Ozone reference models for CIRA

The ozone reference model which is to be incorporated in the COSPAR International Reference Atmosphere (CIRA) is described and compared with other measurements of the Earth's ozone distribution. Ozone vertical structure models from approximately 25 to 90 km are provided combining data from five recent satellite experiments (Nimbus-7 LIMS, Nimbus-7 SBUV, AE-2 SAGE, Solar Mesosphere Explorer (SME) UVS, and SME IR). The results include the latest improvements in the SBUV algorithms using the most recent estimates of ozone cross sections. Also, the latest refinements in SME algorithms are incorporated. These algorithm improvements have improved agreement between the satellite data sets. Standard deviations are provided of monthly zonal means, and an estimate of the interannual variability is given. The models based on satallite data compare well with the Krueger and Minzner mid-latitude model incorporated into the U. S. Standard Atmosphere which is based on rocket and balloon measurements. Other comparisons are shown with Umkehr and more recent balloon data. Models are also provided of total columnar ozone reflecting recent improved estimates of ozone cross section. Information is provided on semiannual and annual variations. Other systematic variations including estimates of diurnal variations in the mesosphere will be included in the CIRA document.     

A mesospheric ozone profile at sunset

An altitude profile of the ozone concentration from 55 to 95 km was measured at sunset in January by simultaneous measurements of the 1.27 μm radiation and the solar UV radiation using rocket-borne radiometers at Uchinoura, Japan (31°N). The ozone profiles deduced by two different methods agree with each other at approximately 70 km. The profile was consistent with our previous results obtained at the same station in September, and with the sunset profile obtained at Wallops Island (38°N) during the WMO/FAA/NASA international ozone rocketsonde intercomparison. Our data show no seasonal variation of ozone in the 55 – 95 km region at Uchinoura.     

中国不同地区剩余臭氧及臭氧探空订正因子

根据中国不同地点臭氧探空数据，研究气球炸点臭氧浓度定值（CMR）法、卫星（SBUV和MLS）纬向平均法确定的剩余臭氧Ω_res及其对订正因子C_ref的影响，同时检验臭氧垂直分布对C_ref的贡献.结果显示: CMR法对气球炸点高度依赖性明显，且易高估Ω_res使C_ref整体低于100%；卫星纬向平均Ω_res对气球炸点高度不敏感，但在中国东部的臭氧总量高值区或青藏高原及低纬度臭氧低值地区，Ω_res呈现近10DU以上低值，这是经向臭氧总量及其垂直分布差异在卫星遥感数据上的反映.地面到100hPa的对流层臭氧（Ω_tro），100~10hPa的平流层臭氧（Ω_str）以及10hPa以上的Ω_res对C_ref贡献平均分别为（16±3.4）%，（65±2.3）%，（19±3.3）%.表明基于C_ref评估或订正探空仪平流层臭氧测值时，需考虑对流层臭氧及确定Ω_res方法的影响.卫星纬向平均法，特别是近似实测的SBUV臭氧廓线的值适用于确定Ω_res.      

Ozone mini-hole observation over the Balkan Peninsula in March 2005

Areas with dimensions of 1000–3000 km in which the total ozone content (TOC) decreases fast are called ozone mini-holes. They are generated mainly dynamically in two ways, either by poor-ozone air mass transport from the tropics to higher latitudes by planetary wave activity or, they are connected with strong adiabatic uplifting of the tropopause height. An ozone mini-hole, generated by the second mechanism, was observed over the Balkan Peninsula on 19/21 March 2005. In the middle of March, the polar vortex was strongly disturbed by Rossby waves, reaching up to the lower stratosphere. Warming episodes over a geographical area, covering the Barents Sea and the Polar Sea north from Central Siberia, displaced a polar vortex fragment extremely southwards. However, the vorticity was weak and the stratospheric temperatures did not reach low values, providing conditions for ozone chemical destruction via heterogenic reactions. At the same time, a Rossby wave ridge was located below the European polar fragment. In the period from 13 to 19 March, the thermal tropopause over Sofia was uplifted almost by 3 km. Ozone distributions observed by the SCIAMACHY instrument on 18–21 March show a fast TOC decrease westwards from Ireland, which was moving eastwards during the next days, increasing the area in which the ozone content decreased. On 20/21 March low ozone content was observed above the Stara Zagora (42°N, 25°E) ground-based station by means of the GASCOD instrument, using DOAS technique. The TOMS Earth probe instrument detected 237 DU over Sofia. This is a record low March value from the beginning of the TOMS instrument measurements in 1978. In March/April the ozone distribution was characterized by its mean annual maximum of 360 DU at 42°N.     

Measurement of middle atmospheric ozone density profile by rocket-borne radiometer onboard KSR-II

KSR-II, a two-stage sounding rocket of KARI was launched successfully at the Korean Peninsula on June 11, 1998. The apogee of the rocket was 137 km. For the ozone measurement, 8-channel UV and visible radiometers were onboard the rocket. The rocket measured an in situ stratospheric and mesospheric ozone density profile over Korea during its ascending phase using the radiometer and transmitted the data to ground station in real time. The maximum ozone density occurs near 25 km. Retrieved profile has a random error (1σ) of approximately 15% for altitude below 20km, 7% between 20-50 km and 10% greater than 50 km. The retrieved data were compared with Dobson spectrophotometer, ozonesonde, and HALOE onboard the UARS. Our results are in reasonable agreements with others.     

Proposed ozone reference models for the middle atmosphere

Since the publication of the last COSPAR International Reference Atmosphere (CIRA 72), large amounts of ozone data acquired from satellites have become available in addition to increasing quantities of rocketsonde, balloonsonde, Dobson, M83, and Umkehr measurements. From the available archived satellite data, models are developed for the new CIRA using 5 satellite experiments (Nimbus 7 SBUV and LIMS, AEM-2 SAGE, and SME IR and UVS) of the monthly latitudinal and altitudinal variations in the ozone mixing ratio in the middle atmosphere. Standard deviations and interannual variations are also quantified. The satellite models are shown to agree well with a previous reference model based on rocket and balloon measurements.     

Assessment of the ozone and temperature variability during 1979–1993 with the chemistry-climate model SOCOL

The chemistry-climate model SOCOL has been applied for the study of ozone and temperature anomalies during 1979–1993. Temperature and ozone anomalies have been obtained for a set of model runs forced by all major stratospheric forcing mechanisms. Forcings have been prescribed separately and together to assess their individual influence on stratospheric ozone and temperature. The results of these simulations have been compared to available satellite data. The model captures well ozone depletion and cooling in the upper stratosphere due to increases in the abundance of greenhouse gases and ozone depleting substances in the atmosphere. In the lower stratosphere, the model reproduces the warming over tropical and middle latitudes caused by the El-Chichon and Pinatubo eruptions. However, the simulated ozone response is overestimated in comparison with SAGE data. The best agreement with observations has been obtained for the run with all forcings included. This emphasizes the importance of the volcanic and solar forcings for the correct reproduction of observed trends. Comparison of near-global total ozone anomalies confirms an overestimation of ozone depletion just after volcanic eruptions, while the overall agreement with the model is fairly good.     

Ozone variability related to several SEP events occurring during solar cycle no. 23

Data from geostationary operational environmental satellite (GOES) series were used to identify intense solar energetic particle (SEP) events occurred during the solar activity cycle no. 23. We retrieved O₃, NO, NO₂, HNO₃, OH, HCl and OHCl profiles coming from different satellite sensors (solar occultation and limb emission) and we looked for the mesospheric/stratospheric response to SEPs at high terrestrial latitudes. The chemistry of the minor atmospheric components is analysed to evaluate the associated odd nitrogen (NO_x) and odd hydrogen (HO_x) production, able to cause short (h) and medium (days) term ozone variations. We investigated the effects of SEPs on the polar atmosphere in three different seasons, i.e., January 2005, April 2002 and July 2000. The inter-hemispheric variability of the ozone, induced by the SEP series of January 2005, has been compared with the effects connected both to larger and quite similar events. We found that during SEP events: (i) solar illumination is the key factor driving SEP-induced effects on the chemistry of the polar atmosphere; (ii) even events with limited particle flux in the range 15–40 MeV are able to change the abundance of the minor constituents in the mesosphere and upper stratosphere.     

Validation of the stratospheric sounding unit

The Stratospheric Sounding Unit (SSU) is part of the TOVS (TIROS Operational Vertical Sounder) on NOAA operational meteorological satellites. SSU measurements can be validated by comparison with temperature measurements from colocated rocket sondes. Systematic differences are found which vary with rocket station and sonde and are a function of height. However, these measurements are not adequate to define the performance of individual SSUs to a precision which would allow the observations from different SSUs to be combined in the study of diurnal and semidiurnal tides and of long term trends in stratospheric temperature. Instead this is achieved by detailed radiometric and spectroscopic investigation of each individual SSU, both prior to launch and during its operational life. Using the techniques descirbed, it is demonstrated that measurements from different SSUs can be combined with a relative error of less than 0.2K in equivalent brightness temperature.     

Middle atmosphere models and comparison with shuttle reentry density data

Several middle atmosphere models will be reviewed, including a new set of models produced by Groves in 1985. The latter models are based on rocket and rawinsonde in situ measurements and satellite remote sounding temperature data. The models are compared with measurements made with instruments on board U. S. Shuttles during their reentry. Very useful atmospheric density data have been obtained in the altitude region from 50 to 80 km. The measurements are unique in that they are made by a vehicle travelling almost horizontally through the atmosphere at a velocity of 6 to 7 km/sec. This results in measurements along a path of approximately 8,000 km in a time interval of about 20 minutes. The results show some unique features.     

Spring-ozone change in Antarctica and the role of the polar vortex

Observations since the late 1970's have shown that from late September until the end of November (austral spring) the total ozone over the southern polar region has declined by up to 30% when compared with the ozone average of the 1957–1978 period. The decline is not uniform in time and space; from January through August, the ozone changes are very small, well within the year-to-year fluctuation limits. Satellite observations confirm that the significant ozone decline is centered over and does not expand outside of the Antarctic continent, e.g. it coincides with the location of the Antarctic stratospheric winter vortex; moreover, the decline increases poleward. Analysis of the stratospheric temperatures and geopotential heights confirms that the spring-to-spring ozone changes closely follow the changes of the thermobaric field, and that the rapid increase of ozone (and stratospheric temperature) in the spring is dependent on the time of the polar vortex breakdown, when favorable conditions for continuous meridional exchange of ozone-rich air from the middle latitudes are re-established. The stratospheric heating rates and the weak gradient in the vortex central region during early spring provide favorable conditions for weak upward motions, responsible for a substantial part of the ozone loss between the date of the solar penetration of the stratosphere, and the date of the vortex breakdown. Since the late 1970's, the breakdown of the Antarctic vortex has occured about mid-November, a month later than in years of early breakdown. It is suggested that an early breakdwon of the Antarctic vortex would interrupt the trend of declining spring ozone established over the past few years.     

平流层臭氧和辐射场的季节分布特征

利用美国NCAR化学气候耦合模式WACCM3对平流层温度场、风场、臭氧及辐射场进行了模拟.结果表明,在适宜飞艇长期驻留的准零风层高度20～22km(对应大气压强范围为50～30hPa,以下均采用气压值表征对应大气高度),7-8月风速小于5m·s-1的风带可长期稳定在40°N以北.臭氧空间分布显示,在30hPa气压高度处中国地区臭氧浓度出现了带状分布,30hPa高度以下低纬度地区臭氧浓度低于中纬度地区.平流层太阳加热率的时空变化表明,在平流层上层,太阳加热率可达100×10-6K·s-1,而在平流层下层,只有10×10-6K·s-1.6-8月中国区域的太阳加热率大于9月;在100～30hPa高度内,中纬度地区太阳加热率高于低纬度地区,在30hPa高度以上,低纬度地区太阳加热率高于中纬度地区;8-9月30～40hPa高度处,太阳加热率的空间变化较小.在30hPa高度上,太阳加热率在40°N昼夜变化最大;50hPa高度处,太阳加热率的昼夜变化小于30hPa高度处,而且白天太阳加热率出现极大值的纬度明显靠北.平流层低纬度地区的长波加热率小于中纬度地区.青藏高原由于地形特殊,其6-7月的臭氧浓度、太阳加热率和长波加热率均小于同纬度其他地区.      

Changes in surface UV solar irradiance and ozone over the balkans during the eclipse of August 11, 1999

Intensive measurements of UV solar irradiance, total ozone and surface ozone were carried out during the solar eclipse of 11 August 1999 at Thessaloniki, Greece and Stara Zagora, Bulgaria, located very close to the footprint of the moon's shadow during the solar eclipse with the maximum coverage of the solar disk reaching about 90% and 96% respectively. It is shown that during the eclipse the diffuse component is reduced less compared to the decline of the direct solar irradiance at the shorter wavelengths. A 20-minute oscillation of erythemal UV-B solar irradiance was observed before and after the time of the eclipse maximum under clear skies, indicating a possible 20-minute fluctuation in total ozone presumably caused by the eclipse induced gravity waves. The surface ozone measurements at Thessaloniki display a decrease of around 10–15 ppbv during the solar eclipse. Similarly, ozone profile measurements with a lidar system indicate a decrease of ozone up to 2 km during the solar eclipse. The eclipse offered the opportunity to test our understanding of tropospheric ozone chemistry. The use of a chemical box model suggested that photochemistry can account for a significant portion of the observed surface ozone decrease.     

The ozonesonde intercomparison experiment at Thumba

An Indo-Soviet collaborative experiment on Ozonesonde Intercomparison was conducted at TERLS in March 1983. Thirteen rocket ozonesondes, eleven balloon ozonesondes and seven meteorological rockets were launched from Thumba. The rocket and balloon soundings were supported by on site Dobson spectrophotometric observations, surface ozone measurements as well as measurements with a Volz type filter photometer. The programme has yielded data on ozone vertical profiles from eleven rocketsondes, seven balloon-sondes and four sets of Umkehr observations. The data is studied with a view to intercompare the various sensors.     

Aerosol observations for climate studies

The SAM II and SAGE satellite systems have provided to date more than 5 years and almost 3 years, respectively, of data on atmospheric aerosol profiles on a near-global scale. Studies with these unique data sets are developing a global aerosol climatology for the first time and have shown the existence and quantification of polar stratospheric clouds (PSC's) and tropical stratospheric cirrus. In addition, a tropospheric cirrus climatology is evolving. Since these two experiments were launched, a series of large volcanic eruptions have occurred which have greatly impacted the stratospheric aerosol loading. The aerosol layer produced by the eruption of El Chichon, for example, increased the 30 mb temperatures in the northern tropics by as much as 4°C for 6 months after the eruption. This paper will describe in detail, from a climate perspective, the evolving aerosol and cloud climatologies as a function of space and time, and show the stratospheric dynamics of volcanic injections and their enhancements on stratospheric optical depth and mass loading.     

Solar UV radiation variations and their stratospheric and climatic effects

NIMBUS-7 SBUV measurements of the short-term solar UV variations caused by solar rotation and active-region evolution have determined the amplitude and wavelength dependence for the active-region component of solar UV variations. Intermediate-term variations lasting several months are associated with rounds of major new active regions. The UV flux stays near the peak value during the current solar cycle variation for more than two years and peaks about two years later than the sunspot number. NIMBUS-7 measurements have observed the concurrent stratospheric ozone variations caused by solar UV variations. There is now no doubt that solar UV variations are an important cause of short- and long-term stratospheric variations, but the strength of the coupling to the troposphere and to climate has not yet been proven.     

紫外后向散射探测臭氧总量的反演误差研究

通过探测紫外后向散射获取臭氧总量目前已经成为臭氧总量探测的主要方法之一. 本文以模拟计算为主要方法, 从模式计算误差, 反演算法误差和仪器误差三方面着手, 对影响臭氧总量反演精度的各个参数进行分析研究, 并对由其引起的臭氧总量反演误差进行定量计算, 研究结果对臭氧总量反演精度的提高和实际观测资料的处理有着重要的指导意义.      

Proposed reference models for ozone

Ozone reference models are proposed here similar to the Keating and Young 1985 models which were prepared for the new COSPAR International Reference Atmosphere. This paper updates tables provided in the Keating and Young ozone model, giving improved monthly zonal mean total column ozone in 10° latitude increments, improved monthly zonal mean ozone volume mixing ratios (ppmv) from 20 to 0.003 mb in 10° latitude increments, and conversion tables providing ozone vertical structure in other units. Also, a new table is provided giving ozone vertical structure as a function of altitude (from 25 to 80 km), latitude, and month. The models are based on measurements from six contemporary satellite instruments.     

The variability of stratospheric nitrogen compounds observed by LIMS in the winter of 1978–1979

The LIMS experiment was launched on the Nimbus 7 satellite for the purpose of sounding the vertical structure of temperature and key upper atmosphere trace gases on a global scale. The technique of thermal infrared limb sounding was used to obtain measurements of O₃, H₂O, NO₂, and HNO₃. LIMS collected data almost continuously from late October to late May over the latitude range from 64°S to 84°N. Two of the gases, NO₂ and HNO₃, are important elements in the NO_x chain of chemical reactions leading to ozone destruction. We will describe results for these gases in terms of zonal mean profiles and latitudinal distributions. The period selected for study is January–May 1979, when a major stratospheric warming occurred.     

Long term solar induced variations in total ozone, stratospheric temperatures and the tropopause

The variations of total ozone, stratospheric temperature and tropopause temperature are presented for the past 3 solar cycles for the summer months of the northern hemisphere. Ground-based, 30-year total column ozone series, filtered from its seasonal, QBO, El Nino/Southern Oscillation (ENSO) and trend components are found to be correlated to the 11-year solar cycle. Model calculations with a 2D chemical transport model are consistent with the observations. Mean stratospheric temperature variations, between levels 100 and 10 hPa, show also the same variation, correlated with the observed 11-year solar cycle, and the tropopause temperature increases in the same manner, in response to a warmer stratosphere during solar maxima.