Dynamic Characteristics of the Stratospheric Polar Vortices

Abstract

The dynamic characteristics of the stratospheric polar vortices at the levels from 100 to 1 hPa (minimum vortex area, minimum mean wind speed along the vortex edge, and the minimum wind speed at which there is a dynamic barrier is maintained) are presented for the first time. These parameters were obtained with the use of the vortex delineation method with the geopotential on the basis of the ERA5 reanalysis data. Seasonal changes and the average winter vertical profiles of the vortex area, mean wind speed along the vortex edge, and mean temperature inside the vortex for the Antarctic and Arctic polar vortices were obtained. The average daily probability of the dynamic barrier weakening along the vortex edge in winter was determined on the basis of data for 1979–2021 over the Arctic and Antarctic. It was shown that the lowest probability of the dynamic barrier weakening (and possible breakdown of the polar vortex) in winter can be traced at levels from 30 to 3 hPa and reaches less than 50% in the Arctic and less than 1% in the Antarctic. At the level of 50 hPa, the probability of the dynamic barrier weakening is 53.7% in the Arctic and 1.4% in the Antarctic.