Compressible Magnetohydrodynamic Turbulence in the Earth’s Magnetosheath: Estimation of the Energy Cascade Rate Using 
in situ
 Spacecraft Data

Using mixed second-order structure functions, a compact exact law is derived for isothermal compressible Hall magnetohydrodynamic turbulence with the assumptions of statistical homogeneity, time stationarity and infinite kinetic/magnetic Reynolds numbers. The resulting law is written as the sum of a Yaglom-like flux term, with an overall expression strongly reminiscent of the incompressible law, and a pure compressible source. Being mainly a function of the increments, the compact law is Galilean invariant but is dependent on the background magnetic field if one is present. Only the magnetohydrodynamic source term requires multi-spacecraft data to be estimated whereas the other components, which include those introduced by the Hall term, can be fully computed with single-spacecraft data using the Taylor hypothesis. These properties make this compact law more appropriate for analysing both numerical simulations and in situ data gathered in space plasmas, in particular when only single-spacecraft data are available.

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Energy cascade rate in isothermal compressible magnetohydrodynamic turbulence

Journal of Plasma Physics ◽

10.1017/s0022377818000788 ◽

2018 ◽

Vol 84 (4) ◽

Cited By ~ 10

Author(s):

N. Andrés ◽

F. Sahraoui ◽

S. Galtier ◽

L. Z. Hadid ◽

P. Dmitruk ◽

...

Keyword(s):

Three Dimensional ◽

Rotation Group ◽

Energy Cascade ◽

Relative Importance ◽

Dominant Contribution ◽

Magnetohydrodynamic Turbulence ◽

Guide Field ◽

Small Scales ◽

Spurious Results

Three-dimensional direct numerical simulations are used to study the energy cascade rate in isothermal compressible magnetohydrodynamic turbulence. Our analysis is guided by a two-point exact law derived recently for this problem in which flux, source, hybrid and mixed terms are present. The relative importance of each term is studied for different initial subsonic Mach numbers$M_{S}$and different magnetic guide fields$\boldsymbol{B}_{0}$. The dominant contribution to the energy cascade rate comes from the compressible flux, which depends weakly on the magnetic guide field$\boldsymbol{B}_{0}$, unlike the other terms whose moduli increase significantly with$M_{S}$and$\boldsymbol{B}_{0}$. In particular, for strong$\boldsymbol{B}_{0}$the source and hybrid terms are dominant at small scales with almost the same amplitude but with a different sign. A statistical analysis undertaken with an isotropic decomposition based on the SO(3) rotation group is shown to generate spurious results in the presence of$\boldsymbol{B}_{0}$, when compared with an axisymmetric decomposition better suited to the geometry of the problem. Our numerical results are compared with previous analyses made within situmeasurements in the solar wind and the terrestrial magnetosheath.

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Uncertainties of the solar wind in-situ velocity measurements

Communications of the Byurakan Astrophysical Observatory ◽

10.52526/25792776-2020.67.2-193 ◽

2020 ◽

pp. 193-197

Author(s):

G. Gogoberidze ◽

E. Gorgaslidze

Keyword(s):

Solar Wind ◽

Independent Method ◽

Inertial Range ◽

Velocity Measurements ◽

Fast Solar Wind ◽

Magnetohydrodynamic Turbulence ◽

Velocity Fluctuations ◽

Measurement Uncertainties ◽

General Instrument

We study spectral features of Alfvénic turbulence in fast solar wind. We propose a general, instrument independent method to estimate the uncertainty in velocity fluctuations obtained by in-situ satellite observations in the solar wind. We show that when the measurement uncertainties of the velocity fluctuations are taken into account the less energetic Elsasser spectrum obeys a unique power law scaling throughout the inertial range as prevailing theories of magnetohydrodynamic turbulence predict.

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Turbulence Characteristics in an Elevated Shear Layer over Owens Valley

Journal of the Atmospheric Sciences ◽

10.1175/2010jas3156.1 ◽

2010 ◽

Vol 67 (7) ◽

pp. 2355-2371 ◽

Cited By ~ 7

Author(s):

Qingfang Jiang ◽

James D. Doyle ◽

Vanda Grubišić ◽

Ronald B. Smith

Keyword(s):

Shear Layer ◽

Energy Cascade ◽

Inertial Subrange ◽

Turbulence Energy ◽

Owens Valley ◽

Turbulent Layer ◽

Aspect Ratios ◽

Rotor Experiment ◽

Large Eddies

Abstract Characteristics of turbulence in the lower and middle troposphere over Owens Valley have been examined using aircraft in situ measurements obtained from the Terrain-Induced Rotor Experiment. The two events analyzed in this study are characterized by a deep turbulent layer from the valley floor up to the midtroposphere associated with the interaction between trapped waves and an elevated shear layer. Kelvin–Helmholtz (KH) instability develops above the mountaintop level and often along the wave crests where the Richardson number is reduced. The turbulence induced by KH instability is characterized by a progressive downscale energy cascade, a well-defined inertial subrange up to 1 km, and large eddies with vertical to horizontal aspect ratios less than unity. The turbulence below the mountaintop level is largely shear induced, associated with wave steepening and breaking, and is more isotropic. Evaluation of structure functions indicates that while the turbulence energy cascade is predominately downscale, upscale energy transfer exists with horizontal scales from a few hundred meters to a few kilometers because of the transient energy dispersion of large eddies generated by KH instability and gravity wave steepening or breaking.

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Energy cascade and its locality in compressible magnetohydrodynamic turbulence

Physical Review E ◽

10.1103/physreve.93.061102 ◽

2016 ◽

Vol 93 (6) ◽

Cited By ~ 18

Author(s):

Yan Yang ◽

Yipeng Shi ◽

Minping Wan ◽

William H. Matthaeus ◽

Shiyi Chen

Keyword(s):

Energy Cascade ◽

Magnetohydrodynamic Turbulence

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Field theoretic calculation of energy cascade rates in non-helical magnetohydrodynamic turbulence

Pramana ◽

10.1007/bf02705480 ◽

2003 ◽

Vol 61 (3) ◽

pp. 577-594 ◽

Cited By ~ 11

Author(s):

Mahendra K. Verma

Keyword(s):

Energy Cascade ◽

Magnetohydrodynamic Turbulence

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Interstellar dust in the solar system: model versus in situ spacecraft data

Astronomy and Astrophysics ◽

10.1051/0004-6361/201834316 ◽

2019 ◽

Vol 626 ◽

pp. A37 ◽

Cited By ~ 6

Author(s):

Harald Krüger ◽

Peter Strub ◽

Nicolas Altobelli ◽

Veerle J. Sterken ◽

Ralf Srama ◽

...

Keyword(s):

Solar System ◽

Model Calibration ◽

Interstellar Dust ◽

Space Missions ◽

Dust Particles ◽

Data Sets ◽

Charged Dust ◽

Time Intervals ◽

Spacecraft Data

Context. In the early 1990s, contemporary interstellar dust penetrating deep into the heliosphere was identified with the in situ dust detector on board the Ulysses spacecraft. Later on, interstellar dust was also identified in the data sets measured with dust instruments on board Galileo, Cassini, and Helios. Ulysses monitored the interstellar dust stream at high ecliptic latitudes for about 16 yr. The three other spacecraft data sets were obtained in the ecliptic plane and cover much shorter time intervals. Aims. To test the reliability of the model predictions, we compare previously published in situ interstellar dust measurements, obtained with these four spacecraft, with predictions of an advanced model for the dynamics of interstellar dust in the inner solar system (Interplanetary Meteoroid environment for EXploration; IMEX). Methods. Micrometer and sub-micrometer-sized dust particles are subject to solar gravity, radiation pressure and the Lorentz force on a charged dust particle moving through the interplanetary magnetic field. These forces lead to a complex size-dependent flow pattern of interstellar dust in the planetary system. The IMEX model was calibrated with the Ulysses interstellar dust measurements and includes these relevant forces. We study the time-resolved flux and mass distribution of interstellar dust in the solar system. Results. The IMEX model agrees with the spacecraft measurements within a factor of 2–3, including time intervals and spatial regions not covered by the original model calibration with the Ulysses data set. The model usually underestimates the dust fluxes measured by the space missions which were not used for the model calibration, i.e. Galileo, Cassini, and Helios. Conclusions. A unique time-dependent model, IMEX is designed to predict the interstellar dust fluxes and mass distributions for the inner and outer solar system. The model is suited to study dust detection conditions for past and future space missions.

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Helios spacecraft data revisited: detection of cometary meteoroid trails by following in situ dust impacts

Astronomy and Astrophysics ◽

10.1051/0004-6361/202038935 ◽

2020 ◽

Vol 643 ◽

pp. A96

Author(s):

Harald Krüger ◽

Peter Strub ◽

Max Sommer ◽

Nicolas Altobelli ◽

Hiroshi Kimura ◽

...

Keyword(s):

Solar System ◽

Dust Cloud ◽

Interplanetary Dust ◽

Dust Particles ◽

True Anomaly ◽

Spatial Density ◽

The Sun ◽

Narrow Region ◽

Spacecraft Data

Context. Cometary meteoroid trails exist in the vicinity of comets, forming a fine structure of the interplanetary dust cloud. The trails consist predominantly of the largest cometary particles (with sizes of approximately 0.1 mm–1 cm), which are ejected at low speeds and remain very close to the comet orbit for several revolutions around the Sun. In the 1970s, two Helios spacecraft were launched towards the inner Solar System. The spacecraft were equipped with in situ dust sensors which measured the distribution of interplanetary dust in the inner Solar System for the first time. Recently, when re-analysing the Helios data, a clustering of seven impacts was found, detected by Helios in a very narrow region of space at a true anomaly angle of 135 ± 1°, which the authors considered as potential cometary trail particles. However, at the time, this hypothesis could not be studied further. Aims. We re-analyse these candidate cometary trail particles in the Helios dust data to investigate the possibility that some or all of them indeed originate from cometary trails and we constrain their source comets. Methods. The Interplanetary Meteoroid Environment for eXploration (IMEX) dust streams in space model is a new and recently published universal model for cometary meteoroid streams in the inner Solar System. We use IMEX to study the traverses of cometary trails made by Helios. Results. During ten revolutions around the Sun, the Helios spacecraft intersected 13 cometary trails. For the majority of these traverses the predicted dust fluxes are very low. In the narrow region of space where Helios detected the candidate dust particles, the spacecraft repeatedly traversed the trails of comets 45P/Honda-Mrkos-Pajdušáková and 72P/Denning-Fujikawa with relatively high predicted dust fluxes. The analysis of the detection times and particle impact directions shows that four detected particles are compatible with an origin from these two comets. By combining measurements and simulations we find a dust spatial density in these trails of approximately 10−8–10−7 m−3. Conclusions. The identification of potential cometary trail particles in the Helios data greatly benefited from the clustering of trail traverses in a rather narrow region of space. The in situ detection and analysis of meteoroid trail particles which can be traced back to their source bodies by spacecraft-based dust analysers provides a new opportunity for remote compositional analysis of comets and asteroids without the necessity to fly a spacecraft to or even land on those celestial bodies. This provides new science opportunities for future missions like DESTINY+ (Demonstration and Experiment of Space Technology for INterplanetary voYage with Phaethon fLyby and dUst Science), Europa Clipper, and the Interstellar Mapping and Acceleration Probe.

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