Investigation of the life cycle of the major sudden stratospheric warming in the Northern Hemisphere

In this study we have used the daily mean data from the Modern Era Retrospective Analysis for Research and Applications version 2 (MERRA2) assimilated data. From the MERRA2 data, zonal wind and temperature were obtained at 10hPa from 01 January 1979 to 04 June 2020.The temperature averaged around the polar cap for latitudes north of 60°N. This is a good measure of the overall temperature in the polar vortex.  Investigation of the polar temperature and zonal-mean zonal wind at 10hPa, is detected 19 and 13 major and minor SSWs events, respectively. According to the shows a rapid increase from 201.6K on 12 January to 253.4K on 23 January 2009 (∆T=51.8K). This is the largest increase in the polar temperature per 11-day in the entire MERRA-2 data set starting from January 1979 to June 2020. In this study life cycle of major SSWs is defined by dividing it into five periods. Onset (the first day of maximum zonal-mean zonal wind is reduced), growth (from onset day to zero day), maturation (from zero day to minimum zonal-mean zonal wind), decline (from minimum value to decay day) and decay (the first day of the easterly wind reversal to westerly) of typical SSWs. The result shows the shortest and longest growth periods, with 6 and 37 days, respectively, were recorded in the cases of January 6, 2013 and January 23, 1987. The longest maturation period, with 17 days of continuity, is dedicated to the warming of January 23, 1987. The longest decline period in this statistical period is 26 days, which is related to the warming of January 24, 2009. The shortest and longest life cycle in this statistical period are dedicated to cases on February 1, 2017 and January 23, 1987, respectively.