scholarly journals On phase space density radial gradients of Earth's outer-belt electrons prior to sudden solar wind pressure enhancements: Results from distinctive events and a superposed epoch analysis

2010 ◽  
Vol 115 (A1) ◽  
pp. n/a-n/a ◽  
Author(s):  
Drew L. Turner ◽  
Xinlin Li ◽  
Geoff D. Reeves ◽  
Howard J. Singer
Keyword(s):  
Solar Wind ◽  
Phase Space ◽  
Wind Pressure ◽  
Phase Space Density ◽  
Space Density ◽  
Superposed Epoch Analysis ◽  
Solar Wind Pressure ◽  
Epoch Analysis

The asymmetric geospace response to rapid changes in solar wind pressure

2021 ◽  
Author(s):  
Michael Madelaire ◽  
Karl Laundal ◽  
Jone Reistad ◽  
Spencer Hatch ◽  
Anders Ohma ◽  
...  
Keyword(s):  
Solar Wind ◽  
Dynamic Pressure ◽  
Interplanetary Shock ◽  
Wind Pressure ◽  
Field Orientation ◽  
Superposed Epoch Analysis ◽  
Rapid Changes ◽  
Solar Wind Structure ◽  
Solar Wind Pressure ◽  
The Impact

<p>The geospace response to rapid changes in solar wind pressure results in a perturbation of the magnetospheric-ionospheric system. Ground magnetometer stations located at polar latitudes have long been known to measure a sudden impulse only minutes after a solar wind structure reaches the magnetopause.<br>Here a list of events associated with a step-like feature in the solar wind dynamic pressure between 1994 and 2020 is compiled based on in situ observations from ACE and Wind. Arrival time estimates are calculated using a simple propagation method and validated with a correlation analysis using SYM-H from low/mid latitude stations. A superposed epoch analysis is carried out to investigate the impact of season, interplanetary magnetic field orientation and other attributes pertaining to the interplanetary shock. All available ground magnetometer stations in SuperMAG, during each event, are used allowing for global coverage. <br>Global data coverage is important for this kind of comparative analysis as it is needed to determine changes in the systems response due to e.g. season, which might lead to an improved understanding of the magnetospheric-ionospheric-thermospheric coupling.</p>

A superposed epoch analysis of geomagnetic storms

1994 ◽  
Vol 12 (7) ◽  
pp. 612-624 ◽  
Author(s):  
J. R. Taylor ◽  
M. Lester ◽  
T. K. Yeoman
Keyword(s):  
Solar Wind ◽  
Wind Speed ◽  
High Speed ◽  
Geomagnetic Storms ◽  
Solar Wind Speed ◽  
Magnetic Activity ◽  
Wind Pressure ◽  
Superposed Epoch Analysis ◽  
Controlling Parameter ◽  
Epoch Analysis

Abstract. A superposed epoch analysis of geomagnetic storms has been undertaken. The storms are categorised via their intensity (as defined by the Dst index). Storms have also been classified here as either storm sudden commencements (SSCs) or storm gradual commencements (SGCs, that is all storms which did not begin with a sudden commencement). The prevailing solar wind conditions defined by the parameters solar wind speed (vsw), density (ρsw) and pressure (Psw) and the total field and the components of the interplanetary magnetic field (IMF) during the storms in each category have been investigated by a superposed epoch analysis. The southward component of the IMF, appears to be the controlling parameter for the generation of small SGCs (-100 nT< minimum Dst ≤ -50 nT for ≥ 4 h), but for SSCs of the same intensity solar wind pressure is dominant. However, for large SSCs (minimum Dst ≤ -100 nT for ≥ 4 h) the solar wind speed is the controlling parameter. It is also demonstrated that for larger storms magnetic activity is not solely driven by the accumulation of substorm activity, but substantial energy is directly input via the dayside. Furthermore, there is evidence that SSCs are caused by the passage of a coronal mass ejection, whereas SGCs result from the passage of a high speed/ slow speed coronal stream interface. Storms are also grouped by the sign of Bz during the first hour epoch after the onset. The sign of Bz at t = +1 h is the dominant sign of the Bz for ~24 h before the onset. The total energy released during storms for which Bz was initially positive is, however, of the same order as for storms where Bz was initially negative.

scholarly journals The use of iron charge state changes as a tracer for solar wind entry and energization within the magnetosphere

2003 ◽  
Vol 21 (11) ◽  
pp. 2155-2164 ◽  
Author(s):  
T. A. Fritz ◽  
T. H. Zurbuchen ◽  
G. Gloeckler ◽  
S. Hefti ◽  
J. Chen
Keyword(s):  
Solar Wind ◽  
Phase Space ◽  
Charge State ◽  
Time Scales ◽  
High Latitude ◽  
Libration Point ◽  
Average Charge ◽  
Phase Space Density ◽  
Space Density ◽  
Magnetospheric Configuration And Dynamics

Abstract. The variation of the charge state of iron [Fe] ions is used to trace volume elements of plasma in the solar wind into the magnetosphere and to determine the time scales associated with the entry into and the action of the magnetospheric energization process working on these plasmas. On 2–3 May 1998 the Advanced Composition Explorer (ACE) spacecraft located at the L1 libration point observed a series of changes to the average charge state of the element Fe in the solar wind plasma reflecting variation in the coronal temperature of their original source. Over the period of these two days the average Fe charge state was observed to vary from + 15 to + 6 both at the Polar satellite in the high latitude dayside magnetosphere and at ACE. During a period of southward IMF the observations at Polar inside the magnetosphere of the same Fe charge state were simultaneous with those at ACE delayed by the measured convection speed of the solar wind to the subsolar magnetopause. Comparing the phase space density as a function of energy at both ACE and Polar has indicated that significant energization of the plasma occurred on very rapid time scales. Energization at constant phase space density by a factor of 5 to 10 was observed over a range of energy from a few keV to about 1 MeV. For a detector with a fixed energy threshold in the range from 10 keV to a few hundred keV this observed energization will appear as a factor of ~103 increase in its counting rate. Polar observations of very energetic O+ ions at the same time indicate that this energization process must be occurring in the high latitude cusp region inside the magnetosphere and that it is capable of energizing ionospheric ions at the same time.Key words. Magnetospheric physics (magnetopause, cusp, and boundary layers; magnetospheric configuration and dynamics; solar wind-magnetosphere interactions)

scholarly journals Solar wind and substorm excitation of the wavy current sheet

2009 ◽  
Vol 27 (6) ◽  
pp. 2457-2474 ◽  
Author(s):  
C. Forsyth ◽  
M. Lester ◽  
R. C. Fear ◽  
E. Lucek ◽  
I. Dandouras ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Solar Wind ◽  
Current Sheet ◽  
Pressure Pulse ◽  
Wind Pressure ◽  
Expansion Velocity ◽  
Solar Wind Pressure ◽  
Wave Models ◽  
Best Fit ◽  
The Magnetic Field

Abstract. Following a solar wind pressure pulse on 3 August 2001, GOES 8, GOES 10, Cluster and Polar observed dipolarizations of the magnetic field, accompanied by an eastward expansion of the aurora observed by IMAGE, indicating the occurrence of two substorms. Prior to the first substorm, the motion of the plasma sheet with respect to Cluster was in the ZGSM direction. Observations following the substorms show the occurrence of current sheet waves moving predominantly in the −YGSM direction. Following the second substorm, the current sheet waves caused multiple current sheet crossings of the Cluster spacecraft, previously studied by Zhang et al. (2002). We further this study to show that the velocity of the current sheet waves was similar to the expansion velocity of the substorm aurora and the expansion of the dipolarization regions in the magnetotail. Furthermore, we compare these results with the current sheet wave models of Golovchanskaya and Maltsev (2005) and Erkaev et al. (2008). We find that the Erkaev et al. (2008) model gives the best fit to the observations.

scholarly journals Cooling of Sr to high phase-space density by laser and sympathetic cooling in isotopic mixtures

2006 ◽  
Vol 73 (2) ◽  
Author(s):  
G. Ferrari ◽  
R. E. Drullinger ◽  
N. Poli ◽  
F. Sorrentino ◽  
G. M. Tino
Keyword(s):  
Phase Space ◽  
Phase Space Density ◽  
Sympathetic Cooling ◽  
Space Density ◽  
High Phase

scholarly journals Comparison of energetic electron flux and phase space density in the magnetosheath and in the magnetosphere

2012 ◽  
Vol 117 (A5) ◽  
pp. n/a-n/a ◽  
Author(s):  
Bingxian Luo ◽  
Xinlin Li ◽  
Weichao Tu ◽  
Jiancun Gong ◽  
Siqing Liu
Keyword(s):  
Phase Space ◽  
Electron Flux ◽  
Energetic Electron ◽  
Phase Space Density ◽  
Space Density
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