[IGPP Everyone] Today - Friday - First EPSS Space Physics seminar - October 1, 2021

[Sowmendran, Margie (IGPP)]

T O D A Y

R E M I N D E R

SPACE PHYSICS SEMINAR

Dear Friends and colleagues, the EPSS Fall Space Physics Seminar series will begin in Zoom, this Friday. We will see how things evolve and may host some seminars live as well.


ZOOM LINK PROVIDED BELOW



 https://ucla.zoom.us/j/92101918782?pwd=Z2o5RmI4OEpBWW4zcG1DZStIUWgrZz09





Date/Time: October 1, 2021/ 03:30 PM Pacific Time (US and Canada)



SPACE PHYSICS SEMINAR



DEPARTMENT OF EARTH, PLANETARY, AND SPACE SCIENCES

DEPARTMENT OF ATMOSPHERIC AND OCEANIC SCIENCES

UNIVERSITY OF CALIFORNIA, LOS ANGELES



Chen Shi

EPSS, UCLA




Evolution of MHD turbulence in the solar wind: Parker Solar Probe observations and numerical simulations

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Parker Solar Probe (PSP) measures the magnetic field and plasma parameters of the solar wind at unprecedentedly close distances to the Sun, providing a great opportunity to study the early-stage evolution of magnetohydrodynamic (MHD) turbulence in the solar wind. Here we use PSP data to explore the nature of solar wind turbulence focusing on the Alfvénic character and power spectra of the fluctuations and their dependence on heliocentric distance and context (i.e., large-scale solar wind properties), aiming to understand the role that different effects such as source properties, solar wind expansion, and stream interaction might play in determining the turbulent state. We carried out a statistical survey of the data from the first five orbits of PSP with a focus on how the fluctuation properties at the MHD scales vary with different solar wind streams and the distance from the Sun. A more in-depth analysis from several selected periods is also presented. By tracing the magnetic footpoints of the wind streams measured by PSP, we show that the source region of the slow solar wind may have a great impact on its Alfvénicity. We compare these observational results with a series of 2D expanding-box-model (EBM) MHD simulations. The simulation results show that the large-scale solar wind structures, e.g. the stream shears and heliospheric current sheets, may explain the observed evolution of certain properties of the turbulence such as the normalized residual energy and normalized cross helicity.




Friday, October 1, 2021

3:30 - 5:00 PM



In-Charge:  Marco Velli
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