Classification of Solar Plasma Flows by Analyzing Out- and Intra-Magnetospheric Magnetohydrodynamic Oscillations During Magnetic Storms

Comparison of wavelet spectrum (skeletons) local maxima for disturbed components of solar plasma flow parameters and geomagnetic field disturbances recorded along the meridional station chain during geomagnetic storm intervals is performed in the range of magnetohydrodynamic (MHD) waves. An algorithm for quantitative evaluation of analyzed skeletons consistency has been developed. It has been used to demonstrate the possibility of the type of solar wind plasma flow elaboration on unique spectral signs of Solar wind speed disturbances, density and interplanetary magnetic field. It is shown that the energy spectrum of oscillations for these parameters reflects the internal structure of the corresponding plasma formation. The skeletons application to the analysis of the interplanetary space main parameters made it possible to estimate the magnetosphere reaction time in geomagnetic field horizontal component oscillations at different latitudes on the disturbance. As a result, the distributed magnetosphere reaction over latitude was determined in the form of geomagnetic field oscillations on the disturbed solar flow parameters. It is shown that the dynamics of the components of the solar wind parameters disturbance spectra corresponding to plasma flows manifest themselves in the MHD spectra of high-latitude stations magnetograms and can be used as a diagnostic tool.

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Low-frequency oscillations while magnetic storms as a tool to determine the types of solar plasma flows

E3S Web of Conferences ◽

10.1051/e3sconf/202022001090 ◽

2020 ◽

Vol 220 ◽

pp. 01090

Author(s):

N. A. Barkhatov ◽

S.E. Revunov ◽

O. T. Cherney ◽

Zh. V. Smirnova ◽

M. V. Mukhina

Keyword(s):

Solar Wind ◽

Plasma Flow ◽

Geomagnetic Field ◽

Interplanetary Space ◽

Solar Wind Speed ◽

Solar Wind Plasma ◽

Mhd Waves ◽

Plasma Flows ◽

Solar Plasma ◽

Flow Parameters

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Long-Term Independence of Solar Wind Polytropic Index on Plasma Flow Speed

Entropy ◽

10.3390/e20100799 ◽

2018 ◽

Vol 20 (10) ◽

pp. 799 ◽

Cited By ~ 14

Author(s):

George Livadiotis

Keyword(s):

Solar Wind ◽

Plasma Flow ◽

Solar Wind Speed ◽

Solar Wind Plasma ◽

Flow Speed ◽

Polytropic Index ◽

Solar Cycles ◽

Solar Wind Proton ◽

Plasma Flow Speed

The paper derives the polytropic indices over the last two solar cycles (years 1995–2017) for the solar wind proton plasma near Earth (~1 AU). We use ~92-s datasets of proton plasma moments (speed, density, and temperature), measured from the Solar Wind Experiment instrument onboard Wind spacecraft, to estimate the moving averages of the polytropic index, as well as their weighted means and standard errors as a function of the solar wind speed and the year of measurements. The derived long-term behavior of the polytropic index agrees with the results of other previous methods. In particular, we find that the polytropic index remains quasi-constant with respect to the plasma flow speed, in agreement with earlier analyses of solar wind plasma. It is shown that most of the fluctuations of the polytropic index appear in the fast solar wind. The polytropic index remains quasi-constant, despite the frequent entropic variations. Therefore, on an annual basis, the polytropic index of the solar wind proton plasma near ~1 AU can be considered independent of the plasma flow speed. The estimated all-year weighted mean and its standard error is γ = 1.86 ± 0.09.

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IPS Observations at Beijing Astronomical Observatory

Highlights of Astronomy ◽

10.1017/s1539299600013903 ◽

2002 ◽

Vol 12 ◽

pp. 398

Author(s):

X.Z. Zhang ◽

J.H. Wu

Keyword(s):

Solar Wind ◽

Radio Wave ◽

High Frequency ◽

Interplanetary Space ◽

Solar Wind Speed ◽

Solar Wind Plasma ◽

Astronomical Observatory ◽

Wind Speeds ◽

Irregular Structures ◽

Good Agreement

The radio wave from distant radio sources will be scattered by the irregular structures of the solar wind plasma when propagating through the interplanetary space, resulting into a randomly fluctuating pattern of the radio wave in observation. This pattern is called interplanetary scintillation (IPS). Observation on IPS can give information of the solar wind speed and irregular structures in solar wind plasma. The IPS observations began at Miyun Station, Beijing Astronomical Observatory from the late half of 1999. The properties of the telescope and description of the data analysis can be found in the papers of Wang (1987) and Wu, Zhang and Zheng (2000) respectively.Table 1 summarizes some observational results using IPS source 3C48 in April and May 2000. The Fresnel knees and the first minima in the IPS spectra were used to estimate solar wind speeds. Comparisons of our results with the unpublished data of Hiraiso Solar Terrestrial Research Center obtained from their web site, have been done and good agreement between the two systems was found. Since the collecting area of Miyun telescope is limited, the system noise is relatively high and dominates the high-frequency parts of the spectra. The Miyun IPS observation and data reduction procedures are still under developing and will soon be completed.

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Low frequency geomagnetic field variations at Dome C (Antarctica)

Annales Geophysicae ◽

10.5194/angeo-21-923-2003 ◽

2003 ◽

Vol 21 (4) ◽

pp. 923-932 ◽

Cited By ~ 5

Author(s):

S. Lepidi ◽

L. Cafarella ◽

P. Francia ◽

A. Meloni ◽

P. Palangio ◽

...

Keyword(s):

Solar Wind ◽

Wind Speed ◽

Geomagnetic Field ◽

Solar Wind Speed ◽

Low Frequency ◽

Mhd Waves ◽

Polar Cap ◽

Ionospheric Currents ◽

Terra Nova Bay ◽

Terra Nova

Abstract. We conduct an analysis of the geomagnetic field variations recorded at the new Antarctic station Dome C, located very close to the geomagnetic pole, which has been operating for approximately one month during the 1999–2000 campaign. We also perform a comparison with simultaneous measurements at the Italian Antarctic station Terra Nova Bay, in order to investigate the spatial extension of the phenomena observed at very high latitude. Our results show that between the two stations the daily variation is similar and the fluctuations with f ~ 1 mHz are coherent, provided that in both cases the comparison is made between geographically oriented components, suggesting that ionospheric currents related to the geographic position, more than field-aligned currents, are responsible for the lowest frequency variations; conversely, higher frequency (Pc5) fluctuations are substantially decoupled between the two stations. We also found that at Dome C the fluctuation power in the 0.55–6.7 mHz frequency band is well related with the solar wind speed during the whole day and that at Terra Nova Bay the correlation is also high, except around local geomagnetic noon, when the station approaches the polar cusp. These results indicate that the solar wind speed control of the geomagnetic field fluctuation power is very strict in the polar cap and less important close to the polar cusp.Key words. Magnetospheric physics (MHD waves and instabilities; Polar cap phenomena; Solar wind-magnetosphere interactions)

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A review of the SCOSTEP’s 5-year scientific program VarSITI—Variability of the Sun and Its Terrestrial Impact

Progress in Earth and Planetary Science ◽

10.1186/s40645-021-00410-1 ◽

2021 ◽

Vol 8 (1) ◽

Author(s):

Kazuo Shiokawa ◽

Katya Georgieva

Keyword(s):

Solar Wind ◽

Interplanetary Space ◽

Solar Wind Plasma ◽

The Sun ◽

Scientific Program ◽

Solar Cycles ◽

Grand Minimum ◽

The Earth ◽

Earth Connection ◽

Near Future

AbstractThe Sun is a variable active-dynamo star, emitting radiation in all wavelengths and solar-wind plasma to the interplanetary space. The Earth is immersed in this radiation and solar wind, showing various responses in geospace and atmosphere. This Sun–Earth connection variates in time scales from milli-seconds to millennia and beyond. The solar activity, which has a ~11-year periodicity, is gradually declining in recent three solar cycles, suggesting a possibility of a grand minimum in near future. VarSITI—variability of the Sun and its terrestrial impact—was the 5-year program of the scientific committee on solar-terrestrial physics (SCOSTEP) in 2014–2018, focusing on this variability of the Sun and its consequences on the Earth. This paper reviews some background of SCOSTEP and its past programs, achievements of the 5-year VarSITI program, and remaining outstanding questions after VarSITI.

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Evolution of the MHD turbulence properties in the inner heliosphere with the PSP/SolO alignment data

10.5194/egusphere-egu21-14585 ◽

2021 ◽

Author(s):

Daniele Telloni ◽

Keyword(s):

Solar Wind ◽

High Frequency ◽

Interplanetary Space ◽

Solar Wind Plasma ◽

Radial Dependence ◽

Physical Processes ◽

Temperature Anisotropy ◽

Mhd Turbulence ◽

Radial Evolution ◽

Inner Heliosphere

<p>Radial alignments between pairs of spacecraft is the only way to observationally investigate the turbulent evolution of the solar wind as it expands throughout interplanetary space. On September 2020 Parker Solar Probe (PSP) and Solar Orbiter (SolO) were nearly perfectly radially aligned, with PSP orbiting around its perihelion at 0.1 au (and crossing the nominal Alfv&#233;n point) and SolO at 1 au. PSP/SolO joint observations of the same solar wind plasma allow the extraordinary and unprecedented opportunity to study how the turbulence properties of the solar wind evolve in the inner heliosphere over the wide distance of 0.9 au. The radial evolution of (i) the MHD properties (such as radial dependence of low- and high-frequency breaks, compressibility, Alfv&#233;nic content of the fluctuations), (ii) the polarization status, (iii) the presence of wave modes at kinetic scale as well as their distribution in the plasma instability-temperature anisotropy plane are just few instances of what can be addressed. Of furthest interest is the study of whether and how the cascade transfer and dissipation rates evolve with the solar distance, since this has great impact on the fundamental plasma physical processes related to the heating of the solar wind. In this talk I will present some of the results obtained by exploiting the PSP/SolO alignment data.</p>

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The Earth's passage of the April 11, 1997 coronal ejecta: geomagnetic field fluctuations at high and low latitude during northward interplanetary magnetic field conditions

Annales Geophysicae ◽

10.1007/s00585-999-1245-4 ◽

1999 ◽

Vol 17 (10) ◽

pp. 1245-1250 ◽

Cited By ~ 5

Author(s):

S. Lepidi ◽

P. Francia ◽

U. Villante ◽

A. Meloni ◽

A. J. Lazarus ◽

...

Keyword(s):

Magnetic Field ◽

Solar Wind ◽

Interplanetary Magnetic Field ◽

Geomagnetic Field ◽

Field Conditions ◽

Mhd Waves ◽

Low Latitude ◽

Terra Nova Bay ◽

Field Fluctuations ◽

Terra Nova

Abstract. An analysis of the low frequency geomagnetic field fluctuations at an Antarctic (Terra Nova Bay) and a low latitude (L'Aquila, Italy) station during the Earth's passage of a coronal ejecta on April 11, 1997 shows that major solar wind pressure variations were followed at both stations by a high fluctuation level. During northward interplanetary magnetic field conditions and when Terra Nova Bay is close to the local geomagnetic noon, coherent fluctuations, at the same frequency (3.6 mHz) and with polarization characteristics indicating an antisunward propagation, were observed simultaneously at the two stations. An analysis of simultaneous measurements from geosynchronous satellites shows evidence for pulsations at approximately the same frequencies also in the magnetospheric field. The observed waves might then be interpreted as oscillation modes, triggered by an external stimulation, extending to a major portion of the Earth's magnetosphere. Key words. Magnetospheric physics (MHD waves and instabilities; solar wind-magnetosphere interactions)

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The role of aerodynamic drag in dynamics of coronal mass ejections

Proceedings of the International Astronomical Union ◽

10.1017/s1743921309029391 ◽

2008 ◽

Vol 4 (S257) ◽

pp. 271-277

Author(s):

Bojan Vršnak ◽

Dijana Vrbanec ◽

Jaša Čalogović ◽

Tomislav Žic

Keyword(s):

Solar Wind ◽

Wind Speed ◽

Coronal Mass Ejections ◽

Weather Forecasting ◽

Aerodynamic Drag ◽

Interplanetary Space ◽

Solar Wind Speed ◽

Standard Form ◽

The Sun

AbstractDynamics of coronal mass ejections (CMEs) is strongly affected by the interaction of the erupting structure with the ambient magnetoplasma: eruptions that are faster than solar wind transfer the momentum and energy to the wind and generally decelerate, whereas slower ones gain the momentum and accelerate. Such a behavior can be expressed in terms of “aerodynamic” drag. We employ a large sample of CMEs to analyze the relationship between kinematics of CMEs and drag-related parameters, such as ambient solar wind speed and the CME mass. Employing coronagraphic observations it is demonstrated that massive CMEs are less affected by the aerodynamic drag than light ones. On the other hand, in situ measurements are used to inspect the role of the solar wind speed and it is shown that the Sun-Earth transit time is more closely related to the wind speed than to take-off speed of CMEs. These findings are interpreted by analyzing solutions of a simple equation of motion based on the standard form for the drag acceleration. The results show that most of the acceleration/deceleration of CMEs on their way through the interplanetary space takes place close to the Sun, where the ambient plasma density is still high. Implications for the space weather forecasting of CME arrival-times are discussed.

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A global study of hot flow anomalies using Cluster multi-spacecraft measurements

Annales Geophysicae ◽

10.5194/angeo-27-2057-2009 ◽

2009 ◽

Vol 27 (5) ◽

pp. 2057-2076 ◽

Cited By ~ 30

Author(s):

G. Facskó ◽

Z. Németh ◽

G. Erdős ◽

A. Kis ◽

I. Dandouras

Keyword(s):

Solar Wind ◽

Particle Density ◽

Solar Wind Speed ◽

Solar Wind Plasma ◽

Separation Distance ◽

Magnetic Shear ◽

The Earth ◽

Global Study ◽

Time Periods ◽

Tangential Discontinuities

Abstract. Hot flow anomalies (HFAs) are studied using observations of the magnetometer and the plasma instrument aboard the four Cluster spacecraft. We study several specific features of tangential discontinuities on the basis of Cluster measurements from the time periods of February–April 2003, December 2005–April 2006 and January–April 2007, when the separation distance of spacecraft was large. The previously discovered condition (Facskó et al., 2008) for forming HFAs is confirmed, i.e. that the solar wind speed and fast magnetosonic Mach number values are higher than average. Furthermore, this constraint is independent of the Schwartz et al. (2000)’s condition for HFA formation. The existence of this new condition is confirmed by simultaneous ACE magnetic field and solar wind plasma observations at the L1 point, at 1.4 million km distance from the Earth. The temperature, particle density and pressure parameters observed at the time of HFA formation are also studied and compared to average values of the solar wind plasma. The size of the region affected by the HFA was estimated by using two different methods. We found that the size is mainly influenced by the magnetic shear and the angle between the discontinuity normal and the Sun-Earth direction. The size grows with the shear and (up to a certain point) with the angle as well. After that point it starts decreasing. The results are compared with the outcome of recent hybrid simulations.

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Observations of interplanetary scintillation in China

Proceedings of the International Astronomical Union ◽

10.1017/s1743921313002998 ◽

2012 ◽

Vol 8 (S294) ◽

pp. 487-488

Author(s):

Li-Jia Liu ◽

Bo Peng

Keyword(s):

Solar Wind ◽

Interplanetary Medium ◽

Interplanetary Space ◽

Solar Wind Speed ◽

Small Diameter ◽

Primary Source ◽

Radio Sources ◽

The Sun ◽

Interplanetary Scintillation ◽

The Earth

AbstractThe Sun affects the Earth in multiple ways. In particular, the material in interplanetary space comes from coronal expansion in the form of solar wind, which is the primary source of the interplanetary medium. Ground-based Interplanetary Scintillation (IPS) observations are an important and effective method for measuring solar wind speed and the structures of small diameter radio sources. In this paper we will discuss the IPS observations in China.

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