Asymmetric multifractal model for solar wind intermittent turbulence

Abstract. We consider nonuniform energy transfer rate for solar wind turbulence depending on the solar cycle activity. To achieve this purpose we determine the generalized dimensions and singularity spectra for the experimental data of the solar wind measured in situ by Advanced Composition Explorer spacecraft during solar maximum (2001) and minimum (2006) at 1 AU. By determining the asymmetric singularity spectra we confirm the multifractal nature of different states of the solar wind. Moreover, for explanation of this asymmetry we propose a generalization of the usual so-called p-model, which involves eddies of different sizes for the turbulent cascade. Naturally, this generalization takes into account two different scaling parameters for sizes of eddies and one probability measure parameter, describing how the energy is transferred to smaller eddies. We show that the proposed model properly describes multifractality of the solar wind plasma.

Download Full-text

Multifractal two-scale Cantor set model for slow solar wind turbulence in the outer heliosphere during solar maximum

Nonlinear Processes in Geophysics ◽

10.5194/npg-18-287-2011 ◽

2011 ◽

Vol 18 (3) ◽

pp. 287-294 ◽

Cited By ~ 6

Author(s):

W. M. Macek ◽

A. Wawrzaszek

Keyword(s):

Solar Wind ◽

Solar Maximum ◽

Multifractal Spectrum ◽

Cantor Set ◽

Slow Solar Wind ◽

Intermittent Turbulence ◽

Outer Heliosphere ◽

Solar Wind Turbulence ◽

Wind Turbulence ◽

Generalized Dimensions

Abstract. To quantify solar wind turbulence, we consider a generalized two-scale weighted Cantor set with two different scales describing nonuniform distribution of the kinetic energy flux between cascading eddies of various sizes. We examine generalized dimensions and the corresponding multifractal singularity spectrum depending on one probability measure parameter and two rescaling parameters. In particular, we analyse time series of velocities of the slow speed streams of the solar wind measured in situ by Voyager 2 spacecraft in the outer heliosphere during solar maximum at various distances from the Sun: 10, 30, and 65 AU. This allows us to look at the evolution of multifractal intermittent scaling of the solar wind in the distant heliosphere. Namely, it appears that while the degree of multifractality for the solar wind during solar maximum is only weakly correlated with the heliospheric distance, but the multifractal spectrum could substantially be asymmetric in a very distant heliosphere beyond the planetary orbits. Therefore, one could expect that this scaling near the frontiers of the heliosphere should rather be asymmetric. It is worth noting that for the model with two different scaling parameters a better agreement with the solar wind data is obtained, especially for the negative index of the generalized dimensions. Therefore we argue that there is a need to use a two-scale cascade model. Hence we propose this model as a useful tool for analysis of intermittent turbulence in various environments and we hope that our general asymmetric multifractal model could shed more light on the nature of turbulence.

Download Full-text

The solar wind at solar maximum: comparisons of EISCAT IPS and in situ observations

Annales Geophysicae ◽

10.5194/angeo-20-1291-2002 ◽

2002 ◽

Vol 20 (9) ◽

pp. 1291-1309 ◽

Cited By ~ 10

Author(s):

A. R. Breen ◽

P. Riley ◽

A. J. Lazarus ◽

A. Canals ◽

R. A. Fallows ◽

...

Keyword(s):

Solar Wind ◽

Large Scale ◽

Solar Maximum ◽

Longitudinal Velocity ◽

Solar Wind Plasma ◽

The Sun ◽

Fast Wind ◽

Interplanetary Physics ◽

Wind Velocities

Abstract. The solar maximum solar wind is highly structured in latitude, longitude and in time. Coronal measurements show a very high degree of variability, with large variations that are less apparent within in situ spacecraft measurements. Interplanetary scintillation (IPS) observations from EISCAT, covering distances from 20 to 100 solar radii (RS), are an ideal source of information on the inner solar wind and can be used, therefore, to cast light on its evolution with distance from the Sun. Earlier comparisons of in situ and IPS measurements under solar minimum conditions showed good large-scale agreement, particularly in the fast wind. In this study we attempt a quantitative comparison of measurements made over solar maximum by EISCAT (20–100 RS) and the Wind and Ulysses spacecraft (at 215 RS and 300–1000 RS, respectively). The intervals studied were August–September 1999, May 2000, September 2000 and May 2001, the last-named being the period of the second Ulysses fast latitude scan. Both ballistic and – when possible – MHD/ballistic hybrid models were used to relate the data sets, and we compare the results obtained from these two mapping methods. The results of this study suggest that solar wind velocities measured in situ were less variable than those estimated from IPS measurements closer to the Sun, with the greatest divergence between IPS velocities and in situ measurements occurring in regions where steep longitudinal velocity gradients were seen in situ. We suggest that the interaction between streams of solar wind with different velocities leads to "smoothing" of solar wind velocities between 30–60 RS and 1 AU, and that this process continues at greater distances from the Sun.Key words. Interplanetary physics (solar wind plasma; sources of the solar wind; instruments and techniques)

Download Full-text

Plasma and Magnetic Field Turbulence in the Earth’s Magnetosheath at Ion Scales

Frontiers in Astronomy and Space Sciences ◽

10.3389/fspas.2020.616635 ◽

2021 ◽

Vol 7 ◽

Author(s):

Liudmila Rakhmanova ◽

Maria Riazantseva ◽

Georgy Zastenker

Keyword(s):

Magnetic Field ◽

Solar Wind ◽

Solar Wind Plasma ◽

Bow Shock ◽

Present Review ◽

Wind Effects ◽

Earth’S Bow Shock ◽

Magnetic Field Turbulence ◽

Plasma Measurements ◽

Turbulent Cascade

Crossing the Earth’s bow shock is known to crucially affect solar wind plasma including changes in turbulent cascade. The present review summarizes results of more than 15 years of experimental exploration into magnetosheath turbulence. Great contributions to understanding turbulence development inside the magnetosheath was made by means of recent multi-spacecraft missions. We introduce the main results provided by them together with first observations of the turbulent cascade based on direct plasma measurements by the Spektr-R spacecraft in the magnetosheath. Recent results on solar wind effects on turbulence in the magnetosheath are also discussed.

Download Full-text

Statistical relations between in-situ measured Bz component and thermospheric density variations

10.5194/egusphere-egu21-4773 ◽

2021 ◽

Author(s):

Sofia Kroisz ◽

Lukas Drescher ◽

Manuela Temmer ◽

Sandro Krauss ◽

Barbara Süsser-Rechberger ◽

...

Keyword(s):

Magnetic Field ◽

Solar Wind ◽

Field Measurements ◽

Satellite Orbit ◽

Solar Wind Plasma ◽

Statistical Investigation ◽

Neutral Density ◽

Special Focus ◽

Short Term

Through advanced statistical investigation and evaluation of solar wind plasma and magnetic field data, we investigate the statistical relation between the magnetic field Bz component, measured at L1, and Earth&#8217;s thermospheric neutral density. We will present preliminary results of the time series analyzes using in-situ plasma and magnetic field measurements from different spacecraft in near Earth space (e.g., ACE, Wind, DSCOVR) and relate those to derived thermospheric densities from various satellites (e.g., GRACE, CHAMP). The long and short term variations and dependencies in the solar wind data are related to variations in the neutral density of the thermosphere and geomagnetic indices. Special focus is put on the specific signatures that stem from coronal mass ejections and stream or corotating interaction regions.&#160; The results are used to develop a novel short-term forecasting model called SODA (Satellite Orbit DecAy). This is a joint study between TU Graz and University of Graz funded by the FFG Austria (project &#8220;SWEETS&#8221;).

Download Full-text

Dynamical evolution of the inner heliosphere approaching solar activity maximum: interpreting Ulysses observations using a global MHD model

Annales Geophysicae ◽

10.5194/angeo-21-1347-2003 ◽

2003 ◽

Vol 21 (6) ◽

pp. 1347-1357 ◽

Cited By ~ 17

Author(s):

P. Riley ◽

Z. Mikić ◽

J. A. Linker

Keyword(s):

Magnetic Field ◽

Solar Wind ◽

Solar Maximum ◽

Dynamical Evolution ◽

Solar Wind Plasma ◽

Polar Regions ◽

Activity Maximum ◽

Interplanetary Magnetic Fields ◽

Interplanetary Physics ◽

Interaction Regions

Abstract. In this study we describe a series of MHD simulations covering the time period from 12 January 1999 to 19 September 2001 (Carrington Rotation 1945 to 1980). This interval coincided with: (1) the Sun’s approach toward solar maximum; and (2) Ulysses’ second descent to the southern polar regions, rapid latitude scan, and arrival into the northern polar regions. We focus on the evolution of several key parameters during this time, including the photospheric magnetic field, the computed coronal hole boundaries, the computed velocity profile near the Sun, and the plasma and magnetic field parameters at the location of Ulysses. The model results provide a global context for interpreting the often complex in situ measurements. We also present a heuristic explanation of stream dynamics to describe the morphology of interaction regions at solar maximum and contrast it with the picture that resulted from Ulysses’ first orbit, which occurred during more quiescent solar conditions. The simulation results described here are available at: http://sun.saic.com.Key words. Interplanetary physics (Interplanetary magnetic fields; solar wind plasma; sources of the solar wind)

Download Full-text

Kinetic Signatures and Intermittent Turbulence in the Solar Wind Plasma

Physical Review Letters ◽

10.1103/physrevlett.108.261103 ◽

2012 ◽

Vol 108 (26) ◽

Cited By ~ 70

Author(s):

K. T. Osman ◽

W. H. Matthaeus ◽

B. Hnat ◽

S. C. Chapman

Keyword(s):

Solar Wind ◽

Solar Wind Plasma ◽

Intermittent Turbulence

Download Full-text

In situ local shock speed and transit shock speed

Annales Geophysicae ◽

10.1007/s00585-998-0370-9 ◽

1998 ◽

Vol 16 (4) ◽

pp. 370-375 ◽

Cited By ~ 10

Author(s):

S. Watari ◽

T. Detman

Keyword(s):

Solar Wind ◽

Solar Wind Plasma ◽

Interplanetary Shock ◽

Propagation Model ◽

Interplanetary Shocks ◽

Shock Speed ◽

Interplanetary Physics ◽

Speed Solar Wind ◽

Transit Speed

Abstract. A useful index for estimating the transit speeds was derived by analyzing interplanetary shock observations. This index is the ratio of the in situ local shock speed and the transit speed; it is 0.6–0.9 for most observed shocks. The local shock speed and the transit speed calculated for the results of the magnetohydrodynamic simulation show good agreement with the observations. The relation expressed by the index is well explained by a simplified propagation model assuming a blast wave. For several shocks the ratio is approximately 1.2, implying that these shocks accelerated during propagation in slow-speed solar wind. This ratio is similar to that for the background solar wind acceleration.Keywords. Interplanetary physics (Flare and stream dynamics; Interplanetary shocks; Solar wind plasma)

Download Full-text

The RPW Low Frequency Receiver (LFR) on Solar Orbiter: in-situ LF electric and magnetic field measurements of the solar wind expansion

10.5194/egusphere-egu2020-10050 ◽

2020 ◽

Author(s):

Thomas Chust ◽

Olivier Le Contel ◽

Matthieu Berthomier ◽

Alessandro Retinò ◽

Fouad Sahraoui ◽

...

Keyword(s):

Solar Wind ◽

Low Frequency ◽

Field Measurements ◽

Solar Wind Plasma ◽

Wind Condition ◽

The Sun ◽

Nasa Mission ◽

Magnetic Field Measurements ◽

Electric And Magnetic Field

Solar Orbiter (SO) is an ESA/NASA mission for exploring the Sun-Heliosphere connection which has been launched in February 2020. The Low Frequency Receiver (LFR) is one of the main subsystems of the Radio and Plasma Wave (RPW) experiment on SO. It is designed for characterizing the low frequency (~0.1Hz&#8211;10kHz) electromagnetic fields & waves which develop, propagate, interact, and dissipate in the solar wind plasma. In correlation with particle observations it will help to understand the heating and acceleration processes at work during its expansion. We will present the first LFR data gathered during the Near Earth Commissioning Phase, and will compare them with MMS data recorded in similar solar wind condition.

Download Full-text

Solar wind charge exchange in cometary atmospheres

Astronomy and Astrophysics ◽

10.1051/0004-6361/201834881 ◽

2019 ◽

Vol 630 ◽

pp. A37 ◽

Cited By ~ 6

Author(s):

Cyril Simon Wedlund ◽

Etienne Behar ◽

Hans Nilsson ◽

Markku Alho ◽

Esa Kallio ◽

...

Keyword(s):

Solar Wind ◽

Charge Exchange ◽

Cross Sections ◽

Extreme Ultraviolet ◽

Solar Wind Plasma ◽

Analytical Models ◽

Sharp Drop ◽

Solar Wind Charge Exchange ◽

Comet 67P

Context. Solar wind charge-changing reactions are of paramount importance to the physico-chemistry of the atmosphere of a comet. The ESA/Rosetta mission to comet 67P/Churyumov-Gerasimenko (67P) provides a unique opportunity to study charge-changing processes in situ. Aims. To understand the role of these reactions in the evolution of the solar wind plasma and interpret the complex in situ measurements made by Rosetta, numerical or analytical models are necessary. Methods. We used an extended analytical formalism describing solar wind charge-changing processes at comets along solar wind streamlines. The model is driven by solar wind ion measurements from the Rosetta Plasma Consortium-Ion Composition Analyser (RPC-ICA) and neutral density observations from the Rosetta Spectrometer for Ion and Neutral Analysis-Comet Pressure Sensor (ROSINA-COPS), as well as by charge-changing cross sections of hydrogen and helium particles in a water gas. Results. A mission-wide overview of charge-changing efficiencies at comet 67P is presented. Electron capture cross sections dominate and favor the production of He and H energetic neutral atoms (ENAs), with fluxes expected to rival those of H+ and He2+ ions. Conclusions. Neutral outgassing rates are retrieved from local RPC-ICA flux measurements and match ROSINA estimates very well throughout the mission. From the model, we find that solar wind charge exchange is unable to fully explain the magnitude of the sharp drop in solar wind ion fluxes observed by Rosetta for heliocentric distances below 2.5 AU. This is likely because the model does not take the relative ion dynamics into account and to a lesser extent because it ignores the formation of bow-shock-like structures upstream of the nucleus. This work also shows that the ionization by solar extreme-ultraviolet radiation and energetic electrons dominates the source of cometary ions, although solar wind contributions may be significant during isolated events.

Download Full-text

Variation of Solar Wind Parameters During Intense Geomagnetic Storms

Himalayan Physics ◽

10.3126/hj.v6i0.18366 ◽

2017 ◽

pp. 80-85 ◽

Cited By ~ 2

Author(s):

Ayush Subedi ◽

Binod Adhikari ◽

Roshan Kumar Mishra

Keyword(s):

Solar Wind ◽

Geomagnetic Storms ◽

Solar Maximum ◽

Coronal Holes ◽

Research Work ◽

Energy Coupling ◽

Solar Wind Plasma ◽

Geomagnetic Disturbance ◽

Strong Impact ◽

Geomagnetic Disturbances

Geomagnetic disturbances are caused by enhanced solar wind magnetospheric energy coupling process. The principal cause of geomagnetic disturbance is the magnetic reconnection that establishes an electrodynamical coupling between the solar wind plasma and magnetosphere. Around solar maximum, the main structures emanating from the sun are sporadic Coronal Mass Ejection (CMEs) and their interplanetary counterparts (ICMEs). During the descending and minimum solar cycle phases, coronal holes occur more often. They appear as dark regions confined to Solar poles during the solar maximum but expand in size and moves toward the solar equator during the descending phase. In this work, we have taken three different geomagnetic storms during solar maxima. For the interpretation of events, we used interplanetary solar wind data and geomagnetic indices. These satellite data and Dst indices (ranging from -100nT to above) are interpreted by using the method of cross correlation. The values of Bz found approximately 20nT, -50nT and -20nT respectively. Similarly, the value of Dst is -250nT, -400nT and -300nT which shows very intense effect. Likewise, the correlation coefficient we obtained from this research work strongly suggest that interplanetary magnetic field Bz has strong impact for the cause of geomagnetic storms.The Himalayan Physics Vol. 6 & 7, April 2017 (80-85)

Download Full-text