Stratospheric polar vortex dynamics according to the vortex delineation method

Abstract

The stratospheric polar vortices play a significant role in stratospheric ozone distribution, air mass movement and temperature changes in the polar and subpolar stratosphere. To characterize the main parameters of the stratospheric polar vortices, in particular, vortex area, wind speed along the vortex edge, average temperature and ozone mass mixing ratio inside the vortex, vortex delineation is necessary. In this work, we use a new method of vortex delineation based on geopotential values determined from the maximum temperature gradient and maximum wind speed, thus, characterizing the polar vortex edges. Using the vortex delineation method based on the ERA5 reanalysis data for 1979–2020, we show a comparative characteristic of the Arctic and Antarctic polar vortices in the lower and middle stratosphere. The average polar vortex area in winter from 1979 to 2020 at the 50 and 10 hPa pressure levels equals 28.6 and 35.3·10⁶ km² in the Arctic, and 41.6 and 54.8·10⁶ km² in the Antarctic. The average wind speed along the vortex edge in winter at the 50 and 10 hPa pressure levels equals 35.5 and 55.5 m/s in the Arctic, and 52.7 and 79.2 m/s in the Antarctic. The average temperature inside the polar vortex in winter at the 50 and 10 hPa pressure levels equals respectively –69.0 and –61.7°C in the Arctic, and –81.9 and –74.2°C in the Antarctic.

Research highlights

• Mean values of the area of the Arctic and Antarctic polar vortices are estimated.

• Mean wind speed along the edges of the Arctic and Antarctic vortices are estimated.

• Mean temperatures inside the Arctic and Antarctic polar vortices are estimated.