Correlated seasonal and climatic variations of trace constituents in the stratosphere

Summary Spectrometric experiments performed, in November 1976, within the framework of the Latitude Survey Mission on board the NASA Convair 990 from Ames Research Center are briefly deseribed. The results presented concern odd nitrogen molecules, HCl and water vapor. In terms of vertical column density, HNO₃ is predominant over NO+NO₂ at all latitudes higher than 40 degrees. A seasonal variation of NO₂ abundance is observed, with larger values in the summer hemisphere at high latitude. The mean zenith column density of HCl above 11 km is 1.5×10¹⁵ mol.cm^–2, with no evidence for any seasonal or climatic variation. Local number densities as high as 1.4×10¹⁰ mol.cm^–3 for HNO₃ and 5.4×10¹⁴ mol.cm^–3 for water vapor have been measured during the same flight near 11 km.     

Nonlinear behavior on an ozone photochemical system in the stratosphere

A nonlinear box system describing ozone photochemistry in the stratosphere is presented. Influences of pollutants, such as odd chlorine (Cl_x) and odd nitrogen (NO_x) discharged by human activities, on photochemical states of the system are investigated in detail. The results show that the solutions of the box system constitute a ‘cusp’ catastrophe manifold in the state-parameter space. An increase of about 30% for Cl_x source strength or a decrease of about 30% for NO_x source strength from their current level may lead to catastrophic transition and results in a reduction of ozone concentration about 50 times. Project supported by the National Natural Science Foundation of China and Laboratory for Aeronomy and Global Environmental Observation of IAP.     

Influence of stratospheric ozone changes on long-term trends in the meso- and lower thermosphere

As predicted by model calculations, long-term changes in the stratospheric ozone content should influence trends in the meso- and thermosphere also. These predictions have been tested by means of ionospheric reflection height data in the low-frequency (LF) range and critical frequency data series of the ionospheric E layer, foE, observed at different stations around the world. It was shown that an essential part of the derived trends in the mesosphere and in the lower thermosphere is correlated with long-term changes of the atmospheric ozone content. During the sub-interval with the strongest ozone decrease (1979–1995) the detected ionospheric trends are most pronounced. Additionally was also demonstrated that the longitudinally dependent ozone trends are related to similar variations in the foE trends.     

A note on the Aitken nuclei and ion flow measurements in the lower stratosphere

In the light of new measurements of small aerosol particles in the lower stratosphere, some of the old investigations—which were only published in part in scientific journals—are reviewed and compared. The discussion focuses on whether the Aitken nuclei (AN) size distribution up to 20 km can be described by Junge’s or log-normal density functions and under what circumstances one can find a bimodal distribution of these particles. The ion flow in correlated to the stratospheric pollution (intercept with the jet aircraft, volcanic activity) and is, in mean, directly proportional to the aircraft altitude in the undisturbed lower stratosphere. Note: The GCCPR, Univ. Missouri at Rolla, reports quoted in the article can be obtained from the author.     

近30年北半球冬季臭氧总量分布特征及其与平流层温度的关系

臭氧的时空分布特征对气候和环境变化具有显著影响,随着臭氧资料数量的增加和质量的提高,有必要对臭氧时空分布特征及其与气候变化的关系进行详细研究.本文利用欧洲中期天气预报中心提供的1979—2013年的全球月平均臭氧总量资料、平流层温度场资料,采用旋转经验正交函数分解(REOF)、Morlet小波分析、合成分析等方法研究了20°N以北的北半球冬季(12—2月)臭氧总量异常的主要空间分布结构与时间演变特征,并进一步分析了主要模态与平流层上层(2 hPa)、中层(30 hPa)以及下层(100 hPa)温度异常的关系.结果表明:近30年北半球冬季臭氧总量异常变化最显著的区域主要有5个,分别位于极地地区(75°N—90°N,0°—360°)、北半球副热带地区(20°N—40°N,0°—360°)、阿拉斯加地区(60°N—75°N,180°—260°E)、北大西洋地区(45°N—60°N,310°E—360°E)及西伯利亚地区(50°N—65°N,80°E—130°E).5个区域的冬季臭氧总量异常具有明显的年际和年代际变化特征.1980年代后期是各个区域的臭氧总量异常由年代际偏多转为偏少的转换时段.此外,各区域存在显著的年际变化周期,而且各个区域的年际周期存在明显的差异.臭氧总量异常变化与平流层温度异常变化的关系表明,臭氧总量异常的增加(减少)能够导致平流层上层温度异常偏冷(暖)和平流层中、下层温度异常偏暖(冷),其中平流层中层温度异常的偏暖(冷)程度要比下层更加明显.     

The vertical distribution of CFM and related species in the stratosphere

Available data on halogenated molecules in the stratosphere will be reviewed. Presently vertical profiles of CFCl₃ and CF₂Cl₂ in the stratosphere exist to 50 km altitude. Only measurements in the lower stratosphere are reported for the other major halocarbons, CCl₄ and CH₃Cl. Profiles of the product species ClO, Cl, HCl, and HF exist to about 35 km.Comparison with theoretical profiles from 1-D models shows generally good agreement except for ClO where the earliest measured concentrations exceed the calculated ones considerably.     

Transport and the seasonal variation of ozone

The transport mechanisms responsible for the seasonal behavior of total ozone are deduced from the comparison of model results to stratospheric data. The seasonal transport is dominated by a combination of the diabatic circulation and transient planetary wave activity acting on a diffusively and photochemically determined background state. The seasonal variation is not correctly modeled as a diffusive process. The buildup of total ozone at high latitudes during winter is dependent upon transient planetary wave activity of sufficient strength to cause the breakdown of the polar vortex. While midwinter warmings are responsible for enhanced ozone transport to high latitudes, the final warming marking the transition from zonal mean westerlies to zonal mean easterlies is the most important event leading to the spring maximum. The final warming is not followed by reacceleration of the mean flow; so that the ozone transport associated with this event is more pronounced than that associated with midwinter warmings.     

Structure and dynamics of the stratosphere and mesosphere revealed by VHF radar investigations

Powerful VHF radars are capable of almost continuously monitoring the threedimensional velocity vector and the distribution of turbulence in the middle atmosphere, i.e. the stratosphere and mesosphere. Methods of radar investigations of the middle atmosphere are outlined and the basic parameters, mean and fluctuating velocities as well as reflectivity and persistency of atmospheric structures, are defined. Results of radar investigations are described which show that the tropopause level as well as a criterion on the stability of the lower stratosphere can be deduced. Besides mean wind velocities, VHF radars can measure instantaneous velocities due to acoustic gravity waves. The interaction of gravity waves with the background wind is discussed, and it is shown that cumulus convection is an effective source of gravity waves in the lower stratosphere. The vertical microstructure of the stratosphere, manifesting itself in thin stratified sheets in which temperature steps occur, is investigated by applying knowledge from investigations of the oceanic thermocline. Possible origins, like shear generation and lateral convection of the microstructure of the stratosphere, are discussed. Observations of gravity waves in the mesosphere are reviewed and their connection with turbulence structures is pointed out. Finally, some open questions which could be answered by further VHF radar investigations are summarized.     

Sulphur emissions to the stratosphere from explosive volcanic eruptions

 Two methods were used to quantify the flux of volcanic sulphur (as the equivalent mass of SO₂) to the stratosphere over different timescales during the Holocene. A combination of satellite-based measurements of sulphur yields from recent explosive volcanic eruptions with an appropriate rate of explosive volcanism for the past 200 years constrains the medium-term (∼10²years) flux of volcanic sulphur to the stratosphere to be ∼1 Mt a^–1, with lower and upper bounds of 0.3 and 3 Mt a^–1. The short-term (∼10- to 20-year) flux due to small magnitude (10¹⁰–10¹²kg) eruptions is of the order of 0.4 Mt a^–1. At any time the instantaneous levels of sulphur in the stratosphere are dominated by the most recent (0–3 years) volcanic events. The flux calculations do not attempt to address this very short timescale variability. Although there are significant errors associated with the raw sulphur emission data on which this analysis is based, the approach presented is general and may be readily modified as the quantity and quality of the data improve. Data from a Greenland ice core support these conclusions. Integration of the sulphate signals from presumed volcanic sources recorded in the GISP2 core provides a minimum estimate of the 10³–year volcanic SO₂ flux to the stratosphere of 0.5–1 Mt a^–1 over the past 9000 years. The short-term flux calculations do not account for the impact of rare, large events. The ice-core record does not fully account for the contribution from small, frequent events. Received: 27 September 1995 / Accepted: 13 December 1995     

Atmospheric ozone and the movement of the air in the stratosphere

Using over 2200 ozonesonde ascents, published byHering andBorden [1]–[5] and byDütsch et al. [6], [7], the average vertical distribution of the ozone mixing ratio is found for different latitudes and for different seasons up to a height of 30 km. The method by which the ozone formed at great heights in low latitudes becomes concentrated in the lower stratosphere of high latitudes is discussed, and the meridional circulation theory is strongly suggested.Oxford, May 1972.     

Extension of Antarctic ozone hole to lower latitudes in the South-American region

A comparison of monthly mean values of total ozone at South Pole, Buenos Aires (Argentina), Cachoeira Paulista and Natal (Brazil), and Huancayo (Peru) revealed that whereas South Pole showed an ozone depletion of 45% in October 1987 (as compared to October, 1977), Buenos Aires showed a small decrease (10%) while the other locations showed very small decreases (1–2%). When daily values are considered, the Antarctic ozone hole of October 1987 seems to have caused 10% depletion at Buenos Aires and 5% at Natal and Huancayo in December 1987. However, a large part of this is normal seasonal variation, except at Huancayo, where a residual effect of 5% depletion in December 1987 remains. The QBO effects (5–8% changes in the ozone level in 2–3 years) could cause 10–15% fluctuations in solar UVB on the ground on clear-sky days and could be a possible health hazard unless factors like cloudiness reduce the UVB intensities.     

Microwave measurements of the ozone content in winter arctic stratosphere

As a result of the long-term observations lead in region of Kola Peninsula, connection between character of variations of the ozone content in a stratosphere of Arctic regions and behavior and structure of a winter polar vortex is established. During winter seasons with well developed cyclone and duration of stable existence not less than 1.5–2 months were observed extremely low ozone number density at heights 20–25 km connected, apparently, with its chemical destruction. On the other hand, during disturbances of the vortex, accompanied strong stratospheric warming, was registered almost double increase of ozone amount in a high-altitude interval from 20 up to 40 km. Comparison of results of ground-based microwave monitoring of an ozone layer to data of the satellite instrument EOS MLS installed on satellite AURA is lead. In most cases comparison has shown satisfactory within the limits of an error of measurements coincidence of results. However in conditions of atmospheric disturbances when arose significant spatial heterogeneity, the discrepancy of results of comparison was marked. The possible reasons which cause the detected disagreement in results are discussed.     

Possible correlation between ozone and aitken nuclei counts in the lower stratosphere

A study is presented of a possible correlation between ozone and Aitken nuclei concentration measured between 6 km and 19 km by the instruments installed on the WB-57F aircraft. Samples were taken between 48°N and 9°S latitudes over the U.S., the Gulf of Mexico, and Central and South America between March 1974 and February 1975.A weak negative correlation between AN and ozone concentrations was found at altitudes higher than the tropical tropopause. Scattering of the signs and magnitudes of correlation coefficients was found below the tropopause. Largest variations of the coefficient values were related to the stratospheric pollution following the eruption of the Guatemalan volcano Fuego.     

Solar response in the vertical structure of ozone and temperature in the tropical stratosphere

The aim of the present paper is to study the solar response in the vertical structure of ozone and temperature over the Indian tropical region and a search for any mutual relationship between their solar coefficients on a decadal scale in the lower stratosphere. For the purpose, the data obtained by ozonesonde and Umkehr methods for the lower stratospheric ozone and that of the total ozone amount from Dobson spectrophotometer during the period 1979–2001 have been analyzed. These data are analyzed using the multi-functional regression model, which takes into account most of the known natural and anthropogenic signals. The NCEP- and MSU-satellite data for the temperature over this region have been used. Results indicate an in-phase correlation of around 0.5 between ozone and solar flux (F10.7) in the vertical structure over the equatorial station, Trivandrum (8.3°N) but no significant correlation over Pune (18.3°N). The solar components of ozone and temperature indicate an in-phase but poor correlation in the lower stratospheric altitudes over both stations. However, when total ozone content data is analyzed, it indicates a very high correlation (⩾0.9) between the solar components of ozone and temperature. The solar trend in the vertical distribution of ozone is found to be of the order of 5–25% per 100 units of F10.7 solar flux for Trivandrum but it is relatively smaller (1.6–15.2%) over Pune. The solar dependence of temperature is found to be quite significant for the entire Indian tropical region with not much latitudinal variation.     

Stratospheric ozone response to a solar proton event: Hemispheric asymmetries

Ozone depression in the polar stratosphere during the energetic solar proton event on 4 August 1972 was observed by the backscattered ultraviolet (BUV) experiment on the Nimbus 4 satellite. Distinct asymmetries in the columnar ozone content, the amount of ozone depressions and their temporal variations above 4 mb level (38 km) were observed between the two hemispheres. The ozone destroying solar particles precipitate rather symmetrically into the two polar atmospheres due to the geomagnetic dipole field These asymmetries can be therefore ascribed to the differences mainly in dynamics and partly in the solar illumination and the vertical temperature structure between the summer and the winter polar atmospheres. The polar stratosphere is less disturbed and warmer in the summer hemisphere than the winter hemisphere since the propagation of planetary wave from the troposphere is inhibited by the wind system in the upper troposphere, and the air is heated by the prolonged solar insolation. Correspondingly, the temporal variations of stratospheric ozone depletion and its recovery appear to be smooth functions of time in the (northern) summer hemisphere and the undisturbed ozone amount is slighily, less than that of its counterpart. On the other hand, the tempotal variation of the upper stratospheric ozone in the winter polar atmosphere (southern hemisphere) indicates large amplitudes and irregularities due to the disturbances produced by upward propagating waves which prevail in the polar winter atmosphere. These characteristic differences between the two polar atmospheres are also evident in the vertical distributions of temperature and wind observed by balloons and rocker soundings.     

Influence of the vertical motion field on ozone concentration in the stratosphere

Computations of the mean meridional motion field in the stratosphere are applied to ozone distributions to evaluate the associated ozone concentration changes. These changes are compared with those produced by photochemical and quasi-horizontal eddy processes. For the period January–April 1964 there is a cooperative action between the mean and eddy motions with mean subsidence in middle latitudes supplying ozone to be carried polawards and equatorwards by quasi-horizontal eddy processes. At low latitudes mean horizontal motions offset the eddy transport while at high latitudes mean rising motion is the offsetting term. The mean ozone flux through 50 mb, 3.5×10²⁹ molecules sec^–1, is comparable with the fluxes evaluated by other techniques.The spring maximum is thought to be due to a modulation of the energy supply to the stratospheric eddies which, in turn, force the mean motions. Longer-term changes are to be expected; for example during Ice Ages when increased tropospheric eddy activity is anticipated there should be higher total ozone.     

Midlatitude mesopause region winds and waves and comparison with stratospheric variability

We present time series of January–May mean mesosphere/lower thermosphere (MLT) mean winds and planetary wave (PW) proxies over Europe together with stratospheric stationary planetary waves (SPW) at 50°N and time series of European ozone laminae occurrence. The MLT winds are connected with stratospheric PW and laminae at time scales of several years to decades. There is a tendency for increased wave activity after 1990, together with more ozone laminae and stronger MLT zonal winds. However, possible coupling processes are not straightforward. While mean MLT winds before the 1990s show similar interannual variations than stratospheric PW at 100 hPa, later a tendency towards a connection of the MLT with the middle stratosphere SPW is registered. There is also a tendency for a change in the correlation between lower and middle stratosphere SPW, indicating that coupling processes involving the European middle atmosphere from the lower stratosphere to the mesopause region have changed.     

Aerosol extinction and ozone measurements

The effect of aerosol extinction on Dobson measurements of total ozone is investigated, and several recent attempts to resolve this problem are reviewed. It is pointed out that the balloon measurements of Paetzold and his colleagues circumvent this problem: Solar-cycle and quasi-biennial effects can be clearly discerned in the balloon data. It is suggested that Paetzold's data would be ideal for testing stratospheric models and searching for man's effect on the stratospheric ozone layer.     

On the theoretical model for vertical ozone density distributions in the mesosphere and upper stratosphere

Diurnal variations in the vertical ozone density distribution have been calculated for the height range 40–150 km by extending our existing computer programs. The steady-state profiles were first calculated for fifteen constituents in the original program and three additional constituents (CH₄, CO and CO₂); the result was used as the initial condition for the time-dependent solution. The profile of the eddy diffusion coefficient used in this study was determined by comparing the model profile with the observations for CH₄, whose density distribution is verysenstive to the eddy diffusion coefficient The effects of hydrogen and nitrogen compounds on the ozone density are discussed somewhat quantitatively; they reduce the ozone density mainly in the mesosphere and stratosphere, respectively. Special attention is given to the large depression of the ozone density at around 70–85 km, which has been obtained in many theoretical models but has neither been explained nor definitely confirmed by observations. Our time-dependent model indicates that the depression develops at night by the effect of hydrogen-oxygen and nitrogen-oxygen reactions and of eddy diffusion transports. The latter effect also produces an increase of the ozone density after midnight at some heights in the depression region.     

Long-term variation of total ozone

The long-term variation of total ozone is studied for 1957 up to date for different latitude zones. The 3-year running averages show that, apart from a small portion showing parallelism with sunspot cycles, the trends in different latitude zones are dissimilar. In particular, where northern latitudes show a rising trend, the southern latitudes show an opposite (decreasing) trend. In the north-temperate group, Europe, North America and Asia show dissimilar trends. The longer data series (1932 ownards) for Arosa shows, besides a solar-cycle-dependent component, a steady level during 1932–1953 and a down-trend thereafter up to date. Very localised but long-lasting circulation patterns, different in different geographical regions, are indicated.