Planetary Wave Interactions across Time Scales

Grant Branstator

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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