Supersensitive Detector of Hydrosphere Pressure Variations

Плотников

2022

Sensors

Self Cite

This paper describes an ocean-bottom laser seismograph, based on the modified laser meter of hydrosphere pressure variations, and designed to record vertical bottom displacements at the place of its location. Its measuring accuracy is about 1 nm, limited by the stability of the laser emission, which can be improved by using more advanced lasers. The purpose of this instrument is to measure the displacements of the seabed’s upper layer in the low-frequency sonic and infrasonic ranges. Theoretically, it can operate in the frequency range from 0 (conditionally) to 1000 Hz; the upper limit is determined by the operating speed of the digital registration system. We demonstrated the capabilities of the ocean-bottom laser seismograph while registering vertical bottom displacements caused by sea wind waves and lower frequency processes—seiches, i.e., eigenoscillations of the bay in which the instrument was installed. Comparison of experimental data of the bottom laser seismograph with the data of the laser hydrosphere pressure variations meter and the velocimeter—installed in close proximity—shows good efficiency of the instrument.

Section: System Descriptionmentioning

confidence: 99%

Ocean-Bottom Laser Seismograph

Плотников

2022

Sensors

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“…The described laser strainmeters have the following technical characteristics: an operating frequency range from 0 (conditionally) to 100 Hz, and measuring accuracy of the displacement of the Earth's crust plates 0.03 nm, which can be improved through appropriate technical measures. The laser meters of hydrosphere pressure variations [15] in their improved version were described in [16]. For several years, we installed them at various shelf points, both inside and outside Vityaz Bay, in the seaward part off Shultz Cape.…”

Section: Experimental Studiesmentioning

confidence: 99%

Dynamics and Transformation of Sea Surface Gravity Waves at the Shelf of Decreasing Depth

Gromasheva

et al. 2021

JMSE

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This paper reviews the results of the processing of synchronized data on hydrosphere pressure variations and the Earth’s crust deformation in the microseismic range (5–15 s), obtained over the course of numerous experiments, using a coastal laser strainmeter and laser meters of hydrosphere pressure variations installed in various points of the Sea of Japan shelf. Interpreting the results, we have discovered new regularities in the dynamics of surface progressive gravity waves, and their transformation into primary microseisms, when waves move at the shelf of decreasing depth. For example, we found non-isochronous behavior of progressive waves, which manifests itself in a decrease in the periods of gravity waves due to the transformation of a part of their energy into the energy of primary microseisms. Furthermore, when processing the synchronous fragments of the records, made by laser strainmeters and laser meters of hydrosphere pressure variations, we identified approximate zones of the most effective transformation of the energy of gravity progressive waves into the energy of primary microseisms, which start from the depth of less than a half-wavelength and stretch to the surf zone.

“…They were used for comparison with QAVIS data in the range of wind and infragravity waves. Moreover, the POI FEB RAS has developed several designs of laser-interference meters for hydrospheric pressure variations-laser hydrophones [12,13]. They were installed at various points in Peter the Great Bay and registered variations in the hydrosphere pressure in the frequency band from 0.00001 to 1000 Hz.…”

Section: Sources Of Geophysical Data Used For Interpretation Of Qavis Video Analysis Datamentioning

confidence: 99%

Express Image and Video Analysis Technology QAVIS: Application in System for Video Monitoring of Peter the Great Bay (Sea of Japan/East Sea)

Fischenko

Goncharova

et al. 2021

JMSE

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The article describes the technology of express analysis of images and videos, recorded by coastal video monitoring systems, developed by the authors. Its main feature is its ability to measure or evaluate in real time the signals of sea waves, sea level fluctuations, variations of underwater currents, etc., on video recordings or streaming video from coastal cameras. The real-time mode is achieved due to processing video information read not from files, but from the graphic memory of the screen. Measurements of sea signals can be carried out continuously for a long time, up to several days, with high sampling rate, up to 16 Hz, at several points of the observed water area simultaneously. This potentially allows studying the entire spectrum of wave movements, from short waves with periods of 0.3–0.5 s to multi-day fluctuations at the sea level of a synoptic scale. The paper provides examples of the use of this technology for analyzing images and videos obtained in the network of scientific video monitoring of the Peter the Great Bay (Sea of Japan/East Sea), deployed by the authors.