The intricate interplay between atmospheric composition changes and climate dynamics is garnering increasing attention due to its implications for weather and climate prediction. In this talk, I leverage advanced modeling techniques and new observational climate data records to provide examples of chemistry-climate coupling on timescales ranging from subseasonal-to-seasonal weather to long-term climate trends. These examples include the impact of dynamical processes and abrupt events such as sudden stratospheric warmings and the Hunga-Tonga eruption on atmospheric composition anomalies and their feedbacks on meteorological and climate phenomena, as well as the impacts of stratospheric ozone depletion and recovery on climate radiative forcing and atmosphere-ocean dynamics. The findings underscore the important feedback loops between atmospheric composition and climate dynamics via radiative processes, emphasizing the need for a realistic representation of composition anomalies in weather forecast systems and climate models.

How to cite: Hegglin, M. I.: Emerging importance of chemistry-climate coupling on weather to climate timescales, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-3155, https://doi.org/10.5194/egusphere-egu24-3155, 2024.

The strength and latitudinal position of the extratropical eddy-driven jet (EDJ) in the Southern Hemisphere (SH) winter and summer is naturally forced by the conditions of the tropical oceans and by the variability of the SH stratospheric polar vortex (SPV). Uncertainty in the responses of these remote drivers (RDs) of extratropical circulation to anthropogenic forcing leads to uncertainty in the future strength and latitude of the EDJ. In turn, these changes in tropospheric circulation can lead to changes at the regional scale. During this century, the combined effect of ozone recovery and the increase in greenhouse gases (GHGs) will influence the SPV. Therefore, understanding the ‘tug-of-war’ between these two anthropogenic forcings is crucial to understand future projections. Moreover, the influences of the stratosphere will be combined with the influences of forced changes in the tropics. This complex interplay between RDs and the magnitude of each RD’s response to anthropogenic forcings differs among Global Climate Models (GCMs), which leads to different responses of the EDJ and regional climate. In this work we analyze an ensemble of CMIP6 models to study the role of forced responses in the SPV in driving changes in climate projections, and how the influence of the stratospheric changes combines with the influence of the changes in a small set of tropical RDs. In particular, we find that a strengthening of the SPV leads to a strengthening and small poleward shift of the EDJ in winter, and that a delay in the SPV breakdown date leads to a strong poleward shift of the EDJ in summer. The evolution of the summer circulation response in CMIP6 models during the twenty-first century can be explained from the combined effect of ozone recovery and GHG increase. At the regional scale, in winter, a strengthening of the SPV leads to drying in Southeastern South America and wetting in Tierra del Fuego, in the south of South America, while in summer, a SPV breakdown delay leads to wetting in the west coast of all three large extratropical continental sectors and the coasts of Antarctica. Finally, we develop storylines of future circulation and precipitation changes in both summer and winter which help understand the relative role of the SPV among other dynamical drivers of change in the SH. 

How to cite: Mindlin, J., Vera, C. S., Shepherd, T. G., and Osman, M.: The Role of the Stratosphere in Driving Uncertainties in the Southern Hemisphere Future Climate, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-8884, https://doi.org/10.5194/egusphere-egu24-8884, 2024.

Stratospheric aerosols play a crucial role in the climate system, but uncertainties persist in understanding the chemical, dynamical, and microphysical processes governing their distribution and variability. The chemical and radiative impacts of stratospheric aerosols hinge on particle size distribution. However, models exhibit significant variations in how they parameterize aerosol microphysical processes and simulate size distributions, leading to divergent predictions of the time evolution of radiative impacts from stratospheric aerosol perturbation events. To refine models for assessing the effects of potential climate intervention strategies, systematic measurements are crucial. In pursuit of this understanding, the Baseline Balloon Stratospheric Aerosol Profiles (B²SAP) project utilizes compact, lightweight payloads carried by meteorological balloons. These payloads measure aerosol number density and size distributions, along with water vapor, ozone, and meteorological data from the surface to the middle stratosphere. The long-term goal of the B²SAP project is to generate climatologies of aerosol number and size distributions up to the middle stratosphere at latitudinally distributed measurement sites. Since March 2019, B²SAP payloads have been launched from Boulder, CO, USA (40°N) once to twice per month and four to six times per year from Lauder, NZ (45°S). Starting in 2022, two tropical sites were added to this evanescent network with quarterly launches: Hilo, HI, USA (20°N) and Reunion Island, FR (20°S). These measurements provide a new record of in situ observations allowing to characterize the natural stratospheric aerosol burden, its variability, and responses to perturbations, providing essential data for refining models and aiding in the validation of satellite-based estimates. In this context, we will present a subset of this growing database, emphasizing the discussion on the stratospheric aerosol layers in the North hemisphere and South hemisphere (SH) mid-latitudes. Perturbations recorded in the SH after the Australian New Year super pyroCb outbreak in 2020 will also be investigated.

How to cite: Baron, A., Asher, E., Smith, K., and Thornberry, T. and the B2SAP extended Team: The NOAA Balloon Baseline Stratospheric Aerosol Profiles (B2SAP) – In situ insight on the stratospheric aerosol layer , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-13753, https://doi.org/10.5194/egusphere-egu24-13753, 2024.

Based on observations and numerical simulations, this study explores the responses of Asian precipitations in summer to the vertical structure of Stratospheric Quasi-Biennial Oscillation (QBO), and the relevant mechanisms. Compared to the QBO phase defined by a particular level traditionally, considering QBO's vertical structure leads to more significant precipitation responses. When the tropical zonal winds exhibit easterlies (westerlies) at 70 hPa and westerlies (easterlies) at both 30 hPa and 50 hPa, there are downwellings (upwellings) over tropics and upwellings (downwellings) over mid-latitudes in the upper troposphere and lower stratosphere (UTLS). The meridional movement of the subtropical westerly jet (SWJ) is related to this secondary circulation, accompanied by anomalies of the South Asian High (SAH). These circulation anomalies lead to anomalous lower tropospheric circulations, causing abnormal vertical velocities and moisture transports, resulting in increased precipitation over South Asia and decreased precipitation in the Yangtze River basin.

How to cite: Luo, F., Luo, J., Xie, F., Tian, W., Hu, Y., Yuan, L., Zhang, R., and Wang, T.: The Key Role of the Vertical Structure of the Stratospheric Quasi-Biennial Oscillation in the Variations of Asian Precipitation in Summer, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-1341, https://doi.org/10.5194/egusphere-egu24-1341, 2024.

Stratospheric water vapor increases are expected in response to greenhouse gas-forced climate warming, and these changes act as a positive feedback to surface climate. Previous efforts at inferring trends from the 3–4 decade-long observational stratospheric water vapor record have yielded conflicting results. Here we show that a robust multi-decadal variation of water vapor concentrations exists in most parts of the stratosphere based on satellite observations and atmospheric model simulations, which clearly divides the past 40 years into two wet decades (1986–1997; 2010–2020) and one dry decade (1998–2009). This multidecadal variation, especially pronounced in the lower to middle stratosphere and in the northern hemisphere, is associated with decadal temperature anomalies (±0.2 K) at the cold point tropopause and a hemispheric asymmetry in changes of the Brewer-Dobson circulation modulating methane oxidation. Multi-decadal variability must be taken into account when evaluating stratospheric water vapor trends over recent decades.

How to cite: Tao, M., Konopka, P., Wright, J. S., Liu, Y., Bian, J., Davis, S. M., Jia, Y., and Ploeger, F.: Multi-decadal variability controls short-termstratospheric water vapor trends, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-8035, https://doi.org/10.5194/egusphere-egu24-8035, 2024.

Sudden Stratospheric Warming (SSW) is an important source of subseasonal-toseasonal predictability due to its significant and long-lasting impacts on surface climate. However, the mechanism of its downward coupling has not yet been fully elucidated. In this study, we investigate the downward coupling mechanism of SSW in terms of mass redistribution. Out of the 65-year dataset of the Japanese 55-year Reanalysis (JRA-55), 40 SSW events are identified. Their composite shows a significant increase of tropospheric geopotential and pressure anomalies over the Arctic (60-90°N) after the onset with a prominent surface amplification. The decomposition of tropospheric anomalies into surface pressure and air temperature components reveals that the downward coupling mainly results from surface pressure change. It is further found that surface pressure change during the SSW onset is primarily caused by the poleward mass flux near the tropopause, which is mainly driven by momentum flux change in the upper troposphere. This momentum flux change is consistent with the poleward propagation of wave, and it is may associated with the warm temperature anomalies during the SSW. These findings provide a new insight on SSW downward coupling and surface amplification.

How to cite: Son, S.-W. and Hong, D.-C.: Downward coupling mechanism of Sudden Stratospheric Warming: A Mass Flux Perspective, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-3026, https://doi.org/10.5194/egusphere-egu24-3026, 2024.

Stratospheric variability can have a significant impact on surface weather extremes in winter, in particular during stratospheric extreme events, so-called sudden stratospheric warming (SSW) events. The stratospheric downward impact has been shown to be communicated by both planetary-scale and synoptic-scale waves, but their relative roles and interactions are not fully understood. Since there is a strong average response to stratospheric forcing over the North Atlantic but a weak response over the North Pacific, studies of SSW downward impact generally focus on the North Atlantic, where the synoptic eddy-feedback plays a strong role. We here examine the relative roles of planetary-scale waves for the North Pacific after SSW events. By examining the case-by-case response over the North Pacific following SSW onset using ERA5 reanalysis, we identify differences between events in terms of their interactions between the wave anomalies induced by the stratosphere and the tropospheric stationary waves. Specifically, the destructive and constructive interference of zonal wavenumber-1 anomalies plays a dominant role in contributing to different responses over the North Pacific, which are associated with an equatorward and a poleward jet shift, respectively. We suggest that SSW events can exhibit opposite responses over the North Pacific, potentially explaining the generally weak response observed in this region when averaging across all SSW events.

How to cite: Wu, R. W.-Y., Afargan-Gerstman, H., and Domeisen, D. I. V.: Exploring the role of tropospheric stationary waves for the North Pacific response to SSWs, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-4343, https://doi.org/10.5194/egusphere-egu24-4343, 2024.

 Using the ERA5 reanalysis data, we identify seven easily calculable indices of the strength of theArctic stratospheric vortex: zonal winds at 10 hPa and temperature or height anomalies at 10 , 50, and 100 hPa.We then compare the climatological statistics and meteorological properties of strong and weak events basedon these indices. We particularly consider the sensitivity of the event statistics to the choice of thresholds, theuse of these indices in capturing stratosphere–troposphere coupling, and meteorological conditions relevant tochemical ozone depletion. The frequency, seasonal distribution, and interdecadal variability of strong eventsis more sensitive to threshold or index choice compared to weak events. Composites of polar-cap geopotentialheight anomalies are found to differ significantly based on the choice of index. In particular, height-basedevents reveal a strong and immediate barotropic response near the central date due to surface pressurefluctuations, making it more difficult to regard central dates of height-based events as purely stratosphericin origin. We further characterize the relationship of all indices to conditions relevant to chemical ozonedepletion, finding that temperature-based indices in the lower stratosphere perform best. Finally, we presentfour dynamical benchmarks used to assess and compare the representation of strong events in climate models.Our results highlight the challenges in determining the optimal definition for strong events and emphasizethe implications of different choices, providing valuable insights for guiding future studies in defining strong events. 

How to cite: Huang, J. and Hitchcock, P.: Defining Arctic Stratospheric Polar Vortex Intensification Events, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-4273, https://doi.org/10.5194/egusphere-egu24-4273, 2024.

This study presents the very first attempt to directly simulate a full cycle of the quasi-biennial oscillation (QBO) in a global storm-resolving model (GSRM) that explicitly resolves deep convection and gravity waves instead of parameterizing them. Using the ICOsahedral Nonhydrostatic (ICON) model with a horizontal and vertical resolution of about 5 km and 400 m, respectively, we show that a GSRM in the convective gray zone is in principle capable of simulating the basic dynamics that lead to a QBO-like oscillation of the zonal wind in the tropical stratosphere. ICON shows overall good fidelity in simulating the downward propagation of QBO jets in the upper tropical stratosphere, which happens also for the right reasons. In the lower stratosphere, however, ICON does not simulate the downward propagation of the QBO jets to the tropopause, predominantly due to a pronounced lack of planetary-scale wave forcing. As a consequence, the QBO jets degrade with increasing simulation time and lose strength substantially. We show that the lack of planetary-scale wave forcing in the lower stratosphere is caused by a lack of planetary-scale wave momentum fluxes entering the stratosphere, which are about 20%–40% too weak. We attribute this lack of planetary-scale wave momentum flux to a substantial underestimation of the spatio-temporal variability of tropical deep convection in general and convectively coupled equatorial waves in the tropical troposphere in particular. While conventional general circulation models can compensate for a lack in resolved wave forcing by tuning the parameterized gravity wave forcing, GSRMs no longer have this tuning screw, making their QBO more susceptible to being influenced by tropospheric mean state biases. We thus conclude that simulating a realistic spatio-temporal variability of tropical convection is currently the main roadblock towards simulating a reasonable QBO in GSRMs.

How to cite: Franke, H. and Giorgetta, M.: Towards a direct simulation of a full cycle of the quasi-biennial oscillation in a global storm-resolving model, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-5302, https://doi.org/10.5194/egusphere-egu24-5302, 2024.

A modulation has been identified of the tropical Madden-Julian oscillation (MJO) by the stratospheric quasi-biennial oscillation (QBO) such that the MJO in boreal winter is ~ 40% stronger and persists ~10 days longer during the easterly QBO phase (QBOE) than during the westerly phase.  A proposed mechanism is reductions of tropical lower stratospheric static stability during QBOE caused by (1) the QBO induced meridional circulation; and (2) QBO influences on extratropical wave forcing of the stratospheric residual meridional circulation during early winter.  Here, long-term variability of the QBO-MJO connection and associated variability of near-tropopause tropical static stability and extratropical wave forcing are investigated using European Center reanalysis data for the 1959-2021 period.  During the most reliable (post-satellite) part of the record beginning in 1979, a strengthening of the QBO-MJO modulation has occurred during a time when tropical static stability in the lowermost stratosphere and uppermost troposphere has been decreasing and extratropical wave forcing in early winter has been increasing.  A high inverse correlation (R = -0.87) is obtained during this period between early winter wave forcing anomalies and wintertime tropical lower stratospheric static stability.  Regression relationships are used to show that positive trends in early winter wave forcing during this period have likely contributed to decreases in tropical static stability, favoring a stronger QBO-MJO connection.  As shown in previous work, increased sea level pressure anomalies over northern Eurasia produced by Arctic sea ice loss may have been a significant source of the observed positive trends in early winter wave forcing.

How to cite: Hood, L. and Hoopes, C. A.: Arctic Sea Ice Loss, Long-Term Trends in Extratropical Wave Forcing, and the Observed Strengthening of the QBO-MJO Connection, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-6801, https://doi.org/10.5194/egusphere-egu24-6801, 2024.

The Quasi-Biennial Oscillation (QBO) is the leading natural model of interannual variability of the zonal mean wind in the equatorial stratosphere, consisting of alternating regions of easterly and westerly zonal wind that descend through the equatorial stratosphere with a mean period of approximately 28 months. Its dominant influence on the dynamical structure of the equatorial stratosphere raises the prospect of teleconnections to the extratropical atmosphere. For example, the QBO has been linked to variability in the Northern Hemisphere winter stratospheric polar vortex, the timing and frequency of sudden stratospheric warmings, the phase of the North Atlantic Oscillation, and the modulation of tropospheric mid-latitude waves in the Pacific region. However, the reproduction of these extratropical teleconnections in free-running models relies upon on a quantitatively realistic internally-generated QBO, and the ability of the model dynamics to respond to this QBO. To isolate the dynamical response, a new experiment protocol, defined by the Atmospheric Processes and their Role in Climate (APARC) Quasi-Biennial Oscillation initiative (QBOi), describes how the observed equatorial stratospheric zonal winds can be imposed in model experiments. This allows the dynamical response across different models with similar and realistic QBOs to be analysed. Using a multi-model ensemble generated by QBOi modelling centres, we present an assessment of the extratropical teleconnections in comparison with observations.

How to cite: Andrews, M., Butchart, N., Anstey, J., Bednarz, E., Elsbury, D., Kumar, V., Palmeiro, F., Trencham, N., Chai, Z., Tang, Q., Xie, J., Lin, P., Lott, F., Watanabe, S., Jaison, A., Knight, J., Naoe, H., and Yoshida, K.: Extratropical teleconnections in an ensemble of models nudged towards the observed equatorial QBO, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-8621, https://doi.org/10.5194/egusphere-egu24-8621, 2024.

The Quasi-Biennial Oscillation (QBO) of equatorial zonal winds is the leading mode of lower-stratospheric variability. Numerous studies have explored its connection with the troposphere, including its sensitivity to tropical convection and the El Niño-Southern Oscillation (ENSO). In particular, the upward ENSO impact on the QBO is known: observational evidence suggests that during El Niño the QBO propagates faster (shorter period). However, the potential downward QBO influence on ENSO has not been thoroughly assessed and needs better understanding. Here, we focus on the strongest ENSO events, dubbed super El Niños, characterized by extreme sea surface temperature (SST) anomalies in the eastern Pacific. Super El Niños are exceptional due to self-limiting ENSO dynamics in the tropical Pacific and seasonal SST cooling during summer and autumn, which prevents strong eastern Pacific SST warming and convective anomalies from developing. Their existence requires one or more factors external to the tropical Pacific to aid the Bjerknes feedback in building an El Niño event. In both observations and models (EC-EARTH), super El Niño events seem to require the westerly QBO phase to coincide with a growing El Niño, i.e. in boreal summer and fall. We thus propose a novel element that contributes to the generation of extreme El Niño events that involve the QBO and its modulation of the Walker circulation. While an El Niño event typically leads to a weaker Walker circulation, the weakening becomes more pronounced if the QBO is in its westerly phase. Consequently, the low-level trade wind anomalies over the equatorial Pacific are intensified, which reinforces the Bjerknes feedback and enhances the warm anomalies over the cold tongue region. Our results suggest that the QBO state could be considered to improve El Niño predictions, especially for extreme events.

How to cite: Rodrigo, M., García-Serrano, J., and Bladé, I.: Modulation of El Niño by the Quasi-Biennial Oscillation, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-20008, https://doi.org/10.5194/egusphere-egu24-20008, 2024.

Through their significant impact on the short- and longwave radiation and their pivotal role in the hydrological cycle, clouds and their response to climate change are a key component in present-day and future climate. As part of the SPARC Reanalysis Intercomparison Project (S-RIP) phase 2, we analyze cloud climatologies from twelve reanalysis datasets including, for instance, ERA5, MERRA2 and JRA-55. The study focuses on parameters that are available from most reanalysis datasets such as cloud fraction, cloud liquid and ice water content as well as cloud radiative effects on monthly to multi-year time scales. Geographical distributions, variability and statistical properties of the cloud parameters from the reanalyses for specific cloud regimes and regions are compared and put into context with satellite observations. First results show that more recent reanalysis products are in closer agreement with the satellite data and that in contrast to multi-model means of models participating in the Coupled Model Intercomparison Project (CMIP), multi-reanalysis means do not outperform individual reanalyses. For a consistent processing of all reanalysis and satellite datasets, the Earth System Model Evaluation Tool (ESMValTool) is applied. ESMValTool is a community developed open-source software tool that provides common operations such regridding data onto the same grid, masking of missing values, area extraction, and basic statistics such as seasonal means, annual means, area means, etc. which facilitates analysis and a fair intercomparison of the datasets. For comparison with satellite data, multiple products for each parameter are used to estimate observational uncertainties.

How to cite: Lauer, A., Bock, L., and Hassler, B.: Cloud climatologies from reanalysis datasets – an intercomparison, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-7531, https://doi.org/10.5194/egusphere-egu24-7531, 2024.

We processed vertical ozone distribution measurements from the Faraday/Vernadsky station made by the Umkehr method for the 1973–2023 period. Ozone profiles in this unique series of ozone observations since 1973 cover pre-ozone hole times and the ozone hole period. Umkehr data from about 1200 Dobson spectrophotometer observations was processed using the UMK92 ozone profile retrieval algorithm. The Faraday/Vernadsky station is located at the edge of the ozone hole area; therefore, the total ozone column values over the station can change rapidly. This feature is seen clearly in Umkehr profiles measured during the same day in the morning and evening. In the pre-ozone hole period 1973–1983, the ozone partial column in ozone profiles maximum varies from 134 DU/layer to 56 DU/layer with the altitude of the profile maximum at 14–18 km. Profiles in ozone hole conditions usually have two maxima. The altitude area of significant depletion in ozone partial column values between these maxima located in the usual highest ozone concentration height. The values in altitudes at expected ozone maximum drop to 14–26 DU/layer. The 50-year trend in ozone profiles in the atmosphere above Faraday/Vernadsky station from pre-ozone hole times till 2023 is described and discussed.

How to cite: Andrienko, Y., Grytsai, A., Milinevsky, G., Shanklin, J., Shi, Y., Yu, R., and Poluden, O.: Peculiarities and trends in the vertical ozone distribution 1973 - 2023 at Faraday/Vernadsky Antarctic station, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-7337, https://doi.org/10.5194/egusphere-egu24-7337, 2024.

At present, volcanic sulfate aerosols can lead to stratospheric ozone loss under the presence of anthropogenic chlorofluorocarbons (CFCs). Recent satellite measurements showed that the 2015 Calbuco eruption, a small-magnitude eruption in Chile with 0.4 Tg of stratospheric sulfur injection, caused large-scale stratospheric ozone depletion during October 2015 in the Antarctic. According to the World Meteorological Organization, atmospheric CFC levels have declined since the 1980s, and the Antarctic ozone hole is expected to be healed by around mid-century. In the absence of CFCs, future volcanic eruptions producing stratospheric volcanic sulfate aerosol are expected to increase stratospheric ozone column concentrations. However, it remains uncertain whether future volcanic eruptions will lead to an earlier or a delayed recovery in stratospheric ozone back to 1980s levels.

To investigate how future volcanic eruptions affect stratospheric ozone recovery, we generated stochastic future eruption scenarios based on an array of bipolar ice cores, satellite measurements and geological records. We then selected the low-end, median and high-end future stochastic scenarios to perform simulations from 2015 to 2100 using a plume-aerosol-chemistry-climate modelling framework, UKESM-VPLUME with interactive volcanic aerosols. Our model results show that future volcanic eruptions can delay the recovery of the global stratospheric ozone column, as opposed to a previous modelling study that suggested future eruptions will lead to an earlier recovery of the global stratospheric ozone column. In addition, our stochastic scenarios show that future eruptions can potentially delay the recovery of Antarctic total ozone column by 2 to 3 years, depending on the timing, magnitude and latitude of the eruptions. Our results offer insights into the role of future volcanic eruptions in affecting global and polar stratospheric ozone recovery. We also highlight the importance of incorporating interactive volcanic sulfate aerosols in future modelling studies to assess the impact of volcanic eruptions on stratospheric ozone.

How to cite: Chim, M. M., Aubry, T. J., Abraham, N. L., and Schmidt, A.: Future volcanic eruptions delay stratospheric ozone recovery, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-1509, https://doi.org/10.5194/egusphere-egu24-1509, 2024.

The January 2022 eruption of the undersea Hunga volcano injected an unprecedented amount of water vapor directly into the stratosphere. In this talk, we will use measurements of gas-phase constituents from Aura MLS (Microwave Limb Sounder) and polar stratospheric clouds (PSCs) from CALIOP (Cloud-Aerosol Lidar with Orthogonal Polarization) on CALIPSO (Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observations) together with meteorological reanalyses to investigate how the extraordinary stratospheric hydration and accompanying anomalies in stratospheric temperature and circulation from Hunga affected chemical processing and ozone destruction in the polar lower stratosphere. We will focus on the Antarctic ozone hole season of 2023, when the excess moisture led to unusually early and vertically extensive PSC activity and heterogeneous chlorine activation (i.e., depleted HCl and enhanced ClO) in early winter. Although unmatched in the satellite record, the early-winter upper-level chlorine activation was insufficient to induce substantial ozone loss. Chlorine activation, denitrification, and dehydration processes saturated in midwinter, with trace gas evolution essentially following the climatological mean thereafter. Thus, despite the exceptional early-winter conditions, cumulative ozone losses in the 2023 austral spring were mostly unremarkable because stratospheric chemical processing saturated, as typically happens in the Antarctic. We will also discuss the 2022 Antarctic winter, when the Hunga plume was effectively excluded from the southern polar region by the strong transport barrier at the edge of the vortex. As a result, Hunga had little effect on either the vortex itself or the chemical processing and ozone loss that took place within it during the 2022 Antarctic winter/spring. Finally, we will touch briefly on the influence of Hunga on the 2023/2024 Arctic winter that will have just concluded.

How to cite: Santee, M., Manney, G., Lambert, A., Millan, L., Livesey, N., Pitts, M., Froidevaux, L., and Read, W.: The Influence of Stratospheric Hydration from the Hunga Eruption on Chemical Processing in the Stratospheric Winter Polar Vortices, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-6876, https://doi.org/10.5194/egusphere-egu24-6876, 2024.