Large-Scale Variations of Sea Level in the Laptev Sea
G.N. Voinov and E.A. Zakharchuk
State Research Center - Arctic and Antarctic Research Institute, 38 Bering St., 199226 St. Petersburg, Russia
Received 28 October 1997 and accepted in revised form 3 March 1998
Abstract - Large-scale sea-level oscillations were investigated at 10 coastal stations in the
Laptev Sea. Daily mean sea-level heights for the years 1962-1984 were used. Spectral
analysis of time series reveals significant energetic peaks at I year, 28-30, 7-8, 5.2-5.3,
4.3, 3.0-3.3, 2.4-2.5 and 2.1-2.2 days. Long-period components were extracted using
harmonic analysis on the basis of the least square method. The observed monthly tide
exceeds the equilibrium tide by a factor of 1.45. Variance analysis of non-tidal (residual)
time series shows that the maximum intensity of the sea-level oscillations is observed for
periods of less than I year (from 66 to 81 % of the total variance). From 13 to 24% of the
total variance is accounted for by the long-period tides and 5 - 18% of the variance is due to
interannual variability. An analysis of the two-dimensional distribution of temporal
variations of amplitudes at the synoptic scale reveals their non-steady-state character for this
range. Cross-spectral analysis of the non-tidal level oscillations indicates high coherence
(0.68 - 0.98) between sea-level variations at the synoptic scale at different stations. The
spatial distribution of phases shows that these sea level variations are mainly progressive
waves in the range of less than 60 days. Calculated velocities of these waves are close to
phase velocities of shelf waves and have a magnitude of 1.3 - 5.2 m/s for periods from 4 to
46 days.
Introduction
Analysis of the daily mean sea-level oscillations at various coastal stations in the Laptev Sea
shows that maximum variations here can be as high as two meters and above. It seems
doubtless that such significant perturbations of sea-level can exert influence on dynamics of ice
cover, variability of currents, regime of polynyas, transference of sediments. However, the
large-scale sea-level variations have not been adequately explored. Study of these processes has
been mainly devoted either to the global sea-level variations (for the periods of a year and
above) using monthly mean data (Dvorkin, et aI, 1989; Bannov-Baykov, 1974), or to storm
surges with periods from I to 6 days, which have been investigated in most cases using
observational data for the navigation period July - September (Alekseyev and Mustafin, 1972).
However, as it was shown by Cartwright (1983) results of spectral analysis of the monthly
mean data are blurred because of irregular lengths of calendar months. Analysis of the daily
mean data has been performed only for the navigation period (Krutskikh, 1974; Yanda, 1989).
Low-frequency regions of the spectrum at the synoptical scale for the periods from 10 to 60
days are poorly known. It is also interesting to estimate power contribution of processes of
various temporary scales into total variability of the large-scale level variations.
The harmonic analysis of the long-period tides for long time series by the least square method
was not made previously. So far studies of the long-period tides in Arctic seas by Vorobyev
(1966,1969,1976) were mainly based on data of yearly sea-level series and not on the least
square method. Vorobyev's results did often not exceed noise level and were of little reliability.
Shelf waves and their contribution to total variability of the level oscillations and currents are
completely unexplored in the Arctic shelf zone.
This paper describes the long-period tides and sea-level oscillations for the synoptic scale on
the basis of analysis of long series of daily mean sea-level values in the Laptev Sea.
In: Kassens, H., H.A. Bauch, l. Dmitrenko, H. Bicken, H.-W. Hubberten, M. Melles, J. Thiede and L. Timokhov (eds.)
Land-Ocean Systems in the Siberian Arctic: Dynamics and History. Springer-Verlag, Berlin, 1999, 25-36.
G.N. Voinov and E.A. Zakharchuk
State Research Center - Arctic and Antarctic Research Institute, 38 Bering St., 199226 St. Petersburg, Russia
Received 28 October 1997 and accepted in revised form 3 March 1998
Abstract - Large-scale sea-level oscillations were investigated at 10 coastal stations in the
Laptev Sea. Daily mean sea-level heights for the years 1962-1984 were used. Spectral
analysis of time series reveals significant energetic peaks at I year, 28-30, 7-8, 5.2-5.3,
4.3, 3.0-3.3, 2.4-2.5 and 2.1-2.2 days. Long-period components were extracted using
harmonic analysis on the basis of the least square method. The observed monthly tide
exceeds the equilibrium tide by a factor of 1.45. Variance analysis of non-tidal (residual)
time series shows that the maximum intensity of the sea-level oscillations is observed for
periods of less than I year (from 66 to 81 % of the total variance). From 13 to 24% of the
total variance is accounted for by the long-period tides and 5 - 18% of the variance is due to
interannual variability. An analysis of the two-dimensional distribution of temporal
variations of amplitudes at the synoptic scale reveals their non-steady-state character for this
range. Cross-spectral analysis of the non-tidal level oscillations indicates high coherence
(0.68 - 0.98) between sea-level variations at the synoptic scale at different stations. The
spatial distribution of phases shows that these sea level variations are mainly progressive
waves in the range of less than 60 days. Calculated velocities of these waves are close to
phase velocities of shelf waves and have a magnitude of 1.3 - 5.2 m/s for periods from 4 to
46 days.
Introduction
Analysis of the daily mean sea-level oscillations at various coastal stations in the Laptev Sea
shows that maximum variations here can be as high as two meters and above. It seems
doubtless that such significant perturbations of sea-level can exert influence on dynamics of ice
cover, variability of currents, regime of polynyas, transference of sediments. However, the
large-scale sea-level variations have not been adequately explored. Study of these processes has
been mainly devoted either to the global sea-level variations (for the periods of a year and
above) using monthly mean data (Dvorkin, et aI, 1989; Bannov-Baykov, 1974), or to storm
surges with periods from I to 6 days, which have been investigated in most cases using
observational data for the navigation period July - September (Alekseyev and Mustafin, 1972).
However, as it was shown by Cartwright (1983) results of spectral analysis of the monthly
mean data are blurred because of irregular lengths of calendar months. Analysis of the daily
mean data has been performed only for the navigation period (Krutskikh, 1974; Yanda, 1989).
Low-frequency regions of the spectrum at the synoptical scale for the periods from 10 to 60
days are poorly known. It is also interesting to estimate power contribution of processes of
various temporary scales into total variability of the large-scale level variations.
The harmonic analysis of the long-period tides for long time series by the least square method
was not made previously. So far studies of the long-period tides in Arctic seas by Vorobyev
(1966,1969,1976) were mainly based on data of yearly sea-level series and not on the least
square method. Vorobyev's results did often not exceed noise level and were of little reliability.
Shelf waves and their contribution to total variability of the level oscillations and currents are
completely unexplored in the Arctic shelf zone.
This paper describes the long-period tides and sea-level oscillations for the synoptic scale on
the basis of analysis of long series of daily mean sea-level values in the Laptev Sea.
In: Kassens, H., H.A. Bauch, l. Dmitrenko, H. Bicken, H.-W. Hubberten, M. Melles, J. Thiede and L. Timokhov (eds.)
Land-Ocean Systems in the Siberian Arctic: Dynamics and History. Springer-Verlag, Berlin, 1999, 25-36.