Study on extreme geomagnetic events and ionospheric response.
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Date
2018
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Abstract
Extreme geomagnetic events are geophysical phenomena that result from the violent
eruptive nature of the Sun. One type Geospace event is magnetic cloud (MC), which
is an attendant of coronal mass ejection (CME). MC-triggered storms can cause injection
of particles into the ionosphere. This can result in an enhance ionization
and conductivity of upper and middle atmosphere. MC can be identi ed based on
geomagnetic parameters and solar wind conditions which show high magnetic eld
magnitudes, low ratio of plasma to magnetic pressure, low proton temperature, and
smooth rotation of the magnetic eld vector. MC events that occurred on 29 April
2014, 17 March 2015, 31 December 2015 and 13 October 2016 were selected for the
study. The hourly average of particle dropouts, precipitation, local ionospheric response
and magnetometer variations in the region over South Africa (33:3oS, 26:5oE)
are examined during geomagnetic storms triggered by MC. The Geostationary Operational
Environmental Satellites (GOES) were inspected for radiation belt particle
dropouts during MC events. Energetic particle precipitation associated with MC
events are obtained from National Oceanic and Atmospheric Administration (NOAA)
Polar Orbiting Environmental Satellites (POES). Results show that particle dropouts
and precipitation vary with the arrival of MC. A closer look of the ground based magnetometer
and the time history of available daytime E-layer critical frequency from
ionosonde indicate that lower ionosphere respond to MC-driven storm.
Description
Master’s Degree. University of KwaZulu-Natal, Durban.