scholarly journals Three-dimensional MHD simulation of interplanetary magnetic field changes at 1 AU as a consequence of simulated solar flares

1996 ◽  
Vol 14 (4) ◽  
pp. 383-399 ◽  
Author(s):  
C.-C. Wu ◽  
M. Dryer ◽  
S. T. Wu
Keyword(s):  
Magnetic Field ◽  
Solar Activity ◽  
Interplanetary Magnetic Field ◽  
Pressure Pulse ◽  
Initial Conditions ◽  
Three Dimensional ◽  
Strong Relationship ◽  
Heliospheric Current Sheet ◽  
Archimedean Spiral ◽  
The North

Abstract. A fully three-dimensional (3D), time-dependent, MHD interplanetary global model (3D IGM) has been used, for the first time, to study the relationship between different forms of solar activity and transient variations of the north-south component, Bz, of the interplanetary magnetic field (IMF) at 1 AU. One form of solar activity, the flare, is simulated by using a pressure pulse at different locations near the solar surface and observing the simulated IMF evolution of Bθ (=–Bz) at 1 AU. Results show that, for a given pressure pulse, the orientation of the corresponding transient variation of Bz has a strong relationship to the location of the pressure pulse and the initial conditions of the IMF. Two initial IMF conditions are considered: a unipolar Archimedean spiral with outward polarity and a flat heliospheric current sheet (HCS) with outward polarity in the northern hemisphere and which gradually reverses polarity in the solar equatorial plane to inward polarity in the southern heliospheric hemisphere. The wave guide effect of the HCS is also demonstrated.

Three-dimensional Multispecies Simulation of the Solar Wind Interaction with Mars Under Different Interplanetary Magnetic Field Orientations

2021 ◽  
Vol 921 (2) ◽  
pp. 139
Author(s):  
Yun Li ◽  
Haoyu Lu ◽  
Jinbin Cao ◽  
Shibang Li ◽  
Christian Mazelle ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Solar Wind ◽  
Interplanetary Magnetic Field ◽  
Three Dimensional ◽  
Polarity Reversal ◽  
Solar Wind Interaction ◽  
Magnetic Structures ◽  
Parker Spiral ◽  
Global Configuration ◽  
Spiral Angle

Abstract Without the intrinsic magnetic field, the solar wind interaction with Mars can be significantly different from the interaction with Earth and other magnetized planets. In this paper, we investigate how a global configuration of the magnetic structures, consisting of the bow shock, the induced magnetosphere, and the magnetotail, is modulated by the interplanetary magnetic field (IMF) orientation. A 3D multispecies numerical model is established to simulate the interaction of solar wind with Mars under different IMF directions. The results show that the shock size including the subsolar distance and the terminator radius increases with Parker spiral angle, as is the same case with the magnetotail radius. The location and shape of the polarity reversal layer and inverse polarity reversal layer in the induced magnetotail are displaced to the y < 0 sector for a nonzero flow-aligned IMF component, consistent with previous analytical solutions and observations. The responses of the Martian global magnetic configuration to the different IMF directions suggest that the external magnetic field plays an important role in the solar wind interaction with unmagnetized planets.

About the Relation Between the Limb Effect of the Redshift on the Sun and the Large-Scale Distribution of Solar activity

1976 ◽  
Vol 71 ◽  
pp. 113-118
Author(s):  
P. Ambrož
Keyword(s):  
Magnetic Field ◽  
Solar Activity ◽  
Magnetic Fields ◽  
Interplanetary Magnetic Field ◽  
Large Scale ◽  
The Sun ◽  
Limb Effect

The measurement of the magnitude of the limb effect was homogenized in time and a recurrent period of maxima of 27.8 days was found. A relation was found between the maximum values of the limb effect of the redshift, the boundaries of polarities of the interplanetary magnetic field, the characteristic large-scale distribution of the background magnetic fields and the complex of solar activity.

scholarly journals Can an interplanetary magnetic field reach the surface of Venus?

2018 ◽  
Vol 36 (6) ◽  
pp. 1537-1543
Author(s):  
Yasuhito Narita ◽  
Uwe Motschmann
Keyword(s):  
Magnetic Field ◽  
Solar Wind ◽  
Solar Activity ◽  
Interplanetary Magnetic Field ◽  
Field Condition ◽  
Diffusion Time ◽  
Field Reversal ◽  
Magnetic Diffusion ◽  
The Magnetic Field ◽  
Magnetic Field Condition

Abstract. We address the question of whether there is a possibility of an interplanetary magnetic field reaching Venus' surface by magnetic diffusion across the ionosphere. We present a model calculation, estimate the magnetic diffusion time at Venus, and find out that the typical diffusion timescale is in a range between 12 and 54 h, depending on the solar activity and the ionospheric magnetic field condition. The magnetic field can thus permeate Venus' surface and even its interior when the solar wind is stationary (i.e., no magnetic field reversal) on the timescale of half a day to several days.

scholarly journals Quasi-periodic changes in the 3D solar anisotropy of Galactic cosmic rays for 1965–2014

2017 ◽  
Vol 609 ◽  
pp. A32 ◽  
Author(s):  
R. Modzelewska ◽  
M. V. Alania
Keyword(s):  
Magnetic Field ◽  
Solar Wind ◽  
Solar Activity ◽  
Solar Cycle ◽  
Cosmic Rays ◽  
Ecliptic Plane ◽  
Galactic Cosmic Rays ◽  
Magnetic Cycle ◽  
The North ◽  
Solar Magnetic Cycle

Aims. We study features of the 3D solar anisotropy of Galactic cosmic rays (GCR) for 1965−2014 (almost five solar cycles, cycles 20−24). We analyze the 27-day variations of the 2D GCR anisotropy in the ecliptic plane and the north-south anisotropy normal to the ecliptic plane. We study the dependence of the 27-day variation of the 3D GCR anisotropy on the solar cycle and solar magnetic cycle. We demonstrate that the 27-day variations of the GCR intensity and anisotropy can be used as an important tool to study solar wind, solar activity, and heliosphere. Methods. We used the components Ar, Aϕ and At of the 3D GCR anisotropy that were found based on hourly data of neutron monitors (NMs) and muon telescopes (MTs) using the harmonic analyses and spectrographic methods. We corrected the 2D diurnal (~24-h) variation of the GCR intensity for the influence of the Earth magnetic field. We derived the north-south component of the GCR anisotropy based on the GG index, which is calculated as the difference in GCR intensities of the Nagoya multidirectional MTs. Results. We show that the behavior of the 27-day variation of the 3D anisotropy verifies a stable long-lived active heliolongitude on the Sun. This illustrates the usefulness of the 27-day variation of the GCR anisotropy as a unique proxy to study solar wind, solar activity, and heliosphere. We distinguish a tendency of the 22-yr changes in amplitude of the 27-day variation of the 2D anisotropy that is connected with the solar magnetic cycle. We demonstrate that the amplitudes of the 27-day variation of the north-south component of the anisotropy vary with the 11-yr solar cycle, but a dependence of the solar magnetic polarity can hardly be recognized. We show that the 27-day recurrences of the GG index and the At component are highly positively correlated, and both are highly correlated with the By component of the heliospheric magnetic field.

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