Yukitoshi Nishimura, PhDAssistant Researcher University of California, Los Angeles

Mechanical Engineering

Yukitoshi Nishimura has deeply engaged in auroral physics, particularly electromagnetic energy transfer processes in the near-Earth space, a fundamental topic for understanding plasma transport and energization. He has revealed precursors of auroral substorms, which manifest as high-latitude auroral intensifications moving toward substorm onset location. This finding was highlighted in the NASA press release and led to a number of related studies and collaborations. He has also discovered the link between pulsating aurora and intensity-modulating chorus and developed a technique to identify magnetic field mapping, whose results have been published in Science. His approach uses not only auroral imaging but radars, equatorial and low-altitude satellites, and magnetometers. In addition, he is active in student education. He has co-supervised eight graduate and two undergraduate students in U.S. and Japan.

Exploring Near-Earth Space Dynamics Using Aurora: Role of Transient Fast Flows

4 PM Wednesday, March 18th Room 245, 110 Cummington MallRefreshments served at 3:45 PM

Junior Faculty Candidate Lecture SeriesHost: Joshua Semeter

Aurora, optical emissions in the upper polar atmosphere, reflects a variety of space phenomena around the Earth, and thus optical observations can be used for remote sensing of space environment. Auroral phenomena are not only important for Space Physics but also impact human society such as radio communication and satellite operation during large space weather events. This talk will firstly introduce a few examples of those, and then present recent progresses in auroral research particularly on the following two science questions. (1) Is there any auroral precursor to substorm onset? (2) Where do auroral precursors (magnetotail flows) originate? Is magnetic reconnection spontaneous or driven? Results from auroral imaging, radars and satellites emphasize that transient flows from dayside to nightside are important for driving nightside aurora and plasma sheet flows. Also found is that such plasma sheet flows influence inner magnetospheric phenomena including subauroral fast flows and diffuse aurora. Finally, I will present my future research plans on (1) space-based imaging experiments motivated by the science mentioned above, (2) ground-based imaging network in coordination with the upcoming NASA Heliophysics system observatory, and (3) numerical modeling of energy transport in the magnetosphere-ionosphere-atmosphere system.