Variable influence on the equatorial troposphere associated with SSW using ERA-Interim

Abstract

Sudden stratospheric warming (SSW) events are identified to investigate their influence on the equatorial tropospheric climate. Composite analysis of warming events from Era-Interim (1979-2013) record a cooling of the tropical lower stratosphere with corresponding changes in the mean meridional stratospheric circulation. A cooling of the upper troposphere induces enhanced convective activity near the equatorial region of the Southern Hemisphere and suppressed convective activity in the off-equatorial Northern Hemisphere. After selecting vortex splits, the seesaw pattern of convective activity in the troposphere grows prominent and robust.

Notes on the correlation between sudden stratospheric warmings and solar activity

“…Moreover, some of the recent works show the enhancement of the frequency of SSWs under forcing of GHGs and ODSs (e.g. Huebener et al, 2007;Charlton-Perez et al, 2008;Bell et al, 2009;Schimanke et al, 2013;Ayarzagüena et al, 2013). Thus, the joint effect of the negative trend in solar cycle strength and the positive trend of GHGs may just reduce positive correlation but cannot be its cause.…”

Enhanced residual mean circulation during the evolution of split type sudden stratospheric warming in observations and model simulations

“…We used the algorithm established by Schimanke et al (2013) which is also used by Bal et al (2017) to calculate the warming dates from Era-Interim. This numerical scheme was developed with a backbone following Charlton and Polvani (2007).…”

“…The competition between planetary waves and gravity waves to the residual mean circulation associated with different types of sudden warming are studied by Limpasuvan et al (2012) and Albers and Birner (2014). Recently, Bal et al (2017) studied the influence of northern hemisphere warming events on the convective activity in the equatorial troposphere using Era-Interim.…”

“…The negative temperature in the upper troposphere invites upwelling from the tropics. It was discussed in the study of Bal et al (2017) that the number of SSW events in observations are too sparse to analyse displacement and vortex split events in the middle atmosphere circulation. Therefore, in this study, we examine the changes in the zonal-mean flow during both of these types of warming event (displacement and vortex split) through composite analysis.…”

Notes on the correlation between SSWs and solar activity

“…A large number of works are devoted to the role and propagations of gravity waves in times of SSWs (Limpasuvan et al, 2011(Limpasuvan et al, , 2012McLandress et al, 2012;de Wit et al, 2014;Ern et al, 2016). Recently, an effect on the troposphere (Hinssen et al, 2011) and equatorial latitudes has been found (Bal et al, 2017). More about SSWs and related fields can be found in reviews of this subject (e.g.…”