scholarly journals Generation of large‐amplitude electric field and subsequent enhancement of O + ion flux in the inner magnetosphere during substorms

2015 ◽  
Vol 120 (6) ◽  
pp. 4825-4840 ◽  
Author(s):  
Y. Nakayama ◽  
Y. Ebihara ◽  
T. Tanaka
Keyword(s):  
Electric Field ◽  
Large Amplitude ◽  
Ion Flux ◽  
Inner Magnetosphere

scholarly journals Large-amplitude wave electric field in the inner magnetosphere during substorms

2008 ◽  
Vol 113 (A7) ◽  
pp. n/a-n/a ◽  
Author(s):  
Y. Nishimura ◽  
J. Wygant ◽  
T. Ono ◽  
M. Iizima ◽  
A. Kumamoto ◽  
...  
Keyword(s):  
Electric Field ◽  
Large Amplitude ◽  
Amplitude Wave ◽  
Inner Magnetosphere ◽  
Large Amplitude Wave

scholarly journals Global estimates of plasmaspheric losses during moderate disturbance intervals

2010 ◽  
Vol 28 (1) ◽  
pp. 27-36 ◽  
Author(s):  
M. Spasojevic ◽  
B. R. Sandel
Keyword(s):  
Solar Wind ◽  
Electric Field ◽  
Boundary Layers ◽  
Total Mass ◽  
Density Ratio ◽  
Individual Case ◽  
Number Density ◽  
Inner Magnetosphere ◽  
Moderate Disturbance ◽  
Global Estimates

Abstract. For a set of five moderate disturbance events, we calculate the total number of He+ ions removed the plasmasphere using calibrated global EUV images. In each of the events, between ~0.6 and 2.2×1030 He+ ions are removed from a region of the inner magnetosphere from L=1.5 to 5.5. This loss constitutes between 20% and 42% of the initial He+ distribution. The lost percentage is correlated with the number of hours of strongly positive solar wind electric field (Ey>2.5 mV/m). Also, the total amount of material removed from the plasmasphere is estimated by using several values of the He+ to H+ number density ratio. The total mass lost is found to be in the range of 20 to 80 metric tons although for each individual case the estimate can vary by over 50% depending on assumed density ratio. We also attempt to distinguish between losses to the ionosphere and losses to the dayside boundary layers by estimating losses interior and exterior to the newly formed plasmapause boundary. For the events studied, losses inside the new plasmapause constitute between 24% to 54% of the total number of He+ ions lost.

scholarly journals Magnetospheric convection electric field dynamics andstormtime particle energization: case study of the magneticstorm of 4 May 1998

2004 ◽  
Vol 22 (2) ◽  
pp. 497-510 ◽  
Author(s):  
G. V. Khazanov ◽  
M. W. Liemohn ◽  
T. S. Newman ◽  
M.-C. Fok ◽  
A. J. Ridley
Keyword(s):  
Electric Field ◽  
Electric Fields ◽  
Transport Model ◽  
Storm Event ◽  
Inner Magnetosphere ◽  
Narrow Channels ◽  
Near Earth Space ◽  
Magnetospheric Convection ◽  
Convection Electric Field ◽  
Seed Population

Abstract. It is shown that narrow channels of high electric field are an effective mechanism for injecting plasma into the inner magnetosphere. Analytical expressions for the electric field cannot produce these channels of intense plasma flow, and thus, result in less entry and adiabatic energization of the plasma sheet into near-Earth space. For the ions, omission of these channels leads to an underprediction of the strength of the stormtime ring current and therefore, an underestimation of the geoeffectiveness of the storm event. For the electrons, omission of these channels leads to the inability to create a seed population of 10-100 keV electrons deep in the inner magnetosphere. These electrons can eventually be accelerated into MeV radiation belt particles. To examine this, the 1-7 May 1998 magnetic storm is studied with a plasma transport model by using three different convection electric field models: Volland-Stern, Weimer, and AMIE. It is found that the AMIE model can produce particle fluxes that are several orders of magnitude higher in the L = 2 – 4 range of the inner magnetosphere, even for a similar total cross-tail potential difference. Key words. Space plasma physics (charged particle motion and acceleration) – Magnetospheric physics (electric fields, storms and substorms)

scholarly journals Analyzing electric field morphology through data-model comparisons of the Geospace Environment Modeling Inner Magnetosphere/Storm Assessment Challenge events

2006 ◽  
Vol 111 (A11) ◽  
Author(s):  
Michael W. Liemohn ◽  
Aaron J. Ridley ◽  
Janet U. Kozyra ◽  
Dennis L. Gallagher ◽  
Michelle F. Thomsen ◽  
...  
Keyword(s):  
Electric Field ◽  
Data Model ◽  
Environment Modeling ◽  
Inner Magnetosphere ◽  
Model Comparisons

scholarly journals Interhemispheric asymmetries in the occurrence of magnetically conjugate sub-auroral polarisation streams

2005 ◽  
Vol 23 (4) ◽  
pp. 1371-1390 ◽  
Author(s):  
M. L. Parkinson ◽  
M. Pinnock ◽  
J. A. Wild ◽  
M. Lester ◽  
T. K. Yeoman ◽  
...  
Keyword(s):  
Electric Field ◽  
Auroral Oval ◽  
Particle Interactions ◽  
Magnetospheric Substorms ◽  
Polarisation Field ◽  
Energetic Ions ◽  
Inner Magnetosphere ◽  
Flux Tubes ◽  
Ion Drift ◽  
Magnetic Flux Tubes

Abstract. Earthward injections of energetic ions and electrons mark the onset of magnetospheric substorms. In the inner magnetosphere (L4), the energetic ions drift westward and the electrons eastward, thereby enhancing the equatorial ring current. Wave-particle interactions can accelerate these particles to radiation belt energies. The ions are injected slightly closer to Earth in the pre-midnight sector, leading to the formation of a radial polarisation field in the inner magnetosphere. This maps to a poleward electric field just equatorward of the auroral oval in the ionosphere. The poleward electric field is subsequently amplified by ionospheric feedback, thereby producing auroral westward flow channels (AWFCs). In terms of electric field strength, AWFCs are the strongest manifestation of substorms in the ionosphere. Because geomagnetic flux tubes are essentially equi-potentials, similar AWFC signatures should be observed simultaneously in the Northern and Southern Hemispheres. Here we present magnetically conjugate SuperDARN radar observations of AWFC activity observed in the pre-midnight sector during two substorm intervals including multiple onsets during the evening of 30 November 2002. The Northern Hemisphere observations were made with the Japanese radar located at King Salmon, Alaska (57, and the Southern Hemisphere observations with the Tasman International Geospace Environment Radar (TIGER) located at Bruny Island, Tasmania (55. LANL geosynchronous satellite observations of energetic ion and electron fluxes monitored the effects of substorms in the inner magnetosphere (L6). The radar-observed AWFC activity was coincident with activity observed at geosynchronous orbit, as well as westward current surges in the ionosphere observed using ground-based magnetometers. The location of AWFCs with respect to the auroral oval was inferred from FUV auroral images recorded on board the IMAGE spacecraft. DMSP SSIES ion drift measurements confirmed the presence of AWFCs equatorward of the auroral oval. Systematic asymmetries in the interhemispheric signatures of the AWFCs probably arose because the magnetic flux tubes were distorted at L shells passing close to the substorm dipolarisation region. Transient asymmetries were attributed to the development of nearby field-aligned potential drops and currents.

A noon-to-midnight electric field and nightside dynamics in Saturn’s inner magnetosphere, using microsignature observations

Icarus ◽  
2012 ◽  
Vol 220 (2) ◽  
pp. 503-513 ◽  
Author(s):  
M. Andriopoulou ◽  
E. Roussos ◽  
N. Krupp ◽  
C. Paranicas ◽  
M. Thomsen ◽  
...  
Keyword(s):  
Electric Field ◽  
Inner Magnetosphere

scholarly journals Plasma transport modelling in the inner magnetosphere: effects of magnetic field, electric field and exospheric models

2011 ◽  
Vol 29 (2) ◽  
pp. 427-442 ◽  
Author(s):  
A. Woelfflé ◽  
D. Boscher ◽  
I. Dandouras
Keyword(s):  
Electric Field ◽  
Particle Trajectory ◽  
Neutral Hydrogen ◽  
Plasma Source ◽  
Particle Dynamics ◽  
Plasma Transport ◽  
Loss Assessment ◽  
Transport Modelling ◽  
Inner Magnetosphere ◽  
Hydrogen Density

Abstract. A qualitative study is performed on plasma transport modelling in the inner magnetosphere, revealing the significance of a model use choice and its parameterization. First, we examine particle transport using comparative analysis of both magnetic and electric field models. This work reveals that the electric field plays an important role in understanding particle dynamics and the models lead to various results in terms of plasma source, energy and particle trajectory. We then concentrate particularly on proton loss assessment considering the charge exchange phenomenon. For that, models are needed to provide a neutral hydrogen density estimation. So, exospheric models were tested in light of the Dynamics Explorer 1 measurements analysed by Rairden.

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