Structure and connectivity of CME-driven shocks and sheaths through the inner heliosphere

2021 ◽  
Author(s):  
Erika Palmerio ◽  
Christina Lee ◽  
Dusan Odstrcil ◽  
Leila Mays
Keyword(s):  
Solar Wind ◽  
Large Scale ◽  
The Sun ◽  
Interplanetary Shocks ◽  
Plasma Parameters ◽  
Wind Structure ◽  
Solar Wind Structure ◽  
Magnetohydrodynamic Simulations ◽  
Comprehensive Study ◽  
Inner Heliosphere

<p>The evolution of coronal mass ejections (CMEs) as they travel away from the Sun is one of the major issues in heliophysics and space weather. During propagation, CMEs and the structures ahead of them (i.e., interplanetary shocks and sheath regions, if present) are significantly affected by the ambient solar wind, which is able to alter their speed, trajectory, and orientation. The scarcity of multi-spacecraft measurements of the same CME, however, implies that little is known about how and where (in terms of distance from the Sun) these various processes exactly come into play.</p><p>To address this issue, we run a series of 3D magnetohydrodynamic simulations using the coupled solar–heliospheric WSA–Enlil model, in which we launch idealised CMEs as hydrodynamic (non-magnetised) structures. This allows us to focus on the evolution of CME-driven shocks and sheath regions through a multi-point study. We launch CMEs of various speeds through different solar wind backgrounds and at different heliolongitudes with respect to the streamer belt position. Then, we investigate the resulting magnetic field and plasma parameters at a series of synthetic spacecraft placed at various longitudes around the CME apex and at various heliocentric distances between 0.5 AU and 2 AU. We also analyse how the magnetic connectivity at these spacecraft evolves as the CME propagates. This work represents a comprehensive study of the interaction of CME-driven shocks and sheath regions with the large-scale solar wind structure throughout the inner heliosphere, with the aim to establish a range of expected behaviours and outcomes useful to interpret real events.</p>

scholarly journals Solar cycle changes of large-scale solar wind structure

2009 ◽  
Vol 5 (S264) ◽  
pp. 356-358 ◽  
Author(s):  
P. K. Manoharan
Keyword(s):  
Solar Wind ◽  
Solar Cycle ◽  
Large Scale ◽  
Interplanetary Space ◽  
The Sun ◽  
Wind Structure ◽  
Level Of Activity ◽  
Solar Wind Structure ◽  
Current Minimum ◽  
Inner Heliosphere

AbstractIn this paper, I present the results on large-scale evolution of density turbulence of solar wind in the inner heliosphere during 1985–2009. At a given distance from the Sun, the density turbulence is maximum around the maximum phase of the solar cycle and it reduces to ~70%, near the minimum phase. However, in the current minimum of solar activity, the level of turbulence has gradually decreased, starting from the year 2005, to the present level of ~30%. These results suggest that the source of solar wind changes globally, with the important implication that the supply of mass and energy from the Sun to the interplanetary space has significantly reduced in the present low level of activity.

Large-scale solar-wind structure near the Sun detected by Doppler scintillation

Nature ◽  
1993 ◽  
Vol 366 (6455) ◽  
pp. 543-545 ◽  
Author(s):  
Richard Woo ◽  
Paul Gazis
Keyword(s):  
Solar Wind ◽  
Large Scale ◽  
The Sun ◽  
Wind Structure ◽  
Solar Wind Structure

Large-scale electron solar wind parameters of the inner heliosphere with Parker Solar Probe/FIELDS

2020 ◽  
Author(s):  
Karine Issautier ◽  
Mingzhe Liu ◽  
Michel Moncuquet ◽  
Nicole Meyer-Vernet ◽  
Milan Maksimovic ◽  
...  
Keyword(s):  
Solar Wind ◽  
Large Scale ◽  
Statistical Study ◽  
Solar Wind Speed ◽  
The Sun ◽  
Solar Wind Parameters ◽  
Power Law Index ◽  
Probe Mission ◽  
Inner Heliosphere

<p>We present in situ properties of electron density and temperature in the inner heliosphere obtained during the three first solar encounters at 35 solar radii of the Parker Solar Probe mission. These preliminary results, recently shown by Moncuquet et al., ApJS, 2020, are obtained from the analysis of the plasma quasi-thermal noise (QTN) spectrum measured by the radio RFS/FIELDS instrument along the trajectories extending between 0.5 and 0.17 UA from the Sun, revealing different states of the emerging solar wind, five months apart. The temperature of the weakly collisional core population varies radially with a power law index of about -0.8, much slower than adiabatic, whereas the temperature of the supra-thermal population exhibits a much flatter radial variation, as expected from its nearly collisionless state. These measured temperatures are close to extrapolations towards the Sun of Helios measurements.</p><p>We also present a statistical study from these in situ electron solar wind parameters, deduced by QTN spectroscopy, and compare the data to other onboard measurements. In addition, we focus on the large-scale solar wind properties. In particular, from the invariance of the energy flux, a direct relation between the solar wind speed and its density can be deduced, as we have already obtained based on Wind continuous in situ measurements (Le Chat et al., Solar Phys., 2012). We study this anti-correlation during the three first solar encounters of PSP.</p>

Solar Wind Anomalies at 1 au and Their Associations with Large-scale Structures

2021 ◽  
Vol 923 (1) ◽  
pp. 105
Author(s):  
Yan Li ◽  
Shaosui Xu ◽  
Janet G. Luhmann ◽  
Benoit Lavraud
Keyword(s):  
Magnetic Field ◽  
Solar Wind ◽  
Solar Minimum ◽  
Large Scale ◽  
Spatial Scales ◽  
Radial Magnetic Field ◽  
Suprathermal Electron ◽  
Wind Structure ◽  
Solar Wind Structure ◽  
Cycle 24

Abstract We study solar wind anomalies and their associations with solar wind structures using the STEREO solar wind and suprathermal electron (STE) data from IMPACT and PLASTIC. We define solar wind anomalies as temporary and local excursions from the average solar wind state, regardless of their origins, for six anomalies: sunward strahls, counterstreaming suprathermal electrons, suprathermal electron depletions, nearly radial magnetic field episodes, anomalously low proton temperatures, and anomalously low proton beta. We first establish the solar wind synoptic contour displays, which show the expected variations in solar wind structure during the solar cycle: recurrent corotating heliospheric magnetic field (HMF) and stream structures are dominant during solar quiet times around the solar minimum (2008 December) preceding cycle 24, while complex structures characterize solar active times around the solar maximum (2014 April). During the declining phase of the cycle (2016–2019), the stream structures remain complex, but the HMF sectors show the structures of the solar minimum. We then systematically study the six anomalies by analyzing the STE data using automated procedures. All anomalies present some degree of dependence on the large-scale solar wind structure, especially around the solar minimum, implying that the solar wind structure plays a role in either the generation or transportation of these anomalies. One common feature of all of the anomalies is that the distributions of the durations of the anomalous episodes all peak at the 1 hr data resolution, but monotonically decrease over longer durations, which may arguably imply that solar anomalies occur on a continuum of temporal and spatial scales.

Large scale solar wind structure: Non-dipolar features and consequences

2013 ◽  
Author(s):  
J. G. Luhmann ◽  
M. Ellenburg ◽  
P. Riley ◽  
D. Odstrcil ◽  
G. Petrie ◽  
...  
Keyword(s):  
Solar Wind ◽  
Large Scale ◽  
Wind Structure ◽  
Solar Wind Structure

scholarly journals EUHFORIA: European heliospheric forecasting information asset

2018 ◽  
Vol 8 ◽  
pp. A35 ◽  
Author(s):  
Jens Pomoell ◽  
S. Poedts
Keyword(s):  
Magnetic Field ◽  
Solar Wind ◽  
Large Scale ◽  
Weather Forecasting ◽  
Mass Density ◽  
Solar Wind Speed ◽  
Plasma Parameters ◽  
Cone Model ◽  
Plasma State ◽  
Inner Heliosphere

The implementation and first results of the new space weather forecasting-targeted inner heliosphere model “European heliospheric forecasting information asset” (EUHFORIA) are presented. EUHFORIA consists of two major components: a coronal model and a heliosphere model including coronal mass ejections. The coronal model provides data-driven solar wind plasma parameters at 0.1 AU by constructing a magnetic field model of the coronal large-scale magnetic field and employing empirical relations to determine the plasma state such as the solar wind speed and mass density. These are then used as boundary conditions to drive a three-dimensional time-dependent magnetohydrodynamics model of the inner heliosphere up to 2 AU. CMEs are injected into the ambient solar wind modeled using the cone model, with their parameters obtained from fits to imaging observations. In addition to detailing the modeling methodology, an initial validation run is presented. The results feature a highly dynamic heliosphere that the model is able to capture in good agreement with in situ observations. Finally, future horizons for the model are outlined.

Empirical inner boundary conditions and rotation rates for solar wind models

2021 ◽  
Author(s):  
Huw Morgan
Keyword(s):  
Magnetic Field ◽  
Solar Wind ◽  
Boundary Conditions ◽  
Coronal Magnetic Field ◽  
Height Range ◽  
Rotation Rates ◽  
Wind Structure ◽  
Solar Wind Structure ◽  
Coronal Electron ◽  
Made In

<p>To date, the inner boundary conditions for solar wind models are either directly or indirectly based on magnetic field extrapolation models of the photosphere. Furthermore, between the photosphere and Earth, there are no other direct empirical constraints on models. New breakthroughs in coronal rotation tomography, applied to coronagraph observations, allow maps of the coronal electron density to be made in the heliocentric height range 4-12 solar radii (Rs). We show that these maps (i) give a new empirical boundary condition for solar wind structure at a height where the coronal magnetic field has become radial, thus avoiding the need to model the complex inner coronal magnetic field, and (ii) give accurate rotation rates for the corona, of crucial importance to the accuracy of solar wind models and forecasts.</p>

HelioSwarm: The Nature of Turbulence in Space Plasmas

2021 ◽  
Author(s):  
Harlan Spence ◽  
Kristopher Klein ◽  
HelioSwarm Science Team
Keyword(s):  
Magnetic Field ◽  
Solar Wind ◽  
Large Scale ◽  
Solar Wind Plasma ◽  
Turbulent Energy ◽  
Space Plasmas ◽  
Plasma Parameters ◽  
Astrophysical Plasmas ◽  
Ion Distributions ◽  
Background Magnetic Field

<p>Recently selected for phase A study for NASA’s Heliophysics MidEx Announcement of Opportunity, the HelioSwarm Observatory proposes to transform our understanding of the physics of turbulence in space and astrophysical plasmas by deploying nine spacecraft to measure the local plasma and magnetic field conditions at many points, with separations between the spacecraft spanning MHD and ion scales.  HelioSwarm resolves the transfer and dissipation of turbulent energy in weakly-collisional magnetized plasmas with a novel configuration of spacecraft in the solar wind. These simultaneous multi-point, multi-scale measurements of space plasmas allow us to reach closure on two science goals comprised of six science objectives: (1) reveal how turbulent energy is transferred in the most probable, undisturbed solar wind plasma and distributed as a function of scale and time; (2) reveal how this turbulent cascade of energy varies with the background magnetic field and plasma parameters in more extreme solar wind environments; (3) quantify the transfer of turbulent energy between fields, flows, and ion heat; (4) identify thermodynamic impacts of intermittent structures on ion distributions; (5) determine how solar wind turbulence affects and is affected by large-scale solar wind structures; and (6) determine how strongly driven turbulence differs from that in the undisturbed solar wind. </p>

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