Displacements Of Water Particles Research Articles

Application of a sound-conducting polymer foil for calibration of hydrophones by optical interferometry

Modern calibration of hydrophones at megahertz frequencies is based on the method of optical interferometry, in which the vibrational velocity of an acoustic wave is measured using a thin sound-transparent polymer foil (membrane), metallized on one side to improve light reflection and installed in an ultrasonic field, followed by its replacement with a hydrophone to be calibrated. The main problem of implementing this calibration method is to assess the adequacy of tracking vibrations of the metallized side of the foil to vibrational displacements of water particles under the action of a sound wave incident on the opposite side of the foil. On the basis of the simplified theory of acoustic plane waves passing through layers of dissimilar materials, methods for measuring the speed of sound in the applied foil and an algorithm for calculating the frequency dependence of the sound wave transmission coefficient (in terms of vibrational velocity) from water through the foil to water or air, introduced as a correction to the results of hydrophone calibration, were developed. The uncertainty of the introduction of this correction is estimated.

Internal Tides in the Denmark Strait

Six-day temperature records carried out at the three mooring levels revealed isotherm fluctuations in the Denmark Strait sill in July 2018 caused by internal waves. In addition to the field measurements, fluctuations of isopycnals were estimated on the basis of a numerical model. It was shown that the wave height (vertical displacements of water particles) caused by semidiurnal internal tides are approximately 50 m in the region of the sill crossing the strait. The wave height decreases to 30 m over a distance of 100 km from the sill. The internal waves in the northern part of the strait are more intense than in the southern part because the wave propagates in the opposite direction to the mean current. In the southern part the waves and the current propagate to the south, which increases the wavelength and decreases their amplitudes.

The horizontal motion of a water layer during the passage of tsunami waves based on data from a dense ocean-floor network of deepwater sea-level stations

A method for the retrieval the horizontal motion of a water layer during the passage of a tsunami wave is proposed based on the data from a dense network of sea-level deepwater stations. The method is applied for calculation of the horizontal velocity of the flow and displacement of water particles in the vicinity of the DONET/JAMSTEC observatories during the passage the 2011 Tohoku tsunami. It was found that the amplitude of the flow speed was ~0.01 m/s, while the amplitude of the displacement exceeded 10 m.

Residual hydrodynamic fields after tsunami generation by an earthquake

The linear theory of long waves was applied to study horizontal motions of the water layer in a rotating ocean which appear after tsunami generation by an earthquake. The structures of residual potential and eddy fields are analyzed on the basis of the analytical solution of a model axisymmetric problem for an ocean of constant depth. The estimates of the horizontal displacements of water particles, velocity of the eddy current, and energy of the geostrophic eddy are calculated for typical conditions of the tsunami source. Particular features of the residual fields related to the existence of stable stratification are considered. Static and dynamic numerical models are described that allow us to calculate the residual potential field and its evolution related to the realistic events. The field of residual horizontal displacements of water particles for the catastrophic earthquake near the coasts of Japan on March 11, 2011, is calculated and analyzed.

The potential and vortex traces of a tsunamigenic earthquake in the ocean

An equation system that describes the potential and vortex residual hydrodynamical fields that emerge in the rotating ocean during tsunami generation by co-seismic deformations of the bottom was obtained in terms of linear long-wave theory. For the model case of a cylindrically symmetrical deformation of the bottom, a completely analytical solution was found. On the basis of this solution, the structure of residual fields was analyzed and estimates of the residual horizontal displacements of water particles, of the speed of the vortex current, and of the energy of a geostrophic vortex were obtained under typical tsunami source conditions.

Circulation on the Continental Shelf of the Southeastern United States. Part III: Modeling the Winter Wind-Driven Flow

Abstract A vertically integrated two-dimensional model has been adapted for the study of the wind-driven flow on the South Atlantic Bight (SAB) shelf during the winter season. Wind data are used as an input to the model and current data are used to verify the model results. Initially, a constant wind field in time and space is applied over the whole domain; the predicted flow pattern shows good agreement with observations. Model results using observed spatially and temporally varying wind fields are also in good agreement with observations. At the shelf-break the comparison is rather poor due to the strong influence of the Gulf Stream in the outer shelf data, which was neglected in the model. Water particle trajectories resulting from wind forcing, tidal forcing, and from the combined effect of an along-shelf surface slope with tidal forcing are compared. The along-shelf slope seems to have a significant effect on the net displacement of water particles as well as on the along-shelf volume transport. Comp...

Über die Reizung des Ferntastsinns bei Fischen und Amphibien

Fishes and aquatic amphibians are able to detect and locate moving bodies and even obstacles at some distance by means of their lateral-line sense organs (Ferntastsinn). As was shown experimentally, the main physical process involved in these reactions are certain local damming phenomena in front of the moving object (rise of pressure, displacement of water particles). Obstacles cause an alteration of the damming phenomena produced by the moving animal's body itself (increase of water resistance).Kramer's different view is rejected; he overlooked the existence of damming phenomena and was not aware of the fact thatXenopus laevis reacts to surface waves even when the animal is totally submerged.