Wind Variations in the Mesosphere and Lower Thermosphere Near 60°S Latitude During the 2019 Antarctic Sudden Stratospheric Warming

Liu, Guiping; Janches, Diego; Lieberman, R. S.; Moffat‐Griffin, Tracy; Mitchell, N. J.; Kim, Jeong‐Han; Lee, Chang-Sup

doi:10.1029/2020ja028909

Cited by 8 publications

(15 citation statements)

References 71 publications

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“…During the 2019 event from MWR observations at King Sejong Station (62°S, 59°W), Eswaraiah et al (2020) noted that the wind reversal in the MLT occurred 20 days earlier than the reversal in the stratosphere. Liu, Janches, et al (2021), using radars located in the vicinity of the Antarctic Peninsula, also detected planetary waves with periods ranging from 8 to 20 days in the MLT before and after the 2019 warming, periods that are consistent with the variability evident in Figure 2.…”

Section: Major Warming Eventssupporting

confidence: 62%

Southern Hemisphere Stratospheric Warmings and Coupling to the Mesosphere‐Lower Thermosphere

et al. 2022

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Twenty six years of medium frequency (MF) radar wind measurements made from 1994 to 2019 at Davis Station (68.6°S, 77.9°E) are used to study the mean response of the mesosphere‐lower thermosphere to stratospheric warmings in the Southern Hemisphere. Warming events were detected using Modern‐Era Retrospective Analysis for Research and Applications (MERRA2) data with a systematic search for reductions in the zonal‐mean circulation at 60°S and corresponding increases in polar temperatures. Some 37 events were identified, including the 2002 major warming and the large event of 2019, with an average of 1–2 warmings per year. At the 10 hPa level, the polar cap temperature increases ranged from 3 to 28 K, with a mean value of 12 K, while the zonal wind speed reductions varied between −6 and −43 ms−1, with a mean value of −15 ms−1. Peak values occurred near 40 km. Warmings occurred mainly between August and October, with a small peak in occurrence in April/May. The MF radar data showed an average reduction in the mesospheric eastward winds of about 5–7 ms−1 at heights near 75 km that occurred 3–4 days prior to the changes in the stratosphere. Warming events were driven by episodic intensifications in planetary wave amplitudes, with quasi‐stationary planetary scale waves (PW) 1 being especially important. PW Eliassen‐Palm flux divergences show a systematic behavior with time and height that is consistent with a poleward residual circulation and downwelling over the pole prior to the warming events and an equatorward flow and upwelling after the peak of the events.

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Section: Major Warming Eventssupporting

confidence: 62%

Southern Hemisphere Stratospheric Warmings and Coupling to the Mesosphere‐Lower Thermosphere

et al. 2022

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“…Here this study extends such a direct comparison to include five radar stations across SH mid‐to‐high latitudes, and the study focuses on the day‐to‐day variations during a rare Antarctic Sudden Stratospheric Warming (SSW) in September 2019. Large disturbances in the MLT winds have been observed during this SSW (e.g., Liu, Janches, et al., 2021; Stober, Janches, et al., 2020). This study further assesses the NAVGEM‐HA results and investigates the MLT tidal variations in response to the SH SSW.…”

Section: Introductionmentioning

confidence: 93%

“…The mesosphere and lower thermosphere (MLT) exhibit dramatic variations during austral winter near 60° latitude in the Southern Hemisphere (SH), covering the Southern Andes, the Drake Passage, and the Antarctic Peninsula area (e.g., Alexander et al., 2008; de Wit et al., 2017; Dowdy et al., 2004; Fritts et al., 2019; Liu, Janches, et al., 2021; Stober, Baumgarten, et al., 2020; Stober, Janches, et al., 2020). These variations account for both large‐ and small‐scale motions including tides and gravity waves.…”

Section: Introductionmentioning

confidence: 99%

Mesosphere and Lower Thermosphere Winds and Tidal Variations During the 2019 Antarctic Sudden Stratospheric Warming

Liu

Janches

et al. 2022

JGR Space Physics

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Realistic modeling of the winds and dynamical variations in the mesosphere and lower thermosphere (MLT) at Southern Hemisphere (SH) mid‐to‐high latitudes near 60°S where dramatic motions occur has been a challenge. This work presents an evaluation of the MLT zonal and meridional winds from ∼80 to 98 km altitude produced by the high‐altitude version of the Navy Global Environmental Model (NAVGEM‐HA) numerical weather prediction system during the Antarctic Sudden Stratospheric Warming (SSW) in September 2019. These results are compared with the coincident measurements by five meteor radars at Tierra del Fuego (TDF; 53.7°S, 67.7°W), King Edward Point (KEP; 54.3°S, 36.5°W), King Sejong Station (KSS; 62.2°S, 58.8°W), Rothera (ROT; 67.5°S, 68.0°W), and Davis (DAV; 68.6°S, 78.0°E) across SH mid‐to‐high latitudes. We find that the day‐to‐day variations in NAVGEM‐HA winds related to tidal motions are overall consistent with variations in the radar winds, and the daily mean winds have a correlation of 0.7–0.9 between them. Three‐hourly NAVGEM‐HA winds have a correlation of ∼0.5 and mean difference <10 m/s to the radar observations at most stations, and the Root Mean Square (RMS) error ranges from ∼25 to 35 m/s. Above 90 km altitude, the correlation coefficient decreases, and the difference and RMS error increase, indicating an upper limit to the validity of the NAVGEM‐HA results. Both the analyzed and observed winds reveal an enhancement in diurnal and semidiurnal tidal amplitude during this SH SSW. NAVGEM‐HA shows some evidence that nonmigrating tidal enhancements are produced through the interaction of migrating tides with planetary waves.

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“…The unusual Q10DWs in the MLT region in both hemispheres are found to be triggered by the extreme Antarctic SSW (Eswaraiah et al., 2020; He et al., 2020; Lee et al., 2021). The Q6DWs are also observed by meteor radars from the middle latitudes in the Southern Hemisphere to the equatorial region in the Northern Hemisphere, which is suggested to be caused by the equatorward propagation of Q6DWs due to the extreme Antarctic SSW (Lee et al., 2021; Liu et al., 2021). However, the excitation mechanism of the global enhanced Q6DWs is still unclear, especially at the middle latitudes in the Northern Hemisphere.…”

Section: Introductionmentioning

confidence: 93%

“…The enhanced Q6DWs in the Southern Hemisphere are believed to be related to the extreme Antarctic SSW, while the excitation mechanism of the global enhanced Q6DWs in the MLT region is still unclear (Eswaraiah et al., 2020; Miyoshi & Yamazaki, 2020). Studies based on meteor radar observations indicated that the equatorward propagation of Q6DWs caused by the SSW might be responsible for the Q6DWs observed at middle latitudes in the Southern Hemisphere and even in the equatorial region in the Northern Hemisphere (Lee et al., 2021; Liu et al., 2021). However, the Q6DWs observed by the meteor radar over Mohe (53.5°N, 122.3°E) suggested that the Q6DWs at mid‐latitudes might be due to their seasonal variations (He et al., 2020).…”

Section: Observationsmentioning

confidence: 99%

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

Ma¹,

Gong²,

Zhang

et al. 2022

JGR Atmospheres

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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 (

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Wind Variations in the Mesosphere and Lower Thermosphere Near 60°S Latitude During the 2019 Antarctic Sudden Stratospheric Warming

Cited by 8 publications

References 71 publications

Southern Hemisphere Stratospheric Warmings and Coupling to the Mesosphere‐Lower Thermosphere

Southern Hemisphere Stratospheric Warmings and Coupling to the Mesosphere‐Lower Thermosphere

Mesosphere and Lower Thermosphere Winds and Tidal Variations During the 2019 Antarctic Sudden Stratospheric Warming

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

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