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

Liu, Yong C.‐M.; Zheng, Qi; Huang, Jia; Wang, Chi; Fu, Hui; Klecker, B.; Wang, Linghua; Farrugia, Charles J.

doi:10.1051/0004-6361/201935884

Cited by 5 publications

(1 citation statement)

References 83 publications

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“…There was observational evidence indicating that switchbacks may be related to velocity shear. For example, Liu et al (2020) argued that these kinds of structures occur at the corotating interaction region, which is known as the 4, namely, the convex-outward turning of the switchback is located at the higher radial velocity region. The second row ((b 1 ) and (b 2 )) corresponds to the second category in Figure 4, namely, the concaveoutward turning is located at the higher radial velocity region.…”

Section: Resultsmentioning

confidence: 99%

How Switchbacks Can Maintain a Longer Time in the Interplanetary Space

Yang,

Su,

Chen

2024

ApJ

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Parker Solar Probe, the closest spacecraft to the Sun, has renewed our understanding of the solar corona and the interplanetary space. One of its important findings is the prevalence of switchbacks, which display localized magnetic reversals along the otherwise Parker spirals. While some switchbacks might disappear quickly, others can maintain for a long period of time, and there are indications that many switchbacks strengthen from the solar corona to the interplanetary space despite their magnetic tension force, which tends to straighten the magnetic field lines. Therefore, how these switchbacks could be maintained for a long period of time remains a mystery. In this paper, we employed a 3D data-driven global full magnetohydrodynamics numerical model to explore the evolution of switchbacks formed in the dynamic corona. Our simulations indicate that two factors can affect the lifetime of a switchback. One factor is the combination of angle and leg length ensures that the switchback with greater curvature after reconnection can last longer, and the greater the angle, the more magnetic field lines that can be reconnected, and thus the longer the duration. We call this influencing factor flux tube shape factor. The other factor is the velocity shear, i.e., when the solar wind at the convex-outward turning of a switchback is faster than that at the concave-outward turning, the switchback becomes enhanced during propagation, and it weakens when the velocity difference is opposite.

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Section: Resultsmentioning

confidence: 99%

How Switchbacks Can Maintain a Longer Time in the Interplanetary Space

Yang,

Su,

Chen

2024

ApJ

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Innovative Design of Traditional Arts and Crafts Based on 3D Digital Technology

Lin

2022

3D Imaging—Multidimensional Signal Processing and Deep Learning

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Radial evolution of the accuracy of ballistic solar wind backmapping

Dakeyo,

Badman,

Rouillard

et al. 2024

A&A

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Solar wind backmapping is a technique employed to connect in situ measurements of heliospheric plasma structures to their origin near the Sun. The most widely used method is ballistic mapping, which neglects the effects of solar wind acceleration and corotation and instead models the solar wind as a constant radial outflow whose speed is determined by measurements in the heliosphere. This results in plasma parcel streamlines that form an Archimedean spiral (the Parker spiral) when viewed in the solar corotating frame. This simplified approach assumes that the effects of solar wind acceleration and corotation compensate for each other in the deviation of the source longitude. Most backmapping techniques so far considered magnetic connectivity from a heliocentric distance of 1 au to the Sun. We quantify the angular deviation between different backmapping methods that depends on the location of the radial probe and on the variation in the solar wind speed with radial distance. We assess these differences depending on source longitude and solar wind propagation time. We estimated backmapping source longitudes and travel times using 1) the ballistic approximation (constant speed), 2) a physically justified method using the empirically constrained acceleration profile Iso-poly, derived from Parker solar wind equations and also a model of solar wind tangential flows that accounts for corotational effects. We compared the differences across mapped heliocentric distances and for different asymptotic solar wind speeds. The ballistic method results in a Carrington longitude of the source with a maximum deviation of 4 below 3 au compared to the physics-based mapping method taken as reference. However, the travel time especially for the slow solar wind could be underestimated by 1.5 days at 1 au compared to non-constant speed profile. This time latency may lead to an association of incorrect solar source regions with given in situ measurements. Neglecting corotational effects and accounting for acceleration alone causes a large systematic shift in the backmapped source longitude. Incorporating both acceleration and corotational effects leads to a more physics-based representation of the plasma trajectories through the heliosphere compared to the ballistic assumption. This approach accurately assesses the travel time and provides a more realistic estimate of the longitudinal separation between a plasma parcel measured in situ and its source region. Nonetheless, it requires knowledge of the radial density and Alfvén speed profiles to compute the tangential flow. Therefore, we propose a compromise for computing the source longitude that employs the commonly used ballistic approach and the travel times computed from the derived radial acceleration speed profile. Moreover, we conclude that this approach remains valid at all radial distances we studied and is not limited to data obtained at 1 au.

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

Cited by 5 publications

References 83 publications

How Switchbacks Can Maintain a Longer Time in the Interplanetary Space

How Switchbacks Can Maintain a Longer Time in the Interplanetary Space

Innovative Design of Traditional Arts and Crafts Based on 3D Digital Technology

Radial evolution of the accuracy of ballistic solar wind backmapping

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