scholarly journals Effect of solar wind density on relativistic electrons at geosynchronous orbit

2008 ◽  
Vol 35 (3) ◽  
Author(s):  
Wladislaw Lyatsky ◽  
George V. Khazanov
Keyword(s):  
Solar Wind ◽  
Geosynchronous Orbit ◽  
Relativistic Electrons ◽  
Solar Wind Density

scholarly journals Average profiles of the solar wind and outer radiation belt during the extreme flux enhancement of relativistic electrons at geosynchronous orbit

2008 ◽  
Vol 26 (6) ◽  
pp. 1335-1339 ◽  
Author(s):  
R. Kataoka ◽  
Y. Miyoshi
Keyword(s):  
Solar Wind ◽  
Large Scale ◽  
Radiation Belt ◽  
Dynamic Pressure ◽  
Recovery Phase ◽  
Geosynchronous Orbit ◽  
Relativistic Electrons ◽  
Outer Radiation Belt ◽  
Flux Enhancement ◽  
Solar Wind Structure

Abstract. We report average profiles of the solar wind and outer radiation belt during the extreme flux enhancement of relativistic electrons at geosynchronous orbit (GEO). It is found that seven of top ten extreme events at GEO during solar cycle 23 are associated with the magnetosphere inflation during the storm recovery phase as caused by the large-scale solar wind structure of very low dynamic pressure (<1.0 nPa) during rapid speed decrease from very high (>650 km/s) to typical (400–500 km/s) in a few days. For the seven events, the solar wind parameters, geomagnetic activity indices, and relativistic electron flux and geomagnetic field at GEO are superposed at the local noon period of GOES satellites to investigate the physical cause. The average profiles support the "double inflation" mechanism that the rarefaction of the solar wind and subsequent magnetosphere inflation are one of the best conditions to produce the extreme flux enhancement at GEO because of the excellent magnetic confinement of relativistic electrons by reducing the drift loss of trapped electrons at dayside magnetopause.

MHD simulations of magnetospheric response to a strong solar wind density pulse

2021 ◽  
Author(s):  
Andrey Samsonov ◽  
Jennifer A. Carter ◽  
Graziella Branduardi-Raymont ◽  
Steven Sembay
Keyword(s):  
Solar Wind ◽  
Dynamic Pressure ◽  
Solar Wind Density ◽  
Ionospheric Currents ◽  
X Ray ◽  
Interplanetary Coronal Mass Ejection ◽  
Explorer Mission ◽  
The One ◽  
Mass Ejection ◽  
Present Simulation

&lt;p&gt;On 16-17 June 2012, an interplanetary coronal mass ejection with an extremely high solar wind density (~100 cm&lt;sup&gt;-3&lt;/sup&gt;) and mostly strong northward (or eastward) interplanetary magnetic field (IMF) interacted with the Earth&amp;#8217;s magnetosphere. We have simulated this event using global MHD models. We study the magnetospheric response to two solar wind discontinuities. The first is characterized by a fast drop of the solar wind dynamic pressure resulting in rapid magnetospheric expansion. The second is a northward IMF turning which causes reconfiguration of the magnetospheric-ionospheric currents. We discuss variations of the magnetopause position and locations of the magnetopause reconnection in response to the solar wind variations. In the second part of our presentation, we present simulation results for the forthcoming SMILE (Solar wind Magnetosphere Ionosphere Link Explorer) mission. SMILE is scheduled for launch in 2024. We produce two-dimensional images that derive from the MHD results of the expected X-ray emission as observed by the SMILE Soft X-ray Imager (SXI).&amp;#160;We discuss how SMILE observations may help to study events like the one presented in this work.&lt;/p&gt;

Microinstabilities and plasma waves at Near-Sun Solar Wind collisionless Shocks: Predictions for PSP and SO

2021 ◽  
Author(s):  
Zhongwei Yang ◽  
Shuichi Matsukiyo ◽  
Huasheng Xie ◽  
Fan Guo ◽  
Mingzhe Liu ◽  
...  
Keyword(s):  
Solar Wind ◽  
Shock Front ◽  
Leading Edge ◽  
Relativistic Electrons ◽  
Interplanetary Shocks ◽  
Particle In Cell ◽  
Drift Instability ◽  
Shock Simulation ◽  
Mass Ejection ◽  
The Impact

&lt;p&gt;&lt;span&gt;Microinstabilities and waves excited at perpendicular interplanetary shocks in the near-Sun solar wind are investigated by full particle-in-cell simulations. By analyzing the dispersion relation of fluctuating field components directly issued from the shock simulation, we obtain key findings concerning wave excitations at the shock front: (1) at the leading edge of the foot, two types of electrostatic (ES) waves are observed. The relative drift of the reflected ions versus the electrons triggers an electron cyclotron drift instability (ECDI) that excites the first ES wave. Because the bulk velocity of gyro-reflected ions shifts to the direction of the shock front, the resulting ES wave propagates obliquely to the shock normal. Immediately, a fraction of incident electrons are accelerated by this ES wave and a ring-like velocity distribution is generated. They can couple with the hot Maxwellian core and excite the second ES wave around the upper hybrid frequency. (2) From the middle of the foot all the way to the ramp, electrons can couple with both incident and reflected ions. ES waves excited by ECDI in different directions propagate across each other. Electromagnetic (EM) waves (X mode) emitted toward upstream are observed in both regions. They are probably induced by a small fraction of relativistic electrons. The impact of shock front rippling, Mach numbers, and dimensions on the ES wave excitation also will be discussed. Results shed new insight on the mechanism for the occurrence of ES wave excitations and possible EM wave emissions at young coronal mass ejection&amp;#8211;driven shocks in the near-Sun solar wind.&lt;/span&gt;&lt;/p&gt;

Deriving CME volume and density from remote sensing data

2021 ◽  
Author(s):  
Manuela Temmer ◽  
Lukas Holzknecht ◽  
Mateja Dumbovic ◽  
Bojan Vrsnak ◽  
Nishtha Sachdeva ◽  
...  
Keyword(s):  
Solar Wind ◽  
Solar Wind Speed ◽  
Remote Sensing Data ◽  
Propagation Speed ◽  
Solar Wind Density ◽  
Sheath Region ◽  
Pile Up ◽  
Mass Ejection ◽  
Interplanetary Propagation

&lt;p&gt;Using combined STEREO-SOHO white-light data, we present a method to determine the&amp;#160;volume and density of a coronal mass ejection (CME) by applying the graduated cylindrical&amp;#160;shell model (GCS) and deprojected mass derivation. Under the assumption that the CME &amp;#160;mass is roughly equally distributed within a specific volume, we expand the CME self-similarly and calculate the CME density for distances close to the Sun (15&amp;#8211;30 Rs) and at 1 AU.&amp;#160;The procedure is applied on a sample of 29 well-observed CMEs and compared to their&amp;#160;interplanetary counterparts (ICMEs). Specific trends are derived comparing calculated and&amp;#160;in-situ measured proton densities at 1 AU, though large uncertainties are revealed due to&amp;#160;the unknown mass and geometry evolution: i) a moderate correlation for the magnetic&amp;#160;structure having a mass that stays rather constant and ii) a weak&amp;#160;correlation for the sheath density by assuming the sheath region is an extra mass&amp;#160;- as expected for a mass pile-up process - that is in its amount comparable to the initial CME&amp;#160;deprojected mass. High correlations are derived between in-situ measured sheath density&amp;#160;and the solar wind density and solar wind speed as measured 24&amp;#160;hours ahead of the arrival of the disturbance. This gives additional confirmation that the&amp;#160;sheath-plasma indeed stems from piled-up solar wind material. While the CME&amp;#160;interplanetary propagation speed is not related to the sheath density, the size of the CME&amp;#160;may play some role in how much material is piled up.&lt;/p&gt;

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