Study of internal wave generation and propagation features in non-tidal seas based on satellite synthetic aperture radar data |
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Authors: | Lavrova O Yu Mityagina M I Sabinin K D |
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Institution: | 1.Space Research Institute, Russian Academy of Sciences, Moscow, Russia ; |
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Abstract: | Despite the intense attention paid to internal wave (IW) investigation, the most experimentally studied and theoretically
described are internal gravitational waves in shelf zones of oceans and tidal seas appearing during the interaction of tidal
currents with the margin of the shelf. Information on surface manifestations of internal waves in enclosed seas, such as the
Black and Caspian seas, is almost absent. In this paper, the results of study of the peculiarities of generation and propagation
of nontidal internal waves are presented; the study is carried out on the basis of combined analysis in data of marine surface
radiolocation and data of optical and infrared satellite-borne sensors. The experimental basis of investigation is radar images
of the marine surface derived with the help of Synthetic Aperture Radars, onboard the Envisat and ERS-2 satellites. Additionally,
the data of the following sensors belonging to the optical and infrared ranges were used for the purpose of radar image interpretation:
MODIS (onboard the Aqua/Terra satellite), MERIS (Envisat), and AVHRR (NOAA). Surface manifestations of IWs in the northeastern
part of the Black Sea and in the Caspian Sea have been found in radar imagery for the first time, their pattern of spatial
and temporal variation has been reconstructed. The possible factors leading to generation of the observed nontidal IWs are
determined and suppositions about the corresponding generation mechanisms are made. In particular, the IW manifestations recorded
in the northeastern part of the Black Sea are localized in the vicinity of the boundaries of eddies or hydrological fronts;
this fact evidences for the frontal mechanism of generation, at which IWs are radiated by a nonstationary (moving and/or inertially
oscillating) front. The most probable main sources of generation of IWs detected in the Caspian Sea are longitudinal one-knot
seiches, whose knot point is located near the Apsheron sill. |
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