Theoretical plasma distributions consistent with Ulysses magnetic field observations in a solar wind tangential discontinuity

At the beginning of September 2020 ACE and BepiColombo spent several hours in an interesting magnetically connected configuration, while at the end of the same month Parker Solar Probe (PSP) and BepiColombo were radially aligned. Being PSP orbiting near 0.1 AU, BepiColombo near 0.6 AU, and ACE at 1 AU, these geometries are of particular interest for investigating the evolution of solar wind properties at different heliocentric distances by observing the same solar wind plasma parcels.&#160; In this contribution we use magnetic field observations from pairs of spacecraft to characterize both the topology of the magnetic field at different heliocentric distances (scalings and high-order statistics) and how it evolves when moving from near-Sun to far-Sun locations. We observe a breakdown of the statistical self-similar nature of the solar wind plasma due to an increase of the intermittency level when moving away from the Sun. These results support previous evidences on the radial dependence of solar wind scaling behavior and can open a novel framework for modeling magnetic field topological changes across the Heliosphere.

Download Full-text

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

Astronomy and Astrophysics ◽

10.1051/0004-6361/201832764 ◽

2018 ◽

Vol 614 ◽

pp. A132 ◽

Cited By ~ 7

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.

Download Full-text

MHD model of magnetosheath flow: comparison with AMPTE/IRM observations on 24 October, 1985

Annales Geophysicae ◽

10.1007/s00585-998-0518-7 ◽

1998 ◽

Vol 16 (5) ◽

pp. 518-527 ◽

Cited By ~ 23

Author(s):

C. J. Farrugia ◽

H. K. Biernat ◽

N. V. Erkaev ◽

L. M. Kistler ◽

G. Le ◽

...

Keyword(s):

Magnetic Field ◽

Solar Wind ◽

Steady State ◽

Depletion Layer ◽

Local Magnetic Field ◽

Tangential Discontinuity ◽

Stagnation Line ◽

Line Flow ◽

Mhd Model ◽

Plasma Depletion

Abstract. We compare numerical results obtained from a steady-state MHD model of solar wind flow past the terrestrial magnetosphere with documented observations made by the AMPTE/IRM spacecraft on 24 October, 1985, during an inbound crossing of the magnetosheath. Observations indicate that steady conditions prevailed during this about 4 hour-long crossing. The magnetic shear at spacecraft entry into the magnetosphere was 15°. A steady density decrease and a concomitant magnetic field pile-up were observed during the 40 min interval just preceding the magnetopause crossing. In this plasma depletion layer (1) the plasma beta dropped to values below unity; (2) the flow speed tangential to the magnetopause was enhanced; and (3) the local magnetic field and velocity vectors became increasingly more orthogonal to each other as the magnetopause was approached (Phan et al., 1994). We model parameter variations along a spacecraft orbit approximating that of AMPTE/IRM, which was at slightly southern GSE latitudes and about 1.5 h post-noon Local Time. We model the magnetopause as a tangential discontinuity, as suggested by the observations, and take as input solar wind parameters those measured by AMPTE/IRM just prior to its bow shock crossing. We find that computed field and plasma profiles across the magnetosheath and plasma depletion layer match all observations closely. Theoretical predictions on stagnation line flow near this low-shear magnetopause are confirmed by the experimental findings. Our theory does not give, and the data on this pass do not show, any localized density enhancements in the inner magnetosheath region just outside the plasma depletion layer.Key words. Steady-state magnetosheath · Plasma depletion layer · Stagnation line flow

Download Full-text

Magnetic field observations of the 1.3-year solar wind oscillation

Geophysical Research Letters ◽

10.1029/95gl01737 ◽

1995 ◽

Vol 22 (14) ◽

pp. 1845-1848 ◽

Cited By ~ 28

Author(s):

Adam Szabo ◽

Ronald P. Lepping ◽

Joseph H. King

Keyword(s):

Magnetic Field ◽

Solar Wind ◽

Field Observations

Download Full-text

Interplanetary magnetic field structure and solar wind parameters as inferred from solar magnetic field observations and by using a numerical 2-D MHD model

Solar Physics ◽

10.1007/bf00646492 ◽

1993 ◽

Vol 143 (2) ◽

pp. 345-363 ◽

Cited By ~ 13

Author(s):

A. V. Usmanov

Keyword(s):

Magnetic Field ◽

Solar Wind ◽

Interplanetary Magnetic Field ◽

Solar Magnetic Field ◽

Field Structure ◽

Field Observations ◽

Magnetic Field Structure ◽

Mhd Model ◽

Solar Wind Parameters

Download Full-text

Large-Scale Coronal Magnetic Field and Density Structures

International Astronomical Union Colloquium ◽

10.1017/s0252921100025239 ◽

1994 ◽

Vol 144 ◽

pp. 155-157

Author(s):

S. Gibson ◽

F. Bagenal

Keyword(s):

Magnetic Field ◽

Solar Wind ◽

Large Scale ◽

Solar Maximum ◽

Coronal Magnetic Field ◽

Field Observations ◽

Solar Maximum Mission ◽

Solar Wind Acceleration ◽

Large Scale Magnetic Field ◽

The Magnetic Field

AbstractWe have modelled the large-scale magnetic field and density structures in the corona using the magnetostatic model of Bogdan and Low (1986) and white light images from both NASA’s Solar Maximum Mission (SMM) Coronagraph/Polarimeter and the High Altitude Observatory Mark III (MkIII) K-coronameter (Bagenal and Gibson, 1991; Gibson and Bagenal, 1992.)We have used the magnetostatic model to calculate the magnetic field, density, pressure, and temperature distribution in the corona. Moreover, we have studied how, if at all, photospheric magnetic field observations could be used to improve predictions of coronal fields.We are at present examining the implications of our predictions of magnetic field and density structures have for coronal heating and solar wind acceleration. We are also analysing the robustness of these predictions, studying both observational and model related errors.

Download Full-text

Significance of Bernoulli Integral Terms for the Solar Wind Protons at 1 au

Applied Sciences ◽

10.3390/app11104643 ◽

2021 ◽

Vol 11 (10) ◽

pp. 4643

Author(s):

Georgios Nicolaou ◽

George Livadiotis ◽

Mihir I. Desai

Keyword(s):

Magnetic Field ◽

Solar Wind ◽

Energy Conservation ◽

Plasma Density ◽

Polytropic Index ◽

Field Observations ◽

Accurate Calculation ◽

Solar Wind Proton ◽

Wind Spacecraft ◽

Bernoulli Integral

The Bernoulli integral describes the energy conservation of a fluid along specific streamlines. The integral is the sum of individual terms that contain the plasma density, speed, temperature, and magnetic field. Typical solar wind analyses use the fluctuations of the Bernoulli integral as a criterion to identify different plasma streamlines from single spacecraft observations. However, the accurate calculation of the Bernoulli integral requires accurately determining the plasma polytropic index from the analysis of density and temperature observations. To avoid this complexity, we can simplify the calculations by keeping only the dominant terms of the integral. Here, we analyze proton plasma and magnetic field observations obtained by the Wind spacecraft at 1 au, during 1995. We calculate the Bernoulli integral terms and quantify their significance by comparing them with each other. We discuss potential simplifications of the calculations in the context of determining solar wind proton thermodynamics using single spacecraft observations.

Download Full-text