seasonal ice camp drifted through the northern part of the Amundsen Basin of the
Arctic Ocean. The measurements of temperature-salinity (TS) variability were
performed at 3 levels within the 60–120 m of the water column as well as vertical
TS profiles were measured in the upper 500 m. Observations of the basic meteorological parameters and ice drift accompanied the measurements of the TS characteristic. The total duration of the collected internal wave data was more than
40 days. The results of the recent experiments were compared with 14 previous
measurements of the same type that had a total duration of about 180 days. They
were carried out in the Arctic Ocean in 1966–1989. The comparison of the data
processing performed using the same method by adjusting parameter r of the GM76
model [7] reveal no trend evident over the 40 year period in spite of the drastic
decline of the sea ice.
The observed absence of any trend in the energy of internal waves can be
explained on the basis of two considerations. First, the existing ideas about the
strong dissipation of energy of internal waves just in the layer under ice as an
important mechanism that determines the well-known low energy of these waves in
the Arctic are not entirely true. In this case, the only cause for the low energy and
the specific form of the spectrum of internal waves in the Arctic remains: this is the
impossibility of the existence of the M 2 tidal semidiurnal internal waves north of
75° N due to inertial frequency limitation. The importance of the absence of tidal
internal waves is evidenced by the fact that the regions of the Arctic, in which the
shape of relatively high internal wave spectral level (for the Arctic) corresponds to
the GM spectrum (see experiments 5–10 in Table 1), are only those regions, in
which the forced waves of tidal periods exist [9]. The second possible cause is that,
instead of ice, highly freshened layers of water are formed at the surface. Hence
internal waves dissipate within these layers as a result of a not yet determined
mechanism.
Acknowledgements The research leading to these results has received funding from the European Union 7th Framework Programme (FP7 2011–2016) under Grant Agreements No.: 265863
ACCESS. R. Schlitzer’s Ocean Data View has been used for making Figs. 2 and 3.
References
1. Levine, M. D., Paulson, C. A., & Morison, J. H. (1985). Internal waves in the Arctic Ocean—
Comparison with lower-latitude observations. Journal of Physical Oceanography, 15(6),
800–809.
2. Levine, M. D., Paulson, C. A., & Morison, J. H. (1987). Observations of internal
gravity-waves under the Arctic Pack Ice. Journal Geophysical Research, 92(C1), 779–782.
https://doi.org/10.1029/JC092iC01p00779.
3. Pisarev, S. V. (1991). Some measurements of the spatial and temporal characteristics of
internal waves in an ice-covered high-latitude basin. Oceanology, 31(1), 42–46.
4. Halle, C., & Pinkel, R. (2003). Internal wave variability in the Beaufort Sea during the winter
of 1993/94. Journal Geophysical Research, 108, 3210. https://doi.org/10.1029/
2000JC000703.
Internal Wave Frequency Spectrum in the Amundsen Basin …
589
Arctic Ocean. The measurements of temperature-salinity (TS) variability were
performed at 3 levels within the 60–120 m of the water column as well as vertical
TS profiles were measured in the upper 500 m. Observations of the basic meteorological parameters and ice drift accompanied the measurements of the TS characteristic. The total duration of the collected internal wave data was more than
40 days. The results of the recent experiments were compared with 14 previous
measurements of the same type that had a total duration of about 180 days. They
were carried out in the Arctic Ocean in 1966–1989. The comparison of the data
processing performed using the same method by adjusting parameter r of the GM76
model [7] reveal no trend evident over the 40 year period in spite of the drastic
decline of the sea ice.
The observed absence of any trend in the energy of internal waves can be
explained on the basis of two considerations. First, the existing ideas about the
strong dissipation of energy of internal waves just in the layer under ice as an
important mechanism that determines the well-known low energy of these waves in
the Arctic are not entirely true. In this case, the only cause for the low energy and
the specific form of the spectrum of internal waves in the Arctic remains: this is the
impossibility of the existence of the M 2 tidal semidiurnal internal waves north of
75° N due to inertial frequency limitation. The importance of the absence of tidal
internal waves is evidenced by the fact that the regions of the Arctic, in which the
shape of relatively high internal wave spectral level (for the Arctic) corresponds to
the GM spectrum (see experiments 5–10 in Table 1), are only those regions, in
which the forced waves of tidal periods exist [9]. The second possible cause is that,
instead of ice, highly freshened layers of water are formed at the surface. Hence
internal waves dissipate within these layers as a result of a not yet determined
mechanism.
Acknowledgements The research leading to these results has received funding from the European Union 7th Framework Programme (FP7 2011–2016) under Grant Agreements No.: 265863
ACCESS. R. Schlitzer’s Ocean Data View has been used for making Figs. 2 and 3.
References
1. Levine, M. D., Paulson, C. A., & Morison, J. H. (1985). Internal waves in the Arctic Ocean—
Comparison with lower-latitude observations. Journal of Physical Oceanography, 15(6),
800–809.
2. Levine, M. D., Paulson, C. A., & Morison, J. H. (1987). Observations of internal
gravity-waves under the Arctic Pack Ice. Journal Geophysical Research, 92(C1), 779–782.
https://doi.org/10.1029/JC092iC01p00779.
3. Pisarev, S. V. (1991). Some measurements of the spatial and temporal characteristics of
internal waves in an ice-covered high-latitude basin. Oceanology, 31(1), 42–46.
4. Halle, C., & Pinkel, R. (2003). Internal wave variability in the Beaufort Sea during the winter
of 1993/94. Journal Geophysical Research, 108, 3210. https://doi.org/10.1029/
2000JC000703.
Internal Wave Frequency Spectrum in the Amundsen Basin …
589