[IGPP Everyone] SPACE PHYSICS SEMINAR, October 18th, 2019

[MARCO VELLI]

PACE PHYSICSÂ SEMINAR

DEPARTMENT OF EARTH, PLANETARY, AND SPACE SCIENCES

DEPARTMENT OF ATMOSPHERIC AND OCEANIC SCIENCES

UNIVERSITY OF CALIFORNIA, LOS ANGELES


Vlacheslav Pilipenko


Institute of Physics of the Earth, Moscow, Russia (pilipenko_va at mail.ru)


*Fine structure of substorm and geomagnetically induced currents*


The rapid changes of magnetic fields, that is high dB/dt, associated with
substorms can excite large geomagnetically-induced currents (GICs) that can
have harmful effects on technological systems. We have analyzed the
characteristics of the dB/dt enhancements observed in Fennoscandia in 2015
using data from the magnetometer array IMAGE, covering a range of magnetic
latitudes from 68° to 78°. The abrupt magnetic field variations may be
associated with substorm onsets, isolated nightside magnetic impulsive
events (MIEs) with ~10 min duration, and Ps6/Pc5 pulsations (periods 3-15
min). For a detailed examination of the latitudinal structure of magnetic
variability enhancements and their association with auroral oval boundaries
we applied the technique of “magnetic keograms”. This technique helps to
visualize the fine structure of a substorm, namely the time and latitudinal
localization of dB/dt enhancements. A location of the auroral oval
boundaries in a given local time sector has been estimated with the
OVATION-prime model based on energetic particle measurements from the DMSP
satellites. Auroral substorm onset provided the largest magnetic response
on the ground and most intense GIC (few tens of A) when the poleward moving
intensification of dB/dt crossed the latitude of power line. Isolated
nightside MIEs are also effective in excitation of GICs (>10 A), but they
are relatively rare. Quasi-periodic series of MIEs, known as Ps6 / Pi3
pulsations, are effective in excitation of GICs with magnitude about 20 A
and even higher. Monochromatic Pc5 pulsations are capable to induce
noticeable GICs, up to ~13 A.


Friday, October 18th, 2019


Room 6704 Geology


3:30 - 5:00 PM


In Charge

M. Velli.
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