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VERSION:2.0
CALSCALE:GREGORIAN
PRODID:UW-Madison-Physics-Events
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SEQUENCE:0
UID:UW-Physics-Event-5300
DTSTART:20200203T180500Z
DTEND:20200203T185500Z
DTSTAMP:20240328T233835Z
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.
\n
\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.
\n
\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
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