Space weather describes the way in which Sun, and conditions space more generally, impact human activity technology both on ground. It is now well understood that represents a significant threat to infrastructure resilience, source of risk wide‐ranging its pathways by this may occur. Although growing rapidly as field, work rigorously assessing overall economic cost appears be infancy. Here, we provide an initial literature review gather assess quality any published assessments impacts...

The anisotropy of turbulence in the fast solar wind, between ion and electron gyroscales, is directly observed using a multispacecraft analysis technique. Second order structure functions are calculated at different angles to local magnetic field, for fluctuations both perpendicular parallel mean field. In components, function value large field ${S}_{\ensuremath{\perp}}$ greater than small ${S}_{\ensuremath{\parallel}}$: component...

Abstract The Wind spacecraft, launched on November 1, 1994, is a critical element in NASA’s Heliophysics System Observatory (HSO)—a fleet of spacecraft created to understand the dynamics Sun‐Earth system. combination its longevity (>25 years service), diverse complement instrumentation, and high resolution accurate measurements has led it becoming “standard candle” solar wind measurements. over 55 selectable public data products with ∼1,100 total variables (including OMNI products)...

We measure the power and spectral index anisotropy of high speed solar wind turbulence from scales larger than outer scale down to ion gyroscale, thus covering entire inertial range. show that indices at are approximately isotropic. The turbulent cascade causes smaller manifested by anisotropic scalings spectrum: close k^{-5/3} across k^{-2} along local magnetic field, consistent with a critically balanced Alfvenic turbulence. By using data different radial distances Sun, we width range does...

We present the first measurement of scale-dependent power anisotropy Elsasser variables in imbalanced fast solar wind turbulence. The dominant mode is isotropic at lower spacecraft frequencies but becomes increasingly anisotropic higher frequencies. sub-dominant throughout, a scale-independent way (at frequencies). There are two distinct subranges exhibiting different scalings within what normally considered inertial range. low Alfven ratio and shallow scaling suggest an interpretation...

We present a measurement of the scale-dependent, three-dimensional structure magnetic field fluctuations in inertial range solar wind turbulence with respect to local, physically motivated coordinate system. The Alfvenic are three-dimensionally anisotropic, sense this anisotropy varying from large small scales. At outer scale, correlations longest local fluctuation direction, consistent Alfven waves. proton gyroscale, they along mean direction and shortest perpendicular fluctuation....

We derive the reduced spectrum of turbulent magnetic fluctuations at different frequencies f which would be observed by a single spacecraft in solar wind when field was an angle θB to flow, if wavevector frame were anisotropic "critical balance" (CB) as proposed Goldreich and Sridhar 1995 (GS95). The power inertial range, P(f, θB), is scaled onto one curve with −5/3 behavior near 90° −2 small θB. transition between two limiting spectra depends on form GS95 CB scaling parameter L. Using...

The Bandt-Pompe permutation entropy and the Jensen-Shannon statistical complexity are used to analyze fluctuating time series of three different turbulent plasmas: magnetohydrodynamic (MHD) turbulence in plasma wind tunnel Swarthmore Spheromak Experiment (SSX), drift-wave ion saturation current fluctuations edge Large Plasma Device (LAPD), fully developed magnetic solar taken from $\mathit{Wind}$ spacecraft. values presented as coordinates on $\mathit{CH}$ plane for comparison among...

ABSTRACT We use audification of 0.092 s cadence magnetometer data from the Wind spacecraft to identify waves with amplitudes <?CDATA $\gt 0.1$?> <?MML <mml:math> <mml:mo>&gt;</mml:mo> <mml:mn>0.1</mml:mn> </mml:math>?> nT near ion gyrofrequency (∼0.1 Hz) duration longer than 1 hr during 2008. present one most common types event for a case study and find it be proton-cyclotron wave storm, coinciding highly radial magnetic field suprathermal proton beam close in density core distribution...

Observations in the solar wind suggest that compressive component of inertial-range solar-wind turbulence is dominated by slow modes. The low collisionality allows for non-thermal features to survive, which suggests requirement a kinetic plasma description. least-damped mode associated with ion-acoustic (IA) wave and non-propagating (NP) mode. We derive analytical expressions IA-wave dispersion relation an anisotropic framework gyrokinetics then compare them fully-kinetic numerical...

Abstract In this study we examine the radial dependence of inertial and dissipation range indices, as well spectral break separating in power density spectra interplanetary magnetic field fluctuations using Parker Solar Probe data from fifth solar encounter between ∼0.1 ∼0.7 au. The derived wavenumber compares reasonably with previous estimates at larger distances is consistent gyro-resonant damping Alfvénic by thermal protons. We find that scale power-law index varies approximately −1.65...

We use magnetic field and ion moment data from the MFI SWE instruments onboard Wind spacecraft to study nature of solar wind turbulence at ion-kinetic scales. analyze spectral properties fluctuations between 0.1 5.5 Hz over 2012 using an automated routine, computing high-resolution 92 s power helicity spectra. To ensure features are physical, we make first in-flight measurement `noise-floor' tail-lobe crossings Earth's magnetosphere during early 2004. utilize Taylor's hypothesis...

Abstract We develop and apply a bespoke fitting routine to large volume of solar wind electron distribution data measured by Parker Solar Probe over its first five orbits, covering radial distances from 0.13 0.5 au. characterize the evolution core, halo, strahl populations in slow during these orbits. The fractional densities three provide evidence for growth combined suprathermal halo 0.17 Moreover, population is not matched decrease at distances, as has been reported previous observations...

A relationship is derived between power anisotropy and wavevector in turbulent fluctuations. This can be used to interpret plasma turbulence measurements, for example the solar wind. If fluctuations are anisotropic shape then ion gyroscale break point spectra directions parallel perpendicular magnetic field would not occur at same frequency, similarly electron point. an important consideration when interpreting wind observations terms of theories. Model presented assuming a cascade...

We investigate the dependence of solar wind fluctuations measured by Wind spacecraft on scale and degree alignment between oppositely directed Elsasser fields. This controls strength non-linear interactions and, therefore, turbulence. find that at scales larger than outer turbulence become average more anti-aligned as is approached from above. Conditioning structure functions using angle reveals turbulent scaling unaligned previously believed to lie outside cascade in `1/f range'. argue 1/f...

We show that the scaling of structure functions magnetic and velocity fields in a mostly highly Alfv\'{e}nic fast solar wind stream depends strongly on joint distribution dimensionless measures cross helicity residual energy. Already at very low frequencies, fluctuations are both more balanced (cross $\sim 0$) equipartitioned (residual energy have steep reminiscent "turbulent" scalings usually associated with inertial range. Fluctuations magnetically dominated -1$), so closely anti-aligned...

We measure the local anisotropy of numerically simulated strong Alfvénic turbulence with respect to two local, physically relevant directions: along mean magnetic field and direction one fluctuating Elsasser fields. find significant scaling both these fluctuations are 'ribbon-like' – statistically, they elongated field. The latter form is due scale-dependent alignment intermittent scalings nth-order conditional structure functions in perpendicular agree well theory Chandran, Schekochihin &...

Abstract A polytropic process describes the transition of a fluid from one state to another through specific relationship between density and temperature. The value index that governs this determines heat transfer effective degrees freedom during process. In study, we analyze solar wind proton plasma measurements, obtained by Faraday cup instrument on board Parker Solar Probe. We examine large-scale variations temperature within inner heliosphere explored spacecraft. then address behavior in...

We use a well-known model [T. Vicsek, Phys. Rev. Lett. 15, 1226 (1995)] for flocking, to test mutual information as tool detecting order-disorder transitions, in particular when observations of the system are limited. show that is sensitive indicator phase transition location terms natural dimensionless parameters which we have identified. When only few particles tracked and subset positional velocity components available, provides better measure than susceptibility data.

Abstract Spacecraft observations allow us to reconstruct the velocity distributions of space plasmas, which fully describe kinetic state plasma. Space plasmas often exist in stationary states out equilibrium, are typically described by kappa distributions. Thus, index and temperature that govern these parameters need be determined for a full accurate description plasmas. In this study, we demonstrate novel reliable way determine plasma distribution functions constructed from counts observed...

Local inversions are often observed in the heliospheric magnetic field (HMF), but their origins and evolution not yet fully understood.Parker Solar Probe has recently rapid, Alfvenic, HMF inner heliosphere, known as 'switchbacks', which have been interpreted possible remnants of coronal jets. It also suggested that inverted may be produced by near-Sun interchange reconnection; a key process mechanisms proposed for slow solar wind release. These cases suggest source is near Sun, it follows...