Understanding the Excitation of Quasi‐6‐Day Waves in Both Hemispheres During the September 2019 Antarctic SSW

Abstract

Stratospheric sudden warming (SSW) is a large meteorological phenomenon, which is characterized by an abrupt increase of the stratospheric temperature in the polar region of the winter hemisphere (Andrews et al., 1987;Baldwin et al., 2020). Attenuations or reversals of zonally mean eastward winds at higher latitudes are associated with SSW events due to the interactions between enhanced stationary planetary waves (SPWs) and zonal mean flows (Matsuno, 1971). Generally, polar warmings occurring with a reversal of zonally mean eastward winds at the latitude of 60° at 10 hPa level are classified as a "major" event, otherwise are regarded as a "minor" event. In the recent 40 years, the major SSW was observed over 20 times in the Northern Hemisphere (Butler et al., 2017;Choi et al., 2019), while it occurred only once in the Southern Hemisphere (Krüger et al., 2005).Responses of planetary waves (PWs) to SSW events have been widely reported in the mesosphere and lower thermosphere (MLT) region (

Record‐Strong Eastward Propagating 4‐Day Wave in the Southern Hemisphere Observed During the 2019 Antarctic Sudden Stratospheric Warming

“…Previous studies have suggested that the onset date of the 2019 Antarctic SSW is 30 August (e.g., Eswaraiah et al, 2020;Kogure et al, 2021;Ma et al, 2022). Using the zonal wind data in the period from 30 August to 8 September (10 days after the SSW onset), we calculate the normalized period-wavenumber spectrum at 50°S and 50 km, which is presented in Figure 1a.…”

“…In September 2019, an extraordinary Antarctic SSW occurs and has been regarded as the strongest SSW after the 2002 Antarctic SSW (e.g., Baldwin et al., 2021; Safieddine et al., 2020). Global responses of planetary wave activities to the 2019 Antarctic SSW, including westward propagating quasi‐6‐day waves (Q6DWs) and quasi‐10‐day waves (Q10DWs), have been extensively reported (He et al., 2020; Lee et al., 2021; Ma et al., 2022; Miyoshi & Yamazaki, 2020; Wang et al., 2021; Yamazaki et al., 2020). Apart from these westward propagating waves, an E4DW is also enhanced in the Southern Hemisphere during the 2019 Antarctic SSW, while its characteristic has not been reported.…”

The Characteristics of Traveling Planetary Waves in the Troposphere and Mesosphere on Mars

“…TPWs are usually linked with barotropic/baroclinic instabilities on the Earth. Generally, regions with a negative meridional gradient of the quasi-geostrophic potential vorticity (QGPV) indicate a higher probability of barotropic/baroclinic instabilities for generating PWs (Ma et al, 2022;Qin et al, 2021;Yamazaki & Matthias, 2019). In addition, Tang et al (2021) found that strong instability with weak background wind 5), and B on the right of A refers to the periods after the solstice (second half of B in Equation 5).…”

Evidence for SSW Triggered Q6DW‐Tide and Q6DW‐Gravity Wave Interactions Observed by Meteor Radars at 30°S

“…During the 2019 SH SSW event, presence of enhanced traveling PW activities throughout the atmosphere were reported (e.g., He et al., 2020; G. Liu et al., 2021; Lee et al., 2021; Ma et al., 2022; Wang et al., 2021) and are believed to have induced significant ionospheric variabilities (e.g., Goncharenko et al., 2020; Yamazaki et al., 2020). In particular, prominent quasi‐6‐day periodicities in the equatorial electrojet (EEJ) were observed and attributed to the quasi‐6‐day wave (Q6DW) simultaneously observed in the middle atmosphere (Yamazaki et al., 2020).…”