scholarly journals Magnetosheath variations during the storm main phase on 20 November 2003: Evidence for solar wind density control of energy transfer to the magnetosphere

2005 ◽  
Vol 32 (21) ◽  
Author(s):  
R. Kataoka ◽  
D. H. Fairfield ◽  
D. G. Sibeck ◽  
L. Rastätter ◽  
M.-C. Fok ◽  
...  
Keyword(s):  
Solar Wind ◽  
Energy Transfer ◽  
Main Phase ◽  
Solar Wind Density ◽  
Storm Main Phase ◽  
Density Control

The Ionospheric Source of the Plasma Sheet During Storm Main Phase

2021 ◽  
Author(s):  
Lynn M. Kistler ◽  
Christopher G. Mouikis ◽  
Kazushi Asamura ◽  
Satoshi Kasahara ◽  
Yoshizumi Miyoshi ◽  
...  
Keyword(s):  
Solar Wind ◽  
Plasma Sheet ◽  
Heavy Ion ◽  
Initial Study ◽  
Main Phase ◽  
Data Sets ◽  
Data Set ◽  
Storm Main Phase ◽  
Ionospheric Source ◽  
Charge State Distributions

<p>The ionospheric and solar wind contributions to the magnetosphere can be distinguished by their composition.  While both sources contain significant H+, the heavy ion species from the ionospheric source are generally singly ionized, while the solar wind consists of highly ionized ions. Both the solar wind and the ionosphere contribute to the plasma sheet.  It has been shown that with both enhanced geomagnetic activity and enhanced solar EUV, the ionospheric contribution, and particularly the ionospheric heavy ions contribution increases.  However, the details of this transition from a solar wind dominated to more ionospheric dominated plasma sheet are not well understood.  An initial study using AMPTE/CHEM data, a data set that includes the full charge state distributions of the major species, shows that the transition can occur quite sharply during storms, with the ionospheric contribution becoming dominant during the storm main phase.  However, during the AMPTE time-period, there were no continuous measurements of the upstream solar wind, and so both the simultaneous solar wind composition and the driving solar wind and IMF parameters were not known.  The HPCA instrument on MMS and both the LEPi and MEPi instruments on Arase are able to measure He++.   With these data sets, the He++/H+ ratio can be compared to the simultaneous He++/H+ ratios in the solar wind to more definitively identify the solar wind contribution to the plasma sheet.  This allows the ionospheric contribution to the H+ population to be determined, so that the full ionospheric population is known. We find that when the IMF turns southward during the storm main phase, the dominant source of the hot plasma sheet becomes ionospheric.  This composition change explains why the storm time ring current also has a high ionospheric contribution.</p>

Ring current and auroral electrojets in connection with interplanetary medium parameters during magnetic storm

1994 ◽  
Vol 12 (7) ◽  
pp. 602-611 ◽  
Author(s):  
Y. I. Feldstein ◽  
A. E. Levitin ◽  
S. A. Golyshev ◽  
L. A. Dremukhina ◽  
U. B. Vestchezerova ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Solar Wind ◽  
Ring Current ◽  
Recovery Phase ◽  
Main Phase ◽  
Storm Main Phase ◽  
Low Latitudes ◽  
Solar Wind Parameters ◽  
Magnetic Field Variations ◽  
Current Magnetic Field

Abstract. The relationship between the auroral electrojet indices (AE) and the ring current magnetic field (DR) was investigated by observations obtained during the magnetic storm on 1-3 April 1973. During the storm main phase the DR development is accompanied by a shift of the auroral electrojets toward the equator. As a result, the standard AE indices calculated on the basis of data from auroral observatories was substantially lower than the real values (AE'). To determine AE' during the course of a storm main phase data from subauroral magnetic observatories should be used. It is shown that the intensity of the indices (AE') which take into account the shift of the electrojets is increased substantially relative to the standard indices during the storm main phase. AE' values are closely correlated with geoeffective solar wind parameters. A high correlation was obtained between AE' and the energy flux into the ring current during the storm main phase. Analysis of magnetic field variations during intervals with intense southward IMF components demonstrates a decrease of the saturation effect of auroral electrojet currents if subauroral stations magnetic field variations are taken into account. This applies both to case studies and statistical data. The dynamics of the electrojets in connection with the development of the ring current and of magnetospheric substorms can be described by the presence (absence) of saturation for minimum (maximum) AE index values during a 1-h interval. The ring current magnetic field asymmetry (ASY) was calculated as the difference between the maximum and minimum field values along a parallel of latitude at low latitudes. The ASY value is closely correlated with geoeffective solar wind parameters and simultaneously is a more sensitive indicator of IMF Bz variations than the symmetric ring current. ASY increases (decreases) faster during the main phase (the recovery phase) than DR. The magnetic field decay at low latitudes in the recovery phase occurs faster in the afternoon sector than at dusk.

Sign in / Sign up

Export Citation Format

Share Document