10.03.2014: FB1-Seminar

 11:00 h, Hörsaal, Düsternbrooker Weg 20

Abstact:

 The winter (DJF) of 1962/63 is the third coldest in the Central England Temperature record, going back to 1659, and lives long in the memory of those who experienced it (including the seminar speaker!).  The cold weather extended across Europe and was centred over Germany and Poland. A set of relaxation experiments using the ECMWF atmospheric model is used to analyse this particularly severe winter. It is argued that the severe weather was associated with a wave train that originated in the tropical Pacific sector (where weak La Nina conditions were present) and was redirected towards Europe, a process we suggest was influenced by the combined effect of the strong easterly phase of the Quasi-Biennial Oscillation (QBO ) and unusually strong easterly winds in the upper equatorial troposphere that winter. A weak tendency towards negative North Atlantic Oscillation (NAO) conditions in December, associated with extratropical sea surface temperature and sea-ice anomalies, might have acted as a favourable preconditioning. The redirection of the wave train towards Europe culminated in the stratospheric sudden warming at the end of January 1963. We argue that in February, the sudden warming event helped maintain the negative NAO regime, allowing the severe weather to persist for a further month. A possible influence from the Madden-Julian Oscillation, as well as a role for internal atmospheric variability, is noted.

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