Investigation of Arctic Sea Level Rise

Instrumental measurements of sea level in the Arctic Seas began in the 1920s and 1930s. Stationary sea level observations were first begun in the Kara Sea (Dickson Island) in 1933, in the Laptev Sea (Tiksi Bay) in 1934, in the Chukchi Sea (Cape Schmidt) in 1935, and in the East Siberian Sea (Ambarchik Bay) in 1939. There were 71 stations involved in the sea level observational program in the mid 1980s. As a result of economic problems in Russia, many stations were closed in the 1990s, and at present there are only 21 stations operating in the Siberian Seas.

Sea level observations at these stations have been conducted according to the "Manual for Stations and Gauges of the Hydrometeorological Service" (1968). The observations based upon manual readings have been carried out four times a day with an accuracy of 1 cm. Automated tide gauge stations equipped with tide-gauge recorders (see figure at right for their locations) have a sampling frequency of 1 hour and an accuracy of 1 cm. Monthly data quality control includes both visual data control and statistical control. Observations at some stations have had different locations in summer and winter, some of which were interrupted during replacement. Therefore much of the sea level data collected before 1949--1950 cannot be used because of the absence of a reliable geodetic survey. All stations shown in the figure at right have one or more geodetic benchmark installed on stable ground. Periodic (usually annually, but for some stations every summer month because of instability related to permafrost) geodetic surveys have been made to each gauge to determine if any vertical changes in the gauge mount have occurred. If a change in the sea level gauge mount occurred, an adjustment was made. The sea level data used in this paper are relative to benchmarks in solid rock.

The monthly sea level data are calculated using daily sea level data. The monthly data based on four measurements per day are very close to the calculated monthly data based on observations made at 1-hour intervals. It is estimated that the error does not exceed 2 cm more than 0.3% of the time. The annual sea level based on 6-hour interval observations coincides with results based on 1-hour observing intervals.

Monthly mean relative sea levels were provided by the Arctic and Antarctic Research Institute for 71 stations (Figure 1 and Table 1) located in the Barents and Siberian Seas. The time series of sea level variability generally cover the period between 1948 and 2000 but temporal coverage differs significantly from station to station. Table 1 shows the names and coordinates of all available stations. In addition to the names and locations, start and end years, number of years with observations, and typical number of months of the year with observations from each time series are indicated. Gaps in the observations exist where the number of years is less than the difference between the start and end years, and only partial year records exist where the number of months is less than 12.