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3 pages, 169 KiB

Open AccessEditorial

Preface: Ozone Evolution in the Past and Future

by Eugene Rozanov

Atmosphere 2020, 11(7), 709; https://doi.org/10.3390/atmos11070709 - 3 Jul 2020

Cited by 5 | Viewed by 2223

Abstract

The stratospheric ozone plays an important role in the protection of the biosphere from the dangerous ultraviolet radiation of the sun [...] Full article

(This article belongs to the Special Issue Ozone Evolution in the Past and Future)

Research

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20 pages, 10491 KiB

Open AccessArticle

Stratosphere–Troposphere Exchange and O₃ Variability in the Lower Stratosphere and Upper Troposphere over the Irene SHADOZ Site, South Africa

by Thumeka Mkololo, Nkanyiso Mbatha, Venkataraman Sivakumar, Nelson Bègue, Gerrie Coetzee and Casper Labuschagne

Atmosphere 2020, 11(6), 586; https://doi.org/10.3390/atmos11060586 - 3 Jun 2020

Cited by 5 | Viewed by 3532

Abstract

This study aims to investigate the Stratosphere-Troposphere Exchange (STE) events and ozone changes over Irene (25.5° S, 28.1° E). Twelve years of ozonesondes data (2000–2007, 2012–2015) from Irene station operating in the framework of the Southern Hemisphere Additional Ozonesodes (SHADOZ) was used to [...] Read more.

This study aims to investigate the Stratosphere-Troposphere Exchange (STE) events and ozone changes over Irene (25.5° S, 28.1° E). Twelve years of ozonesondes data (2000–2007, 2012–2015) from Irene station operating in the framework of the Southern Hemisphere Additional Ozonesodes (SHADOZ) was used to study the troposphere (0–16 km) and stratosphere (17–28 km) ozone (O₃) vertical profiles. Ozone profiles were grouped into three categories (2000–2003, 2004–2007 and 2012–2015) and average composites were calculated for each category. Fifteen O₃ enhancement events were identified over the study period. These events were observed in all seasons (one event in summer, four events in autumn, five events in winter and five events in spring); however, they predominantly occur in winter and spring. The STE events presented here are observed to be influenced by the Southern Hemisphere polar vortex. To strengthen the investigation into STE events, advected potential vorticity maps were used, which were assimilated using Modélisation Isentrope du transport Méso–échelle de l’Ozone Stratosphérique par Advection (MIMOSA) model for the 350 K (~12–13 km) isentropic level. These maps indicated transport of high latitude air masses responsible for the reduction of the O₃ mole fractions at the lower stratosphere over Irene which coincides with the enhancement of ozone in the upper troposphere. In general, the stratosphere is dominated by higher Modern Retrospective Analysis for Research Application (MERRA-2) potential vorticity (PV) values compared to the troposphere. However, during the STE events, higher PV values from the stratosphere were observed to intrude the troposphere. Ozone decline was observed from 12 km to 24 km with the highest decline occurring from 14 km to 18 km. An average decrease of 6.0% and 9.1% was calculated from 12 to 24 km in 2004–2007 and 2012–2015 respectively, when compared with 2000–2003 average composite. The observed decline occurred in the upper troposphere and lower stratosphere with winter and spring showing more decline compared with summer and autumn. Full article

(This article belongs to the Special Issue Ozone Evolution in the Past and Future)

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14 pages, 1717 KiB

Open AccessArticle

Ozone Trends in the United Kingdom over the Last 30 Years

by Florencia M. R. Diaz, M. Anwar H. Khan, Beth M. A. Shallcross, Esther D. G. Shallcross, Ulrich Vogt and Dudley E. Shallcross

Atmosphere 2020, 11(5), 534; https://doi.org/10.3390/atmos11050534 - 21 May 2020

Cited by 19 | Viewed by 4368

Abstract

Previous work regarding the behaviour of ozone surface concentrations over many years in the United Kingdom had predicted that the frequency and severity of ozone episodes would become less marked in the future as a response to environmental regulations. The aim of this [...] Read more.

Previous work regarding the behaviour of ozone surface concentrations over many years in the United Kingdom had predicted that the frequency and severity of ozone episodes would become less marked in the future as a response to environmental regulations. The aim of this study is to extend these studies and compare the results with their predictions. The ozone data of 13 rural and six urban sites in the UK collected from the Department for Environment, Food and Rural Affairs over a period from 1992 to mid-2019 were used to investigate this behaviour. The yearly ozone exceedances (the number of hours that the ozone concentration exceeded the 50 ppbv limit) in the United Kingdom were found to have decreased over the last 30 years regardless of the type of site (rural or urban), showing that the adopted emission controls have so far been successful in the abatement of pollutant emissions. In the past three decades, the highest numbers of exceedances were reached in May regardless of the type of site. Furthermore, these episodes have become less frequent and less severe in recent years. In fact, the number of hours of exceedance is lower than that in previous decades, and it is almost constant throughout the week. Full article

(This article belongs to the Special Issue Ozone Evolution in the Past and Future)

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20 pages, 4547 KiB

Open AccessArticle

Time Series Analysis and Forecasting Using a Novel Hybrid LSTM Data-Driven Model Based on Empirical Wavelet Transform Applied to Total Column of Ozone at Buenos Aires, Argentina (1966–2017)

by Nkanyiso Mbatha and Hassan Bencherif

Atmosphere 2020, 11(5), 457; https://doi.org/10.3390/atmos11050457 - 30 Apr 2020

Cited by 19 | Viewed by 4018

Abstract

Total column of ozone (TCO) time series analysis and accurate forecasting is of great significance in monitoring the status of the Chapman Mechanism in the stratosphere, which prevents harmful UV radiation from reaching the Earth’s surface. In this study, we performed a detailed [...] Read more.

Total column of ozone (TCO) time series analysis and accurate forecasting is of great significance in monitoring the status of the Chapman Mechanism in the stratosphere, which prevents harmful UV radiation from reaching the Earth’s surface. In this study, we performed a detailed time series analysis of the TCO data measured in Buenos Aires, Argentina. Moreover, hybrid data-driven forecasting models, based on long short-term memory networks (LSTM) recurrent neural networks (RNNs), are developed. We extracted the updated trend of the TCO time series by utilizing the singular spectrum analysis (SSA), empirical wavelet transform (EWT), empirical mode decomposition (EMD), and Mann-Kendall. In general, the TCO has been stable since the mid-1990s. The trend analysis shows that there is a recovery of ozone during the period from 2010 to 2017, apart from the decline of ozone observed during 2015, which is presumably associated with the Calbuco volcanic event. The EWT trend method seems to have effective power for trend identification, compared with others. In this study, we developed a robust data-driven hybrid time series-forecasting model (named EWT-LSTM) for the TCO time series forecasting. Our model has the advantage of utilizing the EWT technique in the decomposition stage of the LSTM process. We compared our model with (1) an LSTM model that uses EMD, namely EMD-LSTM; (2) an LSTM model that uses wavelet denoising (WD) (WD-LSTM); (3) a wavelet denoising EWT-LSTM (WD-EWT-LSTM); and (4) a wavelet denoising noise-reducing sequence called EMD-LSTM (WD-EMD-LSTM). The model that uses the EWT decomposition process (EWT-LSTM) outperformed the other five models developed here in terms of various forecasting performance evaluation criteria, such as the root mean square error (RMSE), mean absolute error (MAE), mean absolute percentage error (MAPE), and correlation coefficient (R). Full article

(This article belongs to the Special Issue Ozone Evolution in the Past and Future)

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13 pages, 2465 KiB

Open AccessEditor’s ChoiceArticle

Ozone Layer Evolution in the Early 20th Century

by Tatiana Egorova, Eugene Rozanov, Pavle Arsenovic and Timofei Sukhodolov

Atmosphere 2020, 11(2), 169; https://doi.org/10.3390/atmos11020169 - 6 Feb 2020

Cited by 10 | Viewed by 4857

Abstract

The ozone layer is well observed since the 1930s from the ground and, since the 1980s, by satellite-based instruments. The evolution of ozone in the past is important because of its dramatic influence on the biosphere and humans but has not been known [...] Read more.

The ozone layer is well observed since the 1930s from the ground and, since the 1980s, by satellite-based instruments. The evolution of ozone in the past is important because of its dramatic influence on the biosphere and humans but has not been known for most of the time, except for some measurements of near-surface ozone since the end of the 19th century. This gap can be filled by either modeling or paleo reconstructions. Here, we address ozone layer evolution during the early 20th century. This period was very interesting due to a simultaneous increase in solar and anthropogenic activity, as well as an observed but not explained substantial global warming. For the study, we exploited the chemistry-climate model SOCOL-MPIOM driven by all known anthropogenic and natural forcing agents, as well as their combinations. We obtain a significant global scale increase in the total column ozone by up to 12 Dobson Units and an enhancement of about 20% of the near-surface ozone over the Northern Hemisphere. We conclude that the total column ozone changes during this period were mainly driven by enhanced solar ultra violet (UV) radiation, while near-surface ozone followed the evolution of anthropogenic ozone precursors. This finding can be used to constrain the solar forcing magnitude. Full article

(This article belongs to the Special Issue Ozone Evolution in the Past and Future)

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14 pages, 16516 KiB

Open AccessArticle

A Stratospheric Intrusion-Influenced Ozone Pollution Episode Associated with an Intense Horizontal-Trough Event

by Yiping Wang, Hongyue Wang and Wuke Wang

Atmosphere 2020, 11(2), 164; https://doi.org/10.3390/atmos11020164 - 4 Feb 2020

Cited by 20 | Viewed by 3970

Abstract

Ozone pollution is currently a serious issue in China. As an important source of tropospheric ozone, the stratospheric ozone has received less concern. This study uses a combination of ground-based ozone measurements, the latest ERA5 reanalysis data as well as chemistry-climate model and [...] Read more.

Ozone pollution is currently a serious issue in China. As an important source of tropospheric ozone, the stratospheric ozone has received less concern. This study uses a combination of ground-based ozone measurements, the latest ERA5 reanalysis data as well as chemistry-climate model and Lagrangian Particle Dispersion Modeling (LPDM) simulations to investigate the potential impacts of stratospheric intrusion (SI) on surface ozone pollution episodes in eastern China. Station-based observations indicate that severe ozone pollution occurred from 27 April to 28 April 2018 in eastern China, with maximal values over 140 ppbv. ERA5 meteorological and ozone data suggest that a strong horizontal-trough exists at the same time, which leads to an evident SI event and brings ozone-rich air from the stratosphere to the troposphere. Using a stratospheric ozone tracer defined by NCAR’s Community Atmosphere Model with Chemistry (CAM-Chem), we conclude that this SI event contributed about 15 ppbv (15%) to the surface ozone pollution episode during 27–28 April in eastern China. The potential impacts of SI events on surface ozone variations should be therefore considered in ozone forecast and control. Full article

(This article belongs to the Special Issue Ozone Evolution in the Past and Future)

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16 pages, 1548 KiB

Open AccessEditor’s ChoiceArticle

Numerical Modeling of the Natural and Manmade Factors Influencing Past and Current Changes in Polar, Mid-Latitude and Tropical Ozone

by Sergei P. Smyshlyaev, Vener Y. Galin, Polina A. Blakitnaya and Andrei R. Jakovlev

Atmosphere 2020, 11(1), 76; https://doi.org/10.3390/atmos11010076 - 8 Jan 2020

Cited by 6 | Viewed by 2340

Abstract

A chemistry–climate model of the lower and middle atmosphere is used to compare the role of natural and anthropogenic factors in the observed variability of stratospheric ozone. Numerical experiments have been carried out on several scenarios of separate and combined effects of solar [...] Read more.

A chemistry–climate model of the lower and middle atmosphere is used to compare the role of natural and anthropogenic factors in the observed variability of stratospheric ozone. Numerical experiments have been carried out on several scenarios of separate and combined effects of solar activity, stratospheric aerosol, sea surface temperature, greenhouse gases, and ozone-depleting substances emissions on ozone for the period from 1979 to 2020. Simulations for the past and present periods are compared to the results of ground-based and satellite observations. Estimates of observed trends in column total ozone for the entire period 1980–2018 and separately for the late twentieth and early twenty-first century are presented. Full article

(This article belongs to the Special Issue Ozone Evolution in the Past and Future)

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29 pages, 8764 KiB

Open AccessArticle

Effects of Ozone and Clouds on Temporal Variability of Surface UV Radiation and UV Resources over Northern Eurasia Derived from Measurements and Modeling

by Natalia E. Chubarova, Anna S. Pastukhova, Ekaterina Y. Zhdanova, Elena V. Volpert, Sergey P. Smyshlyaev and Vener Y. Galin

Atmosphere 2020, 11(1), 59; https://doi.org/10.3390/atmos11010059 - 2 Jan 2020

Cited by 13 | Viewed by 4584

Abstract

Temporal variability in erythemal radiation over Northern Eurasia (40°–80° N, 10° W–180° E) due to total ozone column (X) and cloudiness was assessed by using retrievals from ERA-Interim reanalysis, TOMS/OMI satellite measurements, and INM-RSHU chemistry–climate model (CCM) for the 1979–2015 period. For clear-sky [...] Read more.

Temporal variability in erythemal radiation over Northern Eurasia (40°–80° N, 10° W–180° E) due to total ozone column (X) and cloudiness was assessed by using retrievals from ERA-Interim reanalysis, TOMS/OMI satellite measurements, and INM-RSHU chemistry–climate model (CCM) for the 1979–2015 period. For clear-sky conditions during spring and summer, consistent trends in erythemal daily doses (Eery) up to +3%/decade, attributed to decreases in X, were calculated from the three datasets. Model experiments suggest that anthropogenic emissions of ozone-depleting substances were the largest contributor to Eery trends, while volcanic aerosol and changes in sea surface temperature also played an important role. For all-sky conditions, Eery trends, calculated from the ERA-Interim and TOMS/OMI data over the territory of Eastern Europe, Siberia and Northeastern Asia, were significantly larger (up to +5–8%/decade) due to a combination of decrease in ozone and cloudiness. In contrast, all-sky maximum trends in Eery, calculated from the CCM results, were only +3–4%/decade. While Eery trends for Northern Eurasia were generally positive, negative trends were observed in July over central Arctic regions due to an increase in cloudiness. Finally, changes in the ultraviolet (UV) resources (characteristics of UV radiation for beneficial (vitamin D production) or adverse (sunburn) effects on human health) were assessed. When defining a “UV optimum” condition with the best balance in Eery for human health, the observed increases in Eery led to a noticeable reduction of the area with UV optimum for skin types 1 and 2, especially in April. In contrast, in central Arctic regions, decreases in Eery in July resulted in a change from “UV excess” to “UV optimum” conditions for skin types 2 and 3. Full article

(This article belongs to the Special Issue Ozone Evolution in the Past and Future)

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16 pages, 12095 KiB

Open AccessArticle

Discontinuities in the Ozone Concentration Time Series from MERRA 2 Reanalysis

by Peter Krizan, Michal Kozubek and Jan Lastovicka

Atmosphere 2019, 10(12), 812; https://doi.org/10.3390/atmos10120812 - 14 Dec 2019

Cited by 6 | Viewed by 4324

Abstract

Artificial discontinuities in time series are a great problem for trend analysis because they influence the values of the trend and its significance. The aim of this paper is to investigate their occurrence in the Modern-Era Retrospective analysis for Research and Applications, version [...] Read more.

Artificial discontinuities in time series are a great problem for trend analysis because they influence the values of the trend and its significance. The aim of this paper is to investigate their occurrence in the Modern-Era Retrospective analysis for Research and Applications, version 2 (MERRA 2) ozone concentration data. It is the first step toward the utilization of the MERRA 2 ozone data for trend analysis. We use the Pettitt homogeneity test to search for discontinuities in the ozone time series. We showed the data above 4 hPa are not suitable for trend analyses due to the unrealistic patterns in an average ozone concentration and due to the frequent occurrence of significant discontinuities. Below this layer in the stratosphere, their number is much smaller, and mostly, they are insignificant, and the patterns of the average ozone concentration are explainable. In the troposphere, the number of discontinuities increases, but they are insignificant. The transition from Solar Backscatter Ultraviolet Radiometer (SBUV) to Earth Observing System (EOS) Aura data in 2004 is visible only above 1 hPa, where the data are not suitable for trend analyses due to other reasons. We can conclude the MERRA 2 ozone concentration data can be used in trend analysis with caution only below 4 hPa. Full article

(This article belongs to the Special Issue Ozone Evolution in the Past and Future)

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18 pages, 2787 KiB

Open AccessArticle

Assessing the Impact of Ozone and Particulate Matter on Mortality Rate from Respiratory Disease in Seoul, Korea

by Sun Kyoung Park

Atmosphere 2019, 10(11), 685; https://doi.org/10.3390/atmos10110685 - 7 Nov 2019

Cited by 10 | Viewed by 2569

Abstract

The evidence linking ozone and particulate matter with adverse health impacts is increasing. The goal of this study was to assess the impact of air pollution on the mortality rate from respiratory disease in Seoul, Korea, between 2008 and 2017. The analysis was [...] Read more.

The evidence linking ozone and particulate matter with adverse health impacts is increasing. The goal of this study was to assess the impact of air pollution on the mortality rate from respiratory disease in Seoul, Korea, between 2008 and 2017. The analysis was conducted using a decision tree model in two ways: using 24-h average concentrations and using 1-h maximum values to compare any health impacts from the different times of exposure to pollution. Results show that in spring an elevated level of ozone is one of the most important factors, but in summer temperature has a greater impact than air pollution. Nitrogen dioxide is one of the most important factors in fall, while high levels of particles less than 2.5 μm (PM_2.5) and 10 μm in size (PM₁₀) and cooler temperatures are key factors in winter. We checked the accuracy of our results through a 10-fold cross validation method. Error rates using 24-h average and 1-h maximum concentrations were in the ranges of 24.9–42% and 27.6–42%, respectively, indicating that 24-h average concentrations are slightly more directly related with mortality rate. These results could be useful for policy makers in determining the temporal scale of predicted pollutant concentrations for an air quality warning system to help minimize the adverse impacts of air pollution. Full article

(This article belongs to the Special Issue Ozone Evolution in the Past and Future)

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