Simulating the Reiner Gamma Swirl and Magnetic Anomaly: The Impact of the Solar Wind Alpha Population

2020 ◽  
Author(s):  
Jan Deca ◽  
Douglas J. Hemingway ◽  
Andrey Divin ◽  
Charles Lue ◽  
Andrew R. Poppe ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Solar Wind ◽  
Magnetic Anomaly ◽  
Energy Flux ◽  
Spatial Scales ◽  
Magnetic Anomalies ◽  
Lunar Orbit ◽  
Near Surface ◽  
Lunar Prospector ◽  
The Impact

<p>The Reiner Gamma swirl is one of the most prominent albedo features on the lunar surface. Its modest spatial scales and structure allows fully kinetic modelling. The region therefore presents a prime location to investigate the lunar albedo patterns and their co-location with magnetic anomalies. The precise relationship between the impinging plasma and the swirl, and in particular, how these interactions vary over the course of a lunar day, remains an open issue.</p><p>Here we use the fully kinetic particle-in-cell code,  iPIC3D, coupled with a magnetic field model based on Kaguya and Lunar Prospector observations, and simulate the interaction with the Reiner Gamma anomaly for all plasma regimes the region is exposed to along a typical orbit, including different solar wind incidence angles and the Moon's crossing through the terrestrial magnetosphere. We focus on the impact of the solar wind alpha population and construct energy and velocity distributions in key locations surrounding the interaction region of the anomaly.</p><p>The energy flux profile provides a better match to the albedo pattern only when integrating over the full lunar orbit. Including He<sup>2+</sup> as a self-consistent plasma species improves the brightness ratios between the inner and outer bright lobes, the dark lanes, and the mare background. However, substantial differences between the observed albedo pattern and the predicted flux remain.  For example, the bright outer lobes are substantially brighter than predicted and the central portion of the anomaly is darker than predicted. This is likely due to an incomplete model of the near-surface field structure.</p><p>Solar wind standoff can explain the large-scale correlation between the Reiner Gamma swirl and the co-located magnetic anomaly. In particular, the outer bright lobes emerge in the simulated weathering pattern only when integrating over the entire lunar orbit, although they are much weaker than observed. Both the proton and helium energy flux to the surface need to be taken into account to best reproduce the swirl pattern. A complete understanding of the solar wind interaction with lunar magnetic anomalies and swirl formation could be vastly improved by low altitude measurements of the magnetic field and solar wind.</p>

scholarly journals A porcupine Sun? Implications for the solar wind and Earth

2011 ◽  
Vol 7 (S286) ◽  
pp. 210-214 ◽  
Author(s):  
Sarah E. Gibson ◽  
Liang Zhao
Keyword(s):  
Magnetic Field ◽  
Solar Wind ◽  
Spatial Scales ◽  
Coronal Magnetic Field ◽  
Heliospheric Current Sheet ◽  
Magnetic Structures ◽  
Fast Wind ◽  
Global Configuration ◽  
Slow Wind ◽  
The Impact

AbstractThe recent minimum was unusually long, and it was not just the case of the “usual story” slowed down. The coronal magnetic field never became completely dipolar as in recent Space Age minima, but rather gradually evolved into an (essentially axisymmetric) global configuration possessing mixed open and closed magnetic structures at many latitudes. In the process, the impact of the solar wind at the Earth went from resembling that from a sequence of rotating “fire-hoses” to what might be expected from a weak, omnidirectional “lawn-sprinkler”. The previous (1996) solar minimum was a more classic dipolar configuration, and was characterized by slow wind of hot origin localized to the heliospheric current sheet, and fast wind of cold origin emitted from polar holes, but filling most of the heliosphere. In contrast, the more recent minimum solar wind possessed a broad range of speeds and source temperatures (although cooler overall than the prior minimum). We discuss possible connections between these observations and the near-radial expansion and small spatial scales characteristic of the recent minimum's porcupine-like magnetic field.

scholarly journals High-latitude electromagnetic and particle energy flux during an event with sustained strongly northward IMF

2005 ◽  
Vol 23 (4) ◽  
pp. 1295-1310 ◽  
Author(s):  
H. Korth ◽  
B. J. Anderson ◽  
H. U. Frey ◽  
C. L. Waters
Keyword(s):  
Magnetic Field ◽  
Solar Wind ◽  
Energy Flux ◽  
High Latitude ◽  
Energy Transport ◽  
Small Region ◽  
Radial Component ◽  
Particle Energy ◽  
Electromagnetic Energy ◽  
Viscous Interaction

Abstract. We present a case study of a prolonged interval of strongly northward orientation of the interplanetary magnetic field on 16 July 2000, 16:00-19:00 UT to characterize the energy exchange between the magnetosphere and ionosphere for conditions associated with minimum solar wind-magnetosphere coupling. With reconnection occurring tailward of the cusp under northward IMF conditions, the reconnection dynamo should be separated from the viscous dynamo, presumably driven by the Kelvin-Helmholtz (KH) instability. Thus, these conditions are also ideal for evaluating the contribution of a viscous interaction to the coupling process. We derive the two-dimensional distribution of the Poynting vector radial component in the northern sunlit polar ionosphere from magnetic field observations by the constellation of Iridium satellites together with drift meter and magnetometer observations from the Defense Meteorological Satellite Program (DMSP) F13 and F15 satellites. The electromagnetic energy flux is then compared with the particle energy flux obtained from auroral images taken by the far-ultraviolet (FUV) instrument on the Imager for Magnetopause to Aurora Global Exploration (IMAGE) spacecraft. The electromagnetic energy input to the ionosphere of 51 GW calculated from the Iridium/DMSP observations is eight times larger than the 6 GW due to particle precipitation all poleward of 78° MLAT. This result indicates that the energy transport is significant, particularly as it is concentrated in a small region near the magnetic pole, even under conditions traditionally considered to be quiet and is dominated by the electromagnetic flux. We estimate the contributions of the high and mid-latitude dynamos to both the Birkeland currents and electric potentials finding that high-latitude reconnection accounts for 0.8 MA and 45kV while we attribute <0.2MA and ~5kV to an interaction at lower latitudes having the sense of a viscous interaction. Given that these conditions are ideal for the occurrence of the KH instability at the magnetopause and hence the viscous interaction, this result suggests that the viscous interaction is a small contributor to coupling solar wind energy to the magnetosphere-ionosphere system.

scholarly journals Magnetic clouds' structure in the magnetosheath as observed by Cluster and Geotail: four case studies

2014 ◽  
Vol 32 (10) ◽  
pp. 1247-1261 ◽  
Author(s):  
L. Turc ◽  
D. Fontaine ◽  
P. Savoini ◽  
E. K. J. Kilpua
Keyword(s):  
Magnetic Field ◽  
Solar Wind ◽  
Magnetic Fields ◽  
Bow Shock ◽  
Field Direction ◽  
Magnetic Clouds ◽  
Magnetic Field Direction ◽  
Field Orientation ◽  
The Impact ◽  
The Magnetic Field

Abstract. Magnetic clouds (MCs) are large-scale magnetic flux ropes ejected from the Sun into the interplanetary space. They play a central role in solar–terrestrial relations as they can efficiently drive magnetic activity in the near-Earth environment. Their impact on the Earth's magnetosphere is often attributed to the presence of southward magnetic fields inside the MC, as observed in the upstream solar wind. However, when they arrive in the vicinity of the Earth, MCs first encounter the bow shock, which is expected to modify their properties, including their magnetic field strength and direction. If these changes are significant, they can in turn affect the interaction of the MC with the magnetosphere. In this paper, we use data from the Cluster and Geotail spacecraft inside the magnetosheath and from the Advanced Composition Explorer (ACE) upstream of the Earth's environment to investigate the impact of the bow shock's crossing on the magnetic structure of MCs. Through four example MCs, we show that the evolution of the MC's structure from the solar wind to the magnetosheath differs largely from one event to another. The smooth rotation of the MC can either be preserved inside the magnetosheath, be modified, i.e. the magnetic field still rotates slowly but at different angles, or even disappear. The alteration of the magnetic field orientation across the bow shock can vary with time during the MC's passage and with the location inside the magnetosheath. We examine the conditions encountered at the bow shock from direct observations, when Cluster or Geotail cross it, or indirectly by applying a magnetosheath model. We obtain a good agreement between the observed and modelled magnetic field direction and shock configuration, which varies from quasi-perpendicular to quasi-parallel in our study. We find that the variations in the angle between the magnetic fields in the solar wind and in the magnetosheath are anti-correlated with the variations in the shock obliquity. When the shock is in a quasi-parallel regime, the magnetic field direction varies significantly from the solar wind to the magnetosheath. In such cases, the magnetic field reaching the magnetopause cannot be approximated by the upstream magnetic field. Therefore, it is important to take into account the conditions at the bow shock when estimating the impact of an MC with the Earth's environment because these conditions are crucial in determining the magnetosheath magnetic field, which then interacts with the magnetosphere.

Impact of the low/high Alfven Mach number regime of the solar wind on the Aflven transition Layer of the cusp for IMF North: 3D global PIC simulation.

2020 ◽  
Author(s):  
DongSheng Cai ◽  
Bertrand Lembege
Keyword(s):  
Solar Wind ◽  
Transition Layer ◽  
Spatial Scales ◽  
Three Dimensional ◽  
Depletion Region ◽  
Meridian Plane ◽  
Pic Simulation ◽  
Cusp Region ◽  
Global View ◽  
The Impact

&lt;p&gt;&amp;#160;CLUSTER experimental observations of&amp;#160; Lavraud et al. (2005) have evidenced the presence of a particular layer (so &amp;#8211;called herein Alfven Transition Layer or ATL) almost adjacent to the upper edge of the stagnant exterior cusp (SEC), through which the plasma flow transits from super-(from magnetosheath) to sub- (to SEC) Alfvenic regime as the interplanetary magnetic field (IMF) is northward. Three dimensional globa PIC simulations have been recently used &amp;#160;(Cai et al., 2015) to analyze the main features of the cusp for an IMF configuration similar that in the observations. These simulations have allowed us to complete the global view of the cusp region &amp;#160;(in particular the features not accessible by MHD approach).&amp;#160; A&amp;#160; detailed analysis has allowed to retrieve the features of the ATL which reveals to be associated to the complicated 3D particles entry into the cusp region and exhibit an internal conic depletion region (CDR) where the ion fluxes concentrate and are very strong (which suggests very local ion precipitation). Moreover, simulation results show that the ATL expands towards areas out and even far from the cusp region and outside the meridian plane.&lt;/p&gt;&lt;p&gt;&amp;#160;&amp;#160;&amp;#160;&amp;#160;&amp;#160;&amp;#160;&amp;#160;&amp;#160;&amp;#160;&amp;#160;&amp;#160;&amp;#160;&amp;#160;&amp;#160;&amp;#160;&amp;#160;&amp;#160;&amp;#160;&amp;#160;&amp;#160; In the present work, the study is extended for different Ma regimes of the solar wind, as the IMF stays in northward &amp;#160;configuration. Results show the impact of this Ma variation on the 3D features of the overall magnetosphere and in particular on the cusp region, i.e. (i) on the 3D ATL structures/spatial scales, (ii) on the extension of the region surrounded by the ATL, and (iii) on the structures, the spatial scales and the dynamics of the CDR itself.&lt;/p&gt;&lt;p&gt;&amp;#160;&lt;/p&gt;&lt;p&gt;&amp;#160;&lt;/p&gt;

COMMENTS ON “INTERRELATIONSHIPS BETWEEN MAGNETIC ANOMALY COMPONENTS”

Geophysics ◽  
1959 ◽  
Vol 24 (2) ◽  
pp. 366-369 ◽  
Author(s):  
Aivars Celmins
Keyword(s):  
Magnetic Field ◽  
Magnetic Anomaly ◽  
Simple Formula ◽  
Magnetic Anomalies ◽  
Horizontal Component ◽  
Two Dimensional ◽  
Interesting Behavior ◽  
Normal Magnetic Field

On page 748 of the above named paper, Affleck (1958) mentions an interesting behavior of magnetic anomalies which are caused by homogeneous magnetized two‐dimensional bodies. He states that in these cases the airborne magnetometer anomaly can be treated as either the vertical or horizontal component anomaly if the true magnetization is replaced by a pseudo‐magnetization of other direction and intensity. It may be of some interest to formulate this behavior more precisely, so much the more as the interdependence between the magnetization directions and the direction of a normal magnetic field can be expressed by a rather simple formula.

scholarly journals ESTIMASI BADAI GEOMAGNET BERDASARKAN PERILAKU PARAMETER ANGIN SURYA DAN MEDAN MAGNET ANTARPLANET SEBELUM BADAI GEOMAGNET (THE ESTIMATION OF GEOMAGNETIC STORM BASED ON SOLAR WIND PARAMETERS AND INTERPLANETARY MAGNETIC FIELD BEHAVIOR BEFORE GEOMAGNETIC STOR

2017 ◽  
Vol 14 (2) ◽  
pp. 17
Author(s):  
Anwar Santoso ◽  
Mamat Rahimat ◽  
Rasdewita Kesumaningrum ◽  
Siska Filawati
Keyword(s):  
Magnetic Field ◽  
Solar Wind ◽  
Geomagnetic Storm ◽  
Space Weather ◽  
Geomagnetic Storms ◽  
Storm Events ◽  
Science Center ◽  
Solar Wind Parameters ◽  
The Impact ◽  
The Imf

Space weather research is the principal activity at the Space Science Center, Lapan to learn characteristics and generator source of the space weather so that can mitigate its the impact on the Earth's environment as mandated in Law No. 21 Year 2013. One of them is the phenomenon of geomagnetic storms. Geomagnetic storms caused by the entry of solar wind together with the IMF Bz that leads to the south. The behavior of the solar wind parameters together with the IMF Bz before geomagnetic storms can determine the formation of geomagnetic storms that caused it. In spite that, by the solar wind parameters and IMF Bz behavior before geomagnetic storm can be estimated its intensity through the equation Dst * = 1.599 * Ptotal - 34.48. The result of this equation is obtained that the Dst minimum deviation between the raw data and the output of this equation to the geomagnetic storm events on March 17, 2013 is about of -2.51 nT or 1.9% and on the geomagnetic storm events on February 19, 2014 is about of 2.77 nT or 2, 5%. Thus, the equation Dst * = 1.599 * Ptotal - 34.48 is very good for the estimation of geomagnetic storms.

scholarly journals FLIP-MHD-based model sensitivity analysis

2014 ◽  
Vol 21 (2) ◽  
pp. 539-553 ◽  
Author(s):  
C. Skandrani ◽  
M. E. Innocenti ◽  
L. Bettarini ◽  
F. Crespon ◽  
J. Lamouroux ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Solar Wind ◽  
Solar Wind Speed ◽  
Sensitivity Study ◽  
Field Configuration ◽  
Source Surface ◽  
Solar Source ◽  
Surface Magnetic Field ◽  
Model State ◽  
The Impact

Abstract. The state of the art in the forecast of the background solar wind speed and of the interplanetary magnetic field at Earth is based on the use as boundary conditions for heliospheric models of the input data provided by solar observations. Magnetogram synoptic maps are used to obtain information on the magnetic field configuration at the solar source surface. Magnetic field inputs at the solar source surface thus constitute one of the main external sources of errors in solar wind models. The assimilation of data into forecasting models used in the terrestrial domain showed the ability to control model state errors. A sensitivity study performed through the analysis of the ensemble variances and the representers technique is used here to assess how process and model state errors propagate in a nonlinear two-dimensional MagnetoHydro Dynamic (MHD) system. The aim is to understand the impact of the source surface input parameters on the evolution of MHD heliospheric models and the potentialities of data assimilation techniques in solar wind forecasting. The representer technique in fact allows one to understand how far from the observation point the improvement granted from the assimilation of a measure propagates.

scholarly journals Low-frequency magnetic variations at the high-<i>β</i> Earth bow shock

2019 ◽  
Vol 37 (5) ◽  
pp. 877-889
Author(s):  
Anatoli A. Petrukovich ◽  
Olga M. Chugunova ◽  
Pavel I. Shustov
Keyword(s):  
Magnetic Field ◽  
Solar Wind ◽  
Spatial Scales ◽  
Low Frequency ◽  
Background Field ◽  
Bow Shock ◽  
Stable Phase ◽  
Main Magnetic Field ◽  
Astrophysical Plasmas ◽  
Earth’S Bow Shock

Abstract. Observations of Earth's bow shock during high-β (ratio of thermal to magnetic pressure) solar wind streams are rare. However, such shocks are ubiquitous in astrophysical plasmas. Typical solar wind parameters related to high β (here β>10) are as follows: low speed, high density, and a very low interplanetary magnetic field of 1–2 nT. These conditions are usually quite transient and need to be verified immediately upstream of the observed shock crossings. In this report, three characteristic crossings by the Cluster project (from the 22 found) are studied using multipoint analysis, allowing us to determine spatial scales. The main magnetic field and density spatial scale of about a couple of hundred of kilometers generally corresponds to the increased proton convective gyroradius. Observed magnetic variations are different from those for supercritical shocks, with β∼1. Dominant magnetic variations in the shock transition have amplitudes much larger than the background field and have a frequency of ∼ 0.3–0.5 Hz (in some events – 1–2 Hz). The wave polarization has no stable phase and is closer to linear, which complicates the determination of the wave propagation direction. Spatial scales (wavelengths) of variations are within several tens to a couple of hundred of kilometers.

scholarly journals The dynamo-wind feedback loop : Assessing their non-linear interplay

2019 ◽  
Vol 15 (S354) ◽  
pp. 215-223
Author(s):  
Barbara Perri ◽  
Allan Sacha Brun ◽  
Antoine Strugarek ◽  
Victor Réville
Keyword(s):  
Magnetic Field ◽  
Solar Wind ◽  
Coronal Holes ◽  
Coronal Magnetic Field ◽  
Space Environment ◽  
Cycle Phase ◽  
Activity Cycles ◽  
Spatio Temporal ◽  
Field Lines ◽  
The Impact

AbstractThough generated deep inside the convection zone, the solar magnetic field has a direct impact on the Earth space environment via the Parker spiral. It strongly modulates the solar wind in the whole heliosphere, especially its latitudinal and longitudinal speed distribution over the years. However the wind also influences the topology of the coronal magnetic field by opening the magnetic field lines in the coronal holes, which can affect the inner magnetic field of the star by altering the dynamo boundary conditions. This coupling is especially difficult to model because it covers a large variety of spatio-temporal scales. Quasi-static studies have begun to help us unveil how the dynamo-generated magnetic field shapes the wind, but the full interplay between the solar dynamo and the solar wind still eludes our understanding.We use the compressible magnetohydrodynamical (MHD) code PLUTO to compute simultaneously in 2.5D the generation and evolution of magnetic field inside the star via an α-Ω dynamo process and the corresponding evolution of a polytropic coronal wind over several activity cycles for a young Sun. A multi-layered boundary condition at the surface of the star connects the inner and outer stellar layers, allowing both to adapt dynamically. Our continuously coupled dynamo-wind model allows us to characterize how the solar wind conditions change as a function of the cycle phase, and also to quantify the evolution of integrated quantities such as the Alfvén radius. We further assess the impact of the solar wind on the dynamo itself by comparing our results with and without wind feedback.

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