As CMEs are the main driver of interplanetary and geomagnetic disturbances, interplanetary space can be considered as a transmission channel of hazardous space weather effects connecting the Sun and the Earth. CMEs cause phenomena on the Earth such as geomagnetic storms and solar energetic particles that can result in major space weather effects ( Forbes et al., 2006). The background solar wind flow is frequently disturbed by coronal mass ejections (CMEs), large-scale expulsions of plasma and magnetic field from the solar atmosphere. At solar maxima, this bimodal configuration gives way to a more complex mixture of slow and fast streams at all heliospheric latitudes, depending on the distribution of open and closed magnetic regions and the highly tilted magnetic polarity inversion line. According to the Ulysses’ fast-latitudinal scan between ± 80°, the distribution of the solar wind within the heliosphere is clearly bimodal, with differing compositions, temperatures, temperature anisotropies, speeds, small scale fluctuations ( McComas et al., 2002). The solar wind in the heliosphere was locally sampled by Ulysses along its out-of-ecliptic orbit. According to PSP observation during encounter 8, the magnetic field and flow velocity vectors were highly aligned in the sub-Alfvénic solar wind ( Zank et al., 2022). The first in situ detections enabled by PSP reveal the distinct nature of turbulence, anisotropy, intermittency, and directional switchback properties of these sub-Alfvénic winds ( Kasper et al., 2019). The sub-Alfvénic solar wind in the inner heliosphere was firstly measured by Parker Solar Probe ( PSP) during its 8th and 9th solar encounters, at a distance of ≈ 16 solar radii ( R ⊙) from the Sun. The Alfvén surface is the locus where the radial motion of the accelerating solar wind passes the radial Alfvén speed. The solar wind was intuitively conceived as a result of hot coronal expansion. The ion species of the solar wind plasma include protons, alpha particles, and minor heavy ions. The solar wind escapes from the Sun, travels at a supersonic and super-Alfvénic speed, permeates interplanetary space, and ultimately fills the whole heliosphere.
0 Comments
Leave a Reply. |
AuthorWrite something about yourself. No need to be fancy, just an overview. ArchivesCategories |