Prolonged and Pervasive Perturbations in the Composition of the Southern Hemisphere Midlatitude Lower Stratosphere From the Australian New Year's Fires

Santee, M. L.; Lambert, A.; Manney, G. L.; Livesey, N. J.; Froidevaux, L.; Neu, J. L.; Schwartz, M.; Millán, Luis; Werner, Frank; Read, W. G.; Park, M.; Fuller, R. A.; Ward, Bruce

doi:10.1029/2021gl096270

Cited by 28 publications

(52 citation statements)

References 49 publications

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“…By October Cl y partitioning is within the range of previous years. Similar findings reported by Santee et al (2022) and Bernath et al (2022).…”

Section: Observations Of Aerosol Extinction Chlorine and Nitrogen Spe...supporting

confidence: 91%

“…Santee et al. (2022) suggest that the enhancements in MLS 100 hPa water vapor (Figure 1f) may be attributable to the wet phase of the tropical tape recorder. They showed that 2020 MLS SH midlatitude LS water (∼4 ppm) and MERRA2 temperature (212–224 K) were within the 2005–2019 data envelope.…”

Section: Observations Of Aerosol Extinction Chlorine and Nitrogen Spe...mentioning

confidence: 94%

“…The ACE April LS NO 2 anomalies represent record low mixing ratios that are 25%-30% below the decadal mean (Figure S5 in Supporting Information S1), suggesting significant repartitioning. Santee et al (2022) used HCl/N 2 O correlations to demonstrate that transport could not explain the chlorine repartitioning.…”

Section: Observations Of Aerosol Extinction Chlorine and Nitrogen Spe...mentioning

confidence: 99%

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Unexpected Repartitioning of Stratospheric Inorganic Chlorine After the 2020 Australian Wildfires

Strahan

Smale

Solomon

et al. 2022

Geophysical Research Letters

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The inorganic chlorine (Cly) and odd nitrogen (NOy) chemical families influence stratospheric O3. In January 2020 Australian wildfires injected record‐breaking amounts of smoke into the southern stratosphere. Within 1–2 months ground‐based and satellite observations showed Cly and NOy were repartitioned. By May, lower stratospheric HCl columns declined by ∼30% and ClONO2 columns increased by 40%–50%. The Cly perturbations began and ended near the equinoxes, increased poleward, and peaked at the winter solstice. NO2 decreased from February to April, consistent with sulfate aerosol reactions, but returned to typical values by June ‐ months before the Cly recovery. Transport tracers show that dynamics not chemistry explains most of the observed O3 decrease after April, with no significant transport earlier. Simulations assuming wildfire smoke behaves identically to sulfate aerosols couldn't reproduce observed Cly changes, suggesting they have different composition and chemistry. This undermines our ability to predict ozone in a changing climate.

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“…By October Cl y partitioning is within the range of previous years. Similar findings reported by Santee et al (2022) and Bernath et al (2022).…”

Section: Observations Of Aerosol Extinction Chlorine and Nitrogen Spe...supporting

confidence: 91%

Section: Observations Of Aerosol Extinction Chlorine and Nitrogen Spe...mentioning

confidence: 94%

Section: Observations Of Aerosol Extinction Chlorine and Nitrogen Spe...mentioning

confidence: 99%

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Unexpected Repartitioning of Stratospheric Inorganic Chlorine After the 2020 Australian Wildfires

Strahan

Smale

Solomon

et al. 2022

Geophysical Research Letters

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“…Solomon et al (2022) show evidence for mid-latitude chemistry driving large observed nitrogen oxide changes following the fires. Santee et al (2022) and Bernath et al (2022) show remarkable changes in hydrochloric acid and chlorine nitrate at mid-latitudes after the Australian fires, but the chemical mechanism causing those changes has not yet been identified, nor has a clear link to polar chemistry been established. Wildfire soot may also contribute to dynamical changes in the strength of the vortex through changes in radiative heating, but this mechanism has yet to be explored.…”

Section: Discussionmentioning

confidence: 99%

“…Santee et al. (2022) and Bernath et al. (2022) show remarkable changes in hydrochloric acid and chlorine nitrate at mid‐latitudes after the Australian fires, but the chemical mechanism causing those changes has not yet been identified, nor has a clear link to polar chemistry been established.…”

Section: Discussionmentioning

confidence: 99%

Climate Impacts and Potential Drivers of the Unprecedented Antarctic Ozone Holes of 2020 and 2021

Yook

Thompson

Solomon

2022

Geophysical Research Letters

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The radiative effects of polar ozone depletion act to cool and strengthen the stratospheric polar vortex (Randel & Wu, 1999;Waugh et al., 1999), and dynamical coupling between the stratosphere and troposphere acts to connect the changes in the stratospheric flow to the surface (Baldwin & Dunkerton, 2001;Thompson et al., 2005). At the surface, the changes in the flow associated with the ozone hole project onto the southern annular mode (Shindell & Schmidt, 2004;Thompson & Solomon, 2002). Thus the ozone hole has been linked to long-term changes in surface climate that span much of the Southern Hemisphere mid and high latitudes.The linkages between the Antarctic ozone hole and the SAM are important for the interpretation of Southern Hemisphere climate change. Over the 1970-1990s, the development of the ozone hole was associated with widespread changes in Southern Hemisphere surface climate that are consistent with forcing by ozone depletion (Thompson et al., 2011). Paleoclimate studies indicate that the resulting changes in the austral summer SAM index are unprecedented over the last thousand years, pointing toward the remarkable role of the ozone hole in Southern Hemisphere climate change (Fogt & Marshall, 2020).In recent years, the Antarctic ozone hole has exhibited signs of healing consistent with recent decreases in anthropogenic emissions of ozone-depleting substances (Solomon et al., 2016). The healing of the ozone hole is apparent when viewed in the context of decades, especially during September when dynamic variability in the vortex is modest (

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M2-SCREAM: A Stratospheric Composition Reanalysis of Aura MLS data with MERRA-2 transport

Wargan

Weir²,

Manney

et al. 2022

Preprint

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MERRA-2 Stratospheric Composition Reanalysis of Aura Microwave Limb Sounder (M2-SCREAM) is a new reanalysis of stratospheric ozone, water vapor, hydrogen chloride (HCl), nitric acid (HNO 3 ) and nitrous oxide (N 2 O) between 2004 and the present (with a latency of several months). The assimilated fields are provided at a 50-km horizontal resolution and at a three-hourly frequency. M2-SCREAM assimilates version 4.2 Microwave Limb Sounder (MLS) profiles of the five constituents alongside total ozone column from the Ozone Monitoring Instrument. Dynamics and tropospheric water vapor are constrained by the MERRA-2 reanalysis. The assimilated species are in excellent agreement with the MLS observations, except for HNO 3 in polar night, where data are not assimilated. Comparisons against independent observations show that the reanalysis realistically captures the spatial and temporal variability of all the assimilated constituents. In particular, the standard deviations of the differences between M2-SCREAM and constituent mixing ratio data from The Atmospheric Chemistry Experiment Fourier Transform Spectrometer are much smaller than the standard deviations of the measured constituents. Evaluation of the reanalysis against aircraft data and balloon-borne frost point hygrometers indicates a faithful representation of small-scale structures in the assimilated water vapor, HNO 3 and ozone fields near the tropopause. Comparisons with independent observations and a process-based analysis of the consistency of the assimilated constituent fields with the MERRA-2 dynamics and with large-scale stratospheric processes demonstrate the utility of M2-SCREAM for scientific studies of chemical and transport variability on time scales ranging from hours to decades. Analysis uncertainties and guidelines for data usage are provided.

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Prolonged and Pervasive Perturbations in the Composition of the Southern Hemisphere Midlatitude Lower Stratosphere From the Australian New Year's Fires

Cited by 28 publications

References 49 publications

Unexpected Repartitioning of Stratospheric Inorganic Chlorine After the 2020 Australian Wildfires

Unexpected Repartitioning of Stratospheric Inorganic Chlorine After the 2020 Australian Wildfires

Climate Impacts and Potential Drivers of the Unprecedented Antarctic Ozone Holes of 2020 and 2021

M2-SCREAM: A Stratospheric Composition Reanalysis of Aura MLS data with MERRA-2 transport

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