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NIA Seminar by C. Robert Clauer |
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Date: March 8, 2006
Time: 2:00pm
Location: NIA, Rm 137
Current Topics in Geomagnetic Storm Research
C. Robert Clauer, University of Michigan
The Sun’s atmosphere, the solar corona, is so hot (>106K) that it expands (explodes), filling all of interplanetary space with a supersonic magnetized plasma flowing radially outward from the Sun. As this plasma, called the solar wind, passes the Earth, it interacts strongly with the geomagnetic field, severely compressing the field on the day side of the the Earth and drawing it out into a long comet-like tail on the night side. The confined region of geomagnetic field is called the Earth’s magnetosphere.
The solar wind not only confines the geomagnetic field within the magnetospheric cavity, but it also transfers significant mass, momentum, and energy to the magnetosphere, as well as to the ionosphere and upper atmosphere. Consequences of this interaction are the generation of the aurora at high latitudes in both polar regions, the production of a complex set of electrical current systems flowing through the magnetosphere and ionosphere, and the energization of charged particles that can be stored in the radiation belts of the inner magnetosphere or precipitated into the atmosphere. The variations over time of the electric current systems and energetic particle populations can impact human activity in a variety of ways and is consequently the source of what we refer to as space weather.
Along with a brief tutorial, this seminar will discuss two research topics related to geomagnetic storms. The first relates to the identification of an atypical response to interplanetary shocks that produce storm sudden commencements and the suggestion for the development of a new “transition current system” to explain recent observations based on global data. The second topic relates to a newly discovered storm-time magnetospheric convection mode described as global sawtooth oscillations, that are observed during times with unique solar wind driving conditions. Finally, I will discuss the Space Weather Modeling Framework and the recent simulations of the Halloween storms that occurred during October 2003.
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