Vertical structure of currents in the Gulf of Finland

Abstract

In the recent years the synchronous measurements of the three-component current velocity vector U( z, t) on several horizons (z) were executed with the help of ADCP at the point located close to Cape Shepelevsky (Gulf of Finland, Baltic Sea). In the present paper the questions of description of the implementation U( z, t) properties in terms of expectation vector m_U(z), variance tensor D_U(z), co-variation tensor K_U(z), spectral density tensor S_U(ω, z) in stationary approximation are discussed. The method of statistical analysis of vector implementations (which is the generalization of earlier developed one dealing with two-component vector M( z,t) implementations on two horizons) is described. The presence of measurements of vertical component ( w) of vector U( z, t) allows to estimate its contribution in the current structure and to supplement the earlier existing representations of the vertical distribution of two-component (u, v) current velocity vector V( z, t). Vertical profile of current velocity in each time moment is approximated as the decomposition by the system of natural orthogonal functions (eigenvectors of variance tensor).