Decadal changes in the central tropical Pacific teleconnection to the Southern Hemisphere extratropics

Evtushevsky, Oleksandr; Grytsai, Asen; Milinevsky, Gennadi

doi:10.1007/s00382-018-4354-5

Cited by 16 publications

(10 citation statements)

References 71 publications

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“…However, the amplitudes of PW2 stayed at lower values (Figure 1d ) . The unusual growth of PW1 indicates a strong disturbance in the southern polar vortex (Evtushevsky et al, 2019; Watson & Gray, 2014). The strong growth of the PW1 during 2019 could be due to the easterly phase of QBO in the SH tropical region (Anstey et al, 2010).…”

Section: Resultsmentioning

confidence: 99%

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

Eswaraiah

Kim

Lee

et al. 2020

Geophysical Research Letters

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A rare sudden stratosphere warming (SSW) occurred in the Southern Hemisphere polar region in 2019. The polar stratosphere temperature and planetary wave (PW) enhancements are found to be unusual from the history for 40 years; hence, it is an "Extremely-Rare" SSW. The distinct features of the mesosphere winds were observed during the SSW, in association with the traveling PWs in the stratosphere. The mesosphere zonal winds reversed for about 20 days before the peak SSW. Meteor radar (MR) and Modern-Era Retrospective Analysis for Research and Applications (MERRA)-2 observations indicate that the zonal wind reversal was descended with time, and the reversal was larger over~72°S than the MR site (62°S). The MR detected the PWs of 14-22 days before and 8-12 days following the SSW in the mesosphere. We further noticed the enhancement of wavenumber 1 signature in the mesosphere during the peak SSW over the polar region. Thus, the polar middle-atmosphere is greatly affected by the SSW.

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Section: Resultsmentioning

confidence: 99%

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

Eswaraiah

Kim

Lee

et al. 2020

Geophysical Research Letters

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“…In addition, the North Pacific ridge associated with La Niña has shifted closer to North America since 1979 (Kumar et al, ; S. Yang et al, ) where it leads to an enhanced wave‐2 signal (S. Yang et al, ). Decadal variability is also evident in the teleconnection of ENSO to the SH, albeit with a different timing with respect to the decadal variability in the NH (Evtushevsky et al, ).…”

Section: Factors Influencing Enso Teleconnectionsmentioning

confidence: 99%

The Teleconnection of El Niño Southern Oscillation to the Stratosphere

Domeisen

Garfinkel²,

Butler

2019

Reviews of Geophysics

316

284

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El Niño and La Niña events in the tropical Pacific have significant and disrupting impacts on the global atmospheric and oceanic circulation. El Niño Southern Oscillation (ENSO) impacts also extend above the troposphere, affecting the strength and variability of the stratospheric polar vortex in the high latitudes of both hemispheres, as well as the composition and circulation of the tropical stratosphere. El Niño events are associated with a warming and weakening of the polar vortex in the polar stratosphere of both hemispheres, while a cooling can be observed in the tropical lower stratosphere. These impacts are linked by a strengthened Brewer-Dobson circulation. Anomalous upward wave propagation is observed in the extratropics of both hemispheres. For La Niña, these anomalies are often opposite. The stratosphere in turn affects surface weather and climate over large areas of the globe. Since these surface impacts are long-lived, the changes in the stratosphere can lead to improved surface predictions on time scales of weeks to months. Over the past decade, our understanding of the mechanisms through which ENSO can drive impacts remote from the tropical Pacific has improved. This study reviews the possible mechanisms connecting ENSO to the stratosphere in the tropics and the extratropics of both hemispheres while also considering open questions, including nonlinearities in the teleconnections, the role of ENSO diversity, and the impacts of climate change and variability.Plain Language Summary El Niño and La Niña events, the irregular warming and cooling of the tropical Pacific that occurs every couple of years, have disrupting impacts spanning the entire world. These remote impacts, so-called "teleconnections", also reach the stratosphere, the layer of the atmosphere starting at around 10 km above the Earth's surface. El Niño leads to a warming of the stratosphere in both hemispheres, while the lower tropical stratosphere cools. These signatures are linked by a strengthened stratospheric circulation from the tropics to the polar regions. El Niño also leads to more frequent breakdowns of the stratospheric polar vortex, a band of strong eastward winds in the polar stratosphere. For La Niña, these effects tend to be opposite, though they are not always robust, suggesting nonlinear or nonstationary effects, long-term variability, and trends in the teleconnections. The observational data record is not yet long enough to make conclusions with certainty, and models that try to reproduce the teleconnections indicate that teleconnections might be more linear than the limited number of observations indicate. Further research will be needed to separate the El Niño and La Niña teleconnections from other effects and to determine to what extent nonlinearity and nonstationarity are indeed present.

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“…(2020) and Yamazaki et al. (2020) both suggested that the SPW1 amplitudes increased dramatically from the middle of August, which represents a strong disturbance in the SH polar vortex (Evtushevsky et al., 2019), and this unusual enhancement are mainly responsible for the occurrence of this rare Antarctic SSW. Therefore, from a perspective of the zonal structure, this SH SSW can be categorized as a polar vortex displacement event (SPW1 breaking) (Kogure et al., 2021; Yamazaki et al., 2020).…”

Section: Resultsmentioning

confidence: 99%

A New Mechanism for the Generation of Quasi‐6‐Day and Quasi‐10‐Day Waves During the 2019 Antarctic Sudden Stratospheric Warming

Qin

Dou

2021

JGR Atmospheres

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Using the Modern‐Era Retrospective analysis for Research and Applications version 2 reanalysis and Aura Microwave Limb Sounder geopotential height and temperature observations, two unusual planetary waves (PWs) with westward zonal wavenumber 1 (W1) and periods of ∼6.0 and ∼9.6 days are identified during a rare Antarctic sudden stratospheric warming (SSW) event in September 2019, which follow a strong W1 PW with period of ∼7.4 days. It is found that the W1 ∼7.4‐day wave is actually the representation of the climatological W1 quasi‐6‐day wave before the September equinox, which peaks on September 10, 2019. Meanwhile, a strong zonally symmetric wave with period of ∼32.2 days occurs in the Southern Hemisphere with a maximum zonal wind amplitude of ∼27 m/s at 65°S and 48 km. Interestingly, the frequencies and zonal wavenumbers of the W1 ∼7.4‐day, ∼6.0‐day, ∼9.6‐day and zonally symmetric ∼32.2‐day waves exactly satisfy the nonlinear interaction theory between PWs. We thus proposed for the first time the occurrence of nonlinear interaction between a W1 ∼7.4‐day wave and a zonally symmetric ∼32.2‐day wave, which generates two W1 PWs with periods of ∼6.0 and ∼9.6 days. The Eliassen‐Palm flux diagnostics suggest that the zonally symmetric ∼32.2‐day wave also contributes to the wind deceleration during this SSW. Moreover, the baroclinic/barotropic instabilities related to the vertical shear in the zonal wind during the SSW considerably enhance the PW activities in the Antarctic stratosphere. The climatological variations of the instabilities and critical layers in the mesosphere can also influence the propagation of these three W1 PWs.

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Decadal changes in the central tropical Pacific teleconnection to the Southern Hemisphere extratropics

Cited by 16 publications

References 71 publications

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

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

The Teleconnection of El Niño Southern Oscillation to the Stratosphere

A New Mechanism for the Generation of Quasi‐6‐Day and Quasi‐10‐Day Waves During the 2019 Antarctic Sudden Stratospheric Warming

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