Continuous Ozone Depletion over Antarctica After 2000 and Its Relationship with the Polar Vortex

Observations have shown highly variable ozone depletion over the Antarctic in the 2000s, which could affect the long-term ozone trend in this region as well as the global ozone recovery. By using the total column ozone data （1979-2011）, interannual variation of the springtime Antarctic ozone tow is investigated, together with its relationship with the polar vortex evolution in the lower stratosphere. The results show that springtime Antarctic ozone depletion has continued in the 2000s, seemingly contradicting the consensus view of a global ozone recovery expected at the beginning of the 21st century. The spring Antarctic polar vortex in the lower stratosphere is much stronger in the 2000s than before, with a larger area, delayed breakup time, and greater longevity during 2000-2011. Fhrther analyses show that the recent continuation of springtime Antarctic ozone depletion could be largely attributed to the abnormal variation of the Antarctic polar vortex.     

The cause of the spring strengthening of the Antarctic polar vortex

The stratospheric polar vortex strengthening from late winter to spring plays a crucial role in polar ozone depletion. The Arctic polar vortex reaches its peak intensity in mid-winter, whereas the Antarctic vortex usually strengthens in early spring. As a result, the strong ozone depletion is observed every year over the Antarctic, while over the Arctic short-term ozone loss occasionally occurs in late winter or early spring. However, the cause of such a difference in the life cycles of the Arctic and Antarctic polar vortices is still not completely clear. Based on the ERA-Interim reanalysis data, we show a high agreement between the seasonal variations of temperature in the subtropical lower stratosphere and zonal wind in the subpolar and polar lower stratosphere in the Southern Hemisphere. Thus, the spring strengthening of the Antarctic polar vortex can occur due to the seasonal temperature increase in the subtropical lower stratosphere in this period.     

NUMERICAL SIMULATION OF THE FORMATION MECHANISM OF THE ANTARCTIC OZONE HOLE

The global zonally averaged atmospheric chemistry model is developed in this paper.Theformation mechanism of the Antarctic ozone hole is numerically simulated using the model to checkthe viewpoints on the formation mechanism.The results show that:(1)The Antarctic ozone hole is a special phenomenon resulting from the heterogeneousreactions on the surface of the polar stratospheric cloud particles,under the special conditions oftemperature and circulation in Antarctic spring.The heterogeneous reactions reduce the NO_2concentration,resulting in the decrease of ozone production rate.The ozone content decreaseswhen its production is less than its destruction.This is the direct cause for the formation of theAntarctic ozone hole.(2)The impact of the polar vortex on the transport of trace species is not the determinativefactor in the formation of the Antarctic ozone hole.but makes the intensity of the ozone holechanged.(3)The solar cycles have negligible influence on the intensity of the Antarctic ozone holethrough photochemical reactions.     

平流层臭氧季节变化的动力和光化学作用之比较

1992年到2005年的HALOE资料显示, 在臭氧光化损耗中, ClOx 和NOx 的贡献大小和作用位置有所差异。SOCRATES3模式模拟表明, 两半球夏季高纬极区的臭氧减少, 主要是NOx的化学贡献; 北极春季和南极冬季副极地臭氧的变化, 主要是动力输送引起。南、北极春季臭氧减少的化学机制也有所不同, 南极春季的臭氧耗损包括极区内ClOx 的异相化学作用和副极区NOx的化学作用; 北极春季的臭氧耗损主要以NOx 和ClOx 的气相化学作用为主, 其中NOx 的作用更大。动力和光化学在臭氧变化中的贡献表明, 整个中低平流层及低纬平流层高层的动力输送贡献可达到45%, 而高纬平流层中上层, 化学作用贡献在65%以上。     

南极大陆沿岸地面臭氧损耗事件的研究

利用南极大陆沿岸中山站2008-2013年的地面臭氧连续观测数据和相关资料,对地面臭氧损耗事件（ODE）进行研究。结果显示,春季南极中山站常发生臭氧损耗事件。在该事件发生期间,气象要素有明显的突变过程,包括气温明显下降,风向由偏东风转变为偏北风,风速随之下降。来自海冰区的偏北风增多,风速很小,使臭氧浓度维持在较低水平。地面臭氧损耗事件主要与南极沿岸海冰区的活性溴（BrO）浓度有关。春季南极大陆沿岸海冰冻融过程中形成的冰间水道和冰间湖,在低温的作用下会再次冻结,形成薄冰和霜花。卫星资料能够观测到薄冰区释放的活化海盐溴高浓度区,活性溴与臭氧发生化学反应形成地面臭氧损耗事件。臭氧损耗现象是在未受到人为影响的自然状态下发生的,与中高纬度地区光化学反应导致臭氧消耗有所不同。      

Three-Year Observations of Ozone Columns over Polar Vortex Edge Area above West Antarctica

Ozone vertical column densities (VCDs) were retrieved by Zenith Scattered Light-Differential Optical Absorption Spectroscopy (ZSL-DOAS) from January 2017 to February 2020 over Fildes Peninsula, West Antarctica (62.22°S, 58.96°W). Each year, ozone VCDs started to decline around July with a comparable gradient around 1.4 Dobson Units (DU) per day, then dropped to their lowest levels in September and October, when ozone holes appeared (less than 220 DU). Daily mean values of retrieved ozone VCDs were compared with Ozone Monitoring Instrument (OMI) and Global Ozone Monitoring Experiment 2 (GOME-2) satellite observations and the Modern-Era Retrospective analysis for Research and Applications Version 2 (MERRA-2) reanalysis dataset, with correlation coefficients (R2) of 0.86, 0.94, and 0.90, respectively. To better understand the causes of ozone depletion, the retrieved ozone VCDs, temperature, and potential vorticity (PV) at certain altitudes were analyzed. The profiles of ozone and PV were positively correlated during their fluctuations, which indicates that the polar vortex has a strong influence on stratospheric ozone depletion during Antarctic spring. Located at the edge of polar vortex, the observed data will provide a basis for further analysis and prediction of the inter-annual variations of stratospheric ozone in the future.     

极区大气臭氧变化对中国气候影响的数值模拟

首先利用TOMS资料分析了南北极区大气臭氧总量的季节变化特征。结果表明 ,南北极区的臭氧减少都是春季下降最快 ,然后通过数值试验得到 ,极区大气臭氧减少将造成高低层温度差值分布大致相反 ,由于臭氧减少也将使我国的大气环流形势和降水分布特征发生改变。在我国的不同区域 ,各气象要素的变化也具有不同特征。     

The Impact of Arctic Ozone Depletion on Northern Middle Latitudes: Interannual Variability and Dynamical Control

We have investigated the effect of the export of Arctic ozone loss, or`dilution', on mid-latitude ozone depletion during the 1990s, and its relation tointerannual meteorological variability. A stratospheric chemical-transport modelincorporated a simple gas-phase ozone scheme with the addition of a parameterisation ofpolar depletion which depended only on temperature and duration of sunlight. Themodel was forced with the U.K. Meteorological Office analyses from 1991 to 1999 covering eight Northern Hemisphere winters. The modelled Arctic ozone column losses wereabout half the magnitude of those in the Antarctic and showed a considerablevariation from year to year. The northern middle latitudes (40°–60° N)were mainly affected through dilution and experienced a variable 5–20%depletion. Year-round there is a depletion of about 1% in northern middle latitudes due toactivation at the pole but there is no evidence that this depletion increases with timeduring this integration. A series of inert tracer experiments for the winters from 1996 to 1999 showed that the dilution occurs primarily at the 560 K and 465 K isentropic levels where up to 30% of the airoriginating northward of 67° N on 1 March is found at 47° N later in spring. Thestrength and persistence of the Arctic vortex were crucial in determining the severity and the timing of the ozone dilution every year by influencing, respectively, the magnitude of the high-latitude depletion and the effectiveness of mixing to lower latitudes. This spring dilution was correlated with the winter/spring planetary wave activity indicating the important role of dynamical processes in regulating the polar-driven mid-latitude ozone depletion.     

The impact of high altitude aircraft on the ozone layer in the stratosphere

The paper discusses the potential effects on the ozone layer of gases released by the engines of proposed high altitude supersonic aircraft. The major problem arises from the emissions of nitrogen oxides which have the potential to destroy significant quantities of ozone in the stratosphere. The magnitude of the perturbation is highly dependent on the cruise altitude of the aircraft. Furthermore, the depletion of ozone is substantially reduced when heterogeneous conversion of nitrogen oxides into nitric acid on sulfate aerosol particles is taken into account in the calculation. The sensitivity of the aerosol load on stratospheric ozone is investigated. First, the model indicates that the aerosol load induced by the SO₂ released by aircraft is increased by about 10–20% above the background aerosols at mid-high latitude of the Northern Hemisphere at 15 km for the NASA emission scenario A (the NASA emission scenarios are explained in Tables I to III). This increase in aerosol has small effects on stratospheric ozone. Second, when the aerosol load is increased following a volcanic eruption similar to the eruption of El Chichon (Mexico, April 1982), the ozone column in spring increases by as much as 9% in response to the injection of NO _x from the aircraft with the NASA emission scenario A. Finally, the modeled suggests that significant ozone depletion could result from the formation of additional polar stratospheric clouds produced by the injection of H₂O and HNO₃ by the aircraft engines.     

The Role of Ozone Depletion in the Lack of Cooling in the Antarctic Upper Stratosphere during Austral Winter

Temperature trends in the upper stratosphere are investigated using satellite measurements from Stratospheric Sounding Unit(SSU) outputs and simulations from chemistry–climate models(CCMs) and the Coupled Model Intercomparison Project Phase 6(CMIP6). Observational evidence shows a lack of cooling in the Antarctic, in contrast to strong cooling at other latitudes, during austral winter over 1979–97. Analysis of CCM simulations for a longer period of1961–97 also shows a significant contrast in the...     

Numerical Experiment for the Impact of the Ozone Hole over Antarctica on the Global Climate

ＮｕｍｅｒｉｃａｌＥｘｐｅｒｉｍｅｎｔｆｏｒｔｈｅＩｍｐａｃｔｏｆｔｈｅＯｚｏｎｅＨｏｌｅｏｖｅｒＡｎｔａｒｃｔｉｃａｏｎｔｈｅＧｌｏｂａｌＣｌｉｍａｔｅ①ＣｈｅｎＹｕｅｊｕａｎ（陈月娟）,ＺｈａｎｇＨｏｎｇ（张弘）Ｄｅｐｔ．ｏｆＥａｒｔｈａｎｄＳｐ...     

Numerical Modeling of the Influence of Physical and Chemical Factors on the Interannual Variability of Antarctic Ozone

The variability of Antarctic total column ozone in 1980–2018 is considered. The study analyzes trends in Antarctic total column ozone during the study period as well as the physical and chemical processes affecting the seasonal variability of total column ozone. The main attention is paid to the influence of dynamical processes on the stability of the Antarctic polar vortex, to the formation of polar stratospheric clouds, and to the influence of gas-phase and heterogeneous processes on the surface of polar stratospheric clouds and sulfate aerosol. The method of research is the analysis of the results of ground and satellite observations and numerical modeling of physical and chemical processes over the Antarctic using a global chemistry transport model with the dynamical parameters specified from reanalysis data.     

Numerical Experiment for the Impact of the Ozone Hole over Antarctica on the Global Climate

A numerical experiment has been carried out with IAP (Institute of Atmospheric Physics) 9-layer general circulation model to investigate the influence of the Antarctic Ozone Hole on the global climate. The results show that the changes of total amount of ozone over higher latitude and polar region of the Southern Hemisphere affect not only the climate in the Southern Hemisphere, but also that in the Northern Hemisphere significantly. In the next spring, although the total amount of ozone over Antarctica has returned to the normal value, the influences of Ozone Hole still exist. Suppported by LASG and the National Key Project of Fundamental Research “Climate Dynamics and Climate Prediction Theory.≓     

Chemistry of Halogen Oxides in the Troposphere: Comparison of Model Calculations with Recent Field Data

Reactive halogen species (RHS = X, XO, HOX, OXO; X = Cl, Br, I) are known to have an important influence on the chemistry in the polar boundary layer (BL), where they are responsible for ozone depletion events in spring. Recent field campaigns at Mace Head, Ireland, and the Dead Sea, Israel, identified for the first time iodine oxide (IO) at mixing ratios of up to 6.6 ppt and 90 ppt bromine oxide (BrO), respectively, by DOAS also at lower latitudes. These results intensified the discussion about the role of the RHS in the mid-latitude BL.Photochemical box model calculations show that the observed IO mixing ratios can destroy ~0.45 ppb ozone per hour. This is comparable to the rates of the known O₃-loss processes in the boundary layer. The model studies also reveal that IO, at these levels, has a strong influence on the BL photochemistry, increasing the OH/HO₂- and the NO₂/NO - ratios. In combination these changes lead to a reduction of the photochemical ozone formation, which - in addition - reduces ozone mixing ratios by up to 0.15 ppb/h.The studies for the Dead Sea case give no information on the heterogeneous process responsible for the bromine release, but they show that a total of 2 – 4 ppb of total bromine have to be released to explain the observed complete depletion of 60 ppb ozone in 2 – 3 hours.     

2019-2020冬季北半球超强极涡事件

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.     

南极臭氧的短期气候变化特征

利用1957～1992年南极地区大气臭氧总量地面观测站资料，对南极地区臭氧的时空变化特征进行了研究。结果表明，虽然近35年来南极地区的大气臭氧有较明显的减小趋势，但在不同地区、时段和季节，其变化趋势也不同。近年来南极地区大气臭氧的显著亏损，主要是由南极臭氧洞的形成和发展所造成的。南极地区的大气臭氧存在明显的年振荡、准20个月和准30个月的振荡周期。臭氧变化与天文日照、平流层温度场、平流层冰晶云及人类活动排放到大气中的氟氯烃和溴化烃等污染物质有关。     

Intercomparison of Stratospheric Chemistry Models under Polar Vortex Conditions

Several stratospheric chemistry modules from box, 2-D or 3-D models, have been intercompared. The intercomparison was focused on the ozone loss and associated reactive species under the conditions found in the cold, wintertime Arctic and Antarctic vortices. Comparisons of both gas phase and heterogeneous chemistry modules show excellent agreement between the models under constrained conditions for photolysis and the microphysics of polar stratospheric clouds. While the mean integral ozone loss ranges from 4–80% for different 30–50 days long air parcel trajectories, the mean scatter of model results around these values is only about ±1.5%. In a case study, where the models employed their standard photolysis and microphysical schemes, the variation around the mean percentage ozone loss increases to about ±7%. This increased scatter of model results is mainly due to the different treatment of the PSC microphysics and heterogeneous chemistry in the models, whereby the most unrealistic assumptions about PSC processes consequently lead to the least representative ozone chemistry. Furthermore, for this case study the model results for the ozone mixing ratios at different altitudes were compared with a measured ozone profile to investigate the extent to which models reproduce the stratospheric ozone losses. It was found that mainly in the height range of strong ozone depletion all models underestimate the ozone loss by about a factor of two. This finding corroborates earlier studies and implies a general deficiency in our understanding of the stratospheric ozone loss chemistry rather than a specific problem related to a particular model simulation.     

极地大气科学与全球变化研究进展

南极和北极是地球上的气候敏感地区, 也是多个国际科学计划研究全球气候变化的关键地区。极地大气科学考察与研究是极地科学研究的重要组成部分。中国气象科学研究院的极地大气科学考察与研究始于20世纪80年代, 25年来有较大进展。中国气象科学研究院参加了我国组织的23次南极考察、2次北冰洋考察和3次北极考察; 承担了南极长城站和中山站、北极黄河站气象业务建设和维持, 以及中-澳合作南极冰盖3个无人自动气象站工作; 进行了常规地面气象、Brewer大气臭氧、近地面物理、冰雪和大气化学等观测, 获得了较为系统的极地大气环境资料。开展了有关极地大气科学与全球变化的研究, 在极地天气气候特征及气候变化时空多样性、极地海冰变化和南极海冰涛动、极地近地面物理特征和海-冰-气相互作用、中山站臭氧变化特征及南极臭氧洞和大气化学、气候代用资料获取和古气候环境以及极地大气环境变化对东亚环流和中国天气气候影响等方面的研究取得了新进展。中国极地大气科学正积极通过多学科交叉、走国际合作道路, 努力提高对极地在全球变化中作用的认识水平, 并积极探索极地变化对我国气候、环境的影响。     

The Effect of Super Volcanic Eruptions on Ozone Depletion in a Chemistry–Climate Model

With the gradual yet unequivocal phasing out of ozone depleting substances(ODSs), the environmental crisis caused by the discovery of an ozone hole over the Antarctic has lessened in severity and a promising recovery of the ozone layer is predicted in this century. However, strong volcanic activity can also cause ozone depletion that might be severe enough to threaten the existence of life on Earth. In this study, a transport model and a coupled chemistry–climate model were used to simulate the impacts of super volcanoes on ozone depletion. The volcanic eruptions in the experiments were the 1991 Mount Pinatubo eruption and a 100 × Pinatubo size eruption. The results show that the percentage of global mean total column ozone depletion in the 2050 RCP8.5 100 × Pinatubo scenario is approximately 6% compared to two years before the eruption and 6.4% in tropics. An identical simulation, 100 × Pinatubo eruption only with natural source ODSs, produces an ozone depletion of 2.5% compared to two years before the eruption, and with 4.4% loss in the tropics. Based on the model results,the reduced ODSs and stratospheric cooling lighten the ozone depletion after super volcanic eruption.     

2‐D model simulations of anomalous spring variations of ozone,temperature and other minor trace constituents in the southern polar region

Abstract

A 2‐D time‐dependent Eulerian model that takes into account the major interaction between chemistry and dynamical transports in the stratosphere is used to simulate, in a self‐consistent manner, the anomalous spring variations of ozone, temperature and other relevant minor constituents in the southern polar region. The normal transport coefficients and the standard chemistry have been altered to represent the anomalous dynamical and chemical conditions in the extremely cold lower stratosphere of Southern Hemisphere (south of 65° S) spring. The results show that it is necessary to invoke both dynamical and chemical mechanisms in order to explain the observed rapid spring decline of total ozone in the southern polar region.