Joint Seminar: A search for chaotic behavior in stratospheric variability and sea-level fluctuations

Northern Hemisphere stratospheric variability is investigated with respect to chaotic behavior using time series from different variables extracted from different re-analysis products and two numerical model runs with different forcing. The time series show red spectra at all frequencies and the probability distribution functions show persistent deviations from a Gaussian distribution. A finite value of the dimensions of a chaotic attractor can be computed for each variable and data product, suggesting that the variability is chaotic and not stochastic. The model runs show similar values for the attractor dimension for both the seasonally forced run and the perpetual winter run, suggesting that the structure of a possible chaotic attractor is not determined by the seasonality in the forcing, but must be given by other mechanisms. Results are compared with the results for the Southern Hemisphere, where the stratospheric variability is not as strongly influenced by topographic forcing and Sudden Warming events are rare. Finally, the methodology is applied to sea-fluctuations in two different locations. Results show that the fluctuations do not have a chaotic structure, e.g. are stochastic

Date

03.12.2013

Time

15:15 h

Place

Bundesstr. 53, room 022/023
Seminar Room 022/023, Ground Floor, Bundesstrasse 53, 20146 Hamburg, Hamburg

Speaker

Gualtiero Badin, Institut für Meereskunde, Universität Hamburg

Organizers

Armin Köhl

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