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Huijun Wang - One of the best experts on this subject based on the ideXlab platform.
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the impact of preceding spring Antarctic Oscillation on the variations of lake ice phenology over the tibetan plateau
Journal of Climate, 2020Co-Authors: Yong Liu, Huopo Chen, Huijun WangAbstract:ABSTRACTThe lake ice phenology response to climate change has been receiving growing concern in recent years. However, most studies have put emphasis on the spatial and temporal variability of lake...
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verification and improvement of the ability of cfsv2 to predict the Antarctic Oscillation in boreal spring
Advances in Atmospheric Sciences, 2019Co-Authors: Huijun Wang, Dapeng Zhang, Yanyan Huang, Bo SunAbstract:The boreal spring Antarctic Oscillation (AAO) has a significant impact on the spring and summer climate in China. This study evaluates the capability of the NCEP’s Climate Forecast System, version 2 (CFSv2), in predicting the boreal spring AAO for the period 1983–2015. The results indicate that CFSv2 has poor skill in predicting the spring AAO, failing to predict the zonally symmetric spatial pattern of the AAO, with an insignificant correlation of 0.02 between the predicted and observed AAO Index (AAOI). Considering the interannual increment approach can amplify the prediction signals, we firstly establish a dynamical–statistical model to improve the interannual increment of the AAOI (DY AAOI), with two predictors of CFSv2-forecasted concurrent spring sea surface temperatures and observed preceding autumn sea ice. This dynamical–statistical model demonstrates good capability in predicting DY AAOI, with a significant correlation coefficient of 0.58 between the observation and prediction during 1983–2015 in the two-year-out cross-validation. Then, we obtain an improved AAOI by adding the improved DY AAOI to the preceding observed AAOI. The improved AAOI shows a significant correlation coefficient of 0.45 with the observed AAOI during 1983–2015. Moreover, the unrealistic atmospheric response to March–April–May sea ice in CFSv2 may be the possible cause for the failure of CFSv2 to predict the AAO. This study gives new clues regarding AAO prediction and short-term climate prediction.
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the impact of long term oceanic warming on the Antarctic Oscillation in austral winter
Scientific Reports, 2017Co-Authors: Xin Hao, Huijun Wang, Tingting HanAbstract:Increasing greenhouse gas concentration and ozone depletion are generally considered two important factors that affect the variability of the Antarctic Oscillation (AAO). Here, we find that the first leading mode of sea surface temperature (SST) variability (rotated empirical orthogonal functions) shows a long-term upward trend from 1901 to 2004 and is closely related to the AAO index that is obtained using the observationally constrained reanalysis data. Further, regressions of the sea level pressure and the 500-hPa geopotential height anomalies, against the principle component associated with the long-term SST anomalies, display a seesaw behavior between the middle and high latitudes of the Southern Hemisphere in austral winter, which is similar to the high polarity of the AAO. The circulation responses to the long-term oceanic warming in three numerical models are consistent with the observed results. This finding suggests that the long-term oceanic warming is partly responsible for the upward trend of the AAO in austral winter. The thermal wind response to the oceanic warming in South Indian and South Atlantic Ocean may be a possible mechanism for this process.
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strengthened relationship between the Antarctic Oscillation and enso after the mid 1990s during austral spring
Advances in Atmospheric Sciences, 2017Co-Authors: Tingting Han, Huijun Wang, Jianqi SunAbstract:This paper documents a decadal strengthened co-variability of the Antarctic Oscillation (AAO) and ENSO in austral spring after the mid-1990s. During the period 1979–93, the ENSO (AAO) spatial signatures are restricted to the tropics–midlatitudes (Antarctic–midlatitudes) of the Southern Hemisphere (SH), with a weak connection between the two Oscillations. Comparatively, after the mid-1990s, the El Ni˜no-related atmospheric anomalies project on a negative AAO pattern with a barotropic structure in the mid–high latitudes of the SH. The expansion of El Ni˜no-related air temperature anomalies have a heightened impact on the meridional thermal structure of the SH, contributing to a weakened circumpolar westerly and strengthened subtropical jet. Meanwhile, the ENSO-related southern three-cell circulations expand poleward and then strongly couple the Antarctic and the tropics. Numerical simulation results suggest that the intensified connection between ENSO and SST in the South Pacific since the mid-1990s is responsible for the strengthened AAO–ENSO relationship.
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modulation of aleutian low and Antarctic Oscillation co variability by enso
Climate Dynamics, 2015Co-Authors: Huijun Wang, Yongqi GaoAbstract:We use both the National Centers for Environmental Prediction (NCEP)–National Center for Atmospheric Research (NCAR) reanalysis data (1979–2013) and the Community Atmospheric Model Version 3 to explore the modulation of El Nino–Southern Oscillation (ENSO) on the co-variability of the Aleutian Low (AL) and the Antarctic Oscillation (AAO). The empirical orthogonal function analysis on the NCEP–NCAR reanalysis data indicates that after the late-1990s the global sea level pressure (SLP) and 300-hPa geopotential height (Z300) in boreal January are characterized by the concurrence of the AL and the negative phase of the AAO (−AAO). Associated with this AL–AAO co-variation is a sea surface temperature anomaly that resembles the ENSO cycle. Further analyses reveal that the interdecadal change in ENSO signal (westward extension and more La Nina events) is responsible for the co-variability of AL and AAO after the late-1990s. Correspondingly, the El Nino-related anomalous heating and upward motion over the eastern–central equatorial Pacific can lead to the upper-tropospheric divergence in the western–central Pacific. This upper-tropospheric divergence plays an essential role in coupling the equatorial heat anomalies with the variation of the subtropical westerly jet of both hemispheres, and therefore results in the enhanced meridional circulation of the three cells. It thus implies that ENSO might act as a bridge linking AL and AAO after the late-1990s, causing their consistent co-variability. The numerical experiment also supports this hypothesis.
Daoyi Gong - One of the best experts on this subject based on the ideXlab platform.
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is the Antarctic Oscillation trend during the recent decades unusual
Antarctic Science, 2014Co-Authors: Ziyin Zhang, Daoyi Gong, Seongjoong Kim, Rui Mao, Jing YangAbstract:The Antarctic Oscillation (AAO) has been characterized by a persistently positive trend in summer (December–January–February, DJF) during the last 50 years. Thus, the question has arisen of whether the trend is unusual. By investigating five reconstructed historical AAO time series for the past 500 years, recurrences of similar and even stronger trends have been found, indicating that the recent DJF AAO trend is not unprecedented in a historical perspective. To estimate the possible roles played by greenhouse gases or/and ozone, an analysis for DJF AAO trends during the 1969–98 period was conducted using three multiple model ensembles derived from the projects of ‘The twentieth-century climate in coupled models’ (20C3M) and ‘Pre-industrial control experiment models’ (PICTL) of the fourth assessment report of the Intergovernmental Panel on Climate Change (IPCC AR4). The results show that the ozone depletion over Antarctica and global warming may play significant roles in the strengthening trend. Combining the simulations and reconstructions we emphasize that the AAO trend related to global warming may get much stronger when enhanced by low-frequency natural variability.
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is there a linkage between the tropical cyclone activity in the southern indian ocean and the Antarctic Oscillation
AGU Fall Meeting Abstracts, 2013Co-Authors: Rui Mao, Daoyi Gong, Ziyin Zhang, Jing Yang, Seongjoong KimAbstract:[1] In this article, the relationship between the Antarctic Oscillation (AAO) and the tropical cyclone (TC) activity in the southern Indian Ocean (SIO) was examined. It was found that on the interannual time scale, the AAO is well linked with the TC activity in the SIO during TC season (December–March). The rank correlation coefficient between the AAO index and the TC frequency (TCF) in the SIO is 0.37, which is significant at the 95% confidence level. When the AAO is in a positive phase, TC passage in the northwestern coast of Australia (100E°–120°E and 10°S–30°S) increases by approximately 50%–100% from the climatology. The increase in the TC passage is primarily the result of more frequent TCs originating in this region due to enhanced water vapor convergence and ascending motions, which are caused by a cyclonic height anomaly over the western coast of Australia associated with the positive AAO phases. In addition, the AAO-height covariations, which are essential to the formation of the AAO-TC links in the SIO, were investigated through a historical climate simulation using the Community Climate System Model 4 from the Coupled Model Intercomparison Project Phase 5. The AAO-height links were well reproduced in the simulation. The similarity in the AAO-height links between the observation and the simulation supports the physical robustness of the AAO-TC links in the SIO.
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arctic and Antarctic Oscillation signatures in tropical coral proxies over the south china sea
Annales Geophysicae, 2009Co-Authors: Daoyi Gong, S J KimAbstract:Abstract. Arctic Oscillation (AO) and Antarctic Oscillation (AAO) are the leading modes of atmospheric circulation in mid-high latitudes. Previous studies have revealed that the climatic influences of the two modes are dominant in extra-tropical regions. This study finds that AO and AAO signals are also well recorded in coral proxies in the tropical South China Sea. There are significant interannual signals of AO and AAO in the strontium (Sr) content, which represents the sea surface temperature (SST). Among all the seasons, the most significant correlation occurs during winter in both hemispheres: the strongest AO-Sr and AAO-Sr coral correlations occur in January and August, respectively. This study also determined that the Sr content lags behind AO and AAO by 1–3 months. Large-scale anomalies in sea level pressure and horizontal wind at 850 hPa level support the strength of AO/AAO-coral teleconnections. In addition, a comparison with oxygen isotope records from two coral sites in neighboring oceans yields significant AO and AAO signatures with similar time lags. These results help to better understand monsoon climates and their teleconnection to high-latitude climate changes.
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possible influence of the Antarctic Oscillation on tropical cyclone activity in the western north pacific
Journal of Geophysical Research, 2005Co-Authors: Joohong Kim, Hyeongseog Kim, Chunghsiung Sui, Daoyi GongAbstract:[1] The present study investigates how large-scale atmospheric circulation in the Southern Hemisphere (SH) modulates tropical cyclone (TC) activity in the western North Pacific (WNP) during a typhoon season (July, August, and September; boreal summer). The variation of the SH circulation of interest is the Antarctic Oscillation (AAO). In the positive phase of AAO relative to its negative phase, two anomalous highs develop over the western Pacific in both hemispheres: a huge anticyclone in southeastern Australia and a relatively weak anticyclone in the East China Sea. These teleconnection patterns are examined and compared with previous analyses. Related to the AAO variations, a statistically significant alteration of TC activities is found over the WNP. The difference in the mean TC passage numbers over the East China Sea (120°–140°E, 20°–40°N) between the eight highest-AAO years and the eight lowest-AAO years is as large as 2, equivalent to a 50–100% increase from the climatology. This change is primarily a result of more TCs forming over the eastern Philippine Sea. On the other hand, TC passage numbers slightly decrease over the South China Sea. These changes in TC activity are predominant in August and are consistent with changes in low-level vorticity over the subtropical WNP. The influence of SH circulation variability on large-scale environments and tropical convection in the subtropical NH suggest a possible usage of AAO variation for long-range forecasting of TC activity over the WNP.
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definition of Antarctic Oscillation index
Geophysical Research Letters, 1999Co-Authors: Daoyi Gong, Shaowu WangAbstract:Following Walker's work about his thmous three Oscillations published during the 1920-30s, many papers were written about atmospheric Oscillations. A Iburth atmospheric Oscillation in the middle and high southern latitudes was lbund, and nanted the grotarctic Oscillation (AO). A() refiers to a large scale alternation of atmospheric mass between the mid-latitudes and high latitudes surthce pressure. In order to understand the spatial structure of sea level pressure variation in detail, empirical orthogonal fitnction analysis is applied. An objective index of the Antarctic Oscillation Index (AOI) is defined as the diffierence of zonal mean sea level pressure between 40oS and 65oS. The AOI has the potential tbr clarifying climate regimes in the southern hemisphere, similar to how the NA() and the NPO has been used in the northern hemisphere. Were there other Oscillation(s) besides NAO, NPO and S(), especially in the southern hemisphere'? It had been supposed that there might be other atmospheric Oscillation(s) in the high southern latitudes. Although as early as in the first quarter of this century Walker (1928) had stated that: "Just as in the North Atlantic there is a pressure opposition between the Azores and Iceland,... ,there is an opposition between the high pressure belt across Chile and the Argentine on the one hand, and the low pressure area of Weddell Sea and the Bellingshausen Sea on the other.", the scarcity of data in the southern hemisphere hindered the search tbr new Oscillation(s). During the last two decades, more comprehensive data over the southern hemisphere became available, and more analyses were carried out. (see Kidson 1975,' Rogers and van Loon 1982:Mo and l7ite 1985: 24o 1986,' Connolley 1997: Gong and Wang 1998). A tburth atmospheric Oscillation in the middle and high southern latitudes was tbund, and nanted as the Antarctic Oscillation(A()) (Wang 1992: Gong and Wang 1998 ). The term AO relrs to a large scale alternation of atmospheric mass between the mid-latitude sur/hce pressure
Luc Feyen - One of the best experts on this subject based on the ideXlab platform.
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global changes of extreme coastal wave energy fluxes triggered by intensified teleconnection patterns
Geophysical Research Letters, 2017Co-Authors: Lorenzo Mentaschi, Michalis I Vousdoukas, Evangelos Voukouvalas, Alessandro Dosio, Luc FeyenAbstract:In this study we conducted a comprehensive modeling analysis to identify global trends in extreme wave energy flux (WEF) along coastlines in the 21st century under a high emission pathway (Representative Concentration Pathways 8.5). For the end of the century, results show a significant increase up to 30% in 100 year return level WEF for the majority of the coastal areas of the southern temperate zone, while in the Northern Hemisphere large coastal areas are characterized by a significant negative trend. We show that the most significant long-term trends of extreme WEF can be explained by intensification of teleconnection patterns such as the Antarctic Oscillation, El Nino–Southern Oscillation, and North Atlantic Oscillation. The projected changes will have broad implications for ocean engineering applications and disaster risk management. Especially low-lying coastal countries in the Southern Hemisphere will be particularly vulnerable due to the combined effects of projected relative sea level rise and more extreme wave activities.
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global changes of extreme coastal wave energy fluxes triggered by intensified teleconnection patterns
Geophysical Research Letters, 2017Co-Authors: Lorenzo Mentaschi, Michalis I Vousdoukas, Evangelos Voukouvalas, Alessandro Dosio, Luc FeyenAbstract:In this study we conducted a comprehensive modeling analysis to identify global trends in extreme wave energy flux (WEF) along coastlines in the 21st century under a high emission pathway (Representative Concentration Pathways 8.5). For the end of the century, results show a significant increase up to 30% in 100 year return level WEF for the majority of the coastal areas of the southern temperate zone, while in the Northern Hemisphere large coastal areas are characterized by a significant negative trend. We show that the most significant long-term trends of extreme WEF can be explained by intensification of teleconnection patterns such as the Antarctic Oscillation, El Nino–Southern Oscillation, and North Atlantic Oscillation. The projected changes will have broad implications for ocean engineering applications and disaster risk management. Especially low-lying coastal countries in the Southern Hemisphere will be particularly vulnerable due to the combined effects of projected relative sea level rise and more extreme wave activities.
Harald E Rieder - One of the best experts on this subject based on the ideXlab platform.
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on the relationship between total ozone and atmospheric dynamics and chemistry at mid latitudes part 1 statistical models and spatial fingerprints of atmospheric dynamics and chemistry
Atmospheric Chemistry and Physics, 2013Co-Authors: Linda Frossard, J. A. Maeder, Johannes Staehelin, Harald E Rieder, S. Rocco, Anthony C. Davison, Mathieu Ribatet, Thomas PeterAbstract:Abstract. We use statistical models for mean and extreme values of total column ozone to analyze "fingerprints" of atmospheric dynamics and chemistry on long-term ozone changes at northern and southern mid-latitudes on grid cell basis. At each grid cell, the r-largest order statistics method is used for the analysis of extreme events in low and high total ozone (termed ELOs and EHOs, respectively), and an autoregressive moving average (ARMA) model is used for the corresponding mean value analysis. In order to describe the dynamical and chemical state of the atmosphere, the statistical models include important atmospheric covariates: the solar cycle, the Quasi-Biennial Oscillation (QBO), ozone depleting substances (ODS) in terms of equivalent effective stratospheric chlorine (EESC), the North Atlantic Oscillation (NAO), the Antarctic Oscillation (AAO), the El Nino/Southern Oscillation (ENSO), and aerosol load after the volcanic eruptions of El Chichon and Mt. Pinatubo. The influence of the individual covariates on mean and extreme levels in total column ozone is derived on a grid cell basis. The results show that "fingerprints", i.e., significant influence, of dynamical and chemical features are captured in both the "bulk" and the tails of the statistical distribution of ozone, respectively described by mean values and EHOs/ELOs. While results for the solar cycle, QBO, and EESC are in good agreement with findings of earlier studies, unprecedented spatial fingerprints are retrieved for the dynamical covariates. Column ozone is enhanced over Labrador/Greenland, the North Atlantic sector and over the Norwegian Sea, but is reduced over Europe, Russia and the Eastern United States during the positive NAO phase, and vice-versa during the negative phase. The NAO's southern counterpart, the AAO, strongly influences column ozone at lower southern mid-latitudes, including the southern parts of South America and the Antarctic Peninsula, and the central southern mid-latitudes. Results for both NAO and AAO confirm the importance of atmospheric dynamics for ozone variability and changes from local/regional to global scales.
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on the relationship between total ozone and atmospheric dynamics and chemistry at mid latitudes part 2 the effects of the el nino southern Oscillation volcanic eruptions and contributions of atmospheric dynamics and chemistry to long term total ozone
Atmospheric Chemistry and Physics, 2013Co-Authors: Linda Frossard, J. A. Maeder, Johannes Staehelin, Harald E Rieder, S. Rocco, Anthony C. Davison, Mathieu Ribatet, Thomas PeterAbstract:Abstract. We present the first spatial analysis of "fingerprints" of the El Nino/Southern Oscillation (ENSO) and atmospheric aerosol load after major volcanic eruptions (El Chichon and Mt. Pinatubo) in extreme low and high (termed ELOs and EHOs, respectively) and mean values of total ozone for the northern and southern mid-latitudes (defined as the region between 30° and 60° north and south, respectively). Significant influence on ozone extremes was found for the warm ENSO phase in both hemispheres during spring, especially towards low latitudes, indicating the enhanced ozone transport from the tropics to the extra-tropics. Further, the results confirm findings of recent work on the connection between the ENSO phase and the strength and extent of the southern ozone "collar". For the volcanic eruptions the analysis confirms findings of earlier studies for the northern mid-latitudes and gives new insights for the Southern Hemisphere. The results provide evidence that the negative effect of the eruption of El Chichon might be partly compensated by a strong warm ENSO phase in 1982–1983 at southern mid-latitudes. The strong west-east gradient in the coefficient estimates for the Mt. Pinatubo eruption and the analysis of the relationship between the AAO and ENSO phase, the extent and the position of the southern ozone "collar" and the polar vortex structure provide clear evidence for a dynamical "masking" of the volcanic signal at southern mid-latitudes. The paper also analyses the contribution of atmospheric dynamics and chemistry to long-term total ozone changes. Here, quite heterogeneous results have been found on spatial scales. In general the results show that EESC and the 11-yr solar cycle can be identified as major contributors to long-term ozone changes. However, a strong contribution of dynamical features (El Nino/Southern Oscillation (ENSO), North Atlantic Oscillation (NAO), Antarctic Oscillation (AAO), Quasi-Biennial Oscillation (QBO)) to ozone variability and trends is found at a regional level. For the QBO (at 30 and 50 hPa), strong influence on total ozone variability and trends is found over large parts of the northern and southern mid-latitudes, especially towards equatorial latitudes. Strong influence of ENSO is found over the Northern and Southern Pacific, Central Europe and central southern mid-latitudes. For the NAO, strong influence on column ozone is found over Labrador/Greenland, the Eastern United States, the Euro-Atlantic Sector, and Central Europe. For the NAO's southern counterpart, the AAO, strong influence on ozone variability and long-term changes is found at lower southern mid-latitudes, including the southern parts of South America and the Antarctic Peninsula, and central southern mid-latitudes.
Thomas Peter - One of the best experts on this subject based on the ideXlab platform.
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on the relationship between total ozone and atmospheric dynamics and chemistry at mid latitudes part 1 statistical models and spatial fingerprints of atmospheric dynamics and chemistry
Atmospheric Chemistry and Physics, 2013Co-Authors: Linda Frossard, J. A. Maeder, Johannes Staehelin, Harald E Rieder, S. Rocco, Anthony C. Davison, Mathieu Ribatet, Thomas PeterAbstract:Abstract. We use statistical models for mean and extreme values of total column ozone to analyze "fingerprints" of atmospheric dynamics and chemistry on long-term ozone changes at northern and southern mid-latitudes on grid cell basis. At each grid cell, the r-largest order statistics method is used for the analysis of extreme events in low and high total ozone (termed ELOs and EHOs, respectively), and an autoregressive moving average (ARMA) model is used for the corresponding mean value analysis. In order to describe the dynamical and chemical state of the atmosphere, the statistical models include important atmospheric covariates: the solar cycle, the Quasi-Biennial Oscillation (QBO), ozone depleting substances (ODS) in terms of equivalent effective stratospheric chlorine (EESC), the North Atlantic Oscillation (NAO), the Antarctic Oscillation (AAO), the El Nino/Southern Oscillation (ENSO), and aerosol load after the volcanic eruptions of El Chichon and Mt. Pinatubo. The influence of the individual covariates on mean and extreme levels in total column ozone is derived on a grid cell basis. The results show that "fingerprints", i.e., significant influence, of dynamical and chemical features are captured in both the "bulk" and the tails of the statistical distribution of ozone, respectively described by mean values and EHOs/ELOs. While results for the solar cycle, QBO, and EESC are in good agreement with findings of earlier studies, unprecedented spatial fingerprints are retrieved for the dynamical covariates. Column ozone is enhanced over Labrador/Greenland, the North Atlantic sector and over the Norwegian Sea, but is reduced over Europe, Russia and the Eastern United States during the positive NAO phase, and vice-versa during the negative phase. The NAO's southern counterpart, the AAO, strongly influences column ozone at lower southern mid-latitudes, including the southern parts of South America and the Antarctic Peninsula, and the central southern mid-latitudes. Results for both NAO and AAO confirm the importance of atmospheric dynamics for ozone variability and changes from local/regional to global scales.
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on the relationship between total ozone and atmospheric dynamics and chemistry at mid latitudes part 2 the effects of the el nino southern Oscillation volcanic eruptions and contributions of atmospheric dynamics and chemistry to long term total ozone
Atmospheric Chemistry and Physics, 2013Co-Authors: Linda Frossard, J. A. Maeder, Johannes Staehelin, Harald E Rieder, S. Rocco, Anthony C. Davison, Mathieu Ribatet, Thomas PeterAbstract:Abstract. We present the first spatial analysis of "fingerprints" of the El Nino/Southern Oscillation (ENSO) and atmospheric aerosol load after major volcanic eruptions (El Chichon and Mt. Pinatubo) in extreme low and high (termed ELOs and EHOs, respectively) and mean values of total ozone for the northern and southern mid-latitudes (defined as the region between 30° and 60° north and south, respectively). Significant influence on ozone extremes was found for the warm ENSO phase in both hemispheres during spring, especially towards low latitudes, indicating the enhanced ozone transport from the tropics to the extra-tropics. Further, the results confirm findings of recent work on the connection between the ENSO phase and the strength and extent of the southern ozone "collar". For the volcanic eruptions the analysis confirms findings of earlier studies for the northern mid-latitudes and gives new insights for the Southern Hemisphere. The results provide evidence that the negative effect of the eruption of El Chichon might be partly compensated by a strong warm ENSO phase in 1982–1983 at southern mid-latitudes. The strong west-east gradient in the coefficient estimates for the Mt. Pinatubo eruption and the analysis of the relationship between the AAO and ENSO phase, the extent and the position of the southern ozone "collar" and the polar vortex structure provide clear evidence for a dynamical "masking" of the volcanic signal at southern mid-latitudes. The paper also analyses the contribution of atmospheric dynamics and chemistry to long-term total ozone changes. Here, quite heterogeneous results have been found on spatial scales. In general the results show that EESC and the 11-yr solar cycle can be identified as major contributors to long-term ozone changes. However, a strong contribution of dynamical features (El Nino/Southern Oscillation (ENSO), North Atlantic Oscillation (NAO), Antarctic Oscillation (AAO), Quasi-Biennial Oscillation (QBO)) to ozone variability and trends is found at a regional level. For the QBO (at 30 and 50 hPa), strong influence on total ozone variability and trends is found over large parts of the northern and southern mid-latitudes, especially towards equatorial latitudes. Strong influence of ENSO is found over the Northern and Southern Pacific, Central Europe and central southern mid-latitudes. For the NAO, strong influence on column ozone is found over Labrador/Greenland, the Eastern United States, the Euro-Atlantic Sector, and Central Europe. For the NAO's southern counterpart, the AAO, strong influence on ozone variability and long-term changes is found at lower southern mid-latitudes, including the southern parts of South America and the Antarctic Peninsula, and central southern mid-latitudes.