First Detection of a Brief Mesoscale Elevated Stratopause in Very Early Winter

Abstract

Elevated stratopauses are typically associated with prolonged disturbed conditions in the Northern Hemisphere polar winter. The Michelson Interferometer for Passive Atmospheric Sounding (MIPAS) and the Microwave Limb Sounder (MLS) observed a short‐lived and highly zonally asymmetric stratopause at mesospheric altitudes in November 2009, the earliest in the season reported so far. The Arctic climatological winter stratopause vanished, and MIPAS and MLS measured temperatures of 260 K at 82 km and 250 K at 75 km, respectively, in a region smaller than in typical midwinter elevated stratopause events. Planetary wave activity was initially high. Zonal mean zonal winds and the poleward temperature gradient northward of 70°N stayed reversed during 7 days, but the mesosphere did not cool. Wave activity dropped until the eastward stratospheric winds resumed and a strong vortex restored in the mesosphere. The stratopause emerged at high altitudes, staying there for 2–5 days. It was accompanied by enhanced downward transport. It took the stratopause 9 days to move down to its typical winter altitudes.

Abrupt Change in the Lower Thermospheric Mean Meridional Circulation During Sudden Stratospheric Warmings and Its Impact on Trace Species

“…In recent years, considerable interest has arisen in the northern hemispheric sudden stratospheric warming phenomenon whose onset is followed by the reformation of an elevated stratopause at mesospheric altitudes (hereafter, ES-SSW). Since the initial discovery in the Microwave Limb Sounder (MLS) observations by Manney et al (2008Manney et al ( , 2009, ES-SSW events and their impact on trace species have been confirmed in other satellite datasets such as SABER (Smith et al, 2009;Tweedy et al, 2013), SMR (Orsolini et al, 2010;Pérot & Orsolini, 2021), Michelson Interferometer for Passive Atmospheric Sounding (MIPAS) (Damiani et al, 2014;Funke et al, 2010;García-Comas et al, 2020), and Solar Occultation For Ice Experiment (SOFIE) (Siskind et al, 2021). ES-SSWs have also been extensively examined using WACCM (Chandran et al, 2013(Chandran et al, , 2014Harvey et al, 2021;Holt et al, 2013;Limpasuvan et al, 2012Limpasuvan et al, , 2016Orsolini et al, 2017;Pedatella et al, 2014;Siskind et al, 2015;Tweedy et al, 2013) or the thermosphere and ionosphere extension of WACCM (i.e., WACCM-X) (Oberheide et al, 2020;Sassi et al, 2013;Siskind et al, 2021;Zhang et al, 2021), in free-running, specified dynamics, or data assimilation configurations.…”

Zonal Asymmetry of the Stratopause in the 2019/2020 Arctic Winter

“…As noted in Section 1, the zonal asymmetry in the stratopause temperature and height depends on the location of polar vortices and anticyclones associated with wave 1 perturbation. In average, the stratopause in the polar cyclone is higher and warmer than in the anticyclone [1,4,31,32]. It is seen from Figure 2b and 2c, that a clear temperature asymmetry relative to the pole in December 2019 and January 2020 was observed.…”

“…Descent-ascent-descent of the polar stratopause usually occur during the onset and recovery phases of the SSW events, when the zonal wind at 60°N reverses to easterly and the polar vortex breaks down [4,21,22,32]. Special attention was paid to the elevated stratopause events characterized by a rapid reformation of the polar stratopause near 75-80 km and its subsequent gradual descent over a period of several weeks [3,7,23,32,51]. Because of the absence of the zonal wind reversal, this event is not typical for winter 2019/2020 (Figure 3).…”

Zonal Asymmetry of the Stratopause in the 2019/2020 Arctic Winter

“…As noted in Section 1, the zonal asymmetry in the stratopause temperature and height depends on the location of polar vortices and anticyclones associated with wave 1 perturbation. On average, the stratopause in the polar cyclone is higher and warmer than in the anticyclone [1,4,31,32]. It is seen from Figure 2b,c that a clear temperature asymmetry relative to the pole in December 2019 and January 2020 was observed.…”

“…The existence of a zonally asymmetric elevated stratopause was first emphasized in France et al [1] and France and Harvey [31]. The effects of the zonal asymmetry in temperature and height of the stratopause with respect to the location of the polar vortices and anticyclones were considered [1,4,31,32]. Using Aura Microwave Limb Sounder (MLS) satellite data during 2004-2011, France et al [1] found that both the highest and lowest stratopause temperatures are located near the vortex edge and the height of the stratopause in the cyclone is higher than in the anticyclone.…”