[IGPP Everyone] SPACE SCIENCE SEMINAR - Spring Quarter - 3:30pm -Friday April 10, 2020 - Remote

[Marjorie Sowmendran]

SPACE PHYSICS SEMINAR 





Zoom instructions for Remote Attendance 




Date/Time: April 10, 2020/ 03:30 PM Pacific Time (US and Canada) 




Join Zoom Meeting – click on link 



https://ucla.zoom.us/j/208222102 




Meeting ID: 208 222 102 




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SPACE PHYSICS SEMINAR 

DEPARTMENT OF EARTH, PLANETARY, AND SPACE SCIENCES 

DEPARTMENT OF ATMOSPHERIC AND OCEANIC SCIENCES 

UNIVERSITY OF CALIFORNIA, LOS ANGELES 

(AOS M275B, EPSS M288B) 

Ultra-relativistic Electrons in the Earth’s Van Allen Radiation Belts 



Yuri Y. Shprits 

Department of Geophysics,German Research Center for Geociences, GFZ, Potsdam, Germany 

Institute of Physics and Astronomy, University of Potsdam, Germany 

Department of Earth, Planetary, and Space Sciences, UCLA 









Improved understanding of the energization and loss of relativistic electrons in the radiation belts obtained over the last two decades has allowed for the development of VERB-3D and VERB-4D, and models similar to VERB-3D that can accurately reproduce the dynamics of the Van Allen Radiation Belts. The VERB code is now being adopted by AFRL, NASA and NOAA for operational predictions. 




New measurements from the Van Allen Probes clearly demonstrate that the radiation belts cannot be considered as a bulk population above approximately electron rest mass, but ultra-relativistic electrons form a new population that shows a very different morphology (e.g. very narrow remnant belts) and slow but sporadic acceleration. 




We show that acceleration to multi-MeV energies is not a result of a two-step process consisting of local heating and radial diffusion, but occurs locally due to energy diffusion by whistler mode waves. Local heating appears to be able to transport electrons in energy space from 100s of keV all the way to ultra-relativistic energies. Acceleration to such high energies occurs only for the conditions when cold plasma in the trough region shows extreme depletions. 




There is also a clear difference between the loss mechanisms at MeV and multi-MeV energies. The difference between the loss mechanisms at MeV and multi-MeV energies is due to EMIC waves that can very efficiently scatter ultra-relativistic electrons but leave MeV electrons unaffected. 




We also present how the new understanding gained from the Van Allen Probes mission can be used to produce the most accurate data-assimilative forecast. Under the recently funded EU Horizon 2020 Project Prediction of Adverse effects of Geomagnetic storms and Energetic Radiation (PAGER), we will study how ensemble forecasting from the Sun can produce long-term probabilistic forecasts of the radiation environment in the inner magnetosphere. 







Friday April 10, 2020 




In-charge: C. T. Russell 






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