Topic:Space Weather: Understanding and Forecasting

Speaker: Professor S.T. Wu, Center for Space Plasma and Aeronomic Research & Dept. of Mechnical and Aerospace Engineering, UAH

Date & Time: Thursday, January 17, 2002, 1:30 P.M

Place: Room 140 VMC



On October 27, 1998, NOAA's geostationary satellite, GOES-8, encountered a large amplitude disturbance at 0240 EST, preventing photograph of Hurricane Mitch in the Caribbean. There is strong evidence that the large disturbance that triggered this Earth lock was the result of an electro-static discharge event in the controlling Earth sensor. There were also inconsistent outputs from the on-board computer's altitude and orbit control electronics to the momentum wheels connected to this event. This episode indicates high-tech infrastructure's vulnerability to solar-induced environmental hazards. The anomalies in the event are probably due to a geomagnetic storm in the magnetosphere. These storms follow some coronal mass ejections and solar flares, their propagating shock waves, as well as recurrent interplanetary disturbances, all of which can impact the magnetosphere and ionosphere. The electrical power, communications, and cellular phone industries closely watch these solar-induced events. IRIDIUM satellites have experienced anomalies due to spacecraft charging and deep dielectric discharges in microchips that have also plagued other spacecraft. Ground current fluctuations, commencing with interplanetary shock impact and conversion from AC to DC current in high voltage power lines have resulted in burn-outs of multi-million dollar power transformers in the power grid. These technological "anomalies" have attracted the attention because they have great impact on our society's economic well-being. A world-wide research program on "Space Weather" was introduced by each individual government. In this paper, we will present our current understanding of this subject using current Sun-Earth connection observations and theory and lead to the development of a science-based prediction tool. Specifically, space weather is a consequence of the behavior of the Sun and the interaction of the Earth's geomagnetic environment with the solar wind. Three types of transmission lines to carry the solar disturbance to the Earth's environment induce geomagnetic storms which effect 'high-tech' facilities as discussed above. These three types of transmission lines represent three different time scales of physical processes: (i) electromagnetic radiation, with a delay time of the order of minutes, (ii) high energy charged particles with delay times of the order of hours, and (iii) enhanced solar wind with a delay time of the order of a day or days.



Prof. Wu received his B.S. from national Taiwan University, M.S. from IIT , Chicago and Ph.D. from University of Colorado. He is Distinguished Professor of Mechanical Aerospace Engineering at UAH; the Founder-Director of Institute for Space Physics, Astrophysics & Education; and the Founder-Director for Space Plasma and Aeronomic Research. Dr. Wu has published over 300 articles in Solar Physics, Plasma Physics, Atmospheric Physics and Space Physics.

Refreshments will be served at 12:45 P.M.

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