Effect of Southern Hemisphere Sudden Stratospheric Warmings on Antarctica Mesospheric Tides: First Observational Study

Abstract

We analyzed the structure and variability of observed winds and tides in the Antarctica mesosphere and lower thermosphere (MLT) during the 2002 major sudden stratospheric warming (SSW) and the 2010 minor SSWs. We noted the effect of SSW on the variability of MLT tides for the first time in the Southern Hemisphere, although it has been well recognized in the Northern Hemisphere. We utilized the winds measured by Rothera (68°S, 68°W) medium frequency radar and King Sejong Station (62.22°S, 58.78°W) meteor radar for estimating the tidal components (diurnal, semi‐diurnal, and ter‐diurnal) in the MLT region. The unusual behavior of diurnal tide (DT) and semidiurnal tide (SDT) was observed in 2002. Zonal SDT amplitudes were enhanced up to 27 m/s after 18 days from the associated SSW day. However, the meridional tidal amplitudes of both DT and SDT suddenly decreased during the peak SSW, and SDT amplitudes slightly increased to 18 m/s afterward. In the normal years, SDT amplitude stays below 15 m/s. During the 2010 SSW, SDT zonal amplitudes increased up to 40 m/s and 50 m/s at altitudes of 80 km and 90 km, respectively, ~30 days after the associated SSW. Similar but weaker effect is noticed in the meridional components. The ter‐diurnal tide does not show any significant variation during the SSW. The two SSWs offered a challenging issue to answer: why tidal amplitudes are enhanced with a delay after the SSW. The reasons for the delay are discussed in accordance with theoretical predictions.

Unusual Changes in the Antarctic Middle Atmosphere During the 2019 Warming in the Southern Hemisphere

“…However, similar studies for the SH are by far fewer than for the NH (Eswaraiah et al, 2018). A handful of studies have investigated the MLT thermal structure and dynamics during the 2002 major SSW (e.g., Cho et al, 2004; Dowdy et al, 2004) and in the 2010 minor SSW in the SH (Eswaraiah et al, 2016, 2017, 2018). Aside from the 2010 minor SSW, a minor SSW was noticed in 1988 in the SH, but it was fainter than the 2010 SSW (Kanzawa & Kawaguchi, 1990; de Laat & van Weele, 2011).…”

“…Since the first observational evidence of the mesosphere response to the SSWs (Quiroz, 1969), numerous studies have been made on the mesosphere coupling with the polar stratosphere during the SSW in the NH high and midlatitudes (e.g., Charlton & Polvani, 2007; de Wit et al, 2015; Medvedeva et al, 2019). However, similar studies for the SH are by far fewer than for the NH (Eswaraiah et al, 2018). A handful of studies have investigated the MLT thermal structure and dynamics during the 2002 major SSW (e.g., Cho et al, 2004; Dowdy et al, 2004) and in the 2010 minor SSW in the SH (Eswaraiah et al, 2016, 2017, 2018).…”

Temperature tele‐connections between the tropical and polar middle atmosphere in the Southern Hemisphere during the 2010 minor sudden stratospheric warming

“…Recently, a record stratospheric warming event occurred over Antarctica in September 2019 (Lim et al, 2020;Yamazaki et al, 2020). A handful of studies have investigated the thermal structure and dynamics of the mesosphere and lower thermosphere during the 2002 major SSW (e.g., Dowdy et al, 2004;Shepherd et al, 2005) and the 2010 minor SSW (Eswaraiah et al, 2016(Eswaraiah et al, , 2017(Eswaraiah et al, , 2018. However, the studies on the mesosphere response to the 2019 SH SSW are not yet reported.…”

Does the coupling of the mesospheric semiannual oscillation with the quasi-biennial oscillation provide predictability of Antarctic sudden stratospheric warmings?

“…and the temperature increased by about 30 K at 80 • S and 10 hPa (Eswaraiah et al, 2018). The zonal winds at 60 • S at 10 hPa weakened by only 20-25 m/s (Eswaraiah et al, 2016).…”