Free Short-Period Internal Waves in the Arctic Seas of Russia

Abstract

Purpose. The aim of the work is to investigate vertical structure and phase characteristics of free short-period internal waves (IW), and to assess their dependence on density stratification in the Barents, Kara, Laptev and East Siberian seas. Methods and Results. Solving the main boundary problem of the Sturm – Liouville theory resulted in calculating the amplitudes of velocity vertical component, own frequencies and periods of the first mode of internal waves. The density field was calculated using the reanalysis data (World Ocean Atlas 2018) on temperature and salinity for 1955–2017 with a resolution 0.25°× 0.25°. The relation between the internal waves’ vertical structure and dispersion features, and the density depth distribution was analyzed. It is shown that the averaged over the sea area depth of the maximum amplitude of the IW velocity vertical component in the Barents and Kara seas is ~ 90 m in the mid winter and ~ 75–80 m in summer, and in the Laptev and East Siberian seas – ~ 60 m throughout the entire year. Conclusions. In the months when the density gradients are maximal, the internal waves of the highest frequency and the shortest period are observed. The maximum water stability in the Barents Sea takes place in July – August, in the Kara Sea – in July – September and November, in the Laptev Sea – in June, November, and in the East Siberian Sea – in July. Just in the same months, the maximum values of the averaged own frequencies, and the minimum values of the averaged own periods and amplitudes of the vertical component of the internal waves’ velocity are observed.

Keywords

• barents sea
• kara sea
• laptev sea
• east siberian sea
• buoyancy frequency
• internal waves
• own frequency
• own period
• vertical component of velocity