INVESTIGATION OF THE APPLICABILITY OF COHERENT VORTEX STRUCTURES IDENTIFICATION METHODS IN MODEL EXPERIMENTS

Stable in time vortices, which can be considered as coherent vortex structures (CVSs), highly influence processes of momentum, heat and mass transfer in any fluid, including an atmosphere and an ocean. They affect all scales of motion, as a consequence, vortices of all scales play a crucial role in climatological system of Earth. Nowadays the most studied processes in geophysics are large vortices (cyclones), while mesoscale and submesoscale processes in the atmosphere and ocean remain at “gray zone”, especially little information on their impact on the climate scale. Climate assessment requires the ability to automatically identify CVS in spatial data (for example, in numerical modeling data). The main limitation in development of this direction is the lack of strict mathematical definition of a vortex. Some developments in this direction have been carried out in the field of small-scale turbulence, where a number of criteria have been developed. The main advantage of this methodology is the ability to identify vortex motions of any scale and in any continuous medium, the minimum size of the vortex is determined exclusively by the spatial resolution of the data used. The paper examines applicability of these vortex identification methods (VIMs) to significantly largerscale geophysical data. For analysis, the most proven Eulerian methods of vortex identification were chosen, which are Q, Δ, λ2, λci and Rortex criteria. The paper demonstrates the comparison of three generations of VIMs in application to idealized two- and three-dimensional vortices. The study showed that Rortex criterion is the most promising in the case of identification of atmospheric mesoscale processes: it most reliably identifies the CVS, and also provides information about the direction of rotation. The DBSCAN method, used in the study for clustering of individual coherent structures, makes it possible to estimate the geometric properties and various vortex statistics. The developed approach can be used for climate analysis of the dynamics of mesoscale vortices.