Purpose. The paper aims at the studies of features of seasonal variation of the main semidiurnal and diurnal tides in the annual cycle in the Barents and Kara seas according to the long-term data of sea level observations at all points (stations). The structure of seasonal course of the tide is estimated on the example of the M2 and K1 tides and physical mechanisms of its formation.
Methods and Results. The work was carried out according to the data of long-term tide gauge hourly observations of the sea level and 6-hourly interval series of the sea level measurements mainly from the ESIMO database from 1977 to the end of observations. Marine hydrometeorological year-book data since 1951 were also used. On the basis of the harmonic analysis of tides with the least square method of hourly annual and monthly time series of sea level, the average monthly values of amplitudes and phases of the main semidiurnal and diurnal tides at 17 points in the Barents Sea and 19 points in the Kara Sea are estimated. In general, the range of seasonal course of the M2 tide in the Barents Sea increases from north to south and is most significant in the southeast of the sea. According to our classification, classic type 1 of the seasonal course of the M2 tide is not predominant and is 35%, and anomalous type 3 is the most observed one, reaching 41% of 17 points. In the Kara Sea, classic type 1 of seasonal course of the M2 tide is mainly observed with an amplitude maximum and phase minimum in July–September, manifesting itself in 74% of all cases in 19 points.
Conclusions. At each point of the Barents and Kara seas, individual time-stable seasonal annual course of main semidiurnal, diurnal and shallow tides is observed. The seasonal course of harmonic constants differs significantly among the points in terms of the degree of severity, shape of curves, time of occurrence of extreme values and magnitude of oscillation range. Moreover, seasonal variations of the constants of semidiurnal and diurnal tides are different. In the Barents Sea, the influence of drifting ice cover on the seasonal variations of main semidiurnal tides is much weaker than in the Kara Sea. The seasonal variations of amplitudes and phases of the daily K1 tide are dominated by the semiannual period. The maximum deviations of amplitudes from the mean annual value (norm) are mainly 10–20%, and those of phases – 6–16°.