Tidal and nontidal variations in the water level in the northern part of the gulf of Ob

The purpose of the work is to obtain new estimates of the harmonic constants of the tide based on observations of water levels made at points on Halevngo Island, the Peschanka River, the sea channel area, the Tambey and 60 Let VLKSM polar stations. Sources of initial data are arhived 6-hourly observations and hydrological yearbooks for the Kara Sea basin. The characteristics of the spatial and seasonal variability of tides in the northern part of the Gulf of Ob are given based on the results of a harmonic analysis of all available observations using the least squares method (AARI version). Non-periodic water level fluctuations at the Tambey and 60 Let VLKSM polar stations were analyzed using both residual and total water level series. Analysis of the residual series, which represent in their pure form surge fluctuations in level, showed that a continuous level above 5 % of the supply according to the Tambey residual series was observed 395 times over the entire observation period (1976–1993). For decreases in the level relative to 95 % of security at a given post, this characteristic amounted to 348 cases. Observational data from the "60 Years VLKSM" gauge station indicate that during the period 1979-1992, instances of the residual water level continuously exceeding the 5 % exceedance probability level were recorded 191 times, while instances of continuously ramaining below 95 % exceedance probability level occurred 184 times. Total levels (directly measured) allow us to estimate the total contribution of all components (runoff, surge and tidal) to sea level fluctuations. The characteristics of nonperiodic fluctuations of the level at polar station Drovyanaya are estimated only by the total values due to the lack of necessary data for obtaining residual series. Observations of the water level at this station were carried out in the period 1951-1962 and, mainly, only from July to October. The total level fluctuations reach their greatest values in winter. In Tambey, the maximum range of total levels within a calendar month over many years falls in November and is 266 cm, at the 60 let VLKSM station - in January and reaches 277 cm, in Drovyanaya - in September (290 cm). Due to the presence of a winter polynya in the adjacent water area, surge fluctuations are observed here throughout the entire of the year.