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We have analyzed the dynamics of solar wind and interplanetary magnetic field (IMF) parameters during the development of 933 isolated geomagnetic storms, observed over the period from 1964 to 2010. The analysis was carried out using the epoch superposition method at intervals of 48 hrs before and 168 hrs after the moment of Dst minimum. The geomagnetic storms were selected by the type of storm commencement (sudden or gradual) and by intensity (weak, moderate, and strong). The dynamics of the solar wind and IMF parameters was compared with that of the Dst index, which is an indicator of the development of geomagnetic storms. The largest number of storms in the solar activity cycle is shown to occur in the years of minimum average values (close in magnitude to 1) of the solar wind parameter β (β is the ratio of plasma pressure to magnetic pressure). We have revealed that the dynamics of the Dst index is similar to that of the β parameter. The duration of the storm recovery phase follows the characteristic recovery time of the β parameter. We have found out that during the storm main phase the β parameter is close to 1, which reflects the maximum turbulence of solar wind plasma fluctuations. In the recovery phase, β returns to background values β~2‒3.5. We assume that the solar wind plasma turbulence, characterized by the β parameter, can play a significant role in the development of geomagnetic storms.

Studying the direction of the solar wind flow is a topical problem of space weather forecasting. As a rule, the quiet and uniform solar wind propagates radially, but significant changes in the solar wind flow direction can be observed, for example, in compression regions before the interplanetary coronal mass ejections (Sheath) and Corotating Interaction Regions (CIR) that precede high-speed streams from coronal holes. In this study, we perform a statistical analysis of the longitude (φ) and latitude (θ) flow direction angles and their variations on different time scales (30 s and 3600 s) in solar wind large-scale streams of different types, using WIND spacecraft data. We also examine the relationships of the value and standard deviations SD of the flow direction angles with various solar wind parameters, regardless of the solar wind type. We have established that maximum values of longitude and latitude angle modulus, as well as their variations, are observed for Sheath, CIR, and Rare, with the probability of large deviations from the radial direction (>5°) increasing. The dependence on the solar wind type is shown to decrease with scale. We have also found that the probability of large values of SD(θ) and SD(φ) increases with increasing proton temperature (Tp) in the range 5–10 eV and with increasing proton velocity (Vp) in the range 400–500 km/s.

This paper presents the Total Electron Content variability, during the solar cycle 23 maximum under geomagnetic fluctuating activity conditions from 2000 to 2002 at Niamey station (lat. :13°28’N ; long : 2°10’E) in Niger. A comparative study of TEC profiles variation under quiet and fluctuating geomagnetic activity conditions allowed us to analyze the effects of fluctuations in solar wind on equatorial ionosphere. Our investigation argues on that the solar cycle 23 maximum is mostly characterized by a non-effect of fluctuating winds on the ionosphere for equatorial region. Key words: Seasonal variability, total electron content, fluctuating activity.

Magnetic fields provide an important probe of the thermal, material, and structural history of planetary and sub-planetary bodies. Core dynamos are a potential source of magnetic fields for differentiated bodies, but evidence of magnetization in undifferentiated bodies requires a different mechanism. Here we study the amplified field provided by the stellar wind to an initially unmagnetized body using analytic theory and numerical simulations, employing the resistive MHD AstroBEAR adaptive mesh refinement (AMR) multiphysics code. We obtain a broadly applicable scaling relation for the peak magnetization achieved once a wind advects, piles-up, and drapes a body with magnetic field, reaching a quasi-steady state. We find that the dayside magnetic field for a sufficiently conductive body saturates when it balances the sum of incoming solar wind ram, magnetic, and thermal pressures. Stronger amplification results from pileup by denser and faster winds. Careful quantification of numerical diffusivity is required for accurately interpreting the peak magnetic field strength from simulations, and corroborating with theory. As specifically applied to the Solar System, we find that early solar wind-induced field amplification is a viable source of magnetization for observed paleointensities in meteorites from some undifferentiated bodies. This mechanism may also be applicable to other Solar System bodies, including metal-rich bodies to be visited in future space missions such as the asteroid (16) Psyche., 12 pages, 6 figures, accepted by MNRAS

Upon entry into the heliosphere, galactic cosmic-ray fluxes are modulated by the turbulent solar wind with the resulting modulation levels depending on the position inside the heliosphere and the phase of the solar cycle. The main modulation processes, i.e. drifts, convection, adiabatic energy changes, and diffusion can be described by the well-known Parker transport equation. A first order analytical approximation of this equation, which is widely used to describe solar modulation effects at Earth, is the Force-Field approximation, while a similar approximation, the Convection–Diffusion is rarely applied. Based on a comparison with recent top-of-atmosphere galactic cosmic-ray flux measurements, this study presents the Convection–Diffusion approximation as a more suitable alternative to the Force-Field approximation to accurately parameterize the galactic cosmic-ray intensity near Earth which is essential for dosimetry and space weather studies.

The structure and dynamics of the magnetospheres of the outer planets, particularly Saturn and Jupiter, have been explored through both remote and in situ observations. Interpreting these observations often necessitates simultaneous knowledge of the solar-wind conditions impinging on the magnetosphere. Without an available upstream monitor, solar-wind context is typically provided using models initiated with either the output of magnetogram-constrained coronal models or, more commonly, in situ observations from 1 au. While 1-au observations provide a direct measure of solar-wind conditions, they are single-point observations and thus require interpolation to provide inputs to outer-heliosphere solar-wind models. In this study, we test the different interpolation methods using synthetic 1-au observations of time-evolving solar-wind structure. The simplest method is ‘corotation’, which assumes solar-wind structure is a steady state and rotates with the Sun. This method of reconstruction produces discontinuities in the solar-wind inputs as new observations become available. This can be reduced by corotating both backwards and forwards in time, but this still introduces large errors in the magnitude and timing of solar-wind streams. We show how the dynamic time warping (DTW) algorithm can provide around an order-of-magnitude improvement in solar-wind inputs to the outer-heliosphere model from in situ observations near 1 au. This is intended to build the foundation for further work demonstrating and validating methods to improve inner-boundary conditions of outer-heliosphere solar-wind models, including dealing with solar-wind transients and quantifying the improvements at Saturn and Jupiter.

In the present paper, we used two substantially different approaches to analytical description of the merger of magnetic islands. One approach is based on the system of nonlinear hydrodynamic (MHD) equations, while the other is based on the transport equation for the velocity distribution function of the solar-wind particles. In a standard case, these approaches are based on using a single-fluid variant of plasma in which plasma itself represents the fluid. In this work, we apply both approaches to the two-fluid model in which plasma is treated as a combination of an ion and an electron fluids. Physical processes in the solar-wind plasma lead to additional formation of magnetic islands. These processes play an important role in the vicinity of an interplanetary shock front. Merger of magnetic islands is investigated upon realization of the first approach, while the fraction of the high-energy particles in the solar-wind plasma is calculated upon realization of the second. The number of particles acquiring energy exceeding 1 MeV in the solar wind (including processes of magnetic-island merger) is found. Explicit expressions are derived and quantitative estimates for the main parameters of the solar wind are found in all analyzed particular cases.

We present the kinetic Monte-Carlo model, which was developed to describe the influence of a proton flux from the undisturbed solar wind on the daytime atmosphere of Mars. For the first time, the degradation of the solar-wind proton spectrum in the cascade charge-exchange process in the extended hydrogen corona of Mars has been self-consistently modeled; and the energy fluxes and energy spectra of hydrogen atoms penetrating into the daytime upper atmosphere through the boundary of the induced magnetosphere have been determined. The obtained characteristics make it possible to model numerically the proton auroral phenomena observed in the upper atmosphere of Mars with the Imaging Ultraviolet Spectrometer onboard the Mars Atmosphere and Volatile Evolution spacecraft. In our future studies, we plan to compare the results of these calculations to those of observations, which will provide a unique opportunity to determine more accurately the properties of the atmosphere and the magnetic field of Mars, as well as will improve the techniques for determining the solar wind parameters.

Galactic cosmic rays (GCRs) inside the heliosphere are affected by magnetic turbulence and Solar wind disturbances which result in the so-called solar modulation effect. To investigate this phenomenon, we have performed a data-driven analysis of the temporal dependence of the GCR flux over the solar cycle. With a global statistical inference of GCR data collected in space by AMS-02, PAMELA, and CRIS on monthly basis, we have determined the dependence of the GCR diffusion parameters upon time and rigidity. In this conference, we present our results for GCR protons and nuclei, we discuss their interpretation in terms of basic processes of particle transport and their relations with the dynamics of the heliospheric plasma., 8 pages, 3 figures, proceedings of ICRC-2021 conference

Heavy rainfall events causing floods and flash floods are examined in the context of solar wind coupling to the magnetosphere–ionosphere–atmosphere system. The superposed epoch (SPE) analyses of solar wind variables have shown the tendency of severe weather to follow arrivals of high-speed streams from solar coronal holes. Precipitation data sets based on rain gauge and satellite sensor measurements are used to examine the relationship between the solar wind high-speed streams and daily precipitation rates over several midlatitude regions. The SPE analysis results show an increase in the occurrence of high precipitation rates following arrivals of high-speed streams, including recurrence with a solar rotation period of 27 d. The cross-correlation analysis applied to the SPE averages of the green (Fe XIV; 530.3 nm) corona intensity observed by ground-based coronagraphs, solar wind parameters, and daily precipitation rates show correlation peaks at lags spaced by solar rotation period. When the SPE analysis is limited to years around the solar minimum (2008–2009), which was dominated by recurrent coronal holes separated by ∼ 120∘ in heliographic longitude, significant cross-correlation peaks are found at lags spaced by 9 d. These results are further demonstrated by cases of heavy rainfall, floods and flash floods in Europe, Japan, and the USA, highlighting the role of solar wind coupling to the magnetosphere–ionosphere–atmosphere system in severe weather, mediated by aurorally excited atmospheric gravity waves.

The concept of electromotive force appears in various electromagnetic applications in geophysical and astrophysical fluids. A review of the electromotive force and its applications to the solar wind are discussed such as the electromotive force profile during the shock crossings and the observational tests for the mean-field model against the solar wind data. The electromotive force is being recognized as serving as a useful tool to construct a more complete picture of space plasma turbulence when combined with the energy spectra and helicity profiles.

In this study, we examine the nonlinear interdependence between the parameters of the solar wind influencing geomagnetic activity (proton density and solar wind dynamic pressure, IMF B z and solar wind dynamic pressure) and geomagnetic indices (AE and SYM-H) during pre-storm, storm and post-storm of intense, major, moderate and minor geomagnetic storms. Nonlinear analytical tools comprising Cross Recurrence Plot (CRP) and Recurrence Rate (RR) was used to capture the features of nonlinear interdependence in the time series data of the solar wind parameters (solar wind dynamic pressure, IMF B z and Proton density) and geomagnetic indices (AE and SYM-H). The Pearson correlation coefficient was also used to reveal the features of linear dependence between the parameters of the solar wind during the different categories of geomagnetic storms. Our result shows that during the storm, the CRPs of the solar wind parameters investigated pictured a strong deterministic structure of CRP which is an indication of strong interdependence. In particular, the results of our analysis showed that the solar wind dynamic pressure and proton density depicted very strong interdependence features. On the other hand, during pre-storm and post-storm, the CRP of solar wind dynamic pressure in relation to IMF B z and proton density pictured a rare deterministic structure signifying weak interdependence. Furthermore, the values of RR were very high (an indication of strong interdependence between the parameters of the solar wind) during the storm while at pre-storm and post-storm, the values of RR declined significantly in most of the periods which further strengthened the evidence of weak interdependence in the parameters of solar wind. The CRP and RR of the geomagnetic indices (AE and SYM-H) reveals no significant difference between pre-storm, storm and post-storm of the different categories of geomagnetic storms. However, strong interdependence between the geomagnetic indices were observed in most of the periods investigated. Finally, the Pearson correlation coefficient reveals high values of linear dependence between the solar wind parameters without any significant difference between pre-storm, storm and post-storm periods during intense, major, moderate and minor geomagnetic storms.

The present paper reports magnetospheric-thermospheric-ionospheric interactions, observed during geomagnetically disturbed periods in 2015–2016 from mid-latitude stations located in the US-Pacific longitudes (~120°W geographic). These interactions have been analyzed for a series of Coronal Mass Ejection (CME) and High Speed Solar Wind (HSSW) driven geomagnetic storms during the moderate solar activity periods. The geomagnetically disturbed periods under consideration in this paper have an interesting feature of the occurrences of one or more HSSW events following an intense CME driven intense geomagnetic storm. Correlations were observed between the solar and geomagnetic parameters, hemispherically integrated Joule heating, changes in O/N2 ratio, corresponding changes in neutral wind velocities and mid-latitude Vertical Total Electron Content (VTEC) in most of the cases. Prolonged effects of neutral wind driven equatorward plasma transport process were noticed during the period of the summer solstice (June 23–26, 2015) which was correlated with the hemispherically integrated Joule heating and ionospheric conductivities. The effects of storm onset were observed during March 17–18, 2015. The influences of the ‘super-fountain effect’ in terms of Prompt Penetration Electric Field (PPEF) were seen during the main phases of the geomagnetic storms from these mid-latitude stations. This is correlated with the strength of Equatorial Electrojet (EEJ).

One of the key challenges in solar and heliospheric physics is to understand the acceleration of the solar wind. As a super-sonic, super-Alfv\'enic plasma flow, the solar wind carries mass, momentum, energy, and angular momentum from the Sun into interplanetary space. We present a framework based on two-fluid magnetohydrodynamics to estimate the flux of these quantities based on spacecraft data independent of the heliocentric distance of the location of measurement. Applying this method to the Ulysses dataset allows us to study the dependence of these fluxes on heliolatitude and solar cycle. The use of scaling laws provides us with the heliolatitudinal dependence and the solar-cycle dependence of the scaled Alfv\'enic and sonic Mach numbers as well as the Alfv\'en and sonic critical radii. Moreover, we estimate the distance at which the local thermal pressure and the local energy density in the magnetic field balance. These results serve as predictions for observations with Parker Solar Probe, which currently explores the very inner heliosphere, and Solar Orbiter, which will measure the solar wind outside the plane of the ecliptic in the inner heliosphere during the course of the mission., Comment: 13 pages, 9 figures

The review generalizes experimental data on the relationships between the solar activity agents (space weather) and atmosphere constituents. It is shown that high-energy solar protons (SPE) make a powerful impact on photo-chemical processes in the polar areas and, correspondingly, on atmospheric circulation and planetary cloudiness. Variations of the solar UV irradiance modulate the descent rate of the zonal wind in the equatorial stratosphere in the course of quasi-biennial oscillation (QBO), and thus control the total duration (period) of the QBO cycle and, correspondingly, the seasonal ozone depletion in the Antarctic. The geo-effective solar wind impacts on the atmospheric wind system in the entire Southern Polar region, and influences the dynamics of the Southern Oscillation (ENSO).

Currently, the problem of geospace storms and their components, geomagnetic storms, is one of the most important problems in solar-terrestrial physics and space geophysics. The exploration of the geospace and its use for the needs of civilization has led to the fact that our life is increasingly dependent on the manifestations of solar-terrestrial processes, the state of atmospheric-space weather, and ground-to-space systems of various purposes. The more technologically advanced our civilization becomes, the more vulnerable it is to the processes taking place on the Sun, manifestations of solar-terrestrial relationships, and variations in atmospheric-space weather. These circumstances determine the relevance and continuous scientific and practical significance of studies into the manifestations of solar-terrestrial processes and their consequences. Geospace (geomagnetic) storms can be accompanied by a number of effects: variations in the parameters of the atmosphere and geospace; deceleration of spacecraft; impact of increased cosmic radiation on crew and electronic equipment in spacecraft and aircraft; disturbances of conditions of radio wave propagation and channels of radio communication, radio navigation, radio ranging, radio position finding, radio astronomy, and remote sensing; the induction of currents in power transmission lines, cable lines, pipelines, automated railway systems; and the impact on weather- and climate-forming systems. In addition to the physical effects of individual geomagnetic storms, which are described in a large number of scientific papers, a statistical analysis of the parameters of the solar wind, interplanetary magnetic field, and geomagnetic storms over long periods is of interest. The purpose of this study is to statistically analyze the parameters of the solar wind disturbed by solar storms, the interplanetary magnetic field, and the geomagnetic activity indices over the period of solar cycle 24 (2009–2020). The main statistical characteristics of the disturbed solar wind parameters responsible for the geomagnetic storm origins (153 storms in total) over solar cycle 24 have been estimated. The main statistical characteristics of the components of the disturbed interplanetary magnetic field have been estimated, and the main statistical characteristics of the geomagnetic field indices have been obtained. With respect to magnetic activity, solar cycle 24 was quieter than solar cycle 23.

Abstract This paper analyzes the results of modeling coronal mass ejection (CME) propagation in 2010–2011 obtained using input data from different sources: CME catalogs SEEDS and CACTus, and predictions of the velocity of quasi-stationary solar wind fluxes, as an environment, through which CMEs propagate. As the model of quasi-stationary solar wind fluxes, the model for predicting the velocity of the solar wind of the Space Weather Forecast Center of the Skobeltsyn Institute of Nuclear Physics of Moscow State University, operating online, is used. The CME prediction is carried out using the Simple Drag-Based Model. A comparison was performed between the ICME arrival time and their velocities obtained when modeling with data from the open ICME catalogs: the Richardson and Cane ICME catalog and the GMU CME List. Based on the comparison, it was concluded that a more accurate prediction for the growth phase of the 24th solar activity cycle was obtained using data on CME parameters from the CACTus database. The obtained errors in predicting the ICME parameters are comparable with the errors of other existing models.

Abstract— For the first time, the calculations of the penetration of protons of the undisturbed solar wind into the daytime atmosphere of Mars due to charge exchange in the extended hydrogen corona (Shematovich et al., 2021) are used allowing us to determine self-consistently the sources of suprathermal oxygen atoms, as well as their kinetics and transport. An additional source of hot oxygen atoms—collisions accompanied by the momentum and energy transfer from the flux of precipitating high-energy hydrogen atoms to atomic oxygen in the upper atmosphere of Mars—was included in the Boltzmann kinetic equation, which was solved with the Monte-Carlo kinetic model. As a result, the population of the hot oxygen corona of Mars has been estimated; and it has been shown that the proton aurorae are accompanied by the atmospheric loss of atomic oxygen, which is evaluated within a range of (3.5–5.8) × 107 cm–2 s–1. It has been shown that the exosphere becomes populated with a substantial amount of suprathermal oxygen atoms with kinetic energies up to the escape energy, 2 eV. The atomic oxygen loss rate caused by a sporadic source in the Martian atmosphere—the precipitation of energetic neutral atoms of hydrogen (H‑ENAs) during proton aurorae at Mars—was estimated by the self-consistent calculations according to a set of the Monte-Carlo kinetic models. These values turned out be comparable to the atomic oxygen loss supported by a regular source—the exothermic photochemical reactions (Groeller et al., 2014; Jakosky et al., 2018). It is currently supposed that the atmospheric loss of Mars due to the impact of the solar wind plasma and, in particular, the fluxes of precipitating high-energy protons and hydrogen atoms during solar flares and coronal mass ejections may play an important role in the loss of the neutral atmosphere on astronomic time scales (Jakosky et al., 2018).

Convection in Earth’s georeactor sub-shell is responsible for generating the geomagnetic field and for maintaining the critical balances necessary for stable sub-core nuclear fission. External factors capable of disrupting sub-shell convection are trauma at Earth’s surface, for example by meteorite impact, and electrical energy transfer via Faraday’s electromagnetic induction into the georeactor by changes in the solar wind or in the magnetospheric ring current. Reduced sub-shell convection not only leads to decreased geomagnetic field intensity, but to increased uranium settling out into the sub-core where it undergoes uncontrolled nuclear fission until sub-shell convection is reestablished. Periods of uncontrolled georeactor nuclear fission are responsible for causing geophysical phenomena at Earth’s surface that are associated with geomagnetic reversals and excursions. Anticipated consequences of sub-shell convection collapse include increases in volcanic activity, increases in the number and intensity of earthquakes, warming of the oceans, and diminishment of atmospheric convection resulting in global warming at the surface. The most worrisome potentiality is triggering the eruption of the Yellowstone super-volcano. Changes in solar wind flux, too small to cause geomagnetic field collapse, however, may cause increases in earthquakes and volcanic eruptions. The understanding described here potentially provides a basis for the development of earthquake and volcanic eruption prediction methodologies.

In this work, the problem of resonance caused by some gravitational potentials due to Mercury and a third body, namely the Sun, together with some non-gravitational perturbations, specifically coronal mass ejections and solar wind in addition to radiation pressure, are investigated. Some simplifying assumptions without loss of accuracy are employed. The considered force model is constructed. Then the Delaunay canonical set is introduced. The Hamiltonian of the problem is obtained then it is expressed in terms of the Deluanay canonical set. The Hamiltonian is re-ordered to adopt it to the perturbation technique used to solve the problem. The Lie transform method is surveyed. The Hamiltonian is doubly averaged. The resonance capture is investigated. Finally, some numerical simulations are illustrated and are analyzed. Many resonant inclinations are revealed.

Solar wind magnetic holes are localized depressions of the magnetic field strength, on timescales of seconds to minutes. We use Cluster multipoint measurements to identify 26 magnetic holes which are observed just upstream of the bow shock and, a short time later, downstream in the magnetosheath, thus showing that they can penetrate the bow shock and enter the magnetosheath. For two magnetic holes, we show that the relation between upstream and downstream properties of the magnetic holes are well described by the MHD (magnetohydrodynamic) Rankine–Hugoniot (RH) jump conditions. We also present a small statistical investigation of the correlation between upstream and downstream observations of some properties of the magnetic holes. The temporal scale size and magnetic field rotation across the magnetic holes are very similar for the upstream and downstream observations, while the depth of the magnetic holes varies more. The results are consistent with the interpretation that magnetic holes in Earth's and Mercury's magnetosheath are of solar wind origin, as has previously been suggested. Since the solar wind magnetic holes can enter the magnetosheath, they may also interact with the magnetopause, representing a new type of localized solar wind–magnetosphere interaction.

Solar wind turbulence dominated by large-amplitude Alfvénic fluctuations, mainly propagating away from the Sun, is ubiquitous in high-speed solar wind streams. Recent observations performed in the inner heliosphere (from 1 AU down to tens of solar radii) have proved that also slow wind streams show sometimes strong Alfvénic signatures. Within this context, the present paper focuses on a comparative study on the characterization of Alfvénic turbulence in fast and slow solar wind intervals observed at 1 AU where degradation of Alfvénic correlations is expected. In particular, we compared the behavior of different parameters to characterize the Alfvénic content of the fluctuations, using also the Elsässer variables to derive the spectral behavior of the normalized cross-helicity and residual energy. This study confirms that the Alfvénic slow wind stream resembles, in many respects, a fast wind stream. The velocity-magnetic field (v-b) correlation coefficient is similar in the two cases as well as the amplitude of the fluctuations although it is not clear to what extent the condition of incompressibility holds. Moreover, the spectral analysis shows that fast wind and Alfvénic slow wind have similar normalized cross-helicity values but in general the fast wind streams are closer to energy equipartition. Despite the overall similarities between the two solar wind regimes, each stream shows also peculiar features, that could be linked to the intrinsic evolution history that each of them has experienced and that should be taken into account to investigate how and why Alfvénicity evolves in the inner heliosphere.

Scale-invariance has rapidly established itself as one of the most used concepts in space plasmas to uncover underlying physical mechanisms via the scaling-law behavior of the statistical properties of field fluctuations. In this work, we characterize the scaling properties of the magnetic field fluctuations in a sub-alfvénic region in contrast with those of the nearby super-alfvénic zone during the ninth Parker Solar Probe perihelion. With our observations, (i) evidence of an extended self-similarity (ESS) for both the inertial and the sub-ion/kinetic regimes during both solar wind intervals is provided, (ii) a multifractal nature of field fluctuations is observed across inertial scales for both solar wind intervals, and (iii) a mono-fractal structure of the small-scale dynamics is reported. The main novelty is that a universal character is found at the sub-ion/kinetic scale, where a unique rescaling exponent describes the high-order statistics of fluctuations during both wind intervals. Conversely, a multitude of scaling symmetries is observed at the inertial scale with a similar fractal topology and geometrical structures between the magnetic field components in the ecliptic plane and perpendicular to it, in contrast with a different level of intermittency, more pronounced during the super-alfvénic interval rather than the sub-alfvénic one, along the perpendicular direction to the ecliptic plane. The above features are interpreted in terms of the possible underlying heating and/or acceleration mechanisms in the solar corona resulting from turbulence and current sheet formation.

A model capable of reproducing a set of solar wind parameters along the virtual spacecraft orbit out of an ecliptic plane has been developed. In the framework of a quasi-stationary axisymmetric self-consistent MHD model the spatial distributions of magnetic field and plasma characteristics at distances from 20 to 1200 Solar radii at almost all solar latitudes could be obtained and analyzed. This model takes into account the Sun’s magnetic field evolution during the solar cycle, when the dominant dipole magnetic field is replaced by the quadrupole one. Self-consistent solutions for solar wind characteristics were obtained, depending on the phase of the solar cycle. To verify the model, its results are compared with the observed characteristics of solar wind along the Ulysses trajectory during its flyby around the Sun from 1990 to 2009. It is shown that the results of numerical simulation are generally consistent with the observational data obtained by the Ulysses spacecraft. A comparison of the model and experimental data confirms that the model can adequately describe the solar wind parameters and can be used for heliospheric studies at different phases of the solar activity cycle, as well as in a wide range of latitudinal angles and distances to the Sun.

Observations of interplanetary scintillation (IPS) are an efficient remote-sensing method to study the solar wind and inner heliosphere. From 2016 to 2018, some distinctive observations of IPS sources like 3C 286 and 3C 279 were accomplished with the Five-hundred-meter Aperture Spherical radio Telescope (FAST), the largest single-dish telescope in the world. Due to the 270–1620 MHz wide frequency coverage of the ultra-wideband (UWB) receiver, one can use both single-frequency and dual-frequency analyses to determine the projected velocity of the solar wind. Moreover, based on the extraordinary sensitivity owing to the large collecting surface area of FAST, we can observe weak IPS signals. With the advantages of both the wider frequency coverage and high sensitivity, and also with our radio frequency interference (RFI) mitigation strategy and an optimized model-fitting method, in this paper we analyse the fitting confidence intervals of the solar wind velocity and present some preliminary results achieved using FAST, which point to the current FAST system being highly capable of carrying out observations of IPS.

Alfven waves have proven to be important in a range of physical systems due to their ability to transport non-thermal energy over long distances in a magnetized plasma. This property is of specific interest in solar physics, where the extreme heating of the atmosphere of the Sun remains unexplained. In an inhomogeneous plasma such as a flux tube in the solar atmosphere, they manifest as incompressible torsional perturbations. However, despite evidence in the upper atmosphere, they have not been directly observed in the photosphere. Here, we report the detection of antiphase incompressible torsional oscillations observed in a magnetic pore in the photosphere by the Interferometric Bidimensional Spectropolarimeter. State-of-the-art numerical simulations suggest that a kink mode is a possible excitation mechanism of these waves. The excitation of torsional waves in photospheric magnetic structures can substantially contribute to the energy transport in the solar atmosphere and the acceleration of the solar wind, especially if such signatures will be ubiquitously detected in even smaller structures with the forthcoming next generation of solar telescopes. Spectropolarimetric observations of a solar pore at high temporal and spatial resolution identify the presence of magnetic field torsional oscillations. Simulations suggest that such oscillations are triggered by a photospheric kink mode, which can contribute substantially to upward energy transport within the solar atmosphere.

Previous studies have reported that coronal mass ejections (CMEs) and solar flares lead to the development of huge storms and high-speed streams. Our aim in this paper is to investigate the response of the geomagnetic index SYM/H to the solar wind parameters, such as solar wind speed V, dynamic pressure P, input energy IE and the interplanetary magnetic field (IMF) Bz component, associated with solar flares and CME events. The response of the ground geomagnetic field (H-component) to the solar wind parameters and the IMF Bz component at three low-latitude stations has also been analysed. Our findings show that the delay of the solar wind changes in the Earth’s magnetosphere in response to the weak geomagnetic storm (SYM/H = −30 nT) at the beginning of 2014 December 21. A weak storm of SYM/H = −30 nT in the middle of 2014 November 5 is suggested by a low magnetic reconnection process in the magnetosphere. In addition, the strong southward IMF Bz component and high solar wind changes in the magnetosphere system, which were a result of the X2.0 solar flare event and the CMEs on 2014 October 27, responded to the moderate storm (SYM/H = −60 nT) at the beginning of 2014 October 28. This dynamic physical process in the magnetosphere caused by solar wind variation is seen to excite the Earth’s H-component through ultra low frequency at the ground-based magnetometers at the BCL (Vietnam), TIR (India) and SCN (Indonesia) stations during the geomagnetic storm. This study relates to seismic investigations and geomagnetic-induced current on the ground.

The Earth’s magnetosphere is region that is carved out by the solar wind as it flows past and interacts with the terrestrial magnetic field. The inner magnetosphere is the region that contains the plasmasphere, ring current, and the radiation belts all co-located within about 6.6 Re, nominally taken to be bounding this region. This region is highly dynamic and is home to a variety of plasma waves and particle populations ranging in energy from a few eV to relativistic and ultra-relativistic electrons and ions. The interplanetary magnetic field (IMF) embedded in the solar wind via the process of magnetic reconnection at the sub-solar point sets up plasma convection and creates the magnetotail. Magnetic reconnection also occurs in the tail and is responsible for explosive phenomena known as substorms. Substorms inject low-energy particles into the inner magnetosphere and help generate and sustain plasma waves. Transients in the solar wind such as coronal mass ejections (CMEs), co-rotating interaction regions (CIRs), and interplanetary shocks compress the magnetosphere resulting in geomagnetic storms, energization, and loss of energetic electrons in the outer radiation belt nad enhance the ring current, thereby driving the geomagnetic dynamics. The Specification and Prediction of the Coupled Inner-Magnetospheric Environment (SPeCIMEN) is one of the four elements of VarSITI (Variability of the Sun and Its Terrestrial Impact) program which seeks to quantitatively predict and specify the inner magnetospheric environment based on Sun/solar wind driving inputs. During the past 4 years, the SPeCIMEN project has brought together scientists and researchers from across the world and facilitated their efforts to achieve the project goal. This review provides an overview of some of the significant scientific advances in understanding the dynamical processes and their interconnectedness during the VarSITI era. Major space missions, with instrument suites providing in situ measurements, ground-based programs, progress in theory, and modeling are briefly discussed. Open outstanding questions and future directions of inner magnetospheric research are explored.

Designing a spacecraft that can image the Sun as closely as possible without melting the delicate instruments has been a challenge. But scientists' luck could be about to change.LAUNCHED IN February 2020 from Cape Canaveral, a 1.7-tonne spacecraft called the Solar Orbiter aims to get up-close images of the Sun from 42 million kilometres away, while measuring its energetic behaviour in real-time. The suite of 10 on-board instruments will enable it to uniquely marry the study of events in the Sun's gaseous corona, measure its magnetic fields, and sample the solar wind as it flows past the spacecraft as a stream of energetic particles.

The Earth’s magnetosphere is the outermost layer of the geospace system deflecting energetic charged particles from the Sun and solar wind. The solar wind has major impacts on the Earth’s magnetosphere, but it is unclear whether the same holds for solar flares—a sudden eruption of electromagnetic radiation on the Sun. Here we use a recently developed whole geospace model combined with observational data from the 6 September 2017 X9.3 solar flare event to reveal solar flare effects on magnetospheric dynamics and on the electrodynamic coupling between the magnetosphere and its adjacent ionosphere, the ionized part of Earth’s upper atmosphere. We observe a rapid and large increase in flare-induced photoionization of the polar ionospheric E-region at altitudes between 90 km and 150 km. This reduces the efficiency of mechanical energy conversion in the dayside solar wind–magnetosphere interaction, resulting in less Joule heating of the Earth’s upper atmosphere, a reconfiguration of magnetosphere convection, as well as changes in dayside and nightside auroral precipitation. This work thus demonstrates that solar flare effects extend throughout the geospace via electrodynamic coupling, and are not limited—as previously believed—to the atmospheric region where radiation energy is absorbed1. The solar wind affects the magnetosphere, but whether this holds true for solar flares was unclear. By combining geospace modelling with observations, solar flares are shown to influence the dynamics of the magnetosphere and its ionosphere coupling.

Observations and initial analysis of interplanetary scintillation data are briefly described in the framework of the program for the solar wind monitoring with the modernized LPI LPA radio telescope that started in 2014. The examples of detecting interplanetary coronal mass injections (ICME) and co-rotating interaction regions (CIR) of different-speed flows are presented. It is shown that in the first case, enhancements in the scintillation level in extended sounded regions of solar wind are observed 20–30 hours before the arrival of the disturbances to the Earth; in the second case, the evening and night scintillation level decrease is observed several days before the compressed region of disturbances comes to the Earth. These features are considered as a base of using interplanetary scintillation monitoring data for short-time space weather forecasting.

This paper presents the results of calculating the efficiency of solar wind proton charge exchange as a function of variations in the column density of hydrogen atoms in the extended corona of Mars. The presence of regular density variations has been known for a long time and has been associated with the change of seasons on Mars. However, sporadic density variations in the upper Martian atmosphere were detected recently as well. They were caused by various processes in the underlying atmosphere, such as ejection of water vapor and ice particles at altitudes up to 100 km due to global dust storms, which was discovered in the Mars Express and MAVEN observations. Taking into account the variations in the column density with the observed amplitude up to one order of magnitude is absolutely necessary to correctly consider the interaction of solar wind protons with the Martian atmosphere. The calculations using the kinetic Monte Carlo model revealed that with a 2- and 5-fold increase in the column density of H atoms in the corona of Mars, the charge exchange efficiency also increases and reaches 6% and 8%, respectively, as compared to the base value of 4%. The energy spectrum of hydrogen atoms penetrating into the Martian atmosphere does not change and remains identical in structure to the spectrum of undisturbed solar wind protons. These estimates, combined with the previously developed kinetic model of the proton and hydrogen atom precipitation into the planetary atmosphere, make it possible to do the following: to trace all the stages of the penetration of the undisturbed solar wind protons into the dense layers of the atmosphere, as well as interpret the observed characteristics of proton auroras depending on the variations of atomic hydrogen content in the Martian corona.

The results of the forecasting of quasi-stationary and transient solar wind streams velocity for a period from May to December 2010 are presented. The velocity of quasi-stationary solar wind streams on the near-Earth orbit was calculated with the empiric model based on an analysis of solar images obtained in the extreme ultraviolet. The velocity and arrival time of the interplanetary coronal mass ejections were predicted with the Drag-Based Model. The results of the forecast of the velocity of quasi-stationary solar wind streams were used as a parameter of the interplanetary medium through which the transient streams propagate and with which they interact. For the period of May–December 2010, 94 coronal mass ejections were selected from the databases, which were updated in near-real time. Analysis of the forecast results has shown that 67% of the selected interplanetary coronal mass ejections had a predicted velocity of less than 400 km/s, and 96% of them are associated with a quiet geomagnetic conditions (Dst > –30 nT). The forecast of quasi-stationary solar wind streams is improved by the addition of the prediction of interplanetary coronal mass ejections. For the period from May to December 2010, the standard deviation between the solar wind stream velocities measured on the ACE spacecraft and the predicted values, which take into account both quasi-stationary and transient streams, is 82 km/s, and the correlation coefficient is 0.6.

A real-time model for predicting the quasistationary solar wind speed at the near-Earth orbit is presented. The forecast of the high-speed solar wind stream velocity is obtained with an empirical model linking the areas of coronal holes to the solar wind speed. The forecast of the slow solar wind is based on data on the observed solar wind speed from the previous solar rotation. Over the whole analyzed period from May 2010 to December 2019, the coefficient of correlation between the observed and predicted solar wind speed values is 0.45, and the standard deviation is 88 km/s. The accuracy of forecasting the speed of quasistationary solar wind streams is comparable to the results of foreign models.

Using Mars Express data from 2007 until 2020 we show how ion outflow from Mars varied over more than a solar cycle, from one solar minimum to another. The data was divided into intervals with a length of one Martian year, starting from 30 April 2007 and ending 13 July 2020. The net escape rate was about 5 × 1 0 24 s − 1 in the first covered minimum, and 2 − 3 × 1 0 24 s − 1 in the most recent minimum. Ion escape peaked at 1 × 1 0 25 s − 1 during the intervening solar maximum. The outflow is a clear function of the solar cycle, in agreement with previous studies which found a clear relationship between solar EUV flux and ion escape at Mars. The outflow during solar maximum is 2.5 to 3 times higher than in the surrounding solar minima. The average solar wind dynamic pressure over a Martian year was investigated, but does not vary much with the solar cycle. The escape rate at solar maximum is in good agreement with some recent MAVEN studies, and dominated by low energy ions at most sampled locations. A simple linear fit to the data gives a prediction of the escape rate for the much stronger solar maximum during the Phobos mission in 1989 that is consistent with observations. The fit also implies a non-linear response of ion escape for low solar EUV, with a lower initial escape response for lower solar EUV levels than those of the studied data set.

Disruptions of unstable equilibrium in the corresponding tectonic structures causing the onset of earthquakes are put in relation to Sun spot flares and coronal mass ejections. They generate magnetic clouds of solar wind plasma moving at much higher speed than the constant background to the Earth. The author assumes that additional energy is introduced to shallow earthquake foci due to the action of breakthrough injections into the Earth’s near-surface region of plasma clumps of geoeffective solar wind components disconnected into the magnetosphere. As a research tool, we used the method of graphical correlation between bursts of geoeffective solar wind parameter values and the occurrence of subsequent starts and repetitions of earthquake shocks. The examples given for Europe, South Asia, the Indian and Pacific oceans coasts consistently confirm the validity of the author's analytical understanding of the earthquake shocks beginning as a result of the destruction of the subsurface by injections of solar wind plasma clots in earthquake-prone zones. The problem under study is considered to be relevant in connection with the implementation of targeted forecast work. In the General scientific plan, consideration of the influence of solar-meter origins of factors are proposed to be included in the programs of studying earthquakes as one of their items. The obtained results should serve as a dynamic addition to the information placed on the maps of seismic zoning.

This work studies the influence of the structure of inner heliospheric magnetic field on the propagation of Jovian electrons from Jupiter to the Earth orbit. Beginning from 1974, 13-month variations of relativistic Jovian electron fluxes were recorded by spacecraft near the Earth. 22 synodic cycles are analysed. The best connection in each cycle was found within a narrow longitudinal interval with an angular divergence of the planets 230 ± 20°, when the Parker field line connecting the two planets is formed at solar wind speed 450 ± 50 km s−1. Such invariability for more than 45 yr could not be accidental. We attribute the observed phenomenon to the long-term presence of recurrent stationary structures in the solar wind generated near the Sun. This assumption is confirmed by comparing the time profiles of the solar wind speed measured over all solar rotations in the solar activity minima in 1975 and 2007–2008.

A set of studies has been carried out, indicating that solar activity and processes associated with the activity of the Sun: changes in the main magnetic fluxes, areas of polar spots, the number of polar torches at the poles of the Sun; -index of geomagnetic activity and -index of the ratio of plasma pressure to magnetic solar wind (SW), slow and high-speed flows of SW, cosmic ray intensity (CR); average annual values of the interplanetary magnetic field vector and its components; the temperature, density, and flow rate of the SW plasma, the synodic period of the revolution of the Sun as a star, and the radius of the Sun in relative units; the distance of the Earths geographic pole from the conventional international origin, the rate of change of the position of the Earths north magnetic pole, the main ionospheric parameters; the angle of the Earth's axis of rotation and volcanic eruptions; asymmetric movement of the Sun around the solar system of the solar system (in fractions of the solar radius); the distances from the solar systems CM to the Sun in km, the distances from the solar systems CM to the Earth, with high accuracy, are consistent with the movement of the Sun relative to the barycenter. The research is based on the wavelet transformation of the observations listed above variables in various time intervals with the subsequent calculation of their phase-frequency and phase-time characteristics, correlation matrices between characteristics. The studied variables are divided into groups, which include the barycentric movement of the Sun and changes in solar activity. The calculated two correlation matrices of the wavelet characteristics of the group of variables and the graphs of these characteristics in two coordinate systems reflect the consistency of changes in the group. The studies carried out indicate that the thermonuclear reaction occurring in the interior of the Sun, the external manifestation of which is solar activity, is controlled by the movements of the large planets of the Solar System relative to the Sun.

The relative abundances of thermal and suprathermal C, O, and Fe ions are analysed and compared in solar wind streams from near-equatorial coronal holes (CHs) during quiet periods of nearly two solar cycle minima. Ion fluxes with energies of ∼0.04–2 MeV per nucleon are studied using data from the Ultra Low Energy Isotope Spectrometer (ULEIS) instrument aboard the Advanced Composition Explorer (ACE) spacecraft together with thermal ions in the fast and slow (Maxwellian) solar wind using data from the Solar Wind Ion Composition Spectrometer (SWICS) instrument aboard ACE. The analysis was carried out for quiescent periods in 2006–2012 and 2015–2017 when solar wind flows from near-equatorial CHs were detected at 1 au. Near the minimum of SC23, although they displayed large variability, the C/O and Fe/O ratios of suprathermal ions were, on average, near the corresponding relative abundances of the solar wind. During the decreasing solar activity phase of SC24, suprathermal Fe/O ratios matched those of solar wind ions from CHs. In both cycles, the thermal and suprathermal Fe/O ratios exhibited a similar character of dependence on maximum solar wind speed. Our results suggest that the sources of suprathermal ions from CHs in low-solar activity periods are accelerated solar wind thermal ions. The thermal and suprathermal Fe/O ratios were found to be higher in 2015–2017 in comparison to the ratios measured in 2006–2010. This difference can be attributed to that the second quiet period was selected at times when solar activity has not reached its minimum of SC24 yet.

New observations of auroras based on the wide-field aurora imager (WAI) onboard Fengyun-3D (FY-3D) satellite are exhibited in this paper. Validity of the WAI data is analyzed by comparing auroral boundaries derived from WAI observations with results obtained from data collected by the Special Sensor Ultraviolet Spectrographic Imager (SSUSI) aboard the Defense Meteorological Satellite Program (DMSP F18). Dynamic variations of the aurora with the solar wind, interplanetary magnetic field (IMF) parameters, and the SYM-H index are also investigated. The comparison of auroral boundaries indicates that the WAI data are morphologically valid and suitable to the study of auroral dynamics. Effective responses to solar wind parameters indicate that the WAI data can be useful to monitor and predict the Earth’s space weather. Since the configuration of aurora is a good indicator of the solar wind–magnetosphere–ionosphere (SW-M-I) coupling system, and can reflect the disturbance of the space environment, the WAI will provide important data to help us to study the physical processes in space.

Measurements of velocity and magnetic field in near-Earth heliosphere is analized in order to investigate systematical deflection from transversality of the velocity and magnetic field fluctuations in undisturbed solar wind. Fluctuations occurred in the meridional plain of heliosphere (RN plain of the RTN reference system) are transversal with respect to mean magnetic field during periods of high solar activity, but they become non-transversal close to solar cycle minima. This phenomenon is investigated focusing on a role of Alfvén waves. It is shown that deflections from transversality is mostly expressed by fluctuations in slow solar wind streams with low contribution of Alfvén waves, whereas strongly Alfvénic turbulence undergo such deflection in a less degree. In addition, we consider orientation of velocity fluctuations in the azimuthal (RT) plain of heliosphere, which also indicates some interesting features.

The developed Hypersphere World-Universe Model (WUM) is consistent with all Concepts of the World [1]. In WUM, we postulate the principal role of Angular Momentum and Dark Matter in Cosmological theories of the World. The most widely accepted model of Solar System formation, known as the Nebular hypothesis, does not solve the Angular Momentum problem—why is the orbital momentum of Jupiter larger than rotational momentum of the Sun? WUM is the only cosmological model in existence that is consistent with this Fundamental Law. The Nebular hypothesis does not solve Internal Heating and Diversity problems for all Planets and Moons in Solar system—why the actual mean surface temperature of them is higher than their effective temperature calculated based on the Sun’s heat for them and how could each one be so different if all of them came from the same nebula? The proposed concept of Dark Matter Reactors in Cores of all gravitationally-rounded Macroobjects successfully resolves these problems.

The situation with the reliability of calculations of the magnetic field of the solar corona remains a topic of discussion. There is, in particular, the problem of significantly lower calculated values of the magnetic field than those recorded near the Earth. The authors propose an explanation in which the magnetic fields are underestimated due to the existence of magnetic sources at different distances from the photosphere. Sources that are farther away from the photosphere create local zones of weaker photospheric fields, which are not accurately measured against strong fields from sources of another level. Model estimates of the contributions of sources showed that sources located closer to the photosphere give only 30% of the total contribution of sources of both levels. This value corresponds to the observed ratio of the calculated values of the magnetic field and recorded in the solar wind. This fact confirms the assumption that the magnetic fields of sources farther from the photosphere are not really taken into account in the calculations of the magnetic field of the solar corona.

International audience; Eclipse observations of the W-L corona show linear rays above active regions at times of solar maximum. We show that these linear rays are also observed in the field-of-view of the C2-LASCO coronagraph, in perfect correspondence with the eclipse results. A selected prominent case taken from the 2001 eclipse observation in Angola is analysed with several different methods, including the use of a synoptic map constructed using SoHO/LASCO C2 images. A clear signature of time variations near the eclipse observation is detected, suggesting that at least some parts of the beam are collimated. These observations strongly suggest high speed streams that apparently ignore the potential large scale coronal magnetic field rooted rather low in the corona. A possible origin is the neutral magnetic points located above the active region. Several mechanisms exist to explain how the plasma is accelerated in these regions to large quasi-relativistic velocities, possibly related to the occurrence of type III radio bursts. We point out a curious analogy with phenomena occurring inside coronal holes.

International audience; We report observations of reconnection exhausts in the Heliospheric Current Sheet (HCS) during Parker Solar Probe Encounters 08 and 07, at 16 Rs and 20 Rs, respectively. Heliospheric current sheet (HCS) reconnection accelerated protons to almost twice the solar wind speed and increased the proton core energy by a factor of ∼3, due to the Alfvén speed being comparable to the solar wind flow speed at these near-Sun distances. Furthermore, protons were energized to super-thermal energies. During E08, energized protons were found to have leaked out of the exhaust along separatrix field lines, appearing as field-aligned energetic proton beams in a broad region outside the HCS. Concurrent dropouts of strahl electrons, indicating disconnection from the Sun, provide further evidence for the HCS being the source of the beams. Around the HCS in E07, there were also proton beams but without electron strahl dropouts, indicating that their origin was not the local HCS reconnection exhaust.

The solar wind is a highly variable, weakly collisional plasma originating from the Sun. The recent launches of PSP and Solar Orbiter have opened the way for the exploration of the innermost regions of our solar system and will greatly advance our understanding of several plasma phenomena occurring in the near-Sun environment, such as the heating and the acceleration of the solar wind. Plasma waves and wave-particle interactions play a relevant role in such phenomena, determining significant deviations of the Velocity Distribution Function (VDF) from the Local Thermodynamic Equilibrium. These deviations retain information of the interaction of particles with the turbulent electromagnetic fields and can be identified as thermal anisotropy, or non-thermal ion beams and heavy ion differential streaming in the ion component of the solar wind. This study will cover these topics with particular reference to new in-situ data from Solar Orbiter, PSP and with observations at L1 (e.g. Wind), with a focus on the central role Alfvénic fluctuations play in the evolution of the VDF features mentioned above.

During the last decade, MAVEN space mission have emphasized a widespread spatial distribution of escaping O+ ions (Brain et al., 2015; Dong et al., 2015; Curry et al., 2015). Statistical studies have demonstrated that such structure is constant and present an asymmetry with respect to the solar wind convective electric field direction. In the Mars Solar Ecliptic coordinate system, continuous large O+ ion fluxes have been observed from the Martian wake to the Northward hemisphere. Global hybrid models have been developed since more than fiffteen years (Modolo et al., 2005, 2016; Brecht and Ledvina, 2006; Kallio et al., 2006) predicting and reproducing successfully the main characteristics of these escaping ion signatures. To further characterize this heavy-ion escape and its variability due to the solar wind forcing, global hybrid simulations have been performed with different set of upstream solar wind parameters. The impact of the solar wind drivers on the dynamics of O+ ion fluxes are reported and compared to the statistical ion fluxes maps derived from MAVEN/STATIC observations (Dong et al., 2015).Brain, D. A., McFadden, J. P., Halekas, J. S., Connerney, J. E. P., Bougher, S. W., Curry, S., et al. (2015). The spatial distribution of planetary ion fluxes near Mars observed by MAVEN. Geophys. Res. Lett. 42, 9142–9148. doi:10.1002/2015GL065293Dong, Y., Fang, X., Brain, D. A., McFadden, J. P., Halekas, J. S., Connerney, J. E., et al. (2015). Strong plume fluxes at Mars observed by MAVEN: An important planetary ion escape channel. Geophys. Res. Lett. 42, 8942–8950. doi:10.1002/2015GL065346Curry, S. M., Luhmann, J. G., Ma, Y. J., Dong, C. F., Brain, D., Leblanc, F., et al. (2015). Response of Mars O+ pickup ions to the 8 March 2015 ICME: Inferences from MAVEN data-based models. Geophys. Res. Lett. 42, 9095–9102. doi:10.1002/2015GL065304Modolo, R., Chanteur, G. M., Dubinin, E., and Matthews, A. P. (2005). Influence of the solar EUV flux on the Martian plasma environment. Annales Geophysicae 23, 433–444. doi:10.5194/angeo-23-433-2005 Brecht, S. H. and Ledvina, S. A. (2006). The Solar Wind Interaction With the Martian Ionosphere/Atmosphere 126, 15–38. doi:10.1007/s11214-006-9084-zKallio, E., Fedorov, A., Budnik, E., Sa¨les, T., Janhunen, P., Schmidt, W., et al. (2006). Ion escape at Mars: Comparison of a 3-D hybrid simulation with Mars Express IMA/ASPERA-3 measurements 182, 350–359. doi:10.1016/j.icarus.2005.09.018

Since the 1970s it has been empirically known that the area of solar coronal holes affects the properties of high-speed solar wind streams (HSSs) at Earth. We derive a simple analytical model for the propagation of HSSs from the Sun to Earth and thereby show how the area of coronal holes and the size of their boundary regions affect the HSS velocity, temperature, and density near Earth. We assume that velocity, temperature, and density profiles form across the HSS cross section close to the Sun and that these spatial profiles translate into corresponding temporal profiles in a given radial direction due to the solar rotation. These temporal distributions drive the stream interface to the preceding slow solar wind plasma and disperse with distance from the Sun. The HSS properties at 1 AU are then given by all HSS plasma parcels launched from the Sun that did not run into the stream interface at Earth distance. We show that the velocity plateau region of HSSs as seen at 1 AU, if apparent, originates from the center region of the HSS close to the Sun, whereas the velocity tail at 1 AU originates from the trailing boundary region. Small HSSs can be described to entirely consist of boundary region plasma, which intrinsically results in smaller peak velocities. The peak velocity of HSSs at Earth further depends on the longitudinal width of the HSS close to the Sun. The shorter the longitudinal width of an HSS close to the Sun, the more of its “fastest” HSS plasma parcels from the HSS core and trailing boundary region have impinged upon the stream interface with the preceding slow solar wind, and the smaller is the peak velocity of the HSS at Earth. As the longitudinal width is statistically correlated to the area of coronal holes, this also explains the well-known empirical relationship between coronal hole areas and HSS peak velocities. Further, the temperature and density of HSS plasma parcels at Earth depend on their radial expansion from the Sun to Earth. The radial expansion is determined by the velocity gradient across the HSS boundary region close to the Sun and gives the velocity-temperature and density-temperature relationships at Earth their specific shape. When considering a large number of HSSs, the assumed correlation between the HSS velocities and temperatures close to the Sun degrades only slightly up to 1 AU, but the correlation between the velocities and densities is strongly disrupted up to 1 AU due to the radial expansion. Finally, we show how the number of particles of the piled-up slow solar wind in the stream interaction region depends on the velocities and densities of the HSS and preceding slow solar wind plasma.

Identifying the heating mechanisms of the solar corona and the driving mechanisms of solar wind are key challenges in understanding solar physics. A full three-dimensional compressible magnetohydrodynamic (MHD) simulation was conducted to distinguish between the heating mechanisms in the fast solar wind above the open field region. Our simulation describes the evolution of the Alfvénic waves, which includes the compressible effects from the photosphere to the heliospheric distance s of 27 solar radii (R⊙). The hot corona and fast solar wind were reproduced simultaneously due to the dissipation of the Alfvén waves. The inclusion of the transition region and lower atmosphere enabled us to derive the solar mass-loss rate for the first time by performing a full three-dimensional compressible MHD simulation. The Alfvén turbulence was determined to be the dominant heating mechanism in the solar wind acceleration region (s > 1.3 R⊙), as suggested by previous solar wind models. In addition, shock formation and phase mixing are important below the lower transition region (s < 1.03 R⊙) as well.

The roles of the simultaneous effect of Coriolis force and Lorentz force (resulting from MHD flow) in Sunspots, solar wind, and many other natural and physical phenomenon is undoubtedly significant. The impact of fluids heated by the Sun is influenced by the rotation of the earth’s surface and this necessitates the study of fluid flow over such surface as the Earth. For this reason, the significance of Coriolis force on MHD free-convection flow of Newtonian fluid over the rotating upper horizontal surface of paraboloid of revolution is explored. The relevant body forces are derived and included in the Navier-Stokes equations to obtain appropriate equations governing the flow. By nondimensionalizing the governing equations using similarity variables, the system of nonlinear partial differential equations is reduced to a system of nonlinear ordinary differential equations which is solved using Runge-Kutta-Gills method along with Shooting technique and the results are depicted graphically. It is observed that simultaneous increase in both Coriolis force and Lorentz force causes an increase in the temperature profile of the flow. It is also observed that the effect of increasing Coriolis force on the Skin Friction and heat transfer rate is counter-balanced by increasing Lorentz force.