Zhegulin G.V.
Based on the field observations obtained during the experimental work in August 2016 in the deep-water region of the Barents Sea below the critical latitude for the semi-diurnal tide, a statistical analysis of temporal temperature variability and light attenuation indicator at the boundaries of the jump layer was performed. The main features of the field of short-period internal waves are highlighted. The region is dominated by internal waves with a height of 1 to 2 m and a period of 10 to 20 minutes, which is approximately 45 % of the total number of observations. 40 % of registered waves have periods from 20 to 60 minutes. Explosives with a period of more than 20 min have a length of 500 m and more, and a phase velocity of 40—45 cm/s. Well-pronounced, consistent with the criteria of intense internal waves, a train system for the entire period of work was not observed. Statistically significant global time scales of vertical displacements of the thermocline equal to 20 and 40 min were identified. In the ebb phase, in the range of periods of internal waves of 25—50 min, a one-time mutual amplification of thermocline oscillations takes place according to the temperature and light attenuation index, which falls on the syzygy during the maximum period. It has been established that in the range of 20—60 min there is a synchronous relationship between temperature fluctuations and the attenuation coefficient of light with a coherence above 0.9. Such a high coherence value is a sufficient justification for the use of contact and remote optical measuring instruments for recording internal waves in the deep-water areas of the Barents Sea in the range of 20 to 60 minutes. Vibrations of a thermocline with periods of less than 20 min manifest themselves in the form of irregular coherent structures with phase instability, and therefore cannot serve as a reliable indicator of the field of short-period internal waves based on the results of optical observations only.
