BEGIN:VCALENDAR VERSION:2.0 CALSCALE:GREGORIAN PRODID:UW-Madison-Physics-Events BEGIN:VEVENT SEQUENCE:0 UID:UW-Physics-Event-5300 DTSTART:20200203T180500Z DTEND:20200203T185500Z DTSTAMP:20260415T040922Z LAST-MODIFIED:20200117T225458Z LOCATION:2241 Chamberlin Hall SUMMARY:How does the magnetosphere go to sleep? Combining global scale simulations and observations to reveal fundamental behaviors of the m agnetosphere \, Plasma Physics (Physics/ECE/NE 922) Seminar\, Therese Moretto Jørgensen\, University of Bergen\, Norway DESCRIPTION:The Earth's magnetic field presents an obstacle to the str eaming magnetized plasma of the solar wind\, thereby creating the magn etosphere. The solar wind\, magnetosphere\, and ionosphere together co nstitute a fascinating\, complex\, and highly dynamic system of intera cting plasmas in the space environment near Earth\, which we can study with satellites and ground-based observations. Much has been learned over the last several decades about the dynamics of this system and th e processes involved but many intriguing questions remain. This talk w ill present a recent study of one such interesting question in magneto spheric research related to the transition between magnetospheric conf igurations under substantial solar wind driving\, and a putative relax ed state after the driving ceases.
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\nEnergy and circulation in the Earth’s magnetosphere and ionosphere are largely determined by conditions in the solar wind and interplanetary magnetic field. Whe n the driving from the solar wind is turned off (to a minimum)\, we ex pect the activity to die down but exactly how this happens is not know n. Utilizing global MHD modelling\, we have addressed the questions of what constitutes the quietest state for the magnetosphere and how it is approached following a northward turning in the IMF that minimizes the driving. We observed an exponential decay with a decay time of abo ut 1 hr in several integrated parameters related to different aspects of magnetospheric activity\, including the total field-aligned current into and out of the ionosphere. The time rate of change for the cessa tion of activity was also measured in total field aligned current esti mates from the AMPERE project\, adding observational support to this f inding.
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\nThe talk will give a brief introduction to magnet osphere research and the background for the study. The simulation mode ls and observational data will be presented and the results will be ex plained and discussed in terms of their physical interpretation as it relates to magnetosphere dynamics and magnetosphere-ionosphere couplin g.
\n URL:https://www.physics.wisc.edu/events/?id=5300 END:VEVENT END:VCALENDAR