Relation Between Coronal Hole Areas on the Sun and the Solar Wind Parameters at 1 AU

Solar Physics ◽  
2012 ◽  
Vol 281 (2) ◽  
pp. 793-813 ◽  
Author(s):  
T. Rotter ◽  
A. M. Veronig ◽  
M. Temmer ◽  
B. Vršnak
Keyword(s):  
Solar Wind ◽  
Coronal Hole ◽  
The Sun ◽  
Solar Wind Parameters

Large-scale electron solar wind parameters of the inner heliosphere with Parker Solar Probe/FIELDS

2020 ◽  
Author(s):  
Karine Issautier ◽  
Mingzhe Liu ◽  
Michel Moncuquet ◽  
Nicole Meyer-Vernet ◽  
Milan Maksimovic ◽  
...  
Keyword(s):  
Solar Wind ◽  
Large Scale ◽  
Statistical Study ◽  
Solar Wind Speed ◽  
The Sun ◽  
Solar Wind Parameters ◽  
Power Law Index ◽  
Probe Mission ◽  
Inner Heliosphere

<p>We present in situ properties of electron density and temperature in the inner heliosphere obtained during the three first solar encounters at 35 solar radii of the Parker Solar Probe mission. These preliminary results, recently shown by Moncuquet et al., ApJS, 2020, are obtained from the analysis of the plasma quasi-thermal noise (QTN) spectrum measured by the radio RFS/FIELDS instrument along the trajectories extending between 0.5 and 0.17 UA from the Sun, revealing different states of the emerging solar wind, five months apart. The temperature of the weakly collisional core population varies radially with a power law index of about -0.8, much slower than adiabatic, whereas the temperature of the supra-thermal population exhibits a much flatter radial variation, as expected from its nearly collisionless state. These measured temperatures are close to extrapolations towards the Sun of Helios measurements.</p><p>We also present a statistical study from these in situ electron solar wind parameters, deduced by QTN spectroscopy, and compare the data to other onboard measurements. In addition, we focus on the large-scale solar wind properties. In particular, from the invariance of the energy flux, a direct relation between the solar wind speed and its density can be deduced, as we have already obtained based on Wind continuous in situ measurements (Le Chat et al., Solar Phys., 2012). We study this anti-correlation during the three first solar encounters of PSP.</p>

Formation of current sheets and plasmoids within corotating/stream interaction regions

2020 ◽  
Author(s):  
Timofey Sagitov ◽  
Roman Kislov
Keyword(s):  
Magnetic Field ◽  
Solar Wind ◽  
Coronal Hole ◽  
High Speed ◽  
Solar Rotation ◽  
Coronal Holes ◽  
Rotation Period ◽  
The Sun ◽  
Current Sheets ◽  
Interaction Regions

<p>High speed streams originating from coronal holes are long-lived plasma structures that form corotating interaction regions (CIRs) or stream interface regions (SIRs) in the solar wind. The term CIR is used for streams existing for at least one solar rotation period, and the SIR stands for streams with a shorter lifetime. Since the plasma flows from coronal holes quasi-continuously, CIRs/SIRs simultaneously expand and rotate around the Sun, approximately following the Parker spiral shape up to the Earth’s orbit.</p><p>Coronal hole streams rotate not only around the Sun but also around their own axis of simmetry, resembling a screw. This effect may occur because of the following mechanisms: (1) the existence of a difference between the solar wind speed at different sides of the stream, (2) twisting of the magnetic field frozen into the plasma, and  (3) a vortex-like motion of the edge of the mothering coronal hole at the Sun. The screw type of the rotation of a CIR/SIR can lead to centrifugal instability if CIR/SIR inner layers have a larger angular velocity than the outer. Furthermore, the rotational plasma movement and the stream distortion can twist magnetic field lines. The latter contributes to the pinch effect in accordance with a well-known criterion of Suydam instability (Newcomb, 1960, doi: 10.1016/0003-4916(60)90023-3). Owing to the presence of a cylindrical current sheet at the boundary of a coronal hole, conditions for tearing instability can also appear at the CIR/SIR boundary. Regardless of their geometry, large scale current sheets are subject to various instabilities generating plasmoids. Altogether, these effects can lead to the formation of a turbulent region within CIRs/SIRs, making them filled with current sheets and plasmoids. </p><p>We study a substructure of CIRs/SIRs, characteristics of their rotation in the solar wind, and give qualitative estimations of possible mechanisms which lead to splitting of the leading edge a coronal hole flow and consequent formation of current sheets within CIRs/SIRs.</p>

scholarly journals Anomalous Forbush effects from sources far from Sun center

2008 ◽  
Vol 4 (S257) ◽  
pp. 451-456
Author(s):  
E. Eroshenko ◽  
A. Belov ◽  
H. Mavromichalaki ◽  
V. Oleneva ◽  
A. Papaioannou ◽  
...  
Keyword(s):  
Solar Wind ◽  
Cosmic Ray ◽  
The Sun ◽  
Geomagnetic Disturbances ◽  
Cosmic Ray Intensity ◽  
The Earth ◽  
The Common ◽  
Solar Wind Parameters ◽  
Significant Disturbance ◽  
Forbush Effect

AbstractThe Forbush effects associated with far western and eastern powerful sources on the Sun that occurred on the background of unsettled and moderate interplanetary and geomagnetic disturbances have been studied by data from neutron monitor networks and relevant measurements of the solar wind parameters. These Forbush effects may be referred to a special sub-class of events, with the characteristics like the event in July 2005, and incorporated by the common conditions: absence of a significant disturbance in the Earth vicinity; absence of a strong geomagnetic storm; slow decrease of cosmic ray intensity during the main phase of the Forbush effect. General features and separate properties in behavior of density and anisotropy of 10 GV cosmic rays for this subclass are investigated.

Open magnetic fields on the Sun and solar wind parameters at the Earth’s orbit

2011 ◽  
Vol 55 (3) ◽  
pp. 284-291
Author(s):  
V. N. Obridko ◽  
B. D. Shelting ◽  
I. M. Livshits
Keyword(s):  
Solar Wind ◽  
Magnetic Fields ◽  
The Sun ◽  
Solar Wind Parameters

scholarly journals An astrophysical analysis of weather based on the solar wind parameters

2010 ◽  
Vol 25 (3) ◽  
pp. 171-178 ◽  
Author(s):  
Jugoslav Nikolic ◽  
Milan Radovanovic ◽  
Dragana Milijasevic
Keyword(s):  
Solar Wind ◽  
Energy Range ◽  
Weather Condition ◽  
Case Analysis ◽  
The Sun ◽  
Global Level ◽  
Time Period ◽  
Significant Difference ◽  
Solar Wind Parameters ◽  
Mev Protons

The paper represents an attempt to establish whether the specific processes on the Sun had preceded the sudden weather condition changes in Torino for a selected time period by using the method of analogy. The analysis represents a test on the heliocentric approach, i. e., case analysis which is selected arbitrarily. The results of Mann-Whitney U test on the global level are the basis of the approach to the analysis. In case when 100 MeV protons are observed, the significant difference exists only between the day before the origin of the disturbance and the second day after the origin. At protons in the energy range of 10 MeV, the significant difference exists between the second and the first day before the origin of the disturbance, the day in which it came to the disturbance of the atmosphere, as well as the day after that. Observing 1 MeV protons, the significant difference exists between the second day before the origin of the disturbance in the atmosphere and the next three days (the day before the origin, the day of the origin, and the day after the origin of the disturbance).

scholarly journals Unusually low density regions in the compressed slow wind: Solar wind transients of small coronal hole origin

2020 ◽  
Vol 635 ◽  
pp. A49
Author(s):  
Yong C.-M. Liu ◽  
Zhaohui Qi ◽  
Jia Huang ◽  
Chi Wang ◽  
Hui Fu ◽  
...  
Keyword(s):  
Solar Wind ◽  
Coronal Hole ◽  
Proton Density ◽  
Low Density ◽  
The Sun ◽  
Corotating Interaction Region ◽  
Proton Temperature ◽  
Low Latitudes ◽  
Lower Charge ◽  
Slow Wind

We report on two small solar wind transients embedded in the corotating interaction region, characterized by surprisingly lower proton density compared with their surrounding regions. In addition to lower density, these two small solar wind transients showed other interesting features like higher proton temperature, higher alpha-proton ratios, and lower charge states (C+6/C+5 and O+7/O+6). A synthesized picture for event One combining the observations by STEREO B, ACE, and Wind showed that this small solar transient has an independent magnetic field. Back-mapping links the origin of the small solar transient to a small coronal hole on the surface of the Sun. Considering these special features and the back-mapping, we conclude that such small solar wind transients may have originated from a small coronal hole at low latitudes.

Characterisation and comparison of slow coronal hole wind intervals at 0.13au

2021 ◽  
Author(s):  
Thomas Woolley ◽  
Lorenzo Matteini ◽  
Timothy S Horbury ◽  
Ronan Laker ◽  
Lloyd D Woodham ◽  
...  
Keyword(s):  
Solar Wind ◽  
Current Sheet ◽  
Coronal Hole ◽  
Heliocentric Distance ◽  
Heliospheric Current Sheet ◽  
Polar Coronal Hole ◽  
Slow Solar Wind ◽  
The Sun ◽  
Streamer Belt ◽  
Different Origin

<p>The slow solar wind is thought to consist of a component originating close to the Heliospheric Current Sheet (HCS) in the streamer belt and a component from over-expanded coronal hole boundaries. In order to understand the roles of these contributions with different origin, it is important to separate and characterise them. By exploiting the fact that Parker Solar Probe’s fourth and fifth orbits were the same and the solar conditions were similar, we identify intervals of slow polar coronal hole wind sampled at approximately the same heliocentric distance and latitude. Here, solar wind properties are compared, highlighting typical conditions of the slow coronal hole wind closer to the Sun than ever before. We explore different properties of the plasma, including composition, spectra and microphysics, and discuss possible origins for the features that are observed.</p>

scholarly journals On the scaling of waiting-time distributions of the negative IMF <i>B<sub>z</sub></i> component

2006 ◽  
Vol 24 (10) ◽  
pp. 2735-2741 ◽  
Author(s):  
R. D'Amicis ◽  
R. Bruno ◽  
B. Bavassano ◽  
V. Carbone ◽  
L. Sorriso-Valvo
Keyword(s):  
Magnetic Field ◽  
Solar Wind ◽  
Solar Activity ◽  
Solar Cycle ◽  
Interplanetary Magnetic Field ◽  
Power Law ◽  
Waiting Time ◽  
The Sun ◽  
Activity Phase ◽  
Solar Wind Parameters

Abstract. Statistics associated with the fluctuations in solar wind parameters show a remarkable dependence on the solar activity phase. In particular, we focus our attention on the waiting-time statistics governing the MHD fluctuations of the z-component of the interplanetary magnetic field, which are important within the framework of the Sun-Earth connections, and briefly discuss the preliminary results. Data from several spacecrafts, covering different phases of the solar cycle and different radial distances, are used. We found that propagating Alfvénic fluctuations and convected structures strongly influence the statistics which vary from quasi-Poissonian to power law.

Relation of solar wind parameters to high-latitude magnetic pulsations

2006 ◽  
Vol 12 (1) ◽  
pp. 80-84
Author(s):  
S.N. Samsonov ◽  
◽  
I.Ya. Plotnikov ◽  
D.Y. Sibeck ◽  
Yu. Watermann ◽  
...  
Keyword(s):  
Solar Wind ◽  
High Latitude ◽  
Magnetic Pulsations ◽  
Solar Wind Parameters
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