redistribution. For the March 17th storm, we estimate the total fluence of eroded ionospheric / plasmaspheric ions carried antisunward in the polar TOI to be ~5.e25 ions s-1. Concurrently, the RBSP A & B spacecraft observed the redistribution plasma near the magnetic equator at ~ 6 Re altitude in the midnight sector at the point where the TOI exits the polar cap. The observations made during the March 17th event provide quantitative, simultaneous evidence at multiple points within this redistribution chain that significant plasma erosion fluxes are involved both at ionospheric and magnetospheric altitudes.