[IGPP Everyone] TOMORROW: Space Physics seminar - Friday 10/21, 3:30 PM PDT - Modeling the Formation and Expansion of Foreshock Transients (T.Z. Liu, UCLA EPSS)
Emmanuel Masongsong
emasongsong at igpp.ucla.edu
Thu Oct 20 17:54:07 PDT 2022
SPACE PHYSICS SEMINAR
DEPARTMENT OF EARTH, PLANETARY, AND SPACE SCIENCES
DEPARTMENT OF ATMOSPHERIC AND OCEANIC SCIENCES
UNIVERSITY OF CALIFORNIA, LOS ANGELES
Friday, October 21st, 2022
3:30 - 4:30 PM
In-person in Slichter 3853, with refreshments afterwards on Franz Patio
Modeling the Formation and Expansion of Foreshock Transients
Terry Zixu Liu
UCLA EPSS
Hot flow anomalies (HFAs) and foreshock bubbles (FBs) are two types of foreshock transients with the strongest fluctuations, frequently observed in the ion foreshock. They can disturb the magnetosphere-ionosphere system through significant dynamic pressure perturbations and contribute to particle acceleration at shocks. They form due to interaction between the foreshock ions and solar wind discontinuities, but their formation is not yet predictable. This presentation will introduce our recent progress in modeling the formation and expansion of HFAs and FBs. We derive analytical equations of foreshock ion velocities around discontinuities to estimate the foreshock ion-driven current, whose direction provides a quantitative criterion of HFA and FB formation. Through energy conversion from the foreshock ions to the solar wind ions, we derive expansion speed models of FBs during the early formation stage and late expansion stage. We validate and improve the models by comparing with local hybrid simulations, PIC simulations, and observations. Our models provide possibilities to predict the presence of HFAs and FBs by using upstream observations (e.g., at L1 or lunar orbit) so that we can forecast their space weather effects and determine their role in shock acceleration theoretically.
Zoom link: https://ucla.zoom.us/j/98070654630?pwd=aWdrSktueG9xWjU3cDZiQUhGRXV0UT09
In-Charge: Vassilis Angelopoulos
Fall Space Physics Seminar schedule:
October 28, 2022 - Kent Tobiska, Space Envt. Technologies
Radiation hazards as a major space weather on commercial and suborbital aviation
November 4, 2022 - Ben Lynch, UCB SSL
Solar wind (TBC)
November 11, 2022 - Veterans Day - no seminar
November 18, 2022 - Mike Shumko, NASA/GSFC
The Association of Relativistic Electron Microbursts With the Aurora
November 25, 2022 - Thanksgiving - no seminar
December 2, 2022 - Christine Gabrielse-Lin, Aerospace Corp.
Estimating Precipitating Energy Flux, Average Energy, and Hall Auroral Conductance From THEMIS All-Sky-Imagers With Focus on Mesoscales
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