scholarly journals Solar wind test of the de Broglie-Proca's massive photon with Cluster multi-spacecraft data

2016 ◽  
Author(s):  
Alessandro Spallicci
Keyword(s):  
Solar Wind ◽  
Massive Photon ◽  
Spacecraft Data

scholarly journals Solar wind test of the de Broglie-Proca massive photon with Cluster multi-spacecraft data

2016 ◽  
Vol 82 ◽  
pp. 49-55 ◽  
Author(s):  
Alessandro Retinò ◽  
Alessandro D.A.M. Spallicci ◽  
Andris Vaivads
Keyword(s):  
Solar Wind ◽  
Massive Photon ◽  
Spacecraft Data

scholarly journals Internally and externally induced deformations of the magnetospheric equatorial current as inferred from spacecraft data

2015 ◽  
Vol 33 (1) ◽  
pp. 1-11 ◽  
Author(s):  
N. A. Tsyganenko ◽  
V. A. Andreeva ◽  
E. I. Gordeev
Keyword(s):  
Magnetic Field ◽  
Solar Wind ◽  
Essential Feature ◽  
Quantitative Model ◽  
Local Times ◽  
Ram Pressure ◽  
Magnetometer Data ◽  
Equatorial Current ◽  
Spacecraft Data ◽  
Dipole Tilt

Abstract. Based on a data pool of 79 yearly files of space magnetometer data by Polar, Cluster, Geotail, and THEMIS satellites between 1995 and 2013, we developed a new quantitative model of the global shape of the magnetospheric equatorial current sheet as a function of the Earth's dipole tilt angle, solar wind ram pressure, and interplanetary magnetic field (IMF). This work upgrades and generalizes an earlier model of Tsyganenko and Fairfield (2004) by extending the modeling region to all local times, including the dayside sector. In particular, an essential feature of the new model is the bowl-shaped tilt-related deformation of the equatorial surface of minimum magnetic field, similar to that observed at Saturn, whose existence in the Earth's magnetosphere has been demonstrated in our recent work (Tsyganenko and Andreeva, 2014).

scholarly journals Scale dependent anisotropy of electric field fluctuations in solar wind turbulence

2021 ◽  
Author(s):  
Deepali Deepali ◽  
Supratik Banerjee
Keyword(s):  
Magnetic Field ◽  
Solar Wind ◽  
Electric Field ◽  
Electric Power ◽  
Flow Direction ◽  
Power Spectra ◽  
Solar Wind Turbulence ◽  
Wind Turbulence ◽  
Field Fluctuations ◽  
Spacecraft Data

<p>We study the variation of average powers and spectral indices of electric field fluctuations with respect to the angle between average flow direction and the mean magnetic field in solar wind turbulence. Cluster spacecraft data from the years 2002 and 2007 are used for the present analysis. We perform a scale dependent study with respect to the local mean magnetic field using wavelet analysis technique. Prominent anisotropies are found for both the spectral index and power levels of the electric power spectra. Similar to the magnetic field fluctuations, the parallel (or antiparallel) electric fluctuation spectrum is found to be steeper than the perpendicular spectrum. However the parallel (or antiparallel) electric power is found to be greater than the perpendicular one. Below 0.1 Hz, the slope of the parallel electric power spectra deviates substantially from that of the total magnetic power spectra, supporting the existence of Alfvénic turbulence.</p>

scholarly journals Analysis of Magnetohydrodynamic Perturbations in the Radial-field Solar Wind from Parker Solar Probe Observations

2021 ◽  
Vol 923 (2) ◽  
pp. 253
Author(s):  
S. Q. Zhao ◽  
Huirong Yan ◽  
Terry Z. Liu ◽  
Mingzhe Liu ◽  
Mijie Shi
Keyword(s):  
Solar Wind ◽  
Energy Fraction ◽  
Radial Field ◽  
Singular Value Decomposition Method ◽  
Heating Effects ◽  
Damping Rate ◽  
Report Analysis ◽  
Value Decomposition ◽  
Spacecraft Data ◽  
High Degree

Abstract We report analysis of sub-Alfvénic magnetohydrodynamic (MHD) perturbations in the low-β radial-field solar wind employing the Parker Solar Probe spacecraft data from 2018 October 31 to November 12. We calculate wavevectors using the singular value decomposition method and separate MHD perturbations into three eigenmodes (Alfvén, fast, and slow modes) to explore the properties of sub-Alfvénic perturbations and the role of compressible perturbations in solar wind heating. The MHD perturbations show a high degree of Alfvénicity in the radial-field solar wind, with the energy fraction of Alfvén modes dominating (∼45%–83%) over those of fast modes (∼16%–43%) and slow modes (∼1%–19%). We present a detailed analysis of a representative event on 2018 November 10. Observations show that fast modes dominate magnetic compressibility, whereas slow modes dominate density compressibility. The energy damping rate of compressible modes is comparable to the heating rate, suggesting the collisionless damping of compressible modes could be significant for solar wind heating. These results are valuable for further studies of the imbalanced turbulence near the Sun and possible heating effects of compressible modes at MHD scales in low-β plasma.

Evolution of Turbulence in the Kelvin–Helmholtz Instability mediated by the Magnetopause and its Boundary Layer

2020 ◽  
Author(s):  
Francesca Di Mare ◽  
Luca Sorriso-Valvo ◽  
Alessandro Retino' ◽  
Francesco Malara ◽  
Hiroshi Hasegawa
Keyword(s):  
Boundary Layer ◽  
Solar Wind ◽  
Large Scale ◽  
Velocity Shear ◽  
Helmholtz Instability ◽  
Intermittent Turbulence ◽  
Large Scale Structures ◽  
Developed Turbulence ◽  
Spacecraft Data ◽  
Efficient Transfer

<p>The turbulence at the interface between the solar wind and the Earth’s magnetosphere, mediated by the magnetopause and its boundary layer are investigated by using Geotail and THEMIS spacecraft data during ongoing Kelvin-Helmholtz instability (KHI). The efficient transfer of energy across scales for which the turbulence is responsible, achieves the connection between the macroscopic flow and the microscopic dissipation of this energy. This boundary layer is thought to be the result of the observed plasma transfer, driven by the development of the KHI, originating from the velocity shear between the solar wind and the almost static near-Earth plasma. A collection of 20 events spatially located on the tail-flank magnetopause, selected from previously studied by Hasegawa et al. 2006 and Lin et al. 2014, have been tested against standard diagnostics for intermittent turbulence. In light of the results obtained, we have investigated the behaviour of several parameters as a function of the progressive departure along the Geocentric Solar Magnetosphere coordinates, which roughly represent the direction in which we expect the KHI vortices to evolve towards fully developed turbulence. It appears that a fluctuating behaviour of the parameters exist, visible as a decreasing, quasi-periodic modulation with an associated periodicity, estimated to correspond to approximately 6.4 Earth Radii. Such observed wavelength is consistent with the estimated vortices roll-up wavelength reported in the literature for these events. If the turbulence is pre-existent, it is possible that the KHI modulates its properties along the magnetosheath, as we observed. On the other hand, if we assume that the KHI has been initiated near the magnetospheric nose and develops along the flanks, then the different intervals we study may be sampling the plasma at different stages of evolution of the KH-generated turbulence, after the instability has injected energy in a cascading process as large-scale structures.</p>

scholarly journals Wave vector analysis methods using multi-point measurements

2010 ◽  
Vol 17 (5) ◽  
pp. 383-394 ◽  
Author(s):  
Y. Narita ◽  
K.-H. Glassmeier ◽  
U. Motschmann
Keyword(s):  
Magnetic Field ◽  
Solar Wind ◽  
Wave Vector ◽  
Higher Order ◽  
Vector Analysis ◽  
Taylor’S Hypothesis ◽  
Recent Developments ◽  
The Mean ◽  
Point Data ◽  
Spacecraft Data

Abstract. Recent developments of multi-point measurements in space provide a means to analyze spacecraft data directly in the wave vector domain. For turbulence study this means that we are able to estimate energy, helicity, and higher order moments in the wave vector domain without assuming Taylor's hypothesis or axisymmetry around the mean magnetic field. The methods of the wave vector analysis are presented and applied to four-point data of Cluster in the solar wind.

HelioSwarm: Leveraging Multi-Point, Multi-Scale Spacecraft Observations to Characterize Turbulence

2021 ◽  
Author(s):  
Kristopher Klein ◽  
Harlan Spence ◽  
Keyword(s):  
Solar Wind ◽  
Spatial Structure ◽  
Correlation Functions ◽  
Space Plasmas ◽  
Turbulent Transfer ◽  
Analysis Techniques ◽  
Multi Scale ◽  
Temporal And Spatial ◽  
Spacecraft Data ◽  
Characteristic Scales

<p>There are many fundamental questions about the temporal and spatial structure of turbulence in space plasmas. Answering these questions is complicated by the multi-scale nature of the turbulent transfer of mass, momentum, and energy, with characteristic scales spanning many orders of magnitude. The solar wind is an ideal environment in which to measure turbulence, but multi-point observations with spacecraft separations spanning these scales are needed to simultaneously characterize structure and cross-scale couplings. In this work, we use synthetic multi-point spacecraft data extracted from numerical simulations to demonstrate the utility of multi-point, multi-scale measurements, in preparation for data from future multi-spacecraft observatories. We use the baseline orbit design for the HelioSwarm mission concept to explore the effects of different inter-spacecraft separations and geometries on the accuracy of reconstructed magnetic fields, cascade rates, and correlation functions using well-established analysis techniques.</p>

Drivers of the solar wind: then and now

2005 ◽  
Vol 364 (1839) ◽  
pp. 505-527 ◽  
Author(s):  
Joseph V Hollweg
Keyword(s):  
Solar Wind ◽  
Pressure Gradient ◽  
Cyclotron Resonance ◽  
Coronal Holes ◽  
Ion Cyclotron Resonance ◽  
The Sun ◽  
Principal Mechanism ◽  
Fast Wind ◽  
Ion Cyclotron ◽  
Spacecraft Data

Early spacecraft data in the 1960s revealed solar wind properties, which could not be well explained by models in which the electron pressure gradient was the principal accelerating force. The Alfvén waves discovered around 1970 were thought for a while to provide additional energy and momentum, but they ultimately failed to explain the rapid acceleration of the fast wind close to the Sun. By the late 1970s, various data were suggesting the importance of the ion-cyclotron resonance far from the Sun. This notion was soon applied to the acceleration region close to the Sun. The models, which resulted, suggested that the fast wind could be driven mainly by the proton pressure gradient. Since the mid-1990s, Solar and Heliospheric Observatory has provided remarkable data, which have verified some of the predictions of these theories, and given impetus to studies of the ion-cyclotron resonance as the principal mechanism for heating the coronal holes, and ultimately driving the fast wind. After a historical review, we discuss the basic ideas behind current research, emphasizing the particle kinetics. We discuss remaining problems, especially the source of the ion-cyclotron resonant waves.

scholarly journals <i>Letter to the Editor</i>A statistical study of the location and motion of the HF radar cusp

2002 ◽  
Vol 20 (2) ◽  
pp. 275-280 ◽  
Author(s):  
T. K. Yeoman ◽  
P. G. Hanlon ◽  
K. A. McWilliams
Keyword(s):  
Solar Wind ◽  
Continuous Monitoring ◽  
Large Scale ◽  
Statistical Study ◽  
Hf Radar ◽  
Auroral Ionosphere ◽  
Cusp Region ◽  
The North ◽  
Low Altitude ◽  
Spacecraft Data

Abstract. The large-scale and continuous monitoring of the ionospheric cusp region offered by HF radars has been exploited in order to examine the statistical location and motion of the equatorward edge of the HF radar cusp as a function of the upstream IMF BZ component. Although a considerable scatter is seen, both parameters have a clear influence from the north-south component of the IMF. Excellent agreement is achieved with previous observations from low altitude spacecraft data. The HF radar cusp region is seen to migrate equatorward at a rate of 0.02° min-1 nT-1 under IMF BZ south conditions, but remains static for IMF BZ north. The motion of the cusp implies an addition of magnetic flux of ~ 2 × 104 Wbs-1 nT-1 under IMF BZ south conditions, equivalent to a reconnection voltage of 20 kV nT-1, which is consistent with previous estimates from case studies on both the dayside and nightside regions.Key words. Ionosphere (auroral ionosphere) – Magnetospheric physics (magnetosphere-ionosphere interaction; solar wind magnetosphere interactions)

scholarly journals Variations of flow direction in solar wind streams of different types

2021 ◽  
Vol 7 (4) ◽  
pp. 10-18
Author(s):  
Anastasiya Moskaleva ◽  
Mariya Ryazanceva ◽  
Yuriy Ermolaev ◽  
Irina Lodkina
Keyword(s):  
Solar Wind ◽  
High Speed ◽  
Large Scale ◽  
Weather Forecasting ◽  
Flow Direction ◽  
Coronal Holes ◽  
Wind Flow ◽  
Different Types ◽  
Solar Wind Flow ◽  
Spacecraft Data

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.

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