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Date: February 24, 2010 (NOTE DATE – FOURTH WEDNESDAY)
Speaker: Dr. David Straus, Department of Atmospheric, Oceanic and Earth Sciences, George Mason University & Center for Ocean-Land-Atmosphere Studies (COLA)
Topic: Chaos and the Loss of Predictability of Weather and Climate: Jet Streams, Storms and El-Nino
Time and Location: Talk starts at 1:00 pm with Q&A to follow. It will be held in one of the first floor conference rooms at the American Center for Physics, One Physics Ellipse, College Park, MD. This is located off River Road, between Kenilworth Ave. and Paint Branch Parkway.
Abstract: The intrinsic uncertainty of quantum systems seized the public imagination in the 20th century. Yet the inherent uncertainty in the prediction of non-linear classical systems such as the atmosphere and ocean (already hinted at in the 19th century) has also been widely studied recently. Chaos theory describes the loss of our ability to predict analytic non-linear systems beyond a certain range given some error in initial conditions. The atmosphere and ocean systems have even less predictability, since the phase change of water introduces a non-analytic aspect to the fundamental equations.
Examples of loss of predictability in recent medium range forecasts from the best weather-forecasting model in the world will be described. The non-linear dynamics also lead to loss of predictability of winter seasonal means, even in the presence of strong anomalies of surface forcing (as in the case of El Nino, when the tropical eastern Pacific warms significantly). Some results of predictions and simulations of the atmospheric response to El-Nino over North America will illustrate the interplay of storms which may be unpredictable at long range, the statistics of storms (which may be more predictable) and mean climate.
Biography: Dr. David M. Straus received his Ph.D. in theoretical solid state physics from Cornell University in 1977 under Neil Ashcroft, and his Atmospheric Science postdoctoral training at M.I.T under Dr. Jule Charney. He worked at the Goddard Space Flight Center from 1978-1988, when he joined the Center for Ocean-Land-Atmosphere Studies (COLA). He joined George Mason University in 2002, where he is currently the Chair of the Department of Atmospheric, Oceanic and Earth Sciences. He is also Senior Scientist at COLA.
David is interested in the dynamics and predictability of atmospheric motions on a wide range of space and time scales. Specific research topics include the role of mid-latitude non-linear internal dynamics in modulating the response to ENSO, the existence and properties of large scale circulation regimes, the mid-latitude forcing of tropical instabilities and tropical intra-seasonal oscillations, and the role of moist heating in altering the geophysical turbulence properties of the atmosphere. Over the past 25 years he has been fortunate enough to collaborate with J. Shukla, Jule Charney, Richard Lindzen and Franco Molteni, among others. He has helped to develop graduate courses at George Mason in the Physical Climate System, the General Circulation of the Atmosphere, and the Predictability of Weather and Climate. He served as Editor for the Journal of Climate for 4 years.