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>

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.

Understanding Solar Wind Formation by Identifying the Origins of In Situ Observations 

2021 ◽  
Author(s):  
Samantha Wallace ◽  
Nicholeen M. Viall ◽  
Charles N. Arge
Keyword(s):  
Solar Wind ◽  
Solar Wind Speed ◽  
Source Region ◽  
Heliospheric Current Sheet ◽  
Slow Solar Wind ◽  
The Sun ◽  
Flux Transport ◽  
Model Driven ◽  
In Situ Observations

<p>Solar wind formation can be separated into three physical steps – source, release, and acceleration – that each leave distinct observational signatures on plasma parcels.  The Wang-Sheeley-Arge (WSA) model driven by Air Force Data Assimilative Photospheric Flux Transport (ADAPT) time-dependent photospheric field maps now has the ability to connect in situ observations more rigorously to their precise source at the Sun, allowing us to investigate the physical processes involved in solar wind formation.   In this talk, I will highlight my PhD dissertation research in which we use the ADAPT-WSA model to either characterize the solar wind emerging from specific sources, or investigate the formation process of various solar wind populations.  In the first study, we test the well-known inverse relationship between expansion factor (f<sub>s</sub>) and observed solar wind speed (v<sub>obs</sub>) for solar wind that emerges from a large sampling of pseudostreamers, to investigate if field line expansion plays a physical role in accelerating the solar wind from this source region.  We find that there is no correlation between f<sub>s</sub> and v<sub>obs</sub> at pseudostreamer cusps. In the second study, we determine the source locations of the first identified quasiperiodic density structures (PDSs) inside 0.6 au. Our modeling provides confirmation of these events forming via magnetic reconnection both near to and far from the heliospheric current sheet (HCS) – a direct test of the Separatrix-web (S-web) theory of slow solar wind formation.  In the final study, we use our methodology to identify the source regions of the first observations from the Parker Solar Probe (PSP) mission.  Our modeling enabled us to characterize the closest to the Sun observed coronal mass ejection (CME) to date as a streamer blowout.  We close with future ways that ADAPT-WSA can be used to test outstanding questions of solar wind formation.</p>

scholarly journals Dust sputtering within the inner heliosphere: a modelling study

2020 ◽  
Vol 38 (4) ◽  
pp. 919-930
Author(s):  
Carsten Baumann ◽  
Margaretha Myrvang ◽  
Ingrid Mann
Keyword(s):  
Solar Wind ◽  
Solar Wind Speed ◽  
Solid Particles ◽  
Dust Particles ◽  
Slow Solar Wind ◽  
The Sun ◽  
Size Of Particles ◽  
Parameter Values ◽  
Sputtering Yields ◽  
Inner Heliosphere

Abstract. The aim of this study is to investigate through modelling how sputtering by impacting solar wind ions influences the lifetime of dust particles in the inner heliosphere near the Sun. We consider three typical dust materials, silicate, Fe0.4Mg0.6O, and carbon, and describe their sputtering yields based on atomic yields given by the Stopping and Range of Ions in Matter (SRIM) package. The influence of the solar wind is characterized by plasma density, solar wind speed, and solar wind composition, and we assume for these parameter values that are typical for fast solar wind, slow solar wind, and coronal mass ejection (CME) conditions to calculate the sputtering lifetimes of dust. To compare the sputtering lifetimes to typical sublimation lifetimes, we use temperature estimates based on Mie calculations and material vapour pressure derived with the MAGMA chemical equilibrium code. We also compare the sputtering lifetimes to the Poynting–Robertson lifetime and to the collision lifetime. We present a set of sputtering rates and lifetimes that can be used for estimating dust destruction in the fast and slow solar wind and during CME conditions. Our results can be applied to solid particles of a few nanometres and larger. The sputtering lifetimes increase linearly with the size of particles. We show that sputtering rates increase during CME conditions, primarily because of the high number densities of heavy ions in the CME plasma. The shortest sputtering lifetimes we find are for silicate, followed by Fe0.4Mg0.6O and carbon. In a comparison between sputtering and sublimation lifetimes we concentrate on the nanodust population. The comparison shows that sublimation is the faster destruction process within 0.1 AU for Fe0.4Mg0.6O, within 0.05 AU for carbon dust, and within 0.07 AU for silicate dust. The destruction by sputtering can play a role in the vicinity of the Sun. We discuss our findings in the context of recent F-corona intensity measurements onboard Parker Solar Probe.

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 Dust sputtering within the inner heliosphere

2020 ◽  
Author(s):  
Carsten Baumann ◽  
Margaretha Myrvang ◽  
Ingrid Mann
Keyword(s):  
Solar Wind ◽  
Solar Wind Speed ◽  
Solid Particles ◽  
Dust Particles ◽  
Slow Solar Wind ◽  
The Sun ◽  
Intensity Measurements ◽  
Size Of Particles ◽  
Sputtering Yields ◽  
Inner Heliosphere

Abstract. The aim of this study is to investigate how sputtering by impacting solar wind particles influence the lifetime of dust particles in the inner heliosphere near the Sun. We consider three typical dust materials: silicate, Fe0.4Mg0.6O and carbon and describe their sputtering yields based on atomic yields given by the Stopping and Range of Ions in Matter (SRIM) package. The influence of the solar wind is characterized by plasma density, solar wind speed and solar wind composition and we assume for these parameters values that are typical for fast solar wind, slow solar wind and CME conditions to calculate the sputtering lifetimes of dust. To compare the sputtering lifetimes to typical sublimation lifetimes we use temperature estimates based on Mie calculations and material vapour pressure derived with the chemical equilibrium code MAGMA. We also compare the sputtering lifetimes to the Poynting-Robertson lifetime and to the collision lifetime. We present a set of sputtering rates and lifetimes that can be used for estimating dust destruction in the fast and slow solar wind and during CME conditions. Our results can be applied to solid particles of a few nm and larger. The sputtering lifetimes increase linearly with size of particles. We show that sputtering rates increase during CME conditions, primarily because of the high number densities of heavy ions in the CME plasma. The shortest sputtering lifetimes we find are for silicate, followed by Fe0.4Mg0.6O and carbon. In a comparison between sputtering and sublimation lifetimes we concentrate on the nanodust population. The comparison shows that sublimation is the faster destruction process within 0.1 AU for Fe0.4Mg0.6O, within 0.05 AU for carbon dust and within 0.07 AU for silicate dust. The destruction by sputtering can play a role in the vicinity of the Sun. We discuss our findings in the context of recent F-corona intensity measurements onboard Parker-Solar-Probe.

scholarly journals Several special conditions in the solar wind fora supersubstorm appearance.

2020 ◽  
Author(s):  
I.V. Despirak ◽  
◽  
A.A. Lubchich ◽  
N.G. Kleimenova ◽  
◽  
...  
Keyword(s):  
Solar Wind ◽  
Wind Speed ◽  
Data Base ◽  
Space Weather ◽  
Large Scale ◽  
Dynamic Pressure ◽  
Solar Wind Speed ◽  
Weather Conditions ◽  
The Other ◽  
Solar Wind Parameters

Analysis of the space weather conditions associated with supersubstorms (SSS) was carried out. Two magnetic storms, on 11 April and on 18 April 2001 have been studied and compared. During the first storm, there were registered twoevents of the supersubstorms with intensity of the SML index ~2000-3000 nT, whereas during the second storm there were observed two intense substorms with SML ~ 1500 nT. Solar wind conditions before appearance of the SSSs and intense substorms were compared. For this purpose, the OMNI data base, the catalog of large-scale solar wind phenomena and the data from the magnetic ground-based stations of the SuperMAG network (http://supermag.jhuapl.edu/) were combined. It was shown that the onsets of the SSS event were preceded by strong jumps in the dynamic pressure and density of the solar wind, which were observed against the background of the high solar wind speed and high values of the southern ВZcomponent of the IMF. Comparison with the usual substorms showed thatsome solar wind parameters were higher before SSSs, then before usual substorms: the dynamic pressure, the speed and the magnitude of IMF. On the other hand, the PC index values was the same for these all substorms, that leads to the conclusion about the possible independence of SSS appearance on the level of solar energy penetrated to the magnetosphere.

scholarly journals Solar-wind predictions for the Parker Solar Probe orbit

2018 ◽  
Vol 611 ◽  
pp. A36 ◽  
Author(s):  
M. S. Venzmer ◽  
V. Bothmer
Keyword(s):  
Solar Wind ◽  
Solar Activity ◽  
Solar Corona ◽  
Wind Model ◽  
Wind Environment ◽  
Frequency Distributions ◽  
Solar Wind Model ◽  
Solar Wind Parameters ◽  
Inner Heliosphere

Context. The Parker Solar Probe (PSP; formerly Solar Probe Plus) mission will be humanitys first in situ exploration of the solar corona with closest perihelia at 9.86 solar radii (R⊙) distance to the Sun. It will help answer hitherto unresolved questions on the heating of the solar corona and the source and acceleration of the solar wind and solar energetic particles. The scope of this study is to model the solar-wind environment for PSPs unprecedented distances in its prime mission phase during the years 2018 to 2025. The study is performed within the Coronagraphic German And US SolarProbePlus Survey (CGAUSS) which is the German contribution to the PSP mission as part of the Wide-field Imager for Solar PRobe.Aim. We present an empirical solar-wind model for the inner heliosphere which is derived from OMNI and Helios data. The German-US space probes Helios 1 and Helios 2 flew in the 1970s and observed solar wind in the ecliptic within heliocentric distances of 0.29 au to 0.98 au. The OMNI database consists of multi-spacecraft intercalibrated in situ data obtained near 1 au over more than five solar cycles. The international sunspot number (SSN) and its predictions are used to derive dependencies of the major solar-wind parameters on solar activity and to forecast their properties for the PSP mission.Methods. The frequency distributions for the solar-wind key parameters, magnetic field strength, proton velocity, density, and temperature, are represented by lognormal functions. In addition, we consider the velocity distributions bi-componental shape, consisting of a slower and a faster part. Functional relations to solar activity are compiled with use of the OMNI data by correlating and fitting the frequency distributions with the SSN. Further, based on the combined data set from both Helios probes, the parameters frequency distributions are fitted with respect to solar distance to obtain power law dependencies. Thus an empirical solar-wind model for the inner heliosphere confined to the ecliptic region is derived, accounting for solar activity and for solar distance through adequate shifts of the lognormal distributions. Finally, the inclusion of SSN predictions and the extrapolation down to PSPs perihelion region enables us to estimate the solar-wind environment for PSPs planned trajectory during its mission duration.Results. The CGAUSS empirical solar-wind model for PSP yields dependencies on solar activity and solar distance for the solar-wind parameters’ frequency distributions. The estimated solar-wind median values for PSPs first perihelion in 2018 at a solar distance of 0.16 au are 87 nT, 340 km s−1, 214 cm−3, and 503 000 K. The estimates for PSPs first closest perihelion, occurring in 2024 at 0.046 au (9.86 R⊙), are 943 nT, 290 km s−1, 2951 cm−3, and 1 930 000 K. Since the modeled velocity and temperature values below approximately 20 R⊙appear overestimated in comparison with existing observations, this suggests that PSP will directly measure solar-wind acceleration and heating processes below 20 R⊙ as planned.

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.

scholarly journals The solar wind at solar maximum: comparisons of EISCAT IPS and in situ observations

2002 ◽  
Vol 20 (9) ◽  
pp. 1291-1309 ◽  
Author(s):  
A. R. Breen ◽  
P. Riley ◽  
A. J. Lazarus ◽  
A. Canals ◽  
R. A. Fallows ◽  
...  
Keyword(s):  
Solar Wind ◽  
Large Scale ◽  
Solar Maximum ◽  
Longitudinal Velocity ◽  
Solar Wind Plasma ◽  
The Sun ◽  
Fast Wind ◽  
Interplanetary Physics ◽  
Wind Velocities

Abstract. The solar maximum solar wind is highly structured in latitude, longitude and in time. Coronal measurements show a very high degree of variability, with large variations that are less apparent within in situ spacecraft measurements. Interplanetary scintillation (IPS) observations from EISCAT, covering distances from 20 to 100 solar radii (RS), are an ideal source of information on the inner solar wind and can be used, therefore, to cast light on its evolution with distance from the Sun. Earlier comparisons of in situ and IPS measurements under solar minimum conditions showed good large-scale agreement, particularly in the fast wind. In this study we attempt a quantitative comparison of measurements made over solar maximum by EISCAT (20–100 RS) and the Wind and Ulysses spacecraft (at 215 RS and 300–1000 RS, respectively). The intervals studied were August–September 1999, May 2000, September 2000 and May 2001, the last-named being the period of the second Ulysses fast latitude scan. Both ballistic and – when possible – MHD/ballistic hybrid models were used to relate the data sets, and we compare the results obtained from these two mapping methods. The results of this study suggest that solar wind velocities measured in situ were less variable than those estimated from IPS measurements closer to the Sun, with the greatest divergence between IPS velocities and in situ measurements occurring in regions where steep longitudinal velocity gradients were seen in situ. We suggest that the interaction between streams of solar wind with different velocities leads to "smoothing" of solar wind velocities between 30–60 RS and 1 AU, and that this process continues at greater distances from the Sun.Key words. Interplanetary physics (solar wind plasma; sources of the solar wind; instruments and techniques)

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