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.     

Ozone chemical equilibrium in the extended mesopause under the nighttime conditions

For retrieval of atomic oxygen and atomic hydrogen via ozone observations in the extended mesopause region (～70–100?km) under nighttime conditions, an assumption on photochemical equilibrium of ozone is often used in research. In this work, an assumption on chemical equilibrium of ozone near mesopause region during nighttime is proofed. We examine 3D chemistry-transport model (CTM) annual calculations and determine the ratio between the correct (modeled) distributions of the O₃ density and its equilibrium values depending on the altitude, latitude, and season.The results show that the retrieval of atomic oxygen and atomic hydrogen distributions using an assumption on ozone chemical equilibrium may lead to large errors below ～81–87?km. We give simple and clear semi-empirical criterion for practical utilization of the lower boundary of the area with ozone’s chemical equilibrium near mesopause.     

Asymmetrical structure in the thermosphere during magnetic stroms as deduced from the CACTUS accelerometer data

During the last solar activity minimum, a great deal of very precise total density data was obtained in the equatorial regions from the CACTUS accelerometer experiment. Due to the eccentricity of the orbit, it is also possible to determine a density scale height by considering that the density profiles between the perigee (270 km) and 400 km are quasi-vertical. Densities and density scale heights are analysed during magnetic storms and their variations are compared with their behaviour during quiet periods. For densities as well as for scale heights, an asymmetrical structure in latitude and longitude is exhibited with respect to the magnetic equator. Their values are relatively higher in the northern hemisphere than in the southern one. The hypothesis (previously suggested) of a greater energy input in the southern hemisphere inducing asymmetrical winds, explains the results well.     

First results of ozone profiles between 35 and 65 km retrieved from SCIAMACHY limb spectra and observations of ozone depletion during the solar proton events in October/November 2003

Ozone density profiles between 35 and 65 km altitude are derived from scattered sunlight limb radiance spectra measured by the SCIAMACHY instrument on the Envisat satellite. The method is based on the inversion of normalized limb radiance profiles in the Hartley absorption bands of ozone at selected wavelengths between 250 and 310 nm. It employs a non-linear Newtonian iteration version of Optimal Estimation (OE) coupled with the radiative transfer model SCIARAYS. The limb scatter technique combined with a classical OE retrieval in the short-wave UV-B and long-wave UV-C delivers reliable results as shown by a first comparison with MIPAS V4.61 profiles yielding agreement within 10% between 38 and 55 km. An overview of the methodology and an initial error analysis are presented. Furthermore the effect of the solar proton storm between 28 October and 6 November 2003 on the ozone concentration profiles is shown. They indicate large depletion of ozone of about 60% at 50 km in the Northern hemisphere, a weaker depletion in the Southern hemisphere and a dependence of the depletion on the Earth’s magnetic field.     

Global pictures of the ozone field,from high altitudes,from DE-I

Using the imaging instrumentation aboard the Dynamics Explorer spacecraft (DE-I), total column ozone densities are obtained in the sunlit hemisphere by measuring the intensities of backscattered solar ultraviolet radiation with multiple filters and multiple photometers. The high apogee altitude (23,000 km) of the eccentric polar orbit allows high resolution global-scale images of the terrestrial ozone field to be obtained within 12 minutes. Previous ozone-monitoring spacecraft have required much longer time periods for comparable spatial coverage because of their lower altitudes (<1200 km). The much higher altitude of DE-I also provides hours of continuous imaging of features compared to minutes or seconds with previous spacecraft. Near perigee, high resolution images can be gained with pixel size as small as 3 km to view mesoscale atmospheric variations. Utilizing these data, the effects of planetary-scale, synoptic-scale, and mesoscale dynamical processes, which control the distribution of ozone near the tropopause, can be studied. Preliminary results show short-term (less than one day) variations in the synoptic ozone field and these variations appear to be in accord with meteorological data. Spatial variations in the ozone field are found to be highly negatively correlated with tropopause altitude.     

Model simulations of the impact of the 27-day solar rotation period on stratospheric ozone and temperature

Results are presented from two-year simulations of the effects of short-term solar ultraviolet (UV) variability using the Met. Office coupled chemistry-climate model. The model extends from the ground to 0.1 mbar and contains a complete range of chemical reactions allowing representation of all the main ozone formation and destruction processes in the stratosphere. The simulations were achieved by incorporating a 27-day oscillation in the pre-calculated model photolysis rates. Amplitudes for this signal were determined using solar spectral UV observations from the SOLar STellar Irradiance Comparison Experiment (SOLSTICE) instrument. Two experiments were carried out, one in which the UV variability was included in both the photolysis and radiation schemes and one in which only the photolysis scheme was modified.

The model reproduced several main features of observed correlations between short-term solar UV variability and both ozone and temperature in the tropical upper stratosphere, including the downward propagation of the phase lag and sensitivities of ozone and temperature to solar UV which are similar in magnitude to those observed. In the lower stratosphere, the ozone response to solar UV variability has not been well characterised from observations. Both model runs show a reversal of the propagation of phase lag below 10mb. The model response was found to be different between the two runs indicating that radiatively induced dynamical effects may play a significant role in the ozone response to solar UV variability.     

Verification of satellite observations of stratospheric minor constituents

The TIROS-N operational meteorological satellite observing system will have the capability of determining global ozone amounts from two instruments by 1985. The TIROS Operational Vertical Sounder (TOVS) yields total ozone amounts through measurements of atmospheric infrared radiances. The Solar Backscatter Ultraviolet (SBUV/2) spectrometer yields total ozone amounts and vertical ozone profiles through measurements of the solar ultraviolet radiation backscattered by the atmosphere. The current operations plan calls for single satellites containing both instruments system with local afternoon equator crossing times. They will be launched at approximately 18 month intervals.The satellite ozone products will require verification using commonly accepted references. For total ozone, Dobson spectrophotometer determinations are to be used. For vertical profiles, no clear choice now exists among balloon-launched chemical sondes, rocket-launched optical sondes or Dobson Umkehr measurements. The applicability and use of these measurement systems are discussed with emphasis on the need for the verification data consistent with the operational satellite lifetimes.Another major source of data for verification is other satellite systems. Comparisons of vertical ozone profiles from several concurrent satellites is discussed. This includes results from SAGE, LIMS and SBUV.     

对流层顶变化对上对流层/下平流层臭氧分布的影响

上对流层和下平流层(UT／LS)，位于8-25km高度之间，是大气中一个很特殊的区域．大部分的臭氧分布在下平流层，在下平流层臭氧的含量发生一个很小的变化，就会对气候和地面的紫外辐射产生很大的影响．而作为气象参数的对流层顶，是充分混合、缺乏臭氧的上对流层和层结稳定、臭氧丰富的下平流层之间的边界或过渡层，其变化对臭氧总量和分布有直接和明显的影响．本文使用二维模式模拟研究对流层顶变化对臭氧在UT／LS分布的影响．模拟结果表明对流层顶的季节变化对UT/LS的臭氧分布有明显的影响，臭氧的局地变化可以超过10％在冬季北半球中纬度对流层顶高度升高1km时，模式结果表明对臭氧分布的影响比较显著，局地变化可超过6％，但是对臭氧总量的影响较小，变化不超过5DU，小于观测资料统计分析的结果。     

Influence of solar 11-year variability on chemical composition of the stratosphere and mesosphere simulated with a chemistry-climate model

An understanding of observed global chemistry and climate changes caused by solar activity changes is a high priority in modern geosciences. Here, we discuss the influence of the ultraviolet spectral irradiance variability during solar cycle on chemical composition of the stratosphere and mesosphere with chemistry-climate model that fully describes the interactions between chemical and thermo-dynamical processes. We have performed several 20-year long steady-state runs and found a significant influence of solar irradiation on the chemical composition in the stratosphere and mesosphere. An enhanced photolysis during solar maximum results in destruction of methane, nitrous oxide and CFCs providing an increase in the chemical activity of the atmosphere with more pronounced effects in the mesosphere. In the mesosphere, an increase of HO_x caused by more intensive water vapor photolysis results in significant ozone depletion there. More intensive methane oxidation gives statistically significant rise to the stratospheric humidity. The influence of dynamical perturbations has been identified over high latitude areas. The response of OH is found to be in a good agreement with observation data. The response of the other species is hard to validate, because of the lack of theoretical and observational studies.     

Investigation on the MLT tidal variability during September 2019 minor sudden stratospheric warming

Tidal variability in the mesosphere and lower thermosphere (MLT) during September 2019 Southern hemisphere minor sudden stratospheric warming (SSW) is investigated utilizing ground-based meteor radar wind observations from the equatorial, extratropical, middle, and high latitude stations and global reanalysis dataset. The polar warming is found to move from the mesosphere to the stratosphere until the peak warming day (PWD) of the SSW. The diurnal and semidiurnal tides at individual observational sites do not exhibit any consistent response during the observational interval, but a notable and consistent variability in some specific zonal wavenumber components, i. e., DW1 (migrating diurnal tide), DE3 (nonmigrating eastward wavenumber 3 diurnal tide), and SW2 (migrating semidiurnal tide) is found in the global reanalysis dataset. Incidentally, the warming event occurs during Spring equinox when a dominant seasonal change in the tidal activities generally takes place and hence seasonal variability is also looked into while identifying the SSW impact during the observational interval. It is found that the seasonal broad changes in the DW1, DE3, and SW2 amplitudes can be explained by the variability in the tidal sources, i.e., water vapor, convective activity, ozone, etc during the observational period. However, the extracted short-term variability in the global tidal modes on removing seasonal trend reveals noticeable response in connection with the warming event. The deseasoned amplitude of the DW1 significantly enhances around the PWD at most of the present latitudes. The deseasoned DE3 amplitude responds significantly in the middle atmosphere at low latitudes during the warming phase. The deseasoned SW2 exhibit clear enhancement around the PWD at all the latitudes. However, the deseasoned tidal features do not seem to correlate well with that of the source species unlike the seasonal ones that imply involvement of complex processes during the warming event, seeking further future investigations in this regard.     

Greenhouse gases and recovery of the Earth’s ozone layer

A numerical 2-D zonally averaged dynamical radiative-photochemical model of the ozonosphere including aerosol physics is used to examine the role of the greenhouse gases CO₂, CH₄, and N₂O in the recovery of the Earth’s ozone layer after reduction of anthropogenic discharges of chlorine and bromine compounds into the atmosphere. A weakness in efficiencies of all catalytic cycles of the ozone destruction due to cooling of the stratosphere caused by greenhouse gases is shown to be a dominant mechanism of the impact of the greenhouse gases on the ozone layer. Numerical experiments show that the total ozone changes caused by greenhouse gases will be comparable in absolute value with the changes due to chlorine and bromine species in the middle of the 21st century. Continuous anthropogenic growth of CO₂ will lead to a significantly faster recovery of the ozone layer. In this case, the global total ozone in the latitude range from 60°S to 60°N will reach its undisturbed level of 1980 by about 2040. If the CO₂ growth stops, the global total ozone will reach this level only by the end of the century.     

Ozone trends in the mid-latitude stratopause region based on microwave measurements at Lindau (51.66° N, 10.13° E), the ozone reference model,and model calculations

We compared 8 years of ozone measurements taken at Lindau (51.66° N, 10.13° E) at altitudes between 40 and 60 km using the microwave technique with the CIRA ozone reference model that was established 20 years ago (Keating et al., 1990). We observed a remarkable decrease in ozone density in the stratopause region (i.e., an altitude of 50 km), but the decrease in ozone density in the middle mesosphere (i.e., up to 60 km in altitude) is slight. Likewise, we observed only a moderate decrease in the atmospheric region below the stratopause. Other studies have found the strongest ozone decrease at 40 km and a more moderate decrease at 50 km, which is somewhat in contradiction to our results. This decrease in ozone density also strongly depends on the season. Similar results showed model calculations using the GCM COMMA-IAP when considering the increase in methane. In the lower mesosphere/stratopause region, the strongest impact on the concentration of odd oxygen (i.e., O₃ and O) was observed due to a catalytic cycle that destroys odd oxygen, including atomic oxygen and hydrogen radicals. The hydrogen radicals mainly result from an increase in water vapor with the growing anthropogenic release of methane. The finding suggesting that the stratopause region is apparently attacked more strongly by the water vapor increase has been interpreted in terms of the action of this catalytic cycle, which is most effective near the stratopause and amplified by a positive feedback between the ozone column density and the ozone dissociation rate, thereby chemically influencing the ozone density. However, the rising carbon dioxide concentration cools the middle atmosphere, thereby damping the ozone decline by hydrogen radicals.     

Air depression over south pole during Antarctic spring and its possible influence on ozone content in this region

Air depression during Antarctic spring, its long-term behaviour and connection with ozone content has been investigated on base of rocket data for polar regions and total ozone data sets for South pole (TOMS data) for 1979–1990. It was shown, that air pressure depression near South polar region in September in the lower stratosphere has a visible (about 5% per decade) negative trend similar to the tendency which total ozone records reveal. Rather high correlation (+0.82) between air pressure in the stratosphere and total ozone content for spring in Antarctica was found.     

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.     

Photochemical response of neutral and ionized middle atmosphere composition to the strong solar proton event of October 1989

One of the strongest solar proton events (SPE) occurred in October 1989. Its forcing of the middle atmosphere chemistry including ionized components in the D-region is examined. The ionization rate, and ozone, NO and OH density temporal and spatial (vertical) deviations induced by the SPE, calculated by a 1-D time-dependent photochemical model separately for daytime and nighttime (not shown here), are used in a 1-D model of the lower ionosphere to calculate the response of ionized components to combined forcing by ionization rate and neutral chemical composition disturbances. The radio wave absorption caused by electron density disturbances after the SPE is calculated and compared with observations. The computed ozone values are compared with observations, as well.     

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 global distribution and variability of stratospheric constituents measured by LIMS

The purpose of the Nimbus 7 LIMS experiment was to sound the composition and structure of the upper atmosphere and provide data for study of photochemistry, radiation, and dynamics processes. Vertical profiles were measured of temperature and ozone (O₃) over the 10-km to 65-km range and water vapor (H₂O), nitrogen dioxide (NO₂), and nitric acid (HNO₃) over the 10-km to ～50-km range. Latitude coverage extended from 64°S to 84°N. Several general features of the atmosphere have emerged from data analyses thus far. Nitrogen dioxide exhibits rapid latitudinal variations in winter and shows hemispheric asymmetry with generally higher vertical column amount in the summer hemisphere. HNO₃ data show that this gas is highly variable with altitude, latitude, and season. Smallest mixing ratios occur in the tropics, and the largest values occur in the high latitude winter hemisphere. The results show that O₃, NO₂, and HNO₃ are strongly affected during a stratospheric warming. There is a persistently low water vapor mixing ratio in the tropical lower stratosphere (～2–3 ppmv), a poleward gradient at all times in the mission, and evidence of increasing mixing ratio with altitude at tropical and middle latitudes.     

Establishing and maintaining specific pathogen free (SPF) conditions in aqueous solutions using ozone.

The paper discusses the use of ozone in space applications for the elimination of pathogens, and the enhancement of the oxidation potential of ozone using hydrogen peroxide and ultraviolet radiation. These combinations will be possible to set up in space conditions. The sterilizing effect versus free radical generation is an important equilibrium to establish when specific pathogen free conditions are wanted in aqueous solutions containing organic matter. In situ sterilization of plant roots in hydroponic systems, as well as the oxidation of root exudates, will be discussed. The paper will contain examples of the chemical interaction of ozone with some of the other compounds found in hydroponic systems.     

The solar cycle variation of plasma parameters in equatorial and mid latitudinal areas during 2005–2010

Based on the ISL data detected by DEMETER satellite, the solar cycle variation in electron density (Ne) and electron temperature (Te) were studied separately in local daytime 10:30 and nighttime 22:30 during 2005–2010 in the 23rd/24th solar cycles. The semi-annual, annual periods and decreasing trend with the descending solar activity were clearly revealed in Ne. At middle and high latitudes, there exhibited phase shift and even reversed annual variation over Southern and Northern hemisphere, and the annual variation amplitudes were asymmetrical at both hemispheres in local daytime. In local nighttime, the annual variations of Ne at south and north hemispheres were symmetrical at same latitudes, but the annual variation amplitudes at different latitudes differed largely, showing obviously zonal features. As for Te, the phase shift in annual variations was not as apparent as Ne with the increase of latitudes at Southern and Northern hemisphere in local daytime. While in local nighttime the reversed annual variations of Te were shown at low latitudinal areas, not at high latitudes as those in Ne. The correlation study on Ne and Te illustrated that, in local daytime, Ne and Te showed strong negative correlation at equator and low latitudes, but during the solar minimum years the correlation between Ne and Te changed to be positive at 25–30° latitudes in March 2009. The correlation coefficient R between Ne and Te also showed semi-annual periodical variations during 2005–2010. While in local nighttime, Ne and Te exhibited relatively weak positive correlation with R being about 0.6 at low latitudes, however no correlation beyond latitudes of 25° was obtained.     

Boundary of nighttime ozone chemical equilibrium in the mesopause region: Improved criterion of determining the boundary from satellite data

A modified derivation of the criterion of nighttime ozone chemical equilibrium (NOCE) in the mesopause region is presented. According to 3D model calculations, the improved criterion reproduces the lower boundary of the equilibrium much better than its earlier version. Processing of the SABER/TIMED data of 2021 has shown that the modified criterion elevates the NOCE boundary by ～ 0.1–1.7 km, depending on latitude and season. The proposed method of determining the condition of chemical equilibrium can be used to analyse the equilibrium of many trace gases in the stratosphere and troposphere important for different practical applications.