Steady-frequency waves at intradiurnal periods from simultaneous co-located microbarometer and seismometer measurements: a case study

Abstract

Abstract. Simultaneous co-located microbarometer and vertical-pendulum seismometer measurements at St. Petersburg (59.9 • N, 29.8 • E) with total duration of 4 months are used to study atmospheric oscillations at steady frequencies at periods shorter than 8 h. The temporal behavior of the phase shift between oscillations detected simultaneously by both instruments is analyzed for oscillations of periods up to as short as ∼0.5 h. Some of oscillations last up to several days. For the 42-90 min and 2.5-5 h period ranges, the temporal behavior of the power spectra are considered and correlated with the atmospheric angular momentum of zonal wind, tropical cyclones and large earthquakes. Signatures of sequences of subharmonics of the solar tide are revealed with periods up to day/30. There are indications of effects of the 5-day planetary waves and tropical cyclones on wave activity in the ∼1-5 h period range. A weak increase of wave activity is observed when large earthquakes occur.

Corrected Tilt Calculation for Atmospheric Pressure-Induced Seismic Noise

“…[1] and [2] which investigate seismic wind noise above 1 Hz. At the other extreme are papers [79][80][81][82][83][84] which investigate pressure effects on the ground displacement and tilt at very low frequencies (f < 10 −3 Hz) where the parameter ωz/c is negligible even for sensors employed at depths of hundreds of meters. In addition, the gravitational effect of the increased air mass above the sensor dominates the direct vertical displacement at these low frequencies.…”