scholarly journals The Relationship Between Solar Wind Dynamic Pressure Pulses and Solar Wind Turbulence

2021 ◽  
Vol 9 ◽  
Author(s):  
Mengsi Ruan ◽  
Pingbing Zuo ◽  
Zilu Zhou ◽  
Zhenning Shen ◽  
Yi Wang ◽  
...  
Keyword(s):  
Solar Wind ◽  
Large Scale ◽  
Dynamic Pressure ◽  
Solar Wind Dynamic Pressure ◽  
Occurrence Rate ◽  
Time Lags ◽  
Gaussian Distributions ◽  
Solar Wind Turbulence ◽  
Wind Turbulence ◽  
Pressure Pulses

Solar wind dynamic pressure pulses (DPPs) are small-scale plasma structures with abrupt and large-amplitude plasma dynamic pressure changes on timescales of seconds to several minutes. Overwhelming majority of DPP events (around 79.13%) reside in large-scale solar wind transients, i.e., coronal mass ejections, stream interaction regions, and complex ejecta. In this study, the intermittency, which is a typical feature of solar wind turbulence, is determined and compared during the time intervals in the undisturbed solar wind and in large-scale solar wind transients with clustered DPP events, respectively, as well as in the undisturbed solar wind without DPPs. The probability distribution functions (PDFs) of the fluctuations of proton density increments normalized to the standard deviation at different time lags in the three types of distinct regions are calculated. The PDFs in the undisturbed solar wind without DPPs are near-Gaussian distributions. However, the PDFs in the solar wind with clustered DPPs are obviously non-Gaussian distributions, and the intermittency is much stronger in the large-scale solar wind transients than that in the undisturbed solar wind. The major components of the DPPs are tangential discontinuities (TDs) and rotational discontinuities (RDs), which are suggested to be formed by compressive magnetohydrodynamic (MHD) turbulence. There are far more TD-type DPPs than RD-type DPPs both in the undisturbed solar wind and large-scale solar wind transients. The results imply that the formation of solar wind DPPs could be associated with solar wind turbulence, and much stronger intermittency may be responsible for the high occurrence rate of DPPs in the large-scale solar wind transients.

scholarly journals Solar cycle changes in the geo-effectiveness of small-scale solar wind turbulence measured by Wind and ACE at 1 AU

2007 ◽  
Vol 25 (5) ◽  
pp. 1183-1197 ◽  
Author(s):  
M. L. Parkinson ◽  
R. C. Healey ◽  
P. L. Dyson
Keyword(s):  
Solar Wind ◽  
Solar Cycle ◽  
Solar Minimum ◽  
Large Scale ◽  
Small Scale ◽  
Scaling Exponent ◽  
Mhd Turbulence ◽  
Scaling Exponents ◽  
Solar Wind Turbulence ◽  
Wind Turbulence

Abstract. Multi-scale structure of the solar wind in the ecliptic at 1 AU undergoes significant evolution with the phase of the solar cycle. Wind spacecraft measurements during 1995 to 1998 and ACE spacecraft measurements during 1997 to 2005 were used to characterise the evolution of small-scale (~1 min to 2 h) fluctuations in the solar wind speed vsw, magnetic energy density B2, and solar wind ε parameter, in the context of large-scale (~1 day to years) variations. The large-scale variation in ε most resembled large-scale variations in B2. The probability density of large fluctuations in ε and B2 both had strong minima during 1995, a familiar signature of solar minimum. Generalized Structure Function (GSF) analysis was used to estimate inertial range scaling exponents aGSF and their evolution throughout 1995 to 2005. For the entire data set, the weighted average scaling exponent for small-scale fluctuations in vsw was aGSF=0.284±0.001, a value characteristic of intermittent MHD turbulence (>1/4), whereas the scaling exponents for corresponding fluctuations in B2 and ε were aGSF=0.395±0.001 and 0.334±0.001, respectively. These values are between the range expected for Gaussian fluctuations (1/2) and Kolmogorov turbulence (1/3). However, the scaling exponent for ε changed from a Gaussian-Kolmogorov value of 0.373±0.005 during 1997 (end of solar minimum) to an MHD turbulence value of 0.247±0.004 during 2003 (recurrent fast streams). Changes in the characteristics of solar wind turbulence may be reproducible from one solar cycle to the next.

scholarly journals Solar-wind control of plasma sheet dynamics

2015 ◽  
Vol 33 (7) ◽  
pp. 845-855 ◽  
Author(s):  
M. Myllys ◽  
E. Kilpua ◽  
T. Pulkkinen
Keyword(s):  
Solar Wind ◽  
High Speed ◽  
Large Scale ◽  
Dynamic Pressure ◽  
Low Frequency ◽  
Time History ◽  
Solar Wind Plasma ◽  
Flow Speed ◽  
Occurrence Rate ◽  
Time Interval

Abstract. The purpose of this study is to quantify how solar-wind conditions affect the energy and plasma transport in the geomagnetic tail and its large-scale configuration. To identify the role of various effects, the magnetospheric data were sorted according to different solar-wind plasma and interplanetary magnetic field (IMF) parameters: speed, dynamic pressure, IMF north–south component, epsilon parameter, Auroral Electrojet (AE) index and IMF ultra low-frequency (ULF) fluctuation power. We study variations in the average flow speed pattern and the occurrence rate of fast flow bursts in the magnetotail during different solar-wind conditions using magnetospheric data from five Time History of Events and Macroscale Interactions during Substorms (THEMIS) mission spacecraft and solar-wind data from NASA's OMNIWeb. The time interval covers the years from 2008 to 2011 during the deep solar minimum between cycles 23 and 24 and the relatively quiet rising phase of cycle 24. Hence, we investigate magnetospheric processes and solar-wind–magnetospheric coupling during a relatively quiet state of the magnetosphere. We show that the occurrence rate of the fast (|Vtail| > 100 km s−1) sunward flows varies under different solar-wind conditions more than the occurrence of the fast tailward flows. The occurrence frequency of the fast tailward flows does not change much with the solar-wind conditions. We also note that the sign of the IMF BZ has the most visible effect on the occurrence rate and pattern of the fast sunward flows. High-speed flow bursts are more common during the slow than fast solar-wind conditions.

TCV-like event induced by positive-negative pulse pair of solar wind dynamic pressure

2020 ◽  
Author(s):  
Anmin Tian ◽  
Alexander Degeling ◽  
Quanqi Shi ◽  
Zanyang Xing
Keyword(s):  
Solar Wind ◽  
Large Scale ◽  
Dynamic Pressure ◽  
Radar Data ◽  
Step Function ◽  
Solar Wind Dynamic Pressure ◽  
Negative Pulse ◽  
Pulse Pair ◽  
High Latitude Ionosphere ◽  
Flow Vortex

<p>Both simulations and observations had shown that step function-like increase/decrease of solar wind dynamic pressure pulse would excite flow vortex pairs in the dawn and dusk high latitude ionosphere simultaneously. However, some plasma structures, hot flow anomaly, sheath jets etc. existing in the solar wind or magnetosheath are often accompanied with spike-like changes of the dynamic pressure. Whether they can drive the ionospheric vortices or not is still unclear. In this work we report a traveling convection vortex like (TCV-like) event that was induced by a positive-negative pulse pair of dynamic pressure(△p/p~1) accompanying a large scale (~9min) magnetic hole in the solar wind. It is found that following the magnetic hole, two traveling convection vortices first in anticlockwise then in clockwise rotation were detected by geomagnetic stations located along the 10:30MLT meridian. Meanwhile, another pair of ionospheric vortices azimuthally seen up to 3 MLT first in clockwise then in anticlockwise rotation were appeared in the afternoon sector (~14MLT) centered at ~75MLAT with a trend of poleward moving. The duskside vortices were also confirmed by SuperDARN radar data. The processes following magnetosphere struck by a positive-negative pulse pair were simulated and it found that two pairs of flow vortices in the dawn and dusk magnetosphere may provide the field-aligned currents(FACs) required for the flow/current vortices observed in ionosphere. This work provides a way to understand how the momentum and energy injects to the ionosphere under spike-like dynamic pressures imposing on the magnetosphere.</p>

scholarly journals The Evolution and Role of Solar Wind Turbulence in the Inner Heliosphere

2020 ◽  
Author(s):  
Christopher Chen ◽  
Keyword(s):  
Solar Wind ◽  
Kinetic Energy ◽  
Large Scale ◽  
Energy Levels ◽  
Turbulence Energy ◽  
Energy Fraction ◽  
Solar Wind Turbulence ◽  
Rate Of Increase ◽  
Wind Turbulence ◽  
Order Of Magnitude

<p>The first two orbits of the Parker Solar Probe (PSP) spacecraft have enabled the first in situ measurements of the solar wind down to a heliocentric distance of 0.17 au (or 36 Rs). Here, we present an analysis of this data to study solar wind turbulence at 0.17 au and its evolution out to 1 au. While many features remain similar, key differences at 0.17 au include: increased turbulence energy levels by more than an order of magnitude, a magnetic field spectral index of -3/2 matching that of the velocity and both Elsasser fields, a lower magnetic compressibility consistent with a smaller slow-mode kinetic energy fraction, and a much smaller outer scale that has had time for substantial nonlinear processing. There is also an overall increase in the dominance of outward-propagating Alfvenic fluctuations compared to inward-propagating ones, and the radial variation of the inward component is consistent with its generation by reflection from the large-scale gradient in Alfven speed. The energy flux in this turbulence at 0.17 au was found to be ~10% of that in the bulk solar wind kinetic energy, becoming ~40% when extrapolated to the Alfven point, and both the fraction and rate of increase of this flux towards the Sun is consistent with turbulence-driven models in which the solar wind is powered by this flux.</p>

STRONG SOLAR WIND DYNAMIC PRESSURE PULSES: INTERPLANETARY SOURCES AND THEIR IMPACTS ON GEOSYNCHRONOUS MAGNETIC FIELDS

2015 ◽  
Vol 812 (2) ◽  
pp. 152
Author(s):  
Pingbing Zuo ◽  
Xueshang Feng ◽  
Yanqiong Xie ◽  
Yi Wang ◽  
Xiaojun Xu
Keyword(s):  
Solar Wind ◽  
Magnetic Fields ◽  
Dynamic Pressure ◽  
Solar Wind Dynamic Pressure ◽  
Pressure Pulses

Large-scale structure of solar wind turbulence near solar activity minimum

2000 ◽  
Vol 25 (9) ◽  
pp. 1943-1946 ◽  
Author(s):  
M. Tokumaru ◽  
M. Kojima ◽  
Y. Ishida ◽  
A. Yokobe ◽  
T. Ohmi
Keyword(s):  
Solar Wind ◽  
Solar Activity ◽  
Large Scale ◽  
Large Scale Structure ◽  
Scale Structure ◽  
Solar Activity Minimum ◽  
Solar Wind Turbulence ◽  
Wind Turbulence
Sign in / Sign up

Export Citation Format

Share Document