The 2019 Southern Hemisphere Stratospheric Polar Vortex Weakening and Its Impacts

Lim, Eun‐Pa; Hendon, Harry H.; Butler, Amy H.; Thompson, David W. J.; Lawrence, Zachary D.; Scaife, Adam A.; Shepherd, Theodore G.; Polichtchouk, Inna; Nakamura, Hisashi; Kobayashi, Chiaki; Comer, Ruth; Coy, Lawrence; Dowdy, Andrew J.; Garreaud, René; Newman, Paul A.; Wang, Guomin

doi:10.1175/bams-d-20-0112.1

Cited by 86 publications

(94 citation statements)

References 78 publications

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“…Even though no wind reversal at 60°S and 10 hPa was registered in 2019, the polar vortex in this more recent event weakened dramatically and also lead to a smaller ozone hole (Figure ), with almost 30% higher total column ozone values compared to the previous decade (Safieddine et al., 2020). The event has also been linked to the severe bushfire season in South Eastern Australia the following spring and summer (Lim et al., 2021).…”

Section: Introductionmentioning

confidence: 99%

How Frequent Are Antarctic Sudden Stratospheric Warmings in Present and Future Climate?

Jucker

Reichler

Waugh

2021

Geophysical Research Letters

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The stratospheric polar vortex forms in the winter hemisphere due to the lack of solar heating at high latitudes and the resulting strong equator-to-pole temperature gradient. In the Northern Hemisphere (NH), strong and planetary scale waves originating in the troposphere from orographic forcing and land-sea contrast periodically propagate upward into the stratosphere and perturb the polar vortex via momentum deposition, when the waves break (Charney & Drazin, 1961;Eliassen & Palm, 1960;Matsuno, 1971). In extreme cases, this disruption of the polar vortex leads to a rapid warming and reversal of wind directions in the polar stratosphere, a so-called (major) sudden stratospheric warming (SSW) (Butler et al., 2015). These SSWs occur around every other winter in the NH.However, over the six decades that we have station records (and later satellite observations) of the Southern Hemisphere (SH) polar vortex, only one such wind reversal has been recorded in 2002(Esler et al., 2006Roscoe et al., 2005). This event substantially decreased the size of the ozone hole, thanks to higher than usual stratospheric polar temperatures and transport of ozone-rich air from lower latitudes into the polar regions (Figure S2a) (Stolarski et al., 2005). There was also a dynamical effect of the 2002 SSW at the surface, as an extreme negative polarity of the southern annular mode (SAM) was recorded at the surface for the 10-90-day period following the event . Even though no wind reversal at 60°S and 10 hPa was registered in 2019, the polar vortex in this more recent event weakened dramatically and also lead to a smaller ozone hole (Figure S2b), with almost 30% higher total column ozone values compared to the previous decade (Safieddine et al., 2020). The event has also been linked to the severe bushfire season in South Eastern Australia the following spring and summer (Lim et al., 2021).

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Section: Introductionmentioning

confidence: 99%

How Frequent Are Antarctic Sudden Stratospheric Warmings in Present and Future Climate?

Jucker

Reichler

Waugh

2021

Geophysical Research Letters

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“…The burning area was nearly double that of Australia's 2009 Black Saturday fires, which were some of the largest and most devastating bushfires in the nation's history that burnt 450,000 ha (Kepert et al, 2013). The 2019-20 bushfire season was strengthened by the El Niño year (Ehsani et al, 2020;Piper, 2020;Wang and Cai, 2020) and a rare sudden stratospheric warming (SSW) in the Southern Hemisphere (SH) that occurred in austral spring 2019 (Rao et al, 2020a;Rao et al, 2020b;Lim et al, 2021). El Niño years have been shown to be significantly related to high temperatures and low rainfall, leading to increased bushfire activity in Australia and New South Wales (Skidmore, 1987).…”

Section: Introductionmentioning

confidence: 99%

“…El Niño years have been shown to be significantly related to high temperatures and low rainfall, leading to increased bushfire activity in Australia and New South Wales (Skidmore, 1987). In contrast, the 2019 SSW event in the SH, which dramatically weakened the polar vortex throughout the depth of the stratosphere, promoted a record strong swing of the Southern Annular Mode (SAM) to its negative phase and caused extreme hot and dry conditions over subtropical eastern Australia (Birner and Albers, 2017;Lim et al, 2021;Zhang et al, 2021). The strengthened bushfire produced strong plumes that carried large quantities of gases and aerosols through the tropopause into the stratosphere from June 2019 to March 2020 (Yu et al, 2019;Gibson et al, 2020;Kablick et al, 2020).…”

Section: Introductionmentioning

confidence: 99%

“…(Xu et al, 2017;Yu et al, 2019;Dockrill, 2019;NASA Earth Observatory, 2019). The role of SSW in the SH on bushfires has also been investigated (Rao et al, 2020a;Rao et al, 2020b;Lim et al, 2021). In addition, the discrepancy between the observed lifetime and dynamic lifetime of stratospheric smoke is affected by photochemical reactions that destroy organic particulate matter (Yu et al, 2019).…”

Section: Introductionmentioning

confidence: 99%

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Analysis of the Impact of the 2019–20 Australian Bushfire Season on the Atmospheric Environment

Zhang

Sheng

et al. 2021

Front. Earth Sci.

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The 2019–20 Australian bushfire produced strong plumes that carried massive quantities of gases and aerosols through the tropopause into the stratosphere. The 2019 El Niño and a rare sudden stratospheric warming (SSW) in the Southern Hemisphere (SH) that occurred in austral spring 2019 caused reduced precipitation in eastern Australia, which caused the strongest bushfire in history in terms of area and disaster degree. High-intensity bushfires triggered chemical reactions, including the rapid secondary formation of formic acid (FA). The strong intensity of the bushfire and the isolated environment allowed their impacts to be well detected. We identified the most active bushfire period (December 30–January 1) and its impacts on atmospheric components. The trajectory and lifetime of bushfire plumes were analysed to reveal the bushfire process and most active period. Based on multiple satellite and reanalysis products, unique variations in atmospheric components were identified and attributed to three main factors: bushfire development period, stratospheric heating mechanism and rapid secondary formation of FA. The bushfire gradually increased in intensity from June, reached its most active period from December 30–January 1, and then weakened. The bushfire development period caused delays in the plumes and peak values of gases (CO, SO2, FA and ozone) and temperature. The diurnal cycle, particle concentration and time restricted the total radiative forcing of aerosols and gases, which prevented a high rate of temperature increase similar to that of gas input from plumes. The strong intensity of the bushfire caused rapid secondary formation of FA, which caused a sharp increase in FA production from December 30–January 1.

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“…For instance, the 1997 JS Niña event occurred during the developing phase of the 1997-1998 El Niño, and contributed to widespread Indonesian forest res, which resulted in massive coral reef mortality events along the Java-Sumatra coast 28 . In contrast, the 2019 JS Niña event, one of the strongest events ever recorded, developed rapidly in boreal summer under near-neutral ENSO conditions in the Paci c 29,30 , produced heavy rainfall and widespread severe ooding and landslides across South Asia 31 , and caused extreme hot and dry conditions that contributed to severe forest res over southeastern Australia 32,33 .…”

Section: Introductionmentioning

confidence: 99%

Java-Sumatra Niño/Niña and associated regional rainfall variability

Lee¹,

Lopez

Foltz

et al. 2021

Preprint

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A phenomenon referred to here as Java-Sumatra Niño/Niña (JSN or JS Niño/Niña) is characterized by the appearance of warm/cold sea surface temperature anomalies (SSTAs) in the coastal upwelling region off Java-Sumatra in the southeastern equatorial Indian Ocean. JSN develops in July-September and sometimes as a precursor to the Indian Ocean Dipole, but often without corresponding SSTAs in the western equatorial Indian Ocean. Although its spatiotemporal evolution varies considerably between individual events, JSN is essentially an intrinsic mode of variability driven by local atmosphere-ocean positive feedback, and thus does not rely on remote forcing from the Pacific for its emergence. JSN is an important driver of climate variability over the tropical Indian Ocean and the surrounding continents. Notably, JS Niña events developing in July-September project onto the South and Southeast Asian summer monsoons, increasing the probability of heavy rainfall and flooding across the most heavily populated regions of the world.

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The 2019 Southern Hemisphere Stratospheric Polar Vortex Weakening and Its Impacts

Abstract: Capsule SummaryDuring austral spring 2019 the Antarctic stratosphere experienced record-breaking warming and a near-record polar vortex weakening, resulting in predictable extreme climate conditions throughout the Southern Hemisphere through December 2019.

Cited by 86 publications

References 78 publications

How Frequent Are Antarctic Sudden Stratospheric Warmings in Present and Future Climate?

How Frequent Are Antarctic Sudden Stratospheric Warmings in Present and Future Climate?

Analysis of the Impact of the 2019–20 Australian Bushfire Season on the Atmospheric Environment

Java-Sumatra Niño/Niña and associated regional rainfall variability

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