Features of the Field of Internal Waves on the Abkhazian Shelf of the Black Sea according to Remote Sensing Data and In Situ Measurements

Abstract

The field of internal waves in the Black Sea is quite significant. The Black Sea shelf is of particular interest, but it has not been studied enough in some specific regions. For example, a narrow and steep shelf of Abkhazia has been poorly explored. Particularly unexplored are the actual parameters and causes of the generation of internal waves in this area. In this article, we have attempted to fill this gap by analyzing remote sensing data and in situ data. An analysis of a set of optical multispectral satellite images (Sentinel-2, Landsat-8) and a collection of sea-truth data of the shelf zone of Abkhazia was carried out to identify features of internal wave fields of this region. In situ data were acquired over 9 years using ADCP, CTD, and SVP probes and moored stations with point and line temperature sensors. It is shown that internal waves are widespread on the Abkhazian shelf. They appear as trains of short-period waves (as a rule, soliton-like). The quantitative parameters and features of internal waves are shown and analyzed. The form of manifestation and direction of internal wave trains’ travel depend on the mechanisms of their origin, among which are the transformations of inertial internal waves, generation by river plumes, and submesoscale structures. In general, the article is the most complete and relevant study of the field of internal waves on the shelf of Abkhazia.

Observations of Near-Inertial Internal Waves over the Continental Slope in the Northeastern Black Sea

“…The passage of packets of inertial internal waves was indicated by up and down displacements of the isopycnals. NIWs also appeared in the current velocity data on the continental slope in contrast to the coastal zone where the effects of strong alongshore currents and passing eddies significantly distorted the manifestation of NIWs in currents [25]. The rotary spectra of velocity components from 50 m down to 150 m showed that the anticyclonic rotation slightly prevailed over the cyclonic one with a dominant peak close to the local inertial frequency.…”

“…The passage of packets of inertial internal waves was indicated by up and down displacements of the isopycnals. NIWs also appeared in the current velocity data on the continental slope in contrast to the coastal zone where the effects of strong alongshore currents and passing eddies significantly distorted the manifestation of NIWs in currents [25].…”

“…As for the Black Sea, detailed information about the vertical structure and seasonal variability of NIWs is lacking. Previous observations from moored stations have shown that NIW heights vary from 10 to 25 m on the northeastern shelf of the Black Sea [23][24][25]. A variety of forms of inertial hodographs have been revealed on the shelf near the city of Gelendzhik in the northeastern part of the Black Sea [26,27].…”

Water Structure in the Utrish Nature Reserve (Black Sea) during 2020–2021 According to Thermistor Chain Data

“…Based on these data, the estimates of a seasonal cycle, synoptic variability and upwelling were represented. The thermistor chains are also effectively used in the Black Sea for internal waves studies [40,41]. Although ecosystem research in the NR Utrish has been conducted, little attention has been paid to the continuous study of water characteristics.…”

“…Based on these data, the estimates of a seasonal cycle, synoptic variability and upwelling were represented. The thermistor chains are also effectively used in the Black Sea for internal waves studies [40,41].…”