Ozone monitoring: initial six-month data at San Pietro Capofiume (Northern Italy)

Summary In March 1991 the Meteorological Bureau of the Emilia-Romagna Region's Agricultural Development Agency (Ente Regionale di Sviluppo Agricolo-ERSA) and FISBAT-CNR Institute began a program of weekly ozone soundings at the ?G. Fea? station at San Pietro Capofiume (44°39′ N, 11°37′ E, 11 m. s.l.). This monitoring project is supported by the Italian Space Agency (Agenzia Spaziale Italiana-ASI) as well as part of the ENEL-CNR joint research in the balance of the minor atmospheric gases and the processes of stratospheric ozone depletion in the Mediterranean Basin. The initial results and the preliminary evaluation of the seasonal trend in gas concentration in both the troposhere and stratosphere are reported.     

Sensitivity of stratospheric ozone lidar measurements to a change in ozone absorption cross-sections

The effect of a change in ozone absorption cross-section data is evaluated for stratospheric ozone lidar measurements, which are regularly performed for the monitoring of the ozone layer. The change is analysed for the measurements based on both the elastic and Raman scattering of the laser light by the atmosphere. The latter technique is essentially used for measurements performed in the presence of volcanic aerosol layers in the stratosphere. The discrepancy in ozone number densities is evaluated for various ozone cross-section data sets, using an atmospheric model for the evaluation of ozone cross-section temperature dependence. Results show that the difference in both elastic and Raman DIAL retrievals is below 1.5% in absolute values from 10 to 30 km. Above 30 km, the difference, estimated for the elastic DIAL retrieval only, is maximum around 45 km, with largest differences reaching 1.8% in the tropics.     

平流层中部垂直运动年循环异常的模拟研究

利用NCAR提供的包含化学、辐射、动力相互作用的二维模式(SOCRATES)进行模拟试验，进一步探讨年循环年际异常的可能成因.模拟结果的分析表明臭氧高值中心相对于赤道准两年移动是年循环的年际异常的一个重要原因.当臭氧高值区离开赤道偏向夏半球时，夏半球的平流层中部将吸收更多的太阳短波辐射，而冬半球的则相反，因此更大的短波加热率将增大夏半球平流层中部的上升运动，导致年循环的增强；相反地，臭氧高值中心接近赤道时则导致了相对较弱的年循环. 关键词： 臭氧 甲烷 年循环 准两年变率     

Features of interannual variations of ozone in the middle stratosphere over Moscow according to observations at millimeter waves

The features of interannual variations of ozone in the middle stratosphere over Moscow in cold half-years since 1995 to 2015 are considered. These features are most pronounced in two separated groups of winters (six winters in each group) in December–January. It appeared that the seasonal variation of ozone averaged within each group is characterized by a higher ozone concentration \({C_{{O_3}}}\) in group I (in comparison with group II) in December and lower values in January. The differences in the seasonal variation of ozone between these groups at the level of 10 mbar in December and January exceed 2 ppm. A feature of the stratosphere circulation for half-year group I is the existence of a stable polar vortex and the absence of strong midwinter perturbations and sudden stratospheric warmings. On the contrary, for cold half-years of group II, the appearance of strong stratospheric warmings in January–February is in common. The results presented provide a quantitative estimate of the effect of these stratospheric warmings on ozone of the middle stratosphere overMoscow.     

Modeling of atmospheric radiative transfer with polarization and its application to the remote sensing of tropospheric ozone

Light reflected or transmitted by a planetary atmosphere contains information about particles and molecules in the atmosphere. Therefore, accurate modeling of the radiation field may be used to retrieve information on atmospheric composition. In this paper, a multi-layer model for a vertically inhomogeneous atmosphere is implemented by using the doubling-adding method for a plane-parallel atmosphere. By studying the degree of linear polarization of the transmitted and reflected solar light in the Huggins bands, we find significant differences between tropospheric ozone and stratospheric ozone. The effects of tropospheric ozone change on the linear polarization are 10 times more than that of the same amount of stratospheric ozone change. We also show the aerosol effect on the linear polarization, but this effect is wavelength independent as compared to that caused by the tropospheric ozone change. The results provide a theoretical basis for the retrieval of tropospheric ozone from measurement of linear polarization of the scattered sunlight both from the ground and from a satellite.     

Monitoring of the stratospheric ozone layer by laser radar

Monitoring of the height distribution of atmospheric ozone up to 50 km is being performed with a ground-based lidar system, which has been in operation since October 1982 on the summit of Zugspitze in the German Alps. Daily and monthly averages of the ozone profile are being obtained with high precision. Furthermore, stratospheric aerosol layers, originating from the eruption of El Chichon volcano in Mexico in sping 1982 are being recorded.     

Satellite measurements of atmospheric ozone profiles,including tropospheric ozone,from ultraviolet/visible measurements in the nadir geometry: a potential method to retrieve tropospheric ozone

Numerical studies of a new method for the retrieval of ozone profile information from nadir-observing satellite measurements in the ultraviolet and visible are presented. The method combines information from back scattered radiation in the Hartley band down to the O₃ concentration peak, lower atmospheric information from the temperature structure of the Huggins bands, and a constraint on the total column from the Chappuis bands. The Huggins bands' temperature structure provides altitude information on the ozone distribution that includes clear distinction between stratospheric and tropospheric ozone. Studies presented here include dependence of the retrieved O₃ profiles on surface albedo, tropospheric aerosol, and tropospheric O₃ content for a range of atmospheric conditions.     

On the role of water vapour in the heat balance of the antarctic lower stratosphere

Summary A general circulation model (GCM) is used to investigate the effect on Antarctic temperatures due to changes in ozone and water vapour concentrations. It is shown that the stratospheric cooling due to the ozone secular trend is largely compensated by the H₂O loss associated with the formation of type 2 polar stratospheric clouds (PSC-2). The partial dehydration of the Antarctic lower stratosphere acts in such a way to significantly reduce the cooling associated to the O₃ depletion.     

An investigation of a possible dependence of brewer number 67''s total-ozone measurements on some atmospheric parameters, together with a presentation of a peculiar synoptic ozone case at Rome

Summary Brewer total ozone data (January–December 1992) measured at the Physics Department, Rome University ?La Sapienza? (41.9° North, 12.5° East) are analysed for dependence on Brewer internal temperature and some meteorological parameters. Non-parametric correlation analysis reveals the independence of total ozone from the internal Brewer temperature. Attention is focused on a peculiar case to show, by means of vertical wind velocity profile, the possible effects of lower stratospheric vertical advection on ozone fluctuations.     

On the quality of the Nimbus 7 LIMS version 6 ozone for studies of the middle atmosphere

The Nimbus 7 Limb Infrared Monitor of the Stratosphere (LIMS) radiance profile dataset of 1978/79 was reconditioned and reprocessed to Version 6 (V6) profiles of temperature and species that are improved significantly over those from Version 5 (V5). The LIMS V6 dataset was archived for public use in 2002. Improvements for its ozone include: (1) a more accurate accounting for instrument and spacecraft motion effects in the radiances, (2) the use of better spectroscopic line parameters for its ozone forward model, (3) retrievals of all its scans, (4) more accurate and compatible temperature versus pressure profiles (or T(p)) that are needed for the registration of the ozone radiances and for the removal of temperature effects from them, and (5) a better accounting for interfering species in the lower stratosphere. The retrieved V6 ozone profiles extend from near cloud top altitudes to about 80 km and from 64S to 84N latitude with better sampling along the orbit than for the V5 dataset. Calculated estimates of the single-profile precision and accuracy are provided; precision estimates based on the data themselves are of order 3% or better from 1 to 30 hPa. Estimates of total systematic error are hard to generalize because the separate sources of error may not all be of the same sign, and they depend somewhat on the atmospheric state. It is estimated that the accuracy of the V6 zonal mean ozone distribution is within ±9% from 50-10 hPa, improving to ±7% in the uppermost stratosphere. Simulation studies show that the LIMS T(p) retrievals are underestimating slightly the small amplitudes of the atmospheric temperature tides, which affect the retrieved day/night ozone differences. There are also small biases in the middle to lower stratosphere for the ascending versus descending node LIMS ozone, due principally to not accounting for the asymmetric weighting of its radiance within the tangent layer. The total accuracy for the LIMS ozone was assessed by comparing its daily zonal mean, daytime distributions against those from the Nimbus 7 SBUV Version 8 (V8) dataset for the same period. The LIMS V6 ozone agrees well with SBUV, except between 2 and 5 hPa where the LIMS ozone is greater. That bias is related to the differing vertical resolutions and forward models for the two experiments. The accuracy for LIMS V6 ozone in the lower stratosphere is improved over that reported for V5, as indicated by a small set of V6 comparisons with ECC ozonesonde profiles. Comparisons of diurnal, photochemical model calculations with the monthly-averaged, upper stratospheric ozone obtained with LIMS V6 indicate only a slight ozone deficit for the model at about 2 hPa. However, that deficit exhibits little to no seasonal variation and is in good agreement with similar model comparisons for a seasonal time series of ozone obtained with ground-based microwave instruments. Because the LIMS V6 ozone has improved accuracy and sampling versus that of V5 for the lower stratosphere it should now be possible to conduct quantitative studies of ozone transport and chemistry for the northern hemisphere, polar winter/spring of 1978/79—a time period when the catalytic loss of ozone due to reactive chlorine should not have been a major factor for the Arctic stratosphere.     

Ground-based monitoring of pinatubo aerosols and ozone at L''Aquila, Italy I.—Evidences for ozone depletion during 1991/92 winter months

Summary Possible evidence for stratospheric ozone depletion at northern midlatitudes as a consequence of the Pinatubo aerosol cloud is presented in this work. A ten-month record of aerosol and ozone measurements taken at the lidar station of L'Aquila, Italy, is compared to the 1985–1986 SBUV and SAGE II ozone data. Ozonesonde data collected in the station of Hohenpeissenberg, Germany, and S. Pietro Capofiume, Italy, are used to validate the DIAL measurements corrected for the aerosol presence.     

A large coaxial lidar for elastic and inelastic scattering studies of the stratosphere

A very powerful, fixed zenith laser radar system, based upon a liquid dye laser, is described in detail. The laser is a linear flashlamp pumped dye system capable of an average power output of 6W at a prf of 3 s^–1 using rhodamine 6G dye and about 3W with the same prf using esculin monohydrate dye. The use of this laser as a transmitting source in the lidar system has permitted the detection of Stokes shifted vibration/rotation Raman back-scattered light from neutral nitrogen in the stratosphere and from these measurements, stratospheric temperature profiles have been derived. The lidar has also been used to study elastic backscattering from the stratosphere at two wavelengths and preliminary results of a new technique for studying stratospheric aerosol are presented.     

Study of ozone concentration variations in the upper stratosphere using millimeter wave spectroscopy methods

New results of the study of ozone concentration variations in the upper stratosphere over Moscow in the layer at a height of 40 km, which is most sensitive to anthropogenic impacts, are presented. Changes in the ozone concentration and its relation to other atmospheric parameters in cold periods of 2008–2009 and 2009–2010 are analyzed. It was shown that there exist regions with decreased ozone content in the polar vortex and outside of it in air with higher temperature in the upper stratosphere. These phenomena cause deformations of vertical ozone distribution profiles and an appreciable shift of the maximum of the relative content of ozone to lower stratosphere layers.     

Theoretical infrared stratospheric emission spectra from ballons and satellites

A line-by-line and layer-by-layer method is proposed for the analysis and computation of spectra in the far i.r. for a stratospheric medium. Observations of the lower layers of the stratosphere were carried out from a balloon and a satellite. The method is applied to the computation of the spectral luminance of a layer near the maximum ozone concentration. The results are shown as synthetic spectra and the presence of lines of minor gaseous constituents in the stratospheric medium is discussed.     

Destruction of the ozone layer as a result of a meteoroid falling into the ocean

The falling of a large celestial body into the ocean causes a large number of compounds (for example, HCl, Cl, Br, Na, H₂O, OH, and NO) that destroy ozone molecules directly or indirectly to be ejected to stratospheric altitudes. The bleaching of the atmosphere in the UV range as a result of such ozone destruction creates negative feedback that restores the ozone. The characteristic time for such restoration in the stratosphere decreases sharply with altitude, ranging from several months at 30 km to several days at 20 km. Pis’ma Zh. éksp. Teor. Fiz. 70, No. 5, 360–366 (10 September 1999)     

Variations of the vertical ozone distribution over Moscow during sudden stratospheric warming in winter 2012–2013

The new results of remote sensing of atmospheric ozone over the Moscow region in the cold half-year of 2012–2013, including the period of major sudden stratospheric warming are presented. Methods for analyzing the results of observation of the vertical ozone distribution, obtained using spectral equipment operating at the frequencies of the ozone rotational line with a center at 142.175 GHz, are described. The features of the time series of the vertical stratospheric ozone distribution before, during, and after a strong disturbance of the stratospheric dynamics in January 2013 are considered. The data are compared with ozone observations during the period of previous major stratospheric warming in 2009–2010. The considered year to year differences and the diversity of the features of the dynamic processes affecting the vertical ozone distribution point to the importance of further monitoring of atmospheric ozone, which is necessary to develop numerical climate models and to predict the ozonosphere and climate evolution.     

星光掩星剥洋葱法反演臭氧密度

星光掩星技术探测恒星光经大气层消光、折射等作用后的恒星光光谱,利用大气中不同成分对不同波长的光吸收的差异反演得到大气密度信息。低轨卫星与恒星分别位于地球两侧,低轨卫星接收到不同切线高度上光谱,即构成星光掩星观测。光谱探测高度可从平流层至低热层,其中不同波段可用于不同大气痕量成分密度反演。星光掩星技术具有探测参数多、全球覆盖、垂直分辨率高、无需定标等优点。GOMOS(global ozone monitoring by occultation of stars)是搭载在欧洲航天局ENVISAT卫星上的平流层臭氧检测仪器。GOMOS利用星光掩星技术进行探测,设计精密,分辨率高,在轨稳定运行十年（2002年-2012年）,探测波长跨越紫外到可见光波段,采用光谱反演和垂直反演迭代的方法反演大气成分密度,得到了大量关于临近空间区域大气资料,对长期监测平流层至低热层区域变化提供了可靠的数据支持。利用GOMOS掩星数据,提出一种简单的反演方法--剥洋葱法,反演临近空间高度上臭氧数密度。剥洋葱法假设地球大气对称且水平分层,利用单个波段光谱进行反演,假设在此波长上光谱的大气吸收效应全部由臭氧造成,即选择臭氧吸收占据绝对优势的波长。经分析,在50～100 km高度上可以利用290 nm波段进行反演,在15～50 km高度上可以利用600 nm波段进行反演。根据Beer-Lambert定律,随切点高度自上而下,对恒星光光谱透过率利用剥洋葱法进行反演得到臭氧数密度。将剥洋葱法反演结果与GOMOS官方发布结果相对比,两者符合得很好。     

Mechanism of stratospheric ozone depletion. 1. On chain processes in the stratosphere

The characteristics of the chain processes of stratospheric ozone depletion are considered. It is shown that the basic feature of these processes is the presence of a limiting stage, which determines the rate of chain propagation in this process and, accordingly, the rate of ozone depletion. It is also shown that the practice, so far widespread in the stratospheric chemistry, of defining the rate-limiting step of the chain process as a single reaction with the lowest rate throughout the stratosphere does not enable to correctly determine the rare of the chain process and leads to a significant overestimation of the latter. Methods for correctly calculating the rate of the limiting step for an arbitrary number of chain propagation reactions and for determining the termination rate and the chain length are for the first time proposed. Application of the developed method is demonstrated by the example of the nitrogen oxide cycle.     

Cosmic-ray-driven electron-induced reactions of halogenated molecules adsorbed on ice surfaces: Implications for atmospheric ozone depletion and global climate change

The cosmic-ray-driven electron-induced reaction of halogenated molecules adsorbed on ice surfaces has been proposed as a new mechanism for the formation of the polar ozone hole. Here, experimental findings of dissociative electron transfer reactions of halogenated molecules on ice surfaces in electron stimulated desorption, electron trapping and femtosecond time-resolved laser spectroscopic measurements are reviewed. This is followed by a review of the evidence from recent satellite observations of this new mechanism for the Antarctic ozone hole, and all other possible physical mechanisms are discussed. Moreover, new observations of the 11-year cyclic variations of both polar ozone loss and stratospheric cooling and the seasonal variations of CFCs and CH₄ in the polar stratosphere are presented, and quantitative predictions of the Antarctic ozone hole in the future are given. Finally, a new observation of the effects of CFCs and cosmic-ray-driven ozone depletion on global climate change is also presented and discussed.