Latest in physics.space-ph

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The Cosmic Dust Analyzer onboard Cassini: ten years of discoveriesFeb 13 2018The interplanetary space probe Cassini/Huygens reached Saturn in July 2004 after seven years of cruise phase. The Cosmic Dust Analyzer (CDA) measures the interplanetary, interstellar and planetary dust in our solar system since 1999 and provided unique ... More
Common solar wind drivers behind magnetic storm-magnetospheric substorm dependencyFeb 07 2018The dynamical relationship between magnetic storms and magnetospheric substorms presents one of the most controversial problems of contemporary geospace research. Here, we tackle this issue by applying a causal inference approach to two corresponding ... More
Target selection for a small low-thrust mission to near-Earth asteroidsFeb 07 2018The preliminary mission design of spacecraft missions to asteroids often involves, in the early phases, the selection of candidate target asteroids. The final result of such an analysis is a list of asteroids, ranked with respect to the necessary propellant ... More
Magnetohydrodynamic Turbulence in the Plasmoid-Mediated RegimeFeb 06 2018Magnetohydrodynamic turbulence and magnetic reconnection are ubiquitous in astrophysical environments. In most situations, these processes do not occur in isolation, but interact with each other. This renders a comprehensive theory of these processes ... More
Electron Physics in 3D Two-Fluid Ten-Moment Modeling of Ganymede's MagnetosphereFeb 06 2018We studied the role of electron physics in 3D two-fluid 10-moment simulation of the Ganymede's magnetosphere. The model captures non-ideal physics like the Hall effect, the electron inertia, and anisotropic, non-gyrotropic pressure effects. A series of ... More
Uncertainties in the heliosheath ion temperaturesJan 31 2018The Voyager plasma observations show that the physics of the heliosheath is rather complex, and especially that the temperature derived from observation differs from expectations. To explain this fact the temperature in the heliosheath should be based ... More
Regularized $κ$-distributions with non-diverging momentsJan 31 2018Feb 06 2018For various plasma applications the so-called (non-relativistic) $\kappa$-distribution is widely used to reproduce and interpret the suprathermal particle populations exhibiting a power-law distribution in velocity or energy. Despite its reputation the ... More
Assessing the time dependence of reconnection with Poynting's theorem: MMS observationsJan 31 2018Feb 02 2018We investigate the time dependence of electromagnetic-field-to-plasma energy conversion in the electron diffusion region of asymmetric magnetic reconnection. To do so, we consider the terms in Poynting's theorem. In a steady state there is a perfect balance ... More
Detection of short term response of the low ionosphere on gamma ray burstsJan 30 2018In this paper, we study the possibility of detection of short term terrestrial lower ionospheric response to gamma ray bursts (GRBs) using a statistical analysis of perturbations of six very low or low frequency (VLF/LF) radio signals emitted by transmitters ... More
Electrostatic steepening of whistler wavesJan 30 2018We present surprising observations by the NASA Van Allen Probes spacecraft of whistler waves with substantial electric field power at harmonics of the whistler wave fundamental frequency. The wave power at harmonics is due to nonlinearly steepened whistler ... More
The Solar Electron and Proton Telescope aboard STEREO -- understanding proton spectraJan 29 2018The Solar Electron and Proton Telescope (SEPT) aboard the Solar Terrestrial Relations Observatory (STEREO) is designed to provide the three-dimensional distribution of energetic electrons and protons with good energy and time resolution. Each SEPT instrument ... More
Interstellar neutral helium in the heliosphere from IBEX observations. V. Observations in IBEX-Lo ESA steps 1, 2, & 3Jan 29 2018Direct-sampling observations of interstellar neutral (ISN) He by Interstellar Boundary Explorer (IBEX) provide valuable insight into the physical state of and processes operating in the interstellar medium ahead of the heliosphere. The ISN He atom signals ... More
Recurrence based quantification of dynamical complexity in the Earth's magnetosphere at geospace storm timescalesJan 29 2018Magnetic storms are the most prominent global manifestations of out-of-equilibrium magnetospheric dynamics. Investigating the dynamical complexity exhibited by geomagnetic observables can provide valuable insights into relevant physical processes as well ... More
Mean-field theory of differential rotation in density stratified turbulent convectionJan 26 2018A mean-field theory of differential rotation in a density stratified turbulent convection has been developed. This theory is based on a combined effect of the turbulent heat flux and anisotropy of turbulent convection increasing with the rate of rotation ... More
The Structure of Martian Magnetosphere at the Dayside Terminator Region as Observed on MAVEN SpacecraftJan 26 2018We analyzed 44 passes of the MAVEN spacecraft through the magnetosphere, arranged by the angle between electric field vector and the projection of spacecraft position radius vector in the YZ plane in MSE coordinate system (${\theta}$ E ). All passes were ... More
Unexpected cyclic behavior in cosmic ray protons observed by PAMELA at 1 AUJan 24 2018Protons detected by the PAMELA experiment in the period 2006-2014 have been analyzed in the energy range between 0.40-50 GV to explore possible periodicities besides the well known solar undecennial modulation. An unexpected clear and regular feature ... More
Verification of real-time WSA-ENLIL+Cone simulations of CME arrival-time at the CCMC from 2010-2016Jan 24 2018The Wang-Sheeley-Arge (WSA)-ENLIL+Cone model is used extensively in space weather operations world-wide to model CME propagation. As such, it is important to assess its performance. We present validation results of the WSA-ENLIL+Cone model installed at ... More
Observed instability constraints on electron heat flux in the solar windJan 23 2018We present for the first time the joint distribution of electron heat flux and electron plasma beta, and the joint distribution of core electron drift velocity and electron plasma beta using a statistically large dataset of solar wind electrons at 1AU. ... More
Drag-Based Ensemble Model (DBEM) for Coronal Mass Ejection PropagationJan 23 2018The drag-based model (DBM) for heliospheric propagation of coronal mass ejections (CMEs) is a widely used analytical model which can predict CME arrival time and speed at a given heliospheric location. It is based on the assumption that the propagation ... More
Can Hall effect trigger Kelvin-Helmholtz instability in sub-Alfvenic flows?Jan 22 2018In the Hall magnetohydrodynamics, the onset condition of the Kelvin Helmholtz instability is solely determined by the Hall effect and is independent of the nature of shear flows. In addition, the physical mechanism behind the super and sub Alfvenic flows ... More
The Role of Proton-Cyclotron Resonance as a Dissipation Mechanism in Solar Wind Turbulence: A Statistical Study at Ion-Kinetic ScalesJan 22 2018We use magnetic field and particle data from the WIND spacecraft MFI and SWE instruments to study the nature of the solar wind turbulence at ion-kinetic scales. We begin by making the first in-flight measurement of the MFI 'noise-floor' using tail-lobe ... More
Proton fluxes measured by the PAMELA experiment from the minimum to the maximum solar activity for the 24th solar cycleJan 22 2018Jan 24 2018Precise measurements of the time-dependent intensity of the low energy ($<50$ GeV) galactic cosmic rays are fundamental to test and improve the models which describe their propagation inside the heliosphere. Especially, data spanning different solar activity ... More
Evaluation of the Interplanetary Magnetic Field Strength Using the Cosmic-Ray Shadow of the SunJan 22 2018We analyze the Sun's shadow observed with the Tibet-III air shower array and find that the shadow's center deviates northward (southward) from the optical solar disc center in the "Away" ("Toward") IMF sector. By comparing with numerical simulations based ... More
Mesospheric optical signatures of possible lightning on VenusJan 20 2018A self-consistent two-dimensional model is proposed to account for the transient mesospheric nighttime optical emissions associated to possible intra-cloud (IC) lightning occurring in the Venusian troposphere. The model calculates the mesospheric (between ... More
Three-dimensional modeling of lightning-induced electromagnetic pulses on Venus, Jupiter and SaturnJan 20 2018While lightning activity in Venus is still controversial, its existence in Jupiter and Saturn was first detected by the Voyager missions and later on confirmed by Cassini and New Horizons optical recordings in the case of Jupiter, and recently by Cassini ... More
Onset of fast "ideal" tearing in thin current sheets: dependence on the equilibrium current profileJan 19 2018In this paper we study the scaling relations for the triggering of the fast, or "ideal", tearing instability starting from equilibrium configurations relevant to astrophysical as well as laboratory plasmas that differ from the simple Harris current sheet ... More
EUV Irradiance Inputs to Thermospheric Density Models: Open Issues and Path ForwardJan 18 2018One of the objectives of the NASA LWS Institute on Nowcasting of Atmospheric Drag for LEO Spacecraft was to investigate whether and how to increase the accuracy of atmospheric drag models by improving the quality of the solar forcing inputs, namely Extreme ... More
Sun-to-Earth MHD Simulation of the 14 July 2000 "Bastille Day" EruptionJan 18 2018Solar eruptions are the main driver of space-weather disturbances at the Earth. Extreme events are of particular interest, not only because of the scientific challenges they pose, but also because of their possible societal consequences. Here we present ... More
Spatially inhomogeneous acceleration of electrons in solar flaresJan 15 2018The imaging spectroscopy capabilities of the Reuven Ramaty high energy solar spectroscopic imager (RHESSI) enable the examination of the accelerated electron distribution throughout a solar flare region. In particular, it has been revealed that the energisation ... More
Hall Effect in the coma of 67P/Churyumov-GerasimenkoJan 11 2018Magnetohydrodynamics simulations have been carried out in studying the solar wind and cometary plasma interactions for decades. Various plasma boundaries have been simulated and compared well with observations for comet 1P/Halley. The Rosetta mission, ... More
Solar Flares and the Axion Quark Nugget Dark Matter ModelJan 04 2018We advocate the idea that the nanoflares conjectured by Parker long ago to resolve the corona heating problem, may also trigger the larger solar flares. The arguments are based on the model where emission of extreme ultra violet (EUV) radiation and soft ... More
The Physical Foundation of the Reconnection Electric FieldJan 03 2018Jan 05 2018We report on computer simulations and analytic theory to provide a self-consistent understanding of the role of the reconnection electric field, which extends substantially beyond the simple change of magnetic connections. Rather, we find that the reconnection ... More
Compressibility effects in turbulent MHD and passive scalar transport: mean-field theoryDec 30 2017We develop a mean-field theory of compressibility effects in turbulent magnetohydrodynamics and passive scalar transport using the quasi-linear approximation and the spectral $\tau$-approach. We find that compressibility decreases the $\alpha$ effect ... More
Magnetospheric Multiscale Dayside Reconnection Electron Diffusion Region EventsDec 28 2017We have used the high-resolution data of the Magnetospheric Multiscale (MMS) mission dayside phase to identify twenty-one previously unreported encounters with the electron diffusion region (EDR), as evidenced by electron agyrotropy, ion jet reversals, ... More
Parametric Instability, Inverse Cascade, and the $1/f$ Range of Solar-Wind TurbulenceDec 26 2017In this paper, weak turbulence theory is used to investigate the nonlinear evolution of the parametric instability in 3D low-$\beta$ plasmas at wavelengths much greater than the ion inertial length under the assumption that slow magnetosonic waves are ... More
Kinematics of CMEs and associated shock waves as deduced from LASCO data: comparative analysisDec 26 2017From data by LASCO C2 and C3 coronagraphs, depending on time (distance), we have determined positions and velocities of the front for fast limb CMEs' body with their sources near the limb, and for the body of halo-type CME with the sources near the solar ... More
Origin of a CME-related shock within the LASCO C3 field-of-viewDec 25 2017We study the origin of a CME-related shock within the LASCO C3 field-of-view (FOV). A shock originates, when a CME body velocity on its axis surpasses the total velocity $V_A + V_{SW}$, where $V_A$ is the Alfv\'en velocity, $V_{SW}$ is the slow solar ... More
Coronal magnetic field value radial distributions obtained by using the information on fast halo coronal mass ejectionsDec 25 2017Based on the method of finding coronal magnetic field value radial profiles B(R) described in (Gopalswamy and Yashiro, 2011), and applied for the directions close to the sky plane, we determined magnetic field value radial distributions along the directions ... More
Density Fluctuations in the Solar Wind Driven by Alfvén Wave Parametric DecayDec 23 2017Feb 06 2018Measurements and simulations of inertial compressive turbulence in the solar wind are characterized by anti-correlated magnetic fluctuations parallel to the mean field and density structures. This signature has been interpreted as observational evidence ... More
Interplanetary and Geomagnetic Consequences of Interacting CMEs of 13-14 June 2012Dec 22 2017We report on the kinematics of two interacting CMEs observed on 13 and 14 June 2012. Both CMEs originated from the same active region NOAA 11504. After their launches which were separated by several hours, they were observed to interact at a distance ... More
Using Forbush decreases to derive the transit time of ICMEs propagating from 1 AU to MarsDec 19 2017The propagation of 15 interplanetary coronal mass ejections (ICMEs) from Earth's orbit (1 AU) to Mars (~ 1.5 AU) has been studied with their propagation speed estimated from both measurements and simulations. The enhancement of magnetic fields related ... More
Magnetic reconnection in strongly magnetized regions of the low solar chromosphereDec 02 2017Dec 22 2017Magnetic reconnection in strongly magnetized regions around the temperature minimum region of the low solar atmosphere is studied by employing MHD-based simulations of a partially ionized plasma within a reactive 2.5D multi-fluid model. It is shown that ... More
The parametric instability of Alfvén waves: effects of temperature anisotropyNov 17 2017We study the stability of large amplitude, circularly polarized Alfv\'en waves in an anisotropic plasma described by the double-adiabatic/CGL closure, and in particular the effect of a background thermal pressure anisotropy on the well-known properties ... More
An empirical modification of the force field approach to describe the modulation of galactic cosmic rays close to Earth in a broad range of rigiditiesOct 30 2017On their way through the heliosphere, Galactic Cosmic Rays (GCRs) are modulated by various effects before they can be detected at Earth. This process can be described by the Parker equation, which calculates the phase space distribution of GCRs depending ... More
Rosetta photoelectron emission and solar ultraviolet flux at comet 67PSep 12 2017The Langmuir Probe instrument on Rosetta monitored the photoelectron emission cur- rent of the probes during the Rosetta mission at comet 67P/Churyumov-Gerasimenko, in essence acting as a photodiode monitoring the solar ultraviolet radiation at wave- ... More
Attenuation of decameter sky noise during x-ray solar flares in 2013-2017 based on the observations at midlatitude radarsSep 05 2017Based on a joint analysis of the data from 10 midlatitude decameter radars the effects are investigated during 80 x-ray flares in the period 2013-2017. For the investigation nine mid-latitude SuperDARN radars of the northern hemisphere and Ekaterinburg ... More
Catalogue of 55-80 MeV solar proton events extending through solar cycles 23 and 24Jul 03 2017We present a new catalogue of solar energetic particle events near the Earth, covering solar cycle 23 and the majority of solar cycle 24 (1996-2016), based on the 55-80 MeV proton intensity data gathered by the SOHO/ERNE experiment. In addition to ERNE ... More
Cold and warm electrons at comet 67PMay 24 2017Strong electron cooling on the neutral gas in cometary comae has been predicted for a long time, but actual measurements of low electron temperature are scarce. We present in situ measurements of plasma density, electron temperature and spacecraft potential ... More
Evolving waves and turbulence in the outer corona and inner heliosphere: the accelerating expanding boxFeb 09 2017May 08 2017Alfv\'enic fluctuations in the solar wind display many properties reflecting an ongoing nonlinear cascade, e.g. a well-defined spectrum in frequency, together with some characteristics more commonly associated with the linear propagation of waves from ... More
Impact of Solar Activity on the Ionosphere/Thermosphere during Geomagnetic Quiet Time for CTIPe and TIE-GCMJan 23 2017This study examines the impact that solar activity has on model results during geomagnetic quiet time for the ionosphere/thermosphere models: the Coupled Thermosphere Ionosphere Plasmasphere Electrodynamics Model (CTIPe) and the Thermosphere-Ionosphere-Electrodynamics ... More
Assessment of Source and Transport Parameters of Relativistic SEPs Based on Neutron Monitor DataDec 28 2016As part of the HESPERIA Horizon 2020 project, we developed a software package for the direct inversion of Ground Level Enhancements (GLEs) based on data of the worldwide network of Neutron Monitors (NMs). The new methodology to study the release processes ... More
Direct and Inverse Cascades in the Acceleration Region of the Fast Solar WindDec 08 2016Alfv\'{e}n waves are believed to play an important role in the heating and acceleration of the fast solar wind emanating from coronal holes. Nonlinear interactions between the dominant ${\bf z}_{+}$ waves and minority ${\bf z}_{-}$ waves have the potential ... More
The Interaction of Successive Coronal Mass Ejections: A ReviewDec 07 2016We present a review of the different aspects associated with the interaction of successive CMEs in the corona and inner heliosphere, focusing on the initiation of series of CMEs, their interaction in the heliosphere, the particle acceleration associated ... More
Heliosheath Processes and the Structure of the Heliopause: Modeling Energetic Particles, Cosmic Rays, and Magnetic FieldsDec 07 2016This paper summarizes the results obtained by the team "Heliosheath Processes and the Structure of the Heliopause: Modeling Energetic Particles, Cosmic Rays, and Magnetic Fields" supported by the International Space Science Institute in Bern, Switzerland. ... More
Energy Cascade Rate In Compressible Fast And Slow Solar Wind TurbulenceDec 07 2016Estimation of the energy cascade rate in the inertial range of solar wind turbulence has been done so far mostly within the incompressible magnetohydrodynamics (MHD) theory. Here, we go beyond that approximation to include plasma compressibility using ... More
Gravity gradient suppression in spaceborne atomic tests of the equivalence principleDec 06 2016The gravity gradient is one of the most serious systematic effects in atomic tests of the equivalence principle (EP). While differential acceleration measurements performed with different atomic species under free fall test the validity of EP, minute ... More
The Broken Lane of a Type II Radio Burst Caused by Collision of a Coronal Shock with a Flare Current SheetDec 06 2016We investigated a peculiar metric type II solar radio burst with a broken lane structure, which was observed on November 13, 2012. In addition to the radio data, we also studied the data in the other wavelengths. The bursts were associated with two CMEs ... More
Particle-in-cell simulations of the relaxation of electron beams in inhomogeneous solar wind plasmasDec 06 2016Previous theoretical considerations of electron beam relaxation in inhomogeneous plasmas have indicated that the effects of the irregular solar wind may account for the poor agreement of homogeneous modelling with the observations. Quasi-linear theory ... More
Clouds effect on the Atmospheric Total Column Carbon Dioxide Retrieval by Space Orbiting Argus 1000 Micro-spectrometer: Introductory StudyDec 04 2016Carbon Dioxide (CO2) is one of the most important greenhouse gases after water vapor (H2O) which plays significant role in the climate process. Accurate space-based measurement of CO2 is of great significance in inferring the location of CO2 sources and ... More
Historical Auroras in the 990s: Evidence for Great Magnetic StormsDec 04 2016Recently, a significant carbon-14 enhancement in the year 994 in tree rings has been found, suggesting an extremely large cosmic ray flux event during a short period. The origin of this particular cosmic ray event has not been confirmed, but one possibility ... More
Time Evolution of Elemental Ratios in Solar Energetic Particle eventsDec 02 2016Heavy ion ratio abundances in Solar Energetic Particle (SEP) events, e.g.~Fe/O, often exhibit decreases over time. Using particle instruments on the ACE, SOHO and STEREO spacecraft, we analysed heavy ion data from 4 SEP events taking place between December ... More
Variable phase propagation velocity for long-range lightning location systemDec 02 2016The electromagnetic wave propagation velocity at low radio frequencies is an important input parameter for lightning location systems that use time of arrival (TOA) method. This velocity is normally fixed at or near the speed of light. However, this study ... More
Temporal characteristics and energy deposition of pulsating auroral patchesDec 02 2016We present a careful statistical analysis of pulsating aurora (PA) using all-sky green line (557.7 nm) images obtained at 3.3 Hz. Six well-defined individual PA patches are identified and extracted using a contouring technique. Quantitative parameters ... More
Physical Characterization of ~2-meter Diameter Near-Earth Asteroid 2015 TC25: A possible boulder from E-type Asteroid (44) NysaDec 01 2016Dec 03 2016Small near-Earth asteroids (>20 meters) are interesting because they are progenitors for meteorites in our terrestrial collection. Crucial to our understanding of the effectiveness of our atmosphere in filtering low-strength impactors is the physical ... More
Physical Characterization of ~2-meter Diameter Near-Earth Asteroid 2015 TC25: A possible boulder from E-type Asteroid (44) NysaDec 01 2016Small near-Earth asteroids (>20 meters) are interesting because they are progenitors for meteorites in our terrestrial collection. Crucial to our understanding of the effectiveness of our atmosphere in filtering low-strength impactors is the physical ... More
Scintillation and irregularities from the nightside part of a Sun-aligned polar cap arcNov 28 2016In this paper we study the presence of irregularities and scintillation in relation to the nightside part of a long-lived, Sun-aligned transpolar arc on 15 January 2015. The arc was observed in DMSP UV and particle data and lasted at least 3 h between ... More
Observations of planetary waves in the mesosphere-lower thermosphere during stratospheric warming eventsNov 28 2016This study investigates the effect of stratospheric sudden warmings (SSWs) on planetary wave (PW) activity in the mesosphere-lower thermosphere (MLT). PW activity near 95 km is derived from meteor wind data using a chain of eight SuperDARN radars at high ... More
Chromosphere to 1 AU Simulation of the 2011 March 7th Event: A Comprehensive Study of Coronal Mass Ejection PropagationNov 27 2016We perform and analyze results of a global magnetohydrodyanmic (MHD) simulation of the fast coronal mass ejection (CME) that occurred on 2011 March 7. The simulation is made using the newly developed Alfv\'en Wave Solar Model (AWSoM), which describes ... More
Nature of the MHD and kinetic scale turbulence in the magnetosheath of Saturn: Cassini observationsNov 24 2016Low frequency turbulence in Saturn's magnetosheath is investigated using in-situ measurements of the Cassini spacecraft. Focus is put on the magnetic energy spectra computed in the frequency range $\sim[10^{-4}, 1]$Hz. A set of 42 time intervals in the ... More
Cutoff latitude variation during solar proton events: Causes and consequencesNov 24 2016To accurately quantify the effect of solar proton events (SPEs) on the atmosphere requires a good estimate of the particle energy deposition in the middle atmosphere (60- 100 km) and how the energy is distributed globally. Protons in the energy range ... More
On the effect of ocean tides and tesseral harmonics on spacecraft flybys of the EarthNov 24 2016The so-called flyby anomaly has encouraged several authors to analyze in detail the minor perturbative contributions to the trajectory of spacecraft performing a flyby manoeuvre. This anomaly consist of an unexplained increase or decrease of the asymptotic ... More
Revisiting a classic: the Parker-Moffatt problemNov 24 2016The interaction of two colliding Alfv\'en wave packets is here described by means of magnetohydrodynamics (MHD) and hybrid kinetic numerical simulations. The MHD evolution revisits the theoretical insights described by Moffatt, Parker, Kraichnan, Chandrasekhar ... More
Langmuir Wave Electric Fields Induced by Electron Beams in the HeliosphereNov 23 2016Solar electron beams responsible for type III radio emission generate Langmuir waves as they propagate out from the Sun. The Langmuir waves are observed via in-situ electric field measurements. These Langmuir waves are not smoothly distributed but occur ... More
Why does steady-state magnetic reconnection have a maximum local rate of order 0.1?Nov 23 2016Simulations suggest collisionless steady-state magnetic reconnection of Harris-type current sheets proceeds with a rate of order 0.1, independent of dissipation mechanism. We argue this long-standing puzzle is a result of constraints at the magnetohydrodynamic ... More
Geomagnetically Induced Currents in the Irish Power Network during Geomagnetic StormsNov 23 2016Geomagnetically induced currents (GICs) are a well-known terrestrial space weather hazard. They occur in power transmission networks and are known to have adverse effects in both high and mid-latitude countries. Here, we study GICs in the Irish power ... More
Multi-scale Pressure-balanced Structures in Three-dimensional Magnetohydrodynamic TurbulenceNov 22 2016Observations of solar wind turbulence indicate the existence of multi-scale pressure-balanced structures (PBSs) in the solar wind. In this work, we conduct a numerical simulation to investigate multi-scale PBSs and in particular their formation in compressive ... More
Magnetic Coordinate SystemsNov 21 2016Geospace phenomena such as the aurora, plasma motion, ionospheric currents and associated magnetic field disturbances are highly organized by Earth's main magnetic field. This is due to the fact that the charged particles that comprise space plasma can ... More
North-South Asymmetries in Earth's Magnetic Field: Effects on High-Latitude GeospaceNov 21 2016The solar-wind magnetosphere interaction primarily occurs at altitudes where the dipole component of Earth's magnetic field is dominating. The disturbances that are created in this interaction propagate along magnetic field lines and interact with the ... More
Sunlight effects on the 3D polar current system determined from low Earth orbit measurementsNov 21 2016Interaction between the solar wind and the Earth's magnetosphere is associated with large-scale currents in the ionosphere at polar latitudes that flow along magnetic field lines (Birkeland currents) and horizontally. These current systems are tightly ... More
Hybrid simulation of a parallel collisionless shock in the Large Plasma DeviceNov 19 2016We present two-dimensional hybrid kinetic/magnetohydrodynamic simulations of planned laser-ablation experiments in the Large Plasma Device (LAPD). Our results, based on parameters which have been validated in previous experiments, show that a parallel ... More
Action Principles for Relativistic Extended Magnetohydrodynamics: A Unified Theory of Magnetofluid ModelsNov 18 2016Two types of Eulerian action principles for relativistic extended magnetohydrodynamics (MHD) are formulated. With the first, the action is extremized under the constraints of density, entropy, and Lagrangian label conservation, which leads to a Clebsch ... More
The role of guide field in magnetic reconnection driven by island coalescenceNov 18 2016A number of studies have considered how the rate of magnetic reconnection scales in large and weakly collisional systems by the modelling of long reconnecting current sheets. However, this set-up neglects both the formation of the current sheet and the ... More
Energetic particle transport across the mean magnetic field: before diffusionNov 16 2016Current particle transport models describe the propagation of charged particles across the mean field direction in turbulent plasmas as diffusion. However, recent studies suggest that at short time-scales, such as soon after solar energetic particle (SEP) ... More
Earliest Datable Records of Aurora-like Phenomena in the Astronomical Diaries from BabyloniaNov 16 2016The Astronomical Diaries from Babylonia (ADB) are an excellent source of information of natural phenomena, including astronomical ones, in pre-Christ era because it contains the record of highly continuous and systematic observations. In this article ... More
Dynamics of Coronal-Hole BoundariesNov 15 2016Remote and in-situ observations suggest that the slow solar wind consists of plasma from the hot, closed-field corona that is released onto open magnetic field lines. The Separatrix-Web (S-Web) theory for the slow wind proposes that photospheric motions, ... More
Differential kinetic dynamics and heating of ions in the turbulent solar windNov 15 2016The solar wind plasma is a fully ionized and turbulent gas ejected by the outer layers of the solar corona at very high speed, mainly composed by protons and electrons, with a small percentage of helium nuclei and a significantly lower abundance of heavier ... More
Structure, Propagation and Expansion of a CME-Driven Shock in the Heliosphere: A Revisit of the 2012 July 23 Extreme StormNov 14 2016We examine the structure, propagation and expansion of the shock associated with the 2012 July 23 extreme coronal mass ejection (CME). Characteristics of the shock determined from multi-point imaging observations are compared to in situ measurements at ... More
Statistics of Reconnection-Driven TurbulenceNov 11 2016Magnetic reconnection is a process that changes magnetic field topology in highly conducting fluids. Within the standard Sweet-Parker model, this process would be too slow to explain observations (e.g. solar flares). In reality, the process must be ubiquitous ... More
Anthropogenic Space WeatherNov 10 2016Nov 20 2016Anthropogenic effects on the space environment started in the late 19th century and reached their peak in the 1960s when high-altitude nuclear explosions were carried out by the USA and the Soviet Union. These explosions created artificial radiation belts ... More
Anthropogenic Space WeatherNov 10 2016Anthropogenic effects on the space environment started in the late 19th century and reached their peak in the 1960s when high-altitude nuclear explosions were carried out by the USA and the Soviet Union. These explosions created artificial radiation belts ... More
Recent progress in astrophysical plasma turbulence from solar wind observationsNov 10 2016This paper summarises some of the recent progress that has been made in understanding astrophysical plasma turbulence in the solar wind, from in situ spacecraft observations. At large scales, where the turbulence is predominantly Alfvenic, measurements ... More
Effects of Fieldline Topology on Energy Propagation in the CoronaNov 10 2016We study the effect of photospheric footpoint motions on magnetic field structures containing magnetic nulls. The footpoint motions are prescribed on the photospheric boundary as a velocity field which entangles the magnetic field. We investigate the ... More
Solar Energetic Particle Events with Protons above 500 MeV between 1995 and 2015 Measured with SOHO/EPHINNov 10 2016The Sun is an effective particle accelerator producing solar energetic particle (SEP) events during which particles up to several GeVs can be observed. Those events observed at Earth with the neutron monitor network are called ground level enhancements ... More
Space weather research and forecast in USANov 08 2016In the United States, scientific research in space weather is funded by several Government Agencies including the National Science Foundation (NSF) and the National Aeronautics and Space Agency (NASA). For commercial purposes, space weather forecast is ... More
Nanograin densities outside Saturn's A-ringNov 08 2016The observed disparity between the radial dependence of the ion and electron densities measured by the Cassini plasma and radio science instruments are used to show that the region between the outer edge of Saturn's main rings and its tenuous G-ring is ... More
Estimation of the Perturbing Accelerations Induced on the LARES Satellite by Neutral Atmosphere DragNov 08 2016The laser-ranged satellite LARES is expected to provide new refined measurements of relativistic physics, as well as significant contributions to space geodesy and geophysics. The very low area-to-mass ratio of this passive and dense satellite was chosen ... More
Inverting OII 83.4 nm Dayglow Profiles Using Markov Chain Radiative TransferNov 07 2016Emission profiles of the resonantly scattered OII~83.4~nm triplet can in principle be used to estimate \(\mathrm{O}^+\) density profiles in the F2 region of the ionosphere. Given the emission source profile, solution of this inverse problem is possible, ... More
Magnetohydrodynamic Simulation Code CANS+: Assessments and ApplicationsNov 06 2016Nov 08 2016We present a new magnetohydrodynamic (MHD) simulation code with the aim of providing accurate numerical solutions to astrophysical phenomena where discontinuities, shock waves, and turbulence are inherently important. The code implements the HLLD approximate ... More
Evaluation of Ionospheric Densities Using Coincident OII 83.4 nm Airglow and the Millstone Hill RadarNov 04 2016We test the utility of the OII 83.4 nm emission feature as a measure of ionospheric parameters. Observed with the Remote Atmospheric and Ionospheric Detection System (RAIDS) Extreme Ultraviolet Spectrograph on the International Space Station (ISS), limb ... More
Nonmodal analysis of helical and azimuthal magnetorotational instabilitiesNov 03 2016The helical and the azimuthal magnetorotational instabilities operate in rotating magnetized flows with relatively steep negative or extremely steep positive shear. The corresponding lower and upper Liu limits of the shear, which determine the threshold ... More