Variability of the springtime transition date and planetary waves in the stratosphere

Vertical Structure of the Arctic Spring Transition in the Middle Atmosphere

“…In the northern hemisphere there is a large interannual variability in the onset dates of the SFW varying by about 2 months between early March and late May (Butler et al., 2019; Savenkova et al., 2012; Wang et al., 2019; Waugh et al., 1999). The temporal‐vertical structure of the zonal wind reversal also varies from year to year where the wind reversal can first occur in the upper or middle stratosphere or even simultaneously at all altitudes in the stratosphere (Hardiman et al., 2011; Thiélemont et al., 2019).…”

Influence of the QBO and solar activity on interannual variability of the spring-time transition of stratosphere circulation

“…There are several methods to determine the breakup time of stratospheric circulation (Nash et al, 1996;Waugh et al, 1999;Wei et al, 2007;Savenkova et al, 2011). A method of date determination presented in the paper of Savenkova et.al., 2011 is applied: the zonally averaged geostrophic wind at 10 hPa level taken as a proxy for the zonal mean velocity to find the climatic date of spring transition as the day of the year when the geostrophic zonal wind changes (decreases) most rapidly.…”

“…The reversal of zonal mean flow is observed at approximately 10 hPa pressure level typically in the first half of April. However, dynamical processes like nonlinear interaction of planetary waves with the mean flow may also influence the date of the springtime polar vortex breakup (Wei et al, 2007;Savenkova et al, 2011).As a result, there is a -------------Corresponding author. Tel.…”

“…Numerous papers devoted to the investigation of springtime transition date variability present the analysis of different dynamical factors influence on spring transition date, for example, effect of planetary waves activity (Waugh et al,1999;Karpetchko et al,2005;Langematz and Kunze, 2006;and Wei et al, 2007;Waugh and Polvani, 2010;Savenkova et al, 2011). Therefore, the aim of presented study is to consider the impact of solar activity on variability of spring transition date taking into account QBO effect.…”

Stratosphere-troposphere interactions

“…Based on the analysis of reanalysis and simulation data, the group of scientists from the Russian State Hydrometeorological University (St. Petersburg) studied a variability of dynamical processes in the stratosphere and troposphere, including the climatic variability of the times of the spring time breakup of the stratospheric circulation [19], and considered the effect of the free atmospheric oscillations on the fre quency of the SSW origin and intensity [20]. It was shown that in the recent decades a significant ampli tude growth of the stationary planetary wave with a zonal wave number m = 1 has been observed in the stratosphere, which leads to an amplification of the nonlinear interaction of this wave with the zonal mean flow and, as a consequence, to the growth of magni tude of irregular oscillations of wave activity and the mean flow the so called stratospheric vacillations [21].…”