scholarly journals Azimuthally asymmetric ring current as a function of <i>D<sub>st</sub></i> and solar wind conditions

2004 ◽  
Vol 22 (8) ◽  
pp. 2989-2996 ◽  
Author(s):  
Y. P. Maltsev ◽  
A. A. Ostapenko
Keyword(s):  
Magnetic Field ◽  
Solar Wind ◽  
Spatial Distribution ◽  
Interplanetary Magnetic Field ◽  
Ring Current ◽  
Dynamic Pressure ◽  
Solar Wind Dynamic Pressure ◽  
Magnetic Data ◽  
Under Five ◽  
Solar Wind Parameters

Abstract. Based on magnetic data, spatial distribution of the westward ring current flowing at |z|<3 RE has been found under five levels of Dst, five levels of the interplanetary magnetic field (IMF) z component, and five levels of the solar wind dynamic pressure Psw. The maximum of the current is located near midnight at distances 5 to 7 RE. The magnitude of the nightside and dayside parts of the westward current at distances from 4 to 9 RE can be approximated as Inight=1.75-0.041 Dst, Inoon=0.22-0.013 Dst, where the current is in MA. The relation of the nightside current to the solar wind parameters can be expressed as Inight=1.45-0.20 Bs IMF + 0.32 Psw, where BsIMF is the IMF southward component. The dayside ring current poorly correlates with the solar wind parameters.

scholarly journals Cluster survey of the mid-altitude cusp: 1. size, location, and dynamics

2006 ◽  
Vol 24 (11) ◽  
pp. 3011-3026 ◽  
Author(s):  
F. Pitout ◽  
C. P. Escoubet ◽  
B. Klecker ◽  
H. Rème
Keyword(s):  
Magnetic Field ◽  
Solar Wind ◽  
Time Delay ◽  
Interplanetary Magnetic Field ◽  
Statistical Study ◽  
Proper Time ◽  
Dynamic Pressure ◽  
Solar Wind Dynamic Pressure ◽  
Summer Hemisphere ◽  
External Conditions

Abstract. We present a statistical study of four years of Cluster crossings of the mid-altitude cusp. In this first part of the study, we start by introducing the method we have used a) to define the cusp properties, b) to sort the interplanetary magnetic field (IMF) conditions or behaviors into classes, c) to determine the proper time delay between the solar wind monitors and Cluster. Out of the 920 passes that we have analyzed, only 261 fulfill our criteria and are considered as cusp crossings. We look at the size, location and dynamics of the mid-altitude cusp under various IMF orientations and solar wind conditions. For southward IMF, Bz rules the latitudinal dynamics, whereas By governs the zonal dynamics, confirming previous works. We show that when |By| is larger than |Bz|, the cusp widens and its location decorrelates from By. We interpret this feature in terms of component reconnection occurring under By-dominated IMF. For northward IMF, we demonstrate that the location of the cusp depends primarily upon the solar wind dynamic pressure and upon the Y-component of the IMF. Also, the multipoint capability of Cluster allows us to conclude that the cusp needs typically more than ~20 min to fully adjust its location and size in response to changes in external conditions, and its speed is correlated to variations in the amplitude of IMF-Bz. Indeed, the velocity in °ILAT/min of the cusp appears to be proportional to the variation in Bz in nT: Vcusp=0.024 ΔBz. Finally, we observe differences in the behavior of the cusp in the two hemispheres. Those differences suggest that the cusp moves and widens more freely in the summer hemisphere.

scholarly journals Magnetopause energy and mass transfer: results from a global MHD simulation

2006 ◽  
Vol 24 (12) ◽  
pp. 3467-3480 ◽  
Author(s):  
M. Palmroth ◽  
T. V. Laitinen ◽  
T. I. Pulkkinen
Keyword(s):  
Magnetic Field ◽  
Mass Transfer ◽  
Solar Wind ◽  
Energy Transfer ◽  
Dynamic Pressure ◽  
Solar Wind Dynamic Pressure ◽  
Closed Field ◽  
Dayside Magnetopause ◽  
Solar Wind Parameters ◽  
The Imf

Abstract. We use the global MHD model GUMICS-4 to investigate the energy and mass transfer through the magnetopause and towards the closed magnetic field as a response to the interplanetary magnetic field (IMF) clock angle θ=arctan (BY/BZ), IMF magnitude, and solar wind dynamic pressure. We find that the mass and energy transfer at the magnetopause are different both in spatial characteristics and in response to changes in the solar wind parameters. The energy transfer follows best the sin2 (θ/2) dependence, although there is more energy transfer after large energy input, and the reconnection line follows the IMF rotation with a delay. There is no clear clock angle dependence in the net mass transfer through the magnetopause, but the mass transfer through the dayside magnetopause and towards the closed field occurs preferably for northward IMF. The energy transfer occurs through areas at the magnetopause that are perpendicular to the subsolar reconnection line. In contrast, the mass transfer occurs consistently along the reconnection line, both through the magnetopause and towards the closed field. Both the energy and mass transfer are enhanced in response to increased solar wind dynamic pressure, while increasing the IMF magnitude does not affect the transfer quantities as much.

scholarly journals Special features of the September 24-27, 1998 storm during high solar wind dynamic pressure and northward interplanetary magnetic field

2001 ◽  
Vol 106 (A11) ◽  
pp. 25695-25711 ◽  
Author(s):  
C. Robert Clauer ◽  
Igor I. Alexeev ◽  
Elena S. Belenkaya ◽  
Joseph B. Baker
Keyword(s):  
Magnetic Field ◽  
Solar Wind ◽  
Interplanetary Magnetic Field ◽  
Dynamic Pressure ◽  
Solar Wind Dynamic Pressure

scholarly journals A modelling approach to infer the solar wind dynamic pressure from magnetic field observations inside Mercury’s magnetosphere

2018 ◽  
Vol 614 ◽  
pp. A132 ◽  
Author(s):  
S. Fatemi ◽  
N. Poirier ◽  
M. Holmström ◽  
J. Lindkvist ◽  
M. Wieser ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Solar Wind ◽  
Interplanetary Magnetic Field ◽  
Dynamic Pressure ◽  
Solar Wind Plasma ◽  
Solar Wind Dynamic Pressure ◽  
Field Observations ◽  
Simulation Results ◽  
Upstream Solar Wind ◽  
Good Agreement

Aims. The lack of an upstream solar wind plasma monitor when a spacecraft is inside the highly dynamic magnetosphere of Mercury limits interpretations of observed magnetospheric phenomena and their correlations with upstream solar wind variations. Methods. We used AMITIS, a three-dimensional GPU-based hybrid model of plasma (particle ions and fluid electrons) to infer the solar wind dynamic pressure and Alfvén Mach number upstream of Mercury by comparing our simulation results with MESSENGER magnetic field observations inside the magnetosphere of Mercury. We selected a few orbits of MESSENGER that have been analysed and compared with hybrid simulations before. Then we ran a number of simulations for each orbit (~30–50 runs) and examined the effects of the upstream solar wind plasma variations on the magnetic fields observed along the trajectory of MESSENGER to find the best agreement between our simulations and observations. Results. We show that, on average, the solar wind dynamic pressure for the selected orbits is slightly lower than the typical estimated dynamic pressure near the orbit of Mercury. However, we show that there is a good agreement between our hybrid simulation results and MESSENGER observations for our estimated solar wind parameters. We also compare the solar wind dynamic pressure inferred from our model with those predicted previously by the WSA-ENLIL model upstream of Mercury, and discuss the agreements and disagreements between the two model predictions. We show that the magnetosphere of Mercury is highly dynamic and controlled by the solar wind plasma and interplanetary magnetic field. In addition, in agreement with previous observations, our simulations show that there are quasi-trapped particles and a partial ring current-like structure in the nightside magnetosphere of Mercury, more evident during a northward interplanetary magnetic field (IMF). We also use our simulations to examine the correlation between the solar wind dynamic pressure and stand-off distance of the magnetopause and compare it with MESSENGER observations. We show that our model results are in good agreement with the response of the magnetopause to the solar wind dynamic pressure, even during extreme solar events. We also show that our model can be used as a virtual solar wind monitor near the orbit of Mercury and this has important implications for interpretation of observations by MESSENGER and the future ESA/JAXA mission to Mercury, BepiColombo.

Effects of the Solar Wind Conditions on Mercury's Exosphere: Hybrid Simulations

2020 ◽  
Author(s):  
Pavel M. Travnicek ◽  
Dave Schriver ◽  
Thomas Orlando ◽  
James A. Slavin
Keyword(s):  
Magnetic Field ◽  
Solar Wind ◽  
Interplanetary Magnetic Field ◽  
Dynamic Pressure ◽  
Energy Levels ◽  
Solar Wind Plasma ◽  
Deposited Energy ◽  
Solar Wind Parameters ◽  
Primary Focus ◽  
Hybrid Simulations

&lt;pre class=&quot;western&quot;&gt;We carry out a set of global hybrid simulations of the Mercury's magnetosphere with the interplanetary magnetic field oriented in the desired directions. &lt;br /&gt;We study effects of changes of different solar wind parameters on the structure of the plasma circulation within Mercury&amp;#8217;s magnetosphere. We focus our &lt;br /&gt;study on the changes caused by changes in the orientation of the interplanetary magnetic field and the dynamic pressure (velocity) of the solar wind. &lt;br /&gt;We study the structure of the of the Mercury&amp;#8217;s magnetosphere under different solar wind conditions. Our primary focus is the assessment of the &lt;br /&gt;precipitation levels of solar wind hydrogen on the Mercury's surface (the amount, the deposited energy, its spectra and angular distribution) and on the &lt;br /&gt;formation of Mercury's exosphere. We examine density fluxes, energy levels and spectra of protons precipitating on Mercury&amp;#8217;s surface as a function of &lt;br /&gt;longitude and altitude. It has been established, that Mercury has a plasma belt formed by quasi-trapped solar wind plasma close to the Mercury&amp;#8217;s surface. &lt;br /&gt;Charged particles trapped in the belt mostly circle Mercury 1-2 times before they either precipitate on Mercury&amp;#8217;s surface or escape into the Mercury&amp;#8217;s &lt;br /&gt;magnetospheric cavity. Lower dynamic pressure of the solar wind pushes magnetopause up above the Mercury&amp;#8217;s surface and the plasma belt has more &lt;br /&gt;space to develop. Its interaction with Mercury&amp;#8217;s surface and dynamics under different solar wind conditions is essential on the precipitation of the plasma &lt;br /&gt;on the Mercury&amp;#8217;s surface. Higher dynamic pressure of the solar wind can push the bow shock towards Mercury&amp;#8217;s surface and make the surface open to the &lt;br /&gt;direct impact of the solar wind on the Mercury&amp;#8217;s surface. Due to weak magnetic moment of the Mercury&amp;#8217;s magnetosphere, the plasma environment at Mercury &lt;br /&gt;is very dynamic.&lt;/pre&gt;

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