The role of instability during the onset of blocking and cyclogenesis in Northern Hemisphere synoptic flows

J. S. Frederiksen

Research output: Contribution to journalArticleOther

16 Citations (Scopus)

Abstract

A study is made of the three-dimensional instability properties of a sequence of daily instantaneous Northern Hemisphere flow fields during the period 1 November-16 November 1979. The growth rates, phase frequencies, and structures of the ten fastest growing modes have been analyzed on each day. We have concentrated on instability modes associated with the formation of a block in the Gulf of Alaska. The early stages of block formation are characterized by the formation of large-scale westward tilting dipole onset-of-blocking modes with largest amplitudes upstream of the blocking region. Substantial changes in the locations of the cyclogenesis modes take place with the regions of preferential development occurring in the winter climatological storm tracks over the Pacific, Atlantic and Siberian regions during early November. -from Author

Original languageEnglish
Pages (from-to)1076-1092
Number of pages17
JournalJournal of the Atmospheric Sciences
Volume46
Issue number8
Publication statusPublished - 1989
Externally publishedYes

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