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Ann. Geophys., 20, 823-833, 2002
www.ann-geophys.net/20/823/2002/
© European Geosciences Union 2002
Statistical study of seismic and ground pressure oscillations with steady frequencies in the 0.7–5 h period range
N. V. Karpova, L. N. Petrova, and G. M. Shved
Departments of Atmospheric Physics and Earth Physics, Institute of Physics, St. Petersburg State University, St. Petersburg-Petrodvorets 198504, Russia
Correspondence to: G. M. Shved (shved@pobox.spbu.ru)
Abstract. Product spectra of ground
pressure variation and seismic oscillations have been calculated in the period
sub-ranges of 42–90 min and 2.5–5 h, based on synchronous, co-located
microbarograph and seismograph measurements at St. Petersburg (60° N, 30° E).
The 200 records of 2–3.5 days in length and a combined duration of 525 days
have been used. The product spectra have been computed for winter, spring,
summer, and autumn, both individually and in combination. The spectra of
different seasons are distinct from each other for both microbarograph and
seismograph measurements; this can be caused by a seasonal variation in both
frequency and amplitude of free oscillations of the atmosphere. There are
pressure and seismic oscillations with close frequencies in the spectra for
both, for each season and when all seasons are combined. At present,
suggestions may only be made regarding the origin of most of these common
oscillations. Once again, the penetration of the Earth’s free oscillation 0S2
with a period of about 54 min into the atmosphere has been confirmed. A common
pressure and seismic oscillation with the 206 min period has been detected and
has attracted considerable interest. The 159-min periodicity revealed in
pressure variations may be associated with the well-known solar oscillation of
the 160.01 min period.
Key words. Meteorology and
atmospheric dynamics (middle atmosphere dynamics; waves and tides)
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