Representativeness of total ozone trends as derived from satellite BUV and ground-based measurements

The information content of the 7-year BUV data set has been reexamined by a comparison with a fairly large set of ground Dobson and M-83 instruments. The satellite-ground intercomparison of total ozone was done under different types of ground observation techniques (observation code) and different instrument exposure (exposure code) and for various distances of the subsatellite point from the station. Because of the existing latitudinal gradient in total ozone, at a given station the bias ground-BUV tends to be smaller when the subsatellite point is at a latitude higher than the station's latitude. Knowing the total ozone gradient at a given station, the BUV total ozone has been corrected to account for the ozone gradient and the correlation was calculated with the corresponding ground observations. These correlations seem to offer no improvement when compared with the correlations between the ground ozone and the actual BUV ozone at distances of the subsatellite point from the station within 200 km from the station used in previous studies. The seasonal variation of the BUV-ground correlation reveals information on the noise level of the measurements and the geographical distribution of the percentage mean bias: (Ground-BUV)×100/(Ground) is discussed. Both on short and on longer time scales it appears that the BUV derived recommended total ozone data set is reasonably good and possible instrumental drifts are not large. The analysis includes an extension through April 1977 of the BUV and contour-derived total ozone trends byLondon andLing (1980). Over the northern hemisphere both data sets (contour and BUV) show comparable trends over middle and high latitudes which range from –3 D.U./year to –5 D.U./year during the 7-year period April 1970–April 1977. In the southern hemisphere, however, long-term variation in total ozone cannot be determined from ground observations alone. It is concluded that for unknown reasons during the 7-year period of study, total ozone has been decreasing over most of the globe. The negative growth rates at high latitudes of the northern hemisphere are highly significant.     

Annual and semiannual oscillations of stratospheric ozone

The global structures of annual oscillation (AO) and semiannual oscillation (SAO) of stratospheric ozone are examined by applying spherical harmonic analysis to the ozone data obtained from the Nimbus-7 solar backscattered UV-radiation (SBUV) measurements for the period November 1978 to October 1980. Significant features of the results are: (1) while the stratospheric ozone AO is prevalent only in the polar regions, the ozone SAO prevails both in the equatorial and polar stratospheres; (2) the vertical distribution of the equatorial ozone SAO has a broad maximum of the order of 0.5 (mixing ratio in g/g) and the maximum appears earlier at high altitude (shifting from May [and November] at 0.3 mb [60 km] to November [and May] at 40 mb); (3) above the 40 km level, the maximum of the polar ozone SAO shifts upward towards later phase with altitude with a rate of approximately 10 km/month in both hemispheres; (4) vertical distributions of the polar ozone AOs and SAOs show two peaks in amplitude with a minimum (nodal layer) in between and a rapid phase change with altitude takes place in the respective nodal layers; and (5) the heights of the ozone AO- and SAO-peaks decrease with latitude. The main part of AOs and SAOs of stratospheric ozone including hemispheric asymmetries is ascribable to: (i) temperature dependent ozone photochemistry in the upper stratosphere and mesosphere, (ii) variations of radiation field in the lower stratosphere affected by the annual cycle of solar illumination and temperature in the upper stratosphere and (iii) meridional ozone transport by dynamical processes in the lower stratosphere.     

On the relationship between vertical ozone distribution and the synoptic situation

Summary The purpose of the paper is to provide a statistical view of the role of circulation patterns and the origin of low stratospheric air in connection with vertical ozone distribution below the ozone maximum, and also with the total ozone amount. Ozonesonde data from the aerological observatory of the Czech Hydrometeorological Institute (CHMI) Prague-Libu (50·0N, 14·7E) for January to April during the period 1979–1990 have been analyzed using an objective method to find the distribution of laminae in the vertical profile of the ozone partial pressure related to the different types of circulation patterns. The synoptic classification following Grosswetterlagen (GWL) was used, the parameters of the ozone profile such as number, magnitude, thickness and height of laminae, or the appearance of the large laminae were obtained for the individual types of GWL and used in other procedures. The total ozone data from the ozone observatory of CHMI in Hradec Králové (50·2N, 15·8E) was also included together with the height of the tropopause and parameters of ozone profiles in the cluster analysis to investigate connections between the ozone distribution and circulation patterns (types of synoptic situation). The ozone low-level index (LLI), defined as the ratio of the integral amount of ozone in D.U. from the surface up to 50 hPa and total ozone were introduced to provide better information about ozone profile response to circulation patterns and thus provide a better grouping of similar types of GWL. The presented results imply the strong confirmation of the huge ozone laminae below the ozone maximum as the source of total ozone positive extremes under appropriate synoptic situations with the near location of the polar vortex edge, which could be used in common forecasts of atmospheric ozone as well as in remote sensing applications.     

Ozone distribution over Mediterranean,central and southeast Europe during the International Quiet Sun Year (1964–1965)

Summary Ozone observations made during 1964 and 1965 at nine Mediterranean, central and southeast European stations (latitudes 38–52°N, longitudes 9–23°E) reveal patterns of seasonal and shorter time-variations in total ozone as well as in vertical ozone distribution. During the winter-spring season, a significant increase (20%) of ozone occurs essentially simultaneously with the spring stratospheric warming, and is noticed at all stations.—Autocorrelation coefficients show that the total ozone on any day is strongly related to the total ozone of the preceding four days in summer or one or two days in winter-spring or autumn. Changes of total ozone in southeast Europe correlate closely with those in Mediterranean Europe, and less closely with those from north central Europe.—Power spectrum analysis detects the dependence of ozone changes on processes with periods longer than 6–8 days, and indicates a significant oscillation with a period of 14–15 days, perhaps a result of the direct influence of lower stratospheric circumhemispheric circulation. — Reliable vertical ozone soundings were not available from all stations. The mean vertical profiles at Arosa, Switzerland (47°N) and Belsk, Poland (51°) are very similar. More than 60% of the variability of the total ozone is contributed by changes in ozone concentration between 10 and 24 km; less than 10% is due to variations above 33 km. Changes in ozone partial pressure at different altitudes, and relationships of those changes to total ozone, indicates that a mean vertical ozone distribution may be described adequately by considering the ozone changes in four layers: a) the troposphere, b) the lower stratosphere up to 24 km, c) a transition layer from 24 km to a variable upper border at 33–37 km, and d) the layer above 33–37 km.Part of this paper was presented at the Ozone Seminar in Potsdam, Germany, 27 September 1966.     

High-altitude data assimilation system experiments for the northern summer mesosphere season of 2007

A global numerical weather prediction system is extended to the mesosphere and lower thermosphere (MLT) and used to assimilate high-altitude satellite measurements of temperature, water vapor and ozone from MLS and SABER during May–July 2007. Assimilated temperature and humidity from 100 to 0.001 hPa show minimal biases compared to satellite data and existing analysis fields. Saturation ratios derived diagnostically from these assimilated temperature and water vapor fields at PMC altitudes and latitudes compare well with seasonal variations in PMC frequency measured from the aeronomy of ice in the mesosphere (AIM) satellite. Synoptic maps of these diagnostic saturation ratios correlate geographically with three independent transient mesospheric cloud events observed at midlatitudes by SHIMMER on STPSat-1 and by ground observers during June 2007. Assimilated temperatures and winds reveal broadly realistic amplitudes of the quasi 5-day wave and migrating tides as a function of latitude and height. For example, analyzed winds capture the dominant semidiurnal MLT wind patterns at 55°N in June 2007 measured independently by a meteor radar. The 5-day wave and migrating diurnal tide also modulate water vapor mixing ratios in the polar summer MLT. Possible origins of this variability are discussed.     

Short-time period fluctuations in the total ozone

The Toronto spectrophotometer was used to take an extensive series of ozone measurements for the period September 1971 to April 1972. As a result of these measurements it was found that short-lived variations of ozone occur which sometimes amount to more than 0.1 cm. These ozone disturbances are advected because the same disturbance has been observed on the direct sun and the zenith sky at different times. Results which show the general nature of these disturbances will be presented. Also, a discussion will be given which stresses the need for an automated, mesoscale ozone-measuring network, capable of measuring in all weather conditions during all daytime hours.     

El Chichon: The genesis of volcanic sulfur dioxide monitoring from space

The 1982 eruption of El Chichon inspired a new technique for monitoring volcanic clouds. Data from the Total Ozone Mapping Spectrometer (TOMS) instrument on the Nimbus-7 satellite were used to measure sulfur dioxide in addition to ozone. For the first time precise data on the sulfur dioxide mass in even the largest explosive eruption plumes could be determined. The plumes could be tracked globally as they are carried by winds. Magmatic eruptions could be discriminated from phreatic eruptions. The data from El Chichon are reanalyzed in this paper using the latest version of the TOMS instrument calibration (V8). They show the shearing of the eruption cloud into a globe-circling band while still anchored over Mexico in three weeks. The measured sulfur dioxide mass in the initial March 28 eruption was 1.6 Tg; the April 3 eruption produced 0.3 Tg more, and the April 4 eruptions added 5.6 Tg, for a cumulative total of 7.5 Tg, in substantial agreement with estimates from prior data versions. TOMS Aerosol Index (absorbing aerosol) data show rapid fallout of dense ash east and south of the volcano in agreement with Advanced Very High Resolution Radiometer (AVHRR) ash cloud positions.     

The Nimbus-4 Backscatter Ultraviolet (BUV) atmospheric ozone experiment — tow years' operation

Summary In April 1970 the Backscatter Ultraviolet (BUV) experiment was placed into orbit aboard the Nimbus-4 satellite. This double monochromator experiment measures ultraviolet terrestrial radiance at twelve discrete wavelengths between 2550 Å and 3400 Å. Approximately 100 scans covering a 230 km square are made between terminator crossings on the daylight side of the earth. A colinear photometer channel with the same field of view is used to derive the Lambert reflectivity of the lower boundary of the scattering atmosphere. The extraterrestrial solar irradiance is measured at the northern terminator. The instrument has currently produced almost three years of nearly continuous data which are being used to infer the high-level ozone distribution and total ozone on a global basis. The high-level ozone data have been verified by independent coincident rocket ozone soundings, and the total ozone values show good agreement with Dobson spectrophotometer determinations as well as those made with the Infrared Interferometer Spectrometer also on Nimbus-4. An increase has been observed in equatorial radiance at 2550 Å relative to 2900 Å, which seems to indicate that the amount of ozone in the upper stratosphere is related to the eleven-year solar cycle.     

Development of a chemistry module for GCMs: first results of a multiannual integration

The comprehensive chemistry module CHEM has been developed for application in general circulation models (GCMs) describing tropospheric and stratospheric chemistry, including photochemical reactions and heterogeneous reactions on sulphate aerosols and polar stratospheric clouds. It has been coupled to the spectral atmospheric GCM ECHAM3. The model configuration used in the current study has been run in an –off-line mode, i.e. the calculated chemical species do not affect the radiative forcing of the dynamic fields. First results of a 15-year model integration indicate that the model ECHAM3/CHEM runs are numerically efficient and stable, i.e. that no model drift can be detected in dynamic and chemical parameters. The model reproduces the main features regarding ozone, in particular intra- and interannual variability. The ozone columns are somewhat higher than observed (approximately 10%), while the amplitude of the annual cycle is in agreement with observations. A comparison with HALOE data reveals, however, a serious model deficiency regarding lower-stratosphere dynamics at high latitudes. Contrary to what is concluded by observations, the lower stratosphere is characterized by slight upward motions in the polar regions, so that some of the mentioned good agreements must be considered as fortuitous. Nevertheless, ECHAM3/CHEM well describes the chemical processes leading to ozone reduction. It has been shown that the mean fraction of the northern hemisphere, which is covered by polar stratospheric clouds (PSCs) as well as the temporal appearance of PSCs in the model, is in fair agreement with observations. The model results show an activation of chlorine inside the polar vortex which is stronger in the southern than in the northern winter hemisphere, yielding an ozone hole over the Antarctic; this hole, however, is also caused to a substantial degree by the dynamics. Interhemispheric differences concerning reformation of chlorine reservoir species HCl and ClONO₂ in spring have also been well reproduced by the model.     

Total ozone and equatorial zonal wind

Spatial correlations between total column ozone observed by TOMS and equatorial zonal winds from 1979 to 2003 have been assessed. Four months and three different altitude levels have been analyzed: January and July (solstice months), April and October (equinoctial months), and 10, 30 and 50 hPa. The results are different for the months and altitudes considered. The highest correlations values appear in tropical zone at 30 hPa. The Brewer–Dobson circulation plays a key role in regulating the abundance of ozone, influenced by the quasi-biennial oscillation (QBO) circulation. Since the Brewer–Dobson is a slow circulation, correlations considering lags between one and 12 months were estimated. In this case, the highest correlations values are moving to subtropical latitudes at winter hemisphere, with different behaviors for three altitude levels considered.     

中国南部对流层中上层臭氧增加的气象场判识及臭氧变化的多尺度特征

副热带急流对中国南部地区对流层中上层臭氧浓度的影响程度及地理范围目前还研究较少,且缺乏综合使用常规气象资料及卫星资料来判识对流层中上层臭氧浓度增高的方法.本文利用NCEP再分析与最终分析资料、日本GMS-5地球静止卫星水汽云图资料,以2001年3月27~29日中国南部的临安、昆明、香港臭氧探测个例为基础,结合1996年3月29日香港与2001年4月13日临安对流层中上层高浓度臭氧分布个例对副热带急流对中国南部对流层中上层臭氧浓度的影响进行了详细分析,提出根据气象要素场判识春季中国南部对流层中上层臭氧浓度增高的充分条件为根据卫星水汽图像上的暗区、高空急流入口区的左侧辐合区、高空锋区、对流层中上层≥1 PVU的向下伸展的舌状高位涡区来综合判断.本文的分析结果表明,本文个例中对流层中上层高浓度臭氧来自平流层;香港对流层中上层低浓度臭氧来自热带海洋地区.不仅臭氧垂直廓线的多个极小与极大值表明臭氧垂直分布的多尺度变化特征,而且对流层中上层PV分布以及卫星水汽图像分析也表明大气中的多尺度运动对臭氧垂直分布特征有显著影响.本文的结果表明与副热带高空急流相联系的平流层空气侵入不仅发生在中国大陆的较高纬度地区,较低纬度的昆明与香港地区也有平流层空气侵入导致对流层中上层臭氧浓度升高.     

北太平洋上空臭氧总量长期变化趋势及其影响因素分析

本文基于1979—2014年臭氧总量的卫星遥感数据,利用多元线性回归模型对臭氧总量数据序列进行模拟计算,考察了北太平洋上空臭氧总量长期变化趋势及其影响因素的作用.结果表明,北太平洋地区大气臭氧总量长期变化呈现减少趋势,但是减少速率随季节和纬度带表现出差异性,在各纬度带臭氧峰值季节臭氧下降趋势最为显著.在0°—15°N地区臭氧高值出现在夏秋季节并在8月达到峰值,峰值月份臭氧年均下降率约为0.2DU/a;15°—30°N亚热带地区臭氧高值出现在春夏季并在5月达到峰值,峰值月份臭氧年均下降速率约为0.22DU/a;而在30°—45°N中纬度地区臭氧高值出现在冬春季并在2月达到峰值,峰值月份臭氧年均下降率0.75DU/a.在臭氧分布年平均态基础上,影响臭氧总量分布变化的因素主要有臭氧损耗物质(EESC)、太阳辐射周期(Solar)、准两年振荡(QBO)和厄尔尼诺-南方涛动(ENSO)等.其中,EESC导致臭氧损耗效应随着纬度升高而增大,在从低到高的三个纬度带损耗最大值分别为11DU、16DU和66DU;Solar增强导致臭氧增加,在三个纬度带的增加效应最大值分别为16DU、17DU和19DU;QBO@10hPa和QBO@30hPa对臭氧影响幅度基本在±10DU内波动,只有QBO@10hPa对30°—45°N区域的影响作用达到14DU,值得注意的是QBO影响作用随着纬度变化存在相位差异,在0°—15°N区域臭氧变化与QBO呈现相同相位,而在15°—30°N和30°—45°N区域臭氧变化与QBO呈现相反相位;ENSO对各个纬度带臭氧影响幅度也在±10DU内,ENSO影响作用在不同纬度带也存在相位差异,臭氧总量变化在0°—15°N、15°—30°N区域与ENSO相位相反,在30°—45°N区域与ENSO相位一致.     

Scientific objectives of the Solar Mesosphere Explorer mission

The 1981–82 Solar Mesosphere Explorer (SME) mission is described. The SME experiment will provide a comprehensive study of mesospheric ozone and the processes which form and destroy it. Five instruments will be carried on the spinning spacecraft to measure the ozone density and its altitude distribution from 30 to 80 km, monitor the incoming solar ultraviolet radiation, and measure other atmospheric constituent which affect ozone. The polar-orbiting spacecraft will be placed into a 3pm-3 am Sun-synchronous orbit. The atmospheric measurements will scan the Earth's limb and measure: (1) the mesospheric and stratospheric ozone density distribution by inversion of Rayleigh-scattered ultraviolet limb radiance, and the thermal emission from ozone at 9.6 m; (2) the water vapor density distribution by inversion of thermal emission at 6.3 m; (3) the ozone photolysis rate by inversion of the O₂(¹g) 1.27 m limb radiance; (4) the temperature profile by a combination of narrow-band and wide-band measurements of the 15 m thermal emission by CO₂; and, (5) theNO₂ density distribution by inversion of Rayleighscattered limb radiance at 0.439 m. The solar ultraviolet monitor will measure both the 0.2–0.31 m spectral region and the Lyman-alpha (0.1216 m) contribution to the solar irradiance. This combination of measurements will provide a rigorous test of the photochemical equilibrium theory of the mesospheric oxygen-hydrogen system, will determine what changes occur in the ozone distribution as a result of changes in the incoming solar radiation, and will detect changes that may occur as a result of meteorological disturbances.     

Inference of total ozone from photometric measurements of sky radiation

Summary Ground-based photometric measurements of spectral sky radiation have been made using a simple filter instrument. Sky radiation intensities measured in the solar vertical at =3200 Å and 3600 Å are compared to infer total ozone. A model of multiple scattering Rayleigh atmosphere serves as a primary reduction parameter. Spectral measurements of all-sky radiance distribution are used to study the effects of haze and clouds on the inference of total ozone. The brightness distribution of clear and overcast sky in ultraviolet is also described.     

High-level warmings and total ozone over a tropical region

The rocketsonde data obtained from the launchings made at Thumba (8°3215N, 76°5148E) during the winter period 1970–71, as already reported, have indicated that warmings of noticeable magnitude occurred at high levels (upper stratosphere and mesosphere) over this tropical station during the period mentioned. The mean monthly radiosonde temperatures of 50, 100 and 300 mb levels at Thumba (Trivandrum) and Delhi (28°35N, 77°12E) during the same period have also pointed out certain anomalies consistent with the warmings referred to above at Thumba. The radiosonde temperatures of the two stations, Thumba (Trivandrum) and Delhi, have now been examined, along with the values of total ozone, for the ten winter periods commencing from 1961–1962. The analysis has pointed out the possibility of high-level warmings also having occurred in the past over the Indian region during the winters of 1963–1964 and 1967–1968, which are also the periods when prominent warmings are definitely known to have occurred at higher latitudes. The behaviour of total ozone has been found to be different in the different years of the warmings. The features noticed have been presented and discussed.     

The spatial structure of the dayside ionospheric trough

Tomographic imaging provides a powerful technique for obtaining images of the spatial distribution of ionospheric electron density at polar latitudes. The method, which involves monitoring radio transmissions from the Navy Navigation Satellite System at a meridional chain of ground receivers, has particular potential for complementing temporal measurements by other observing techniques such as the EISCAT incoherent-scatter radar facility. Tomographic reconstructions are presented here from a two-week campaign in November 1995 that show large-scale structuring of the polar ionosphere. Measurements by the EISCAT radar confirm the authenticity of the technique and provide additional information of the plasma electron and ion temperatures. The dayside trough, persistently observed at high latitudes during a geomagnetically quiet period but migrating to lower latitudes with increasing activity, is discussed in relationship to the pattern of the polarcap convection.     

对流层-平流层之间过渡层中臭氧含量及其加热率的变化研究

利用1958~2001年共44年的ECMWF资料及参数化方法,计算了对流层顶上、下3 km气层间的臭氧含量及其吸收太阳辐射加热率的时空分布.结果表明: (1) 臭氧分布的空间梯度从赤道指向两极,而加热率则是分别由高纬和低纬指向副热带,这样的经向梯度可能是驱动对流层顶结构变化的一种重要因素;两者空间分布的季节变化显著,但其对应关系并不完全一致,1月和4月的空间结构与7月和10月的相反,随季节调整具有突变现象;东亚及青藏高原是季节变化相对稳定的区域.(2) 在热带对流层顶控制区加热率与臭氧含量呈正相关,而极地对流层顶控制区各季节有所不同,还与太阳赤纬变化相关联;各纬度间加热率季节变化的位相和变率都存在差异,但南半球相对较为一致,最大距平为±2×10^-4 K·d^-1,北半球则较复杂,最大正距平为4×1010^-4 K·d^-1;两半球的季节周期位相趋于相反.(3) 除赤道外,臭氧距平的季节变化位相超前于加热率距平2~3月,并且发生在季节变化的调整期;最大距平出现在南极的8月大于0.4 DU,3~4月则小于-0.2 DU,而北极为±0.2 DU.(4) 臭氧含量和加热率的年际与年代际演变关系对应一致,并具有多尺度的结构特征;但两半球及赤道的时空演变差异明显,30° S~30° N间副热带控制区的加热率变幅剧烈,最大距平为±2.5×10^-4 K·d^-1,高纬和两极的变幅在不同演变期各不相同;臭氧的变幅结构与之相反,北极的最大距平分别大于0.25 DU和小于-0.35 DU.(5) 20世纪70年代以前及70年代中期,两半球的正负距平具有相反的演变结构,而90年代是负距平演变最剧烈的时期.     

The global distribution of long-term total ozone variations during the period 1957–1975

Total ozone observations in the international network have been used as a basis for the analysis of the mean monthly ozone distribution over the globe for the period 1957–75. It has been found that during the period 1961–70 the total ozone amount increased in the Northern Hemisphere by about 12 percent and that this increase seems to be significant at all latitudes. Although the data were sparse for the Southern Hemisphere, there did not appear to be any significant ozone changes during the 10 year period. Relatively large geographic variations were found in the ozone trends and it is suggested that these variations are related to large scale changes in the atmospheric circular pattern.     

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.     

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.