[IGPP Everyone] 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]

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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