Abstract

A detailed investigation of air-pressure micro-oscillations of periods less than one minute, as recorded by the Macelwane electromagnetic microbarographs at Florissant, Missouri, and Ottawa, Canada, shows that a definite relationship exists between these oscillations and the concurrent synoptic pattern.

The typical time sequence, with relative amplitudes, of atmospheric micro-oscillations characteristic of certain synoptic patterns is as follows: (1) small-amplitude oscillations occurring concurrently with an extensive surface high-pressure area, (2) a transition activity of medium amplitude accompanying the flow on the back, or trailing, side of a high, and (3) a period of relative quiescence occurring during the time of passage of a cold front, with maximum-amplitude oscillations existing for a relatively short period of time immediately prior to this in the pre-cold-front interval and for an extended period in the post-cold-front interval.

It is shown that high-velocity flows of cold air are much more efficient mechanisms for producing extended intervals of maximum-amplitude oscillations than corresponding warm-air flows.

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