Jet Regimes and the Predictability of Euro-Atlantic Weather – Kristian Strommen, Department of Physics, University of Oxford

When:
November 9, 2020 @ 1:00 pm – 2:00 pm
2020-11-09T13:00:00+00:00
2020-11-09T14:00:00+00:00
Where:
Zoom webinar
link to follow
Contact:
Dr. Jerome Neufeld

In recent years, numerical weather prediction models have begun to show notable levels of skill at predicting the winter North Atlantic Oscillation (NAO) when initialised one month ahead. Because the NAO gives a good first-order approximation of European winter weather, this has garnered a lot of interest. At the same time, model predictions exhibit unusually low signal-to-noise ratios, in what has been dubbed a `signal-to-noise paradox’. We present a new framework for understanding this behaviour in terms of the regime dynamics of the trimodal, North Atlantic eddy-driven jet. It is shown that systematically weak persistence in models may be a key factor in producing the signal-to-noise paradox, and that this is likely in part due to weak transient eddy forcing in models. Sources of predictability in this regime system are also discussed.

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