Analysis of the velocity profile in Lake Shira in summer using principal component analysis

Abstract

The development of modern technologies allows us to solve the problem of carrying out long-term measurements of velocity and temperature in lakes. The long-term local measurements of velocity have been conducted in Lake Shira (Khakassia) in the period 2014-2015. The velocity profile along the column of the liquid in Lake Shira occurs due to density summer stratification and wind. The horizontal velocities vary greatly in depth as well as in time. The principal component method has been performed to analyze the horizontal velocities. This method is widely used to evaluate complex space-time structures, since it allowsto describe the data compactly. The obtained data have been decomposed into empirically determined modes with different scales. This makes it possible to extract dominant modes in the data and in some cases to determine the corresponding physical process. The first empirical modes in all measures are analogous to the Ekman spiral of the stationary motion of a homogeneous liquid and the remaining modes can correspond to internal waves.