Dates of start, maximum, end of Sudden Stratospheric Warming from 1979 to 2021

<p>We used SSW criteria established by WMO. &nbsp;We analyze parameters such as zonal mean air temperature along 80&deg;N and mean zonal wind speed at 60&deg;N at the height 10 hPa on a 2.5&times;2.5&deg; grid according to ECMWF ERA5 data. The date of the start of the SSW was taken as the day with a sharp (more than 5&deg;K/day) increase in temperature, the day of the end of the SSW was taken as the day when either the wind reversed from east to west (in the case of major SSW) or the temperature dropped by more than 3 K/day (in the case of minor SSW&#39;s).&nbsp;The date with the maximum temperature was taken as the central day of the SSW.&nbsp;All cases of SSW&nbsp;were divided into major and minor. Also, for all SSWs, the type was determined: D - displacement, S -&nbsp; split, F - final SSW (as of March 31, the end of the eastward reversal of the zonal wind was not observed, or the temperature drop was not measured). Types of SSW were estimated from the synoptic analysis of potential vorticity maps on the 850 K isentropic surface.</p>