%0 Journal Article %T Short-Period Internal Waves under an Ice Cover in Van Mijen Fjord, Svalbard %A E. G. Morozov %A S. V. Muzylev %A A. S. Shestov %A A. V. Marchenko %J Advances in Meteorology %D 2011 %I Hindawi Publishing Corporation %R 10.1155/2011/573269 %X Temperature and velocity fluctuations measured in Van Mijen Fjord in Svalbard and interpreted as the fluctuations induced by internal waves revealed the existence of short-period internal waves with an amplitude of approximately 1£żm and a period of approximately 5¨C10£żmin that correlate with the ice cover fluctuations of the same period with an amplitude of a few millimeters. 1. Introduction We analyze the measurements of temperature, velocity, and pressure at the bottom to study the influence of internal waves on the ice cover. The Ħ°rigid lidĦħ approximation is almost always used in the theoretical study of internal waves under the ice cover or even without it. This approximation filters off the surface mode and adequately describes the properties of both the internal waves in ice-free conditions and long internal waves under the ice cover [1, 2]. In the Ħ°rigid lidĦħ approximation, the vertical velocity at the surface is assumed to be equal to zero; therefore, due to the kinematic condition, the internal waves cannot cause any vertical displacements of the ice cover. Such conclusion is, however, inconsistent with the experimental data obtained for relatively deep parts of the Arctic Ocean [3¨C6] and also contradicts the theoretical results [7, 8], according to which internal waves may be reflected in the fluctuations of the ice cover at frequencies comparable with the Brunt-V£żis£żl£ż frequency. Scientists from the Shirshov Institute of Oceanology (Russian Academy of Sciences) and The University Centre in Svalbard (UNIS) carried out marine studies in the shallow Van Mijen Fjord in Svalbard to perform experimental tests of the theoretical conclusion concerning the possible influence of short internal waves on the fluctuations of the compact ice cover. 2. Brief Theory of Internal Waves under an Ice Cover In the theoretical approach, the ice cover of the ocean surface can be considered as a thin elastic plate floating on the sea surface. The theoretical description of the ice cover fluctuations should take into account the elastic properties of the ice plate, the compression forces, and the ice inertia. If the processes inside the ice cover are ignored the main equations and boundary conditions of the ice cover should be similar to the equations and conditions in the situation when the sea surface is free of ice. The only exception is the dynamic condition that may be expressed under the constant ice thickness h in the following form [7¨C11]: Here, is the pressure, the ice surface deflection, the acceleration due to gravity, the seawater density at the boundary %U http://www.hindawi.com/journals/amete/2011/573269/