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Planetary Wave Interactions across Time Scales
Grant Branstator
NCAR
Abstract
Tropospheric fluctuations on planetary scales take place at all
observed time scales between daily and decadal. Though there is no
gap in the temporal spectrum the structure of the fluctuations is
highly dependent on frequency. In this presentation we characterize
the frequency dependence of this structure differentiating between the
seasonally varying mean state, interannual variability, and synoptic
variability. Furthermore we study the mutual interactions between
fluctuations in various frequency bands making use of various
diagnostic tools and mechanistic models. Special emphasis is placed
on understanding feedbacks between interannual patterns of variability
and storm track anomalies. One of the novel applications of these
ideas concerns the intermittency of extreme events with their timing
being largely controlled by fluctuations on intraseasonal time scales.
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