Total Column Ozone Research Articles

Evaluation of Total Ozone Column from Multiple Satellite Measurements in the Antarctic Using the Brewer Spectrophotometer

The ground-based ozone observation instrument, Brewer spectrophotometer (Brewer), was used to evaluate the quality of the total ozone column (TOC) produced by multiple polar-orbit satellite measurements at three stations in Antarctica (King Sejong, Jang Bogo, and Zhongshan stations). While all satellite TOCs showed high correlations with Brewer TOCs (R = ~0.8 to 0.9), there are some TOC differences among satellite data in austral spring, which is mainly attributed to the bias of Atmospheric Infrared Sounder (AIRS) TOC. The quality of satellite TOCs is consistent between Level 2 and 3 data, implying that “which satellite TOC is used” can induce larger uncertainty than “which spatial resolution is used” for the investigation of the Antarctic TOC pattern. Additionally, the quality of satellite TOC is regionally different (e.g., OMI TOC is a little higher at the King Sejong station, but lower at the Zhongshan station than the Brewer TOC). Thus, it seems necessary to consider the difference of multiple satellite data for better assessing the spatiotemporal pattern of Antarctic TOC.

Persistent Stratospheric Warming Due to 2019–2020 Australian Wildfire Smoke

AbstractAustralian wildfires burning from December 2019 to January 2020 injected approximately 0.9 Tg of smoke into the stratosphere; this is the largest amount observed in the satellite era. A comparison of numerical simulations to satellite observations of the plume rise suggests that the smoke mass contained 2.5% black carbon. Model calculations project a 1 K warming in the stratosphere of the Southern Hemisphere midlatitudes for more than 6 months following the injection of black‐carbon containing smoke. The 2020 average global mean clear sky effective radiative forcing at top of atmosphere is estimated to be −0.03 W m−2 with a surface value of −0.32 W m−2. Assuming that smoke particles coat with sulfuric acid in the stratosphere and have similar heterogeneous reaction rates as sulfate aerosol, we estimate a smoke‐induced chemical decrease in total column ozone of 10–20 Dobson units from August to December in mid‐high southern latitudes.

Indicators of Antarctic ozone depletion: 1979 to 2019

Abstract. The National Institute of Water and Atmospheric Research/Bodeker Scientific (NIWA–BS) total column ozone (TCO) database and the associated BS-filled TCO database have been updated to cover the period 1979 to 2019, bringing both to version 3.5.1 (V3.5.1). The BS-filled database builds on the NIWA–BS database by using a machine-learning algorithm to fill spatial and temporal data gaps to provide gap-free TCO fields over Antarctica. These filled TCO fields then provide a more complete picture of wintertime changes in the ozone layer over Antarctica. The BS-filled database has been used to calculate continuous, homogeneous time series of indicators of Antarctic ozone depletion from 1979 to 2019, including (i) daily values of the ozone mass deficit based on TCO below a 220 DU threshold; (ii) daily measures of the area over Antarctica where TCO levels are below 150 DU, below 220 DU, more than 30 % below 1979 to 1981 climatological means, and more than 50 % below 1979 to 1981 climatological means; (iii) the date of disappearance of 150 DU TCO values, 220 DU TCO values, values 30 % or more below 1979 to 1981 climatological means, and values 50 % or more below 1979 to 1981 climatological means, for each year; and (iv) daily minimum TCO values over the range 75 to 90∘ S equivalent latitude. Since both the NIWA–BS and BS-filled databases provide uncertainties on every TCO value, the Antarctic ozone depletion metrics are provided, for the first time, with fully traceable uncertainties. To gain insight into how the vertical distribution of ozone over Antarctica has changed over the past 36 years, ozone concentrations, combined and homogenized from several satellite-based ozone monitoring instruments as well as the global ozonesonde network, were also analysed. A robust attribution to changes in the drivers of long-term secular variability in these metrics has not been performed in this analysis. As a result, statements about the recovery of Antarctic TCO from the effects of ozone-depleting substances cannot be made. That said, there are clear indications of a change in trend in many of the metrics reported on here around the turn of the century, close to when Antarctic stratospheric concentrations of chlorine and bromine peaked.

Total Ozone Column Variability of Selected Stations over Iraq

This study aims to know the annual, monthly, and daily changes of total ozone in some selected stations in Iraq (Baghdad, Mosul, and Basra). The data presented from the Ozone Monitoring Instrument (OMI) for the period (2003-2015) were used to study the total ozone column. It was found that the total ozone column has temporal variation. As for the annual and daily changes. In the annual changes, we find that the tendency has negative value in both the station (Mosul and Baghdad) by (-0.606 and -0.459) DU with maximum annual mean value was (330.13) DU in Mosul station, while the amount of the tendency is a positive value by (0.115) and the minimum annual mean value was (292.74) DU in Basra station, and the same is the case for the daily change has a value negative (-3.88—-0.699) for each Mosul and Baghdad stations and positive (1.902) for Basra station. The monthly total ozone varied between a maximum value in spring of (353 and 344) DU - (334and321) DU in the station (Mosul and Baghdad) respectively, while the maximum value of total ozone varied between (304 and 313) DU in the summer about the station Basra.

Evaluating stratospheric ozone and water vapour changes in CMIP6 models from 1850 to 2100

Abstract. Stratospheric ozone and water vapour are key components of the Earth system, and past and future changes to both have important impacts on global and regional climate. Here, we evaluate long-term changes in these species from the pre-industrial period (1850) to the end of the 21st century in Coupled Model Intercomparison Project phase 6 (CMIP6) models under a range of future emissions scenarios. There is good agreement between the CMIP multi-model mean and observations for total column ozone (TCO), although there is substantial variation between the individual CMIP6 models. For the CMIP6 multi-model mean, global mean TCO has increased from ∼ 300 DU in 1850 to ∼ 305 DU in 1960, before rapidly declining in the 1970s and 1980s following the use and emission of halogenated ozone-depleting substances (ODSs). TCO is projected to return to 1960s values by the middle of the 21st century under the SSP2-4.5, SSP3-7.0, SSP4-3.4, SSP4-6.0, and SSP5-8.5 scenarios, and under the SSP3-7.0 and SSP5-8.5 scenarios TCO values are projected to be ∼ 10 DU higher than the 1960s values by 2100. However, under the SSP1-1.9 and SSP1-1.6 scenarios, TCO is not projected to return to the 1960s values despite reductions in halogenated ODSs due to decreases in tropospheric ozone mixing ratios. This global pattern is similar to regional patterns, except in the tropics where TCO under most scenarios is not projected to return to 1960s values, either through reductions in tropospheric ozone under SSP1-1.9 and SSP1-2.6, or through reductions in lower stratospheric ozone resulting from an acceleration of the Brewer–Dobson circulation under other Shared Socioeconomic Pathways (SSPs). In contrast to TCO, there is poorer agreement between the CMIP6 multi-model mean and observed lower stratospheric water vapour mixing ratios, with the CMIP6 multi-model mean underestimating observed water vapour mixing ratios by ∼ 0.5 ppmv at 70 hPa. CMIP6 multi-model mean stratospheric water vapour mixing ratios in the tropical lower stratosphere have increased by ∼ 0.5 ppmv from the pre-industrial to the present-day period and are projected to increase further by the end of the 21st century. The largest increases (∼ 2 ppmv) are simulated under the future scenarios with the highest assumed forcing pathway (e.g. SSP5-8.5). Tropical lower stratospheric water vapour, and to a lesser extent TCO, shows large variations following explosive volcanic eruptions.

The world Brewer reference triad – updated performance assessment and new double triad

Abstract. The Brewer ozone spectrophotometer (the Brewer) was designed at Environment and Climate Change Canada (ECCC) in the 1970s to make accurate automated total ozone column measurements. Since the 1980s, the Brewer instrument has become a World Meteorological Organization (WMO) Global Atmosphere Watch (GAW) standard ozone monitoring instrument. Now, more than 230 Brewers have been produced. To assure the quality of the Brewer measurements, a calibration chain is maintained, i.e., first, the reference instruments are independently absolutely calibrated, and then the calibration is transferred from the reference instrument to the travelling standard, and subsequently from the travelling standard to field instruments. ECCC has maintained the world Brewer reference instruments since the 1980s to provide transferable calibration to field instruments at monitoring sites. Three single-monochromator (Mark II) type instruments (serial numbers 008, 014, and 015) formed this world Brewer reference triad (BrT) and started their service in Toronto, Canada, in 1984. In the 1990s, the Mark III type Brewer (known as the double Brewer) was developed, which has two monochromators to reduce the internal instrumental stray light. The double-Brewer world reference triad (BrT-D) was formed in 2013 (serial numbers 145, 187 and 191), co-located with the BrT. The first assessment of the BrT's performance was made in 2005, covering the period between 1984 and 2004 (Fioletov et al., 2005). The current work provides an updated assessment of the BrT's performance (from 1999 to 2019) and the first comprehensive assessment of the BrT-D. The random uncertainties of individual reference instruments are within the WMO/GAW requirement of 1 % (WMO, 2001): 0.49 % and 0.42 % for BrT and BrT-D, respectively, as estimated in this study. The long-term stability of the reference instruments is also evaluated in terms of uncertainties of the key instrument characteristics: the extraterrestrial calibration constant (ETC) and effective ozone absorption coefficients (both having an effect of less than 2 % on total column ozone). Measurements from a ground-based instrument (Pandora spectrometer), satellites (11 datasets, including the most recent high-resolution satellite, TROPOspheric Monitoring Instrument), and reanalysis model (the second Modern-Era Retrospective analysis for Research and Applications, MERRA-2) are used to further assess the performance of world Brewer reference instruments and to provide a context for the requirements of stratospheric ozone observations during the last two decades.

The Unusual Stratospheric Arctic Winter 2019/20: Chemical Ozone Loss From Satellite Observations and TOMCAT Chemical Transport Model

AbstractSatellite observations of relevant trace gases and meteorological data from ERA5 were used to describe the dynamics and chemistry of the spectacular Arctic 2019/20 winter/spring season. Exceptionally low total ozone values of slightly less than 220 DU were observed in mid‐March within an unusually large stratospheric polar vortex. Very high OClO and very low NO2 column amounts observed by GOME‐2A were indicative of unusually large active chlorine levels and significant denitrification, which likely contributed to large chemical ozone loss. Using results from the TOMCAT chemical transport model (CTM) and ozone observations from S5P/TROPOMI, GOME‐2 (total column), SCIAMACHY, and OMPS‐LP (vertical profiles), chemical ozone loss was evaluated and compared with the previous record Arctic winter 2010/11. The polar‐vortex‐averaged total column ozone loss in 2019/20 reached 88 DU (23%) and 106 DU (28%) based upon observations and model, respectively, by the end of March, which was similar to that derived for 2010/11. The maximum ozone loss (∼80%) observed by OMPS‐LP was near the 450 K potential temperature level (∼18 km altitude). Because of the larger polar vortex area in March 2020 compared to March 2011 (about 25% at 450 K), ozone mass loss was larger in Arctic winter 2019/20. It is shown that Arctic cap temperatures were at a record 40‐year low in winter, suggesting that Arctic cold winters are getting colder. Tropical UTLS temperatures show an apparent upward trend during the last two decades that may indicate a weakening of the Brewer‐Dobson circulation and strengthening of the polar vortex.

Impacts of the atmospheric apparent heat source over the Tibetan Plateau on summertime ozone vertical distributions over Lhasa

The Tibetan Plateau (TP) is an area sensitive to climate change, where the ozone distribution affects the atmospheric environment of the TP and its surrounding regions. The relatively low total column ozone over the TP in boreal summer and its spatiotemporal variations have received extensive attention. In this study, five-year balloon-borne measurements of ozone over Lhasa in boreal summer are used to investigate the influences of the apparent heat source (Q1) on the ozone vertical structure over the plateau. The mechanisms for the above processes are also explored. The results show that the tropospheric ozone mixing ratio over Lhasa decreases when the total atmospheric Q1 in the troposphere over the TP is relatively high. Strengthened ascending motions are accompanied by enhanced Q1 over the main TP region. Consequently, the tropospheric ozone mixing ratio over Lhasa decreases when Q1 is higher in summer, which is attributed to the upward transport of the ozone-poor surface air.摘要青藏高原(TP)是一个对气候变化敏感的地区, 其上空的臭氧分布影响着青藏高原及其周边地区的大气环境.北半球夏季青藏高原上空臭氧柱总量相对较低的现象, 及其时空变化受到广泛关注.本研究利用北半球夏季5年的拉萨上空臭氧的气球测量数据, 研究高原上空大气视热源(Q1)对臭氧垂直分布的影响并探讨了该过程的机制.结果表明, 当TP上空对流层整体的Q1相对较高时, 拉萨上空对流层臭氧浓度下降.大气更强的上升运动伴随着TP主体区域上空的Q1的增大.因此, 当夏季Q1较高时, 由于近地表低浓度臭氧空气向上输送, 拉萨上空的对流层臭氧浓度下降.

Forecasting upper atmospheric scalars advection using deep learning: an $$O_3$$ experiment

Weather forecast based on extrapolation methods is gathering a lot of attention due to the advance of artificial intelligence. Recent works on deep neural networks (CNN, RNN, LSTM, etc.) are enabling the development of spatiotemporal prediction models based on the analysis of historical time-series, images, and satellite data. In this paper, we focus on the use of deep learning for the forecast of stratospheric Ozone ( $$O_3$$ ), especially in the cases of exchanges between the polar vortex and mid-latitudes known as Ozone Secondary Events (OSE). Secondary effects of the Antarctic Ozone Hole are regularly observed above populated zones on South America, south of Africa, and New Zealand, resulting in abrupt reductions in the total ozone column of more than 10% and a consequent increase in UV radiation in densely populated areas. We study different OSE events from the literature, comparing real data with predictions from our model. We obtained interesting results and insights that may lead to accurate and fast prediction models to forecast stratospheric Ozone and the occurrence of OSE.

Improving ECC Ozonesonde Data Quality: Assessment of Current Methods and Outstanding Issues

AbstractWe review the current state of knowledge of ozonesonde uncertainty and bias, with reference to recent developments in laboratory and field experiments. In the past 20 years ozonesonde precision has improved by a factor of 2, primarily through the adoption of strict standard operating procedures. The uncertainty budget for the ozone partial pressure reading has contributions from stoichiometry, cell background current, pump efficiency and temperature, sensing solution type, and volume. Corrections to historical data for known issues may reduce biases but simultaneously introduce additional uncertainties. This paper describes a systematic approach to quantifying these uncertainties by considering the physical and chemical processes involved and attempts to place our estimates on a firm theoretical or empirical footing. New equations or tables for ozone/iodine conversion efficiency, humidity and temperature corrections to pump flow rate, and altitude‐dependent pump flow corrections are presented, as well as detailed discussion of stoichiometry and conversion efficiencies. The nature of the so‐called “background current” is considered in detail. Two other factors particularly affecting past measurements, uncertainties and biases in the pressure measurement, and the comparison of sonde profiles to spectrophotometric measurements of total column ozone, are also discussed. Several quality assurance issues remain, but are tractable problems that can be addressed with further research. This will be required if the present goal of better than 5% overall uncertainty throughout the global ozonesonde network is to be achieved.

Intercomparison Between Surrogate, Explicit, and Full Treatments of VSL Bromine Chemistry Within the CAM-Chem Chemistry-Climate Model.

Many Chemistry‐Climate Models (CCMs) include a simplified treatment of brominated very short‐lived (VSLBr) species by assuming CH3Br as a surrogate for VSLBr. However, neglecting a comprehensive treatment of VSLBr in CCMs may yield an unrealistic representation of the associated impacts. Here, we use the Community Atmospheric Model with Chemistry (CAM‐Chem) CCM to quantify the tropospheric and stratospheric changes between various VSLBr chemical approaches with increasing degrees of complexity (i.e., surrogate, explicit, and full). Our CAM‐Chem results highlight the improved accuracy achieved by considering a detailed treatment of VSLBr photochemistry, including sea‐salt aerosol dehalogenation and heterogeneous recycling on ice‐crystals. Differences between the full and surrogate schemes maximize in the lowermost stratosphere and midlatitude free troposphere, resulting in a latitudinally dependent reduction of ∼1–7 DU in total ozone column and a ∼5%–15% decrease of the OH/HO2 ratio. We encourage all CCMs to include a complete chemical treatment of VSLBr in the troposphere and stratosphere.

Effect of meteorology on the variability of ozone in the troposphere and lower stratosphere over a tropical station Thumba (8.5°N, 76.9°E)

Seasonal variability in the vertical distribution of ozone over a tropical station, Thumba (8.5°N, 76.9°E) is investigated using nine-years (2011–2019) of ECC ozonesonde data obtained as part of Tropical Tropopause Dynamics (TTD) campaigns. Ozone exhibits a clear annual variation in the lower troposphere (0–2 km) with winter maximum (49.2 ± 3.6 ppbv) and summer monsoon minimum (21.9 ± 0.7 ppbv). In the middle (2–10 km) and upper (11–17 km) troposphere, ozone is maximum in pre-monsoon and minimum in summer monsoon. Ozone in the lower stratosphere exhibits a clear annual variation with summer monsoon maximum and winter minimum in tandem with the temperature cycle. The relative standard deviation (RSD) of ozone computed at different altitudes exhibits large intra-seasonal variability in the troposphere (~20–30%) compared to the stratosphere (~5%) and is significantly high close to the surface and in the tropical tropopause layer (TTL) (≥30%). Maximum RSD is observed during summer monsoon (June–September) in the upper troposphere (~50%) close to cold point tropopause (CPT). RSD in ozone and temperature profiles show a sharp peak immediately above the CPT in all the seasons, coinciding with the altitude of maximum wind shear. Tropospheric ozone shows an in phase relationship with temperature and is opposite in phase with water vapour. A significant negative correlation is observed between ozone and water vapour in the 2–5 km altitude region. Long-range transport and local convection contribute substantially to the observed variability in tropospheric ozone. The tropospheric column ozone shows a semi-annual variation with maximum contribution to the total columnar ozone during pre-monsoon (~16%) and minimum during summer monsoon (~8%). Mid-tropospheric ozone contributes more to the tropospheric column ozone (40–60%) compared to lower and upper tropospheric ozone. Tropospheric column ozone exhibits a similar seasonality as that of its precursors like NO2, CO and CH4.

Interannual variations and long-term trends in total ozone over the North Caucasus

Results of analysis of variations in the total column ozone content measured at the Kislovodsk High-Altitude Scientific Station are presented. The station is located at a height of 2070 m in the North Caucasus 50 km north of the Main Caucasian Ridge and Mt. Elbrus, the highest summit in Europe. The total ozone content has been measured since 1989 with the Brewer MkII #043 spectrophotometer using standard methods. The 31-year series of observations has made it possible to analyze interannual variations and long-term trends in total ozone. The multiple regression method taking into account data autocorrelation in a wide range of time scales has been used. Seasonally dependent estimates of linear trends and interannual variations in total ozone associated with effects of the 11-year solar cycle, the quasi-biennial oscillation (QBO) in the equatorial stratosphere, the North Atlantic Oscillation (NAO), and the El Niño–Southern Oscillation (ENSO) have been obtained. The trends in total ozone over the North Caucasus contrast in sign from the trends of zonal mean total ozone. The annual trend in total ozone at the station was positive in 1989–2002 (1.6% per decade) and negative in 2003–2020 (−1.2% per decade). The strongest trends are characteristic of spring; they reach 4% per decade (in absolute value). Changes in total ozone during the 11-year solar cycle are especially significant in summer and amount to about 4%. The QBO-related interannual variations of total ozone with amplitude of about 6% are manifested in the cold season. The total ozone variations due to the NAO are pronounced in the winter-spring period. The ENSO effect on total ozone is noticeable in summer and lags approximately a year behind variations in sea surface temperature in the Niño3.4 region so that total ozone decreases after El Niño events and increases after La Niña events. The obtained characteristics of total ozone variability point at the evidence of a special character of interannual and multiyear evolutions of total ozone over the North Caucasus.

The relation between total column ozone with UV radiation and CO2 concentration on the island of Kalimantan during the Covid-19 Pandemic

The concentration of ozone in the ozone layer is minimal, but it means a lot to live. The total amount of column ozone varies, mainly influenced by solar radiation and anthropogenic activity. In this study, the total column ozone during the Covid-19 pandemic, and the effect of UV radiation and CO2 concentration on Kalimantan’s island was reviewed. Based on the research results, it can be seen that on Borneo’s island in September and October 2019, the total column ozone reached 0.0056 J/m2. From November 2019 to March 2020, the total amount of column ozone decreased to 0.005 J/m2. The total amount of column ozone increased in April 2020 but declined in May 2020, and from June to September 2020, it increased to reach 0.006 J/m2. The numbers are related but not significant with UV radiation (correlation 0.25) and CO2 concentration (correlation -0.40). It can be concluded that UV radiation and anthropogenic activity affect the total column ozone.

Correlations Between Total Ozone Column and Some Metrological Elements in different regions in Iraq

Aluminium, The aim of this paper, is to find a correlation between Total Ozone Column[ TOC] and different meteorological elements [Ta, Rs, RH, WS ] at five stations well distributed in Iraq [Mosul, Kirkuk, Baghdad, Nasiriya, and Basra] using several Mathematical Models. Five Mathematical Models were used for that [Linear Models, Quadratic Models, Exponential Models, Logarithmic Models, and Power Models]. Several statistical tests [R, R2, MAE, and RMSE] were used to control these Models' validation and goodness. The quadratic model gave the highest R and R2 among the other models in all stations. The highest R and R2 means that there are a high significance Correlations between the measured Total Ozone Column (TOC) and the estimated (TOC) from the Models using [Ta, Rs, RH, WS] elements in all stations.

The Combined Effect of Ozone and Aerosols on Erythemal Irradiance in an Extremely Low Ozone Event during May 2020

In this study we focus on measurements and modeled UV index in the region of Athens, Greece, during a low ozone event. During the period of 12–19 May 2020, total ozone column (TOC) showed extremely low values, 35–55 Dobson Units (up to 15%) decrease from the climatic mean (being lower than the −2σ). This condition favors the increase of UV erythemal irradiance, since stratospheric ozone is the most important attenuator at the UVB spectral region. Simultaneously, an intrusion of Saharan dust aerosols in the region has masked a large part of the low ozone effect on UV irradiance. In order to investigate the event, we have used spectral solar irradiance measurements from the Precision Solar Radiometer (PSR), TOC from the Brewer spectrophotometer, and Radiative Transfer Model (RTM) calculations. Model calculations of the UV Index (UVI) showed an increase of ~30% compared to the long-term normal UVI due to the low TOC while at the same time and for particular days, aerosols masked this effect by ~20%. The RTM has been used to investigate the response in the UV spectral region of these variations at different solar zenith angles (SZAs). Spectra simulated with the RTM have been compared to measured ones and an average difference of ~2% was found. The study points out the importance of accurate measurements or forecasts of both ozone and aerosols when deriving UVI under unusual low ozone–high aerosol conditions.

Attribution of the Principal Components of the Summertime Ozone Valley in the Upper Troposphere and Lower Stratosphere

The key factors affecting the variation of the ‘ozone valley’, which appears during the boreal summer in the upper troposphere and lower stratosphere (UTLS) over the South Asian High (SAH) and its adjacent areas, have not been determined. This study has performed statistical analysis to improve the understanding of the roles of the sea surface temperature (SST), tropopause height, and the West Pacific Subtropical High (WPSH) on the ozone valley. Based on the European Center for Medium-Range Weather Forecasts Interim Re-Analysis (ERA5), Modern Era Retrospective Analysis for Research and Applications dataset version 2 (MERRA2), and the Stratospheric Water and Ozone Satellite Homogenized (SWOOSH) observation dataset, we examined the principal components of the zonal deviation of the total column ozone (TCO*) in the UTLS by applying the empirical orthogonal function (EOF), Liang-Kleeman information flow method, regression analysis, and composite analysis. The variations of the TCO* anomalies show three dominant modes, namely the east-west dipole mode in the low latitude region, the east-west tripole mode in the middle latitude region, and the south-north mode. According to the regression analysis and information flow, the three leading principal components of TCO* variations are related to the SST near Indonesia and the western Pacific Ocean in low latitudes, the tropopause height over the Iranian Plateau (IP), and the strength of the SAH over the eastern part of the Tibetan Plateau (TP), which is linked to the synchronousness between the SAH and the WPSH. For the east-west dipole mode in the low latitude region, composite analysis shows the interaction between the atmosphere and ocean causes the strengthening of the southern trough at 850 hPa and the divergence at 200 hPa, resulting in a decrease of the TCO* in the UTLS near the low latitude region around the TP. For the east-west tripole mode in the middle latitude region, the composite analysis shows obvious negative anomalies over the IP, where the TCO* reduces and the extent of the ozone valley over the IP increases with the rise of the tropopause. Comparatively, the south-north mode shows obvious positive anomalies over the TP, where the TCO* increases and the extent of the ozone valley over the TP decreases with a weak SAH. This mode is closely related to the location of the WPSH. In summary, the leading factors affecting the three dominant modes for the variations of the TCO* anomalies are SST, tropopause height, and the WPSH.

The exceptionally strong and persistent Arctic stratospheric polar vortex in the winter of 2019–2020: 2019-2020冬季北半球超强极涡事件

The Arctic stratospheric polar vortex was exceptional strong, cold and persistent in the winter and spring of 2019–2020. Based on reanalysis data from the National Centers for Environmental Prediction/National Center for Atmospheric Research and ozone observations from the Ozone Monitoring Instrument, the authors investigated the dynamical variation of the stratospheric polar vortex during winter 2019–2020 and its influence on surface weather and ozone depletion. This strong stratospheric polar vortex was affected by the less active upward propagation of planetary waves. The seasonal transition of the stratosphere during the stratospheric final warming event in spring 2020 occurred late due to the persistence of the polar vortex. A positive Northern Annular Mode index propagated from the stratosphere to the surface, where it was consistent with the Arctic Oscillation and North Atlantic Oscillation indices. As a result, the surface temperature in Eurasia and North America was generally warmer than the climatology. In some places of Eurasia, the surface temperature was about 10 K warmer during the period from January to February 2020. The most serious Arctic ozone depletion since 2004 has been observed since February 2020. The mean total column ozone within 60°–90°N from March to 15 April was about 80 DU less than the climatology.摘要2019-2020冬季北极平流层极涡异常并且持续的偏强,偏冷.利用NCEP再数据和OMI臭氧数据, 本文分析了此次强极涡事件中平流层极涡的动力场演变及其对地面暖冬天气和臭氧低值的影响.此次强极涡的形成是由于上传行星波不活跃.持续的强极涡使得2020年春季的最后增温出现时间偏晚.平流层正NAM指数向下传播到地面, 与地面AO指数和NAO指数相一致, 欧亚大陆和北美地面气温均比气候态偏暖, 在欧亚大陆的一些地区, 2020年1月和2月的气温甚至偏高了10K.2020年2月以来北极臭氧出现了2004年以来的最低值, 2020年3-4月60°–90°N的平均臭氧柱总量比气候态偏低了80DU.

Record low ozone values over the Arctic in boreal spring 2020

Abstract. Ozone data derived from the Tropospheric Monitoring Instrument (TROPOMI) sensor on board the Sentinel-5 Precursor satellite show exceptionally low total ozone columns in the polar region of the Northern Hemisphere (Arctic) in spring 2020. Minimum total ozone column values around or below 220 Dobson units (DU) were seen over the Arctic for 5 weeks in March and early April 2020. Usually the persistence of such low total ozone column values in spring is only observed in the polar Southern Hemisphere (Antarctic) and not over the Arctic. These record low total ozone columns were caused by a particularly strong polar vortex in the stratosphere with a persistent cold stratosphere at higher latitudes, a prerequisite for ozone depletion through heterogeneous chemistry. Based on the ERA5, which is the fifth generation of the European Centre for Medium-Range Weather Forecasts (ECMWF) atmospheric reanalysis, the Northern Hemisphere winter 2019/2020 (from December to March) showed minimum polar cap temperatures consistently below 195 K around 20 km altitude, which enabled enhanced formation of polar stratospheric clouds. The special situation in spring 2020 is compared and discussed in context with two other Northern Hemisphere spring seasons, namely those in 1997 and 2011, which also displayed relatively low total ozone column values. However, during these years, total ozone columns below 220 DU over several consecutive days were not observed in spring. The similarities and differences of the atmospheric conditions of these three events and possible explanations for the observed features are presented and discussed. It becomes apparent that the monthly mean of the minimum total ozone column value for March 2020 (221 DU) was clearly below the respective values found in March 1997 (267 DU) and 2011 (252 DU), which highlights the special evolution of the polar stratospheric ozone layer in the Northern Hemisphere in spring 2020. A comparison with a typical ozone hole over the Antarctic (e.g., in 2016) indicates that although the Arctic spring 2020 situation is remarkable, with total ozone column values around or below 220 DU observed over a considerable area (up to 0.9 million km2), the Antarctic ozone hole shows total ozone columns typically below 150 DU over a much larger area (of the order of 20 million km2). Furthermore, total ozone columns below 220 DU are typically observed over the Antarctic for about 4 months.

Ozone Variation Trends under Different CMIP6 Scenarios

This study compares and analyzes simulations of ozone under different scenarios by three CMIP6 models (IPSL-CM6A, MRI-ESM2 and CESM-WACCM). Results indicate that as the social vulnerability and anthropogenic radiative forcing is increasing, the change of total column ozone in the tropical stratosphere is not linear. Compared to the SSP2-4.5 and SSP5-8.5 scenarios, the SSP1-2.6 and SSP3-7.0 are more favorable for the increase in stratospheric ozone mass in the tropics. Arctic ozone would never recover under the SSP1-2.6 scenario; however, the Antarctica ozone would gradually recover in all scenarios. Under the SSP1-2.6 and SSP2-4.5 scenarios, the trend of tropical total column ozone is mainly determined by the trend of column ozone in the tropical troposphere. Under the SSP3-7.0 scenario, tropospheric ozone concentration will significantly increase; under the SSP5-8.5 scenario, ozone concentration will distinctly increase in the middle and lower troposphere.