Purpose. The work aims to investigate the spatial-temporal variability of the vertical structure of the density field and characteristics of internal waves at the climatological scale in the Barents and Kara seas.

Methods and Results. Water density was calculated using the ORAS5 reanalysis data on monthly average potential temperature and salinity at the ~ 10 km grid nodes for the period 1958–2022. The resulting array of density data made it possible to determine the maximum values of buoyancy frequency and their depths. The amplitudes of the vertical component of the first-mode velocity of free internal waves were calculated, and the maximum amplitude values and their depths were defined for the Barents and Kara seas.

Conclusions. The performed analysis has revealed that during the considered time period, the sea-mean climatological maximum of buoyancy frequency had a tendency to decrease and deepen both in the Barents and Kara seas. The most manifested trends in the changes of buoyancy frequency maximum are noted in the warm half-year (June–November): positive trends occur in September–November in the southern Barents Sea where Atlantic water influence is significant, and negative ones occur in June–August in the Franz Josef Land and Svalbard region where there is an inflow of cold Arctic waters and ice from the Arctic Ocean. The most pronounced trends in changes in the maximum amplitude of the vertical component of internal wave velocity are observed in the cold half-year (December–May): positive trends occur in the northern regions of the Barents and Kara seas from January to April, and negative ones occur in the southern Barents Sea in November–January.