Methods of Identifying Atmospheric Mesoscale Coherent Structures Over the North Atlantic

Abstract

Coherent structures (CSs), which are the most often understood as time-stable vortices, play an important role in the Earth’s climate system, since they make a significant contribution to the processes of momentum and heat and mass transfer of any fluid medium, including the atmosphere and the ocean. This is true for all scales of motion, but is particularly important for more chaotic mesoscale processes. A reliable methodology for identifying mesoscale vortices can potentially stimulate the development of a deterministic climatology of mesoscale processes. The main difficulty in developing this direction is the absence of a rigorously mathematical definition of a vortex, which makes it impossible to automatically search for CSs in spatial data. At the same time, the increase in the spatial resolution of numerical models makes this problem increasingly urgent. Some developments in this direction have been carried out in the field of small-scale turbulence: a number of criteria have been developed that allow for the identification of vortices with varying degrees of reliability. In this paper, the applicability of the three most popular criteria for CS identification in significantly larger-scale geophysical data is studied.