Physical Oceanography (Oct 2023)
Packages of Short-Period Internal Waves on the Black Sea Shelf Based on the Measurement Data of the Thermoresistor Chains Cluster
Abstract
Purpose. The study is purposed at calculating and analyzing the characteristics of short-period internal wave (IW) packages based on the long-term measurements of vertical temperature distributions by a cluster of three moored thermoresistor chains spaced apart from each other and placed on the Black Sea shelf in the Golubaya Bay area (the Southern Branch of IO RAS, Gelendzhik). Methods and Results. Measurements were carried out in 2018–2020. A cluster of three thermoresistor chains at the moored buoy stations supplied with the submerged buoys was located at a distance of about 1300 m from the coast and connected to a multi-modem station, through which the data was transmitted online to the onshore data server via a fiber optic cable. The moored buoy stations with the thermoresistor chains were installed several times at the depths 24–28 m in the corners of a triangle with the sides that varied from setting to setting in the range from 40 to 130 m. Frequent (every 10 s) temperature measurements were performed by highly sensitive sensors spaced vertically at a distance of about 1 m from each other. Data processing made it possible to identify more than 50 recorded cases of IW packages with the 1–10 m amplitude of oscillations, at that they were observed most often in spring (during the thermocline development). The values of the IW oscillation period, phase velocity of their propagation (magnitude and direction), length and amplitude, and also their number in a package were calculated. Conclusions. It was revealed that the IW packages propagate mainly from the deep part of the sea to the coast. They are often observed in the frontal zones related to the intrusion of warmer or colder waters to the thermoresistor chains location area. The IW phase velocity was established to be in a statistically significant dependence on the temperature stratification parameters as well as on the IW nonlinearity parameter.
