scholarly journals Unusual Location of the Geotail Magnetopause Near Lunar Orbit: A Case Study

2021 ◽  
Author(s):  
Wensai Shang ◽  
Binbin Tang ◽  
Quanqi Shi ◽  
Et al
Keyword(s):  
Solar Wind ◽  
Velocity Vector ◽  
Solar Wind Velocity ◽  
Full Moon ◽  
Interplanetary Shock ◽  
Time Intervals ◽  
Mhd Simulation ◽  
Mhd Simulations ◽  
Solar Wind Flow

<p>The Earth's magnetopause is highly variable in location and shape and is modulated by solar wind conditions. On 8 March 2012, the ARTEMIS probes were located near the tail current sheet when an interplanetary shock arrived under northward interplanetary magnetic field conditions and recorded an abrupt tail compression at ∼(-60, 0, -5) Re in Geocentric Solar Ecliptic coordinate in the deep magnetotail. ~ 10 minutes later, the probes crossed the magnetopause many times within an hour after the oblique interplanetary shock passed by. The solar wind velocity vector downstream from the shock was not directed along the Sun-Earth line but had a significant Y component. We propose that the compressed tail was pushed aside by the appreciable solar wind flow in the Y direction. Using a virtual spacecraft in a global magnetohydrodynamic (MHD) simulation, we reproduce the sequence of magnetopause crossings in the X-Y plane observed by ARTEMIS under oblique shock conditions, demonstrating that the compressed magnetopause is sharply deflected at lunar distances in response to the shock and solar wind Vy effects. The results from two global MHD simulations show that the shocked magnetotail at lunar distances is mainly controlled by the solar wind direction with a timescale of about a quarter hour, which appears to be consistent with the windsock effect. The results also provide some references for investigating interactions between the solar wind/magnetosheath and lunar nearside surface during full moon time intervals, which should not happen in general.</p>

Unusual location of the geotail magnetopause at lunar distance: ARTEMIS observation

2020 ◽  
Author(s):  
Wensai Shang ◽  
Binbin Tang ◽  
Quanqi Shi ◽  
Anmin Tian ◽  
Xiaoyan Zhou ◽  
...  
Keyword(s):  
Solar Wind ◽  
Velocity Vector ◽  
Solar Wind Velocity ◽  
Full Moon ◽  
Interplanetary Shock ◽  
Time Intervals ◽  
Mhd Simulation ◽  
Mhd Simulations ◽  
The Earth ◽  
Solar Wind Flow

<p>The Earth’s magnetopause is highly variable in location and shape, and is modulated by solar wind conditions. On 8 March 2012, the ARTEMIS probes were located near the tail current sheet when an interplanetary shock arrived under northward interplanetary magnetic field (IMF) conditions, and recorded an abrupt tail compression at ~(-60, 0, -5) R<sub>E</sub> in Geocentric Solar Ecliptic (GSE) coordinate in the deep magnetotail. Approximately 10 minutes later, the probes crossed the magnetopause many times within an hour after the oblique interplanetary shock passed by. The solar wind velocity vector downstream from the shock was not directed along the Sun-Earth line, but had a significant Y component. We propose that the compressed tail was pushed aside by the appreciable solar wind flow in the Y direction. Using a virtual spacecraft in a global magnetohydrodynamic (MHD) simulation, we reproduce the sequence of magnetopause crossings in the X-Y plane observed by ARTEMIS probes under oblique shock conditions, demonstrating that the compressed magnetopause is sharply deflected at lunar distances in response to the shock and solar wind V<sub>Y</sub> effects. The results of the two different global MHD simulations show that the shocked magnetotail at lunar distances is mainly controlled by the solar wind direction with a timescale of about a quarter hour, which appears to be consistent with the windsock effect. The results also provide some references for investigating interactions between the solar wind/magnetosheath and lunar nearside surface during full moon time intervals, which should not happen in general.</p>

Interplanetary Shock-driven Magnetopause Compressions in Gorgon Global-MHD Simulations

2021 ◽  
Author(s):  
Ravindra Desai ◽  
Jonathan Eastwood ◽  
Joseph Eggington ◽  
Mervyn Freeman ◽  
Martin Archer ◽  
...  
Keyword(s):  
Solar Wind ◽  
Large Scale ◽  
Interplanetary Shock ◽  
Interplanetary Shocks ◽  
Pressure Balance ◽  
Interplanetary Coronal Mass Ejections ◽  
Corotating Interaction Regions ◽  
Mhd Simulations ◽  
Interaction Regions ◽  
Space Weather Event

<p>Fast-forward interplanetary interplanetary shocks, as occur at the forefront of interplanetary coronal mass ejections and at corotating interaction regions, can rapidly compress the magnetopause inside the drift paths of electrons and protons, and expose geosynchonous satellites directly to the solar wind.  Here, we use Gorgon Global-MHD simulations to study the response of the magnetopause to different fast-forward interplanetary shocks, with strengths extending from the median shocks observed during solar minimum up to that representing an extreme space weather event. The subsequent magnetopause response can be characterised by three distinct phases; an initial acceleration as inertial forces are overcome, a rapid compression well-represented by a power law, and large-scale damped oscillatory motion of the order of an Earth radius, prior to reaching pressure-balance equilibrium. The subsolar magnetopause is found to oscillate with notable frequencies in the range of 2–13 mHz over several periods of diminishing amplitudes.  These results provide an explanation for similar large-scale magnetopause oscillations observed previously during the extreme events of August 1972 and March 1991 and highlight why static magnetopause models break down during periods of strong solar wind driving.</p>

scholarly journals Periodic variations of the geomagnetic activity indices Ap and Kp

2021 ◽  
Vol 23 (2) ◽  
Author(s):  
Pandey A.C. ◽  
◽  
Sham Singh ◽  
Dinesh Kumar Pathak ◽  
Archana Shukla ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Solar Wind ◽  
Solar Cycle ◽  
Interplanetary Magnetic Field ◽  
Wind Velocity ◽  
Geomagnetic Activity ◽  
Solar Wind Velocity ◽  
Data Sets ◽  
Time Intervals ◽  
Activity Indices

Yearly averages of geomagnetic activity indices Kp and Ap for the years 1984 to 2018 be compared to the relevant averages of VxBs, where V is the solar wind velocity and Bs is the southward interplanetary magnetic field (IMF) component. The correlation of both quantities is known to be rather good. Comparing the averages of Ap and Kp with V and Bs separately. We found that, during the declining phase of solar cycle, V and during the ascending phase Bs have more influence on Ap and Kp indices. According to this observation the 27 days and semiannual, Ap and Kp variations be analysed discretely for years after and before sunspot minima. The time intervals prior to sunspot minima with a significant 27-day recurrent period of the IMF structure and those intervals after sunspot minima with a significant 28 to28.5 day recurrent phase of the structure be used. The averaged spectra of the two Ap and Kp data sets obviously show a period of 27 days before and a period of 28 to 29 days after sunspot minimum.

scholarly journals Energy conversion through mass loading of escaping ionospheric ions for different Kp values

2018 ◽  
Vol 36 (1) ◽  
pp. 1-12 ◽  
Author(s):  
Masatoshi Yamauchi ◽  
Rikard Slapak
Keyword(s):  
Solar Wind ◽  
Kinetic Energy ◽  
Geomagnetic Field ◽  
Solar Wind Velocity ◽  
Electrical Energy ◽  
Wind Flow ◽  
Energy Extraction ◽  
Mass Loading ◽  
Ion Escape ◽  
Solar Wind Flow

Abstract. By conserving momentum during the mixing of fast solar wind flow and slow planetary ion flow in an inelastic way, mass loading converts kinetic energy to other forms – e.g. first to electrical energy through charge separation and then to thermal energy (randomness) through gyromotion of the newly born cold ions for the comet and Mars cases. Here, we consider the Earth's exterior cusp and plasma mantle, where the ionospheric origin escaping ions with finite temperatures are loaded into the decelerated solar wind flow. Due to direct connectivity to the ionosphere through the geomagnetic field, a large part of this electrical energy is consumed to maintain field-aligned currents (FACs) toward the ionosphere, in a similar manner as the solar wind-driven ionospheric convection in the open geomagnetic field region. We show that the energy extraction rate by the mass loading of escaping ions (ΔK) is sufficient to explain the cusp FACs, and that ΔK depends only on the solar wind velocity accessing the mass-loading region (usw) and the total mass flux of the escaping ions into this region (mloadFload), as ΔK ∼ −mloadFloadu2sw∕4. The expected distribution of the separated charges by this process also predicts the observed flowing directions of the cusp FACs for different interplanetary magnetic field (IMF) orientations if we include the deflection of the solar wind flow directions in the exterior cusp. Using empirical relations of u0 ∝ Kp + 1.2 and Fload ∝ exp(0.45Kp) for Kp = 1–7, where u0 is the solar wind velocity upstream of the bow shock, ΔK becomes a simple function of Kp as log10(ΔK) = 0.2 ⋅ Kp + 2 ⋅ log10(Kp + 1.2) + constant. The major contribution of this nearly linear increase is the Fload term, i.e. positive feedback between the increase of ion escaping rate Fload through the increased energy consumption in the ionosphere for high Kp, and subsequent extraction of more kinetic energy ΔK from the solar wind to the current system by the increased Fload. Since Fload significantly increases for increased flux of extreme ultraviolet (EUV) radiation, high EUV flux may significantly enhance this positive feedback. Therefore, the ion escape rate and the energy extraction by mass loading during ancient Earth, when the Sun is believed to have emitted much higher EUV flux than at present, could have been even higher than the currently available highest values based on Kp = 9. This raises a possibility that the ion escape has substantially contributed to the evolution of the Earth's atmosphere.

scholarly journals Dynamic evolution of interplanetary shock waves driven by CMEs

2011 ◽  
Vol 7 (S286) ◽  
pp. 159-163 ◽  
Author(s):  
P. Corona-Romero ◽  
J. A. Gonzalez-Esparza
Keyword(s):  
Shock Wave ◽  
Solar Wind ◽  
Shock Waves ◽  
Coronal Mass Ejections ◽  
Initial Conditions ◽  
Interplanetary Shock ◽  
Dynamic Evolution ◽  
The Sun ◽  
Dynamic Relationship

AbstractWe present a study about the propagation of interplanetary shock waves driven by super magnetosonic coronal mass ejections (CMEs). The discussion focuses on a model which describes the dynamic relationship between the CME and its driven shock and the way to approximate the trajectory of shocks based on those relationships, from near the Sun to 1 AU. We apply the model to the analysis of a case study in which our calculations show quantitative and qualitative agreements with different kinds of data. We discuss the importance of solar wind and CME initial conditions on the shock wave evolution.

Embedding particle-in-cell simulations in global magnetohydrodynamic simulations of the magnetosphere

2019 ◽  
Vol 85 (1) ◽  
Author(s):  
Raymond J. Walker ◽  
Giovanni Lapenta ◽  
Jean Berchem ◽  
Mostafa El-Alaoui ◽  
David Schriver
Keyword(s):  
Solar Wind ◽  
Mhd Simulation ◽  
Magnetospheric Substorm ◽  
Pic Simulation ◽  
Particle In Cell ◽  
Mhd Simulations ◽  
Dayside Magnetopause ◽  
Thin Current Sheet ◽  
Cell Simulation ◽  
Magnetohydrodynamic Simulations

We have combined global magnetohydrodynamic (MHD) simulations of the solar wind and magnetosphere interaction with an implicit particle-in-cell simulation (PIC) and used this approach to model magnetic reconnection at both the dayside magnetopause and in the magnetotail plasma sheet. In this approach, we first model the magnetospheric configuration driven by the solar wind using the MHD simulation. At a time of interest (usually when a thin current sheet has formed in the MHD simulation), we load a large particle-in-cell simulation with plasma and fields based on the MHD state. We use the MHD results to set the boundary conditions on the PIC simulation. The coupling between the two models is one way – the PIC results do not change the MHD results. In these calculations, we use the UCLA global MHD code and the iPic3D implicit particle-in-cell code. In this paper we describe this technique in detail. As an example of this approach, we present PIC results on reconnection in the magnetotail during a magnetospheric substorm.

scholarly journals Magnetopause reconnection and interlinked flux tubes

2013 ◽  
Vol 31 (10) ◽  
pp. 1853-1866 ◽  
Author(s):  
F. R. Cardoso ◽  
W. D. Gonzalez ◽  
D. G. Sibeck ◽  
M. Kuznetsova ◽  
D. Koga
Keyword(s):  
Magnetic Field ◽  
Solar Wind ◽  
Magnetic Reconnection ◽  
Large Scale ◽  
Time Dependent ◽  
Mhd Simulation ◽  
Flux Tubes ◽  
Magnetic Structures ◽  
Mhd Simulations ◽  
Magnetopause Reconnection

Abstract. Magnetic reconnection can be a continuous or a transient process. Global magnetohydrodynamics (MHD) simulations are important tools to understand the relevant magnetic reconnection mechanisms and the resulting magnetic structures. We have studied magnetopause reconnection using a global 3-D MHD simulation in which the interplanetary magnetic field (IMF) has been set to large positive By and large negative Bz components, i.e., a south-duskward direction. Flux tubes have been observed even during these constant solar wind conditions. We have focused on the interlinked flux tubes event resulting from time-dependent, patchy and multiple reconnection. At the event onset, two reconnection modes seem to occur simultaneously: a time-dependent, patchy and multiple reconnection for the subsolar region; and, a steady and large-scale reconnection for the regions far from the subsolar site.

Development and Validation of CME Arrival-Time Forecasting System by MHD Simulations based on Interplanetary Scintillation Observations

2021 ◽  
Author(s):  
Kazumasa Iwai ◽  
Daikou Shiota ◽  
Munetoshi Tokumaru ◽  
Ken’ichi Fujiki ◽  
Mitsue Den ◽  
...  
Keyword(s):  
Solar Wind ◽  
Arrival Time ◽  
Interplanetary Space ◽  
Space Environment ◽  
Environmental Research ◽  
Interplanetary Scintillation ◽  
Mhd Simulation ◽  
Arrival Times ◽  
Mhd Simulations ◽  
Forecasting System

<p>Coronal mass ejections (CMEs) cause various disturbances of the space environment; therefore, forecasting their arrival time is very important. However, forecasting accuracy is hindered by limited CME observations in interplanetary space. This study developed a CME arrival-time forecasting system using a three-dimensional (3D) magnetohydrodynamic (MHD) simulations based on interplanetary scintillation (IPS) observations. The base MHD simulation is SUSANO-CME (Shiota and Kataoka 2016), in which CMEs are approximated as spheromaks. In the developed forecasting system, many MHD simulations with different CME initial speed are tested. The IPS responses of each MHD simulation run is calculated from the density distributions derived from the MHD simulation, and compared with IPS data observed by the Institute for Space-Earth Environmental Research (ISEE), Nagoya University. The CME arrival time of the simulation run that most closely agrees with the IPS data is automatically selected as the forecasted time.</p><p>We then validate the accuracy of this forecast using 12 halo CME events. The average absolute arrival-time error of the IPS-based MHD forecast is approximately 5.0 h, which is one of the most accurate predictions that ever been validated, whereas that of MHD simulations without IPS data, in which the initial CME speed is derived from white-light coronagraph images, is approximately 6.7 h. This suggests that the assimilation of IPS data into MHD simulations can improve the accuracy of CME arrival-time forecasts. The average predicted arrival times are earlier than the actual arrival times. These early predictions may be due to overestimation of the magnetic field included in the spheromak and/or underestimation of the drag force from the background solar wind, the latter of which could be related to underestimation of CME size or background solar wind density.</p>

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