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Chaos & Complex Systems Seminar
“Wet chaos”: Characteristics of extreme rains in a changing climate
Date: Tuesday, April 4th
Time: 12:05 pm - 1:00 pm
Place: 4274 Chamberlin (refreshments will be served)
Speaker: John Young, UW Department of Atmospheric and Oceanic Science
Abstract: Edward Lorenz (1917- 2008) produced a series of theoretical papers on the predictability of idealized weather systems which led him to be known as a “Father of Chaos”. He concentrated on weather circulation models which yielded non-periodic behavior. Since “climate” is simply the long-term statistics of weather variability, it also reflects chaos properties which include irregularity of extreme states.<br>
The implication for real weather systems is that precipitation, an important climate variable and by-product of rising moist air, possesses some form of chaos. This is made more complex because precipitating weather releases condensational heating, a positive feedback on the circulation. The properties of chaotic precipitation necessarily depend on the wide varieties space and time scales, ranging from local transient torrential thunderstorms to regional monthly heavy rain totals.<br>
The edges of the attractor basin of precipitation are important because of their impact on ecology and human activities. Examples show how the probability distributions of heavy rain differ greatly from those of temperature, wind, etc. These empirical distributions are uncertain due to limited data length (e.g., 120 years) and improbability of extreme events.

Some questions of interpretation for power law-like relations and dependence on duration will be discussed. Finally, the implications of a temperature-dependent water vapor constraint suggest how global warming may lead to increasing limits of extreme precipitation.
Host: Clint Sprott
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