Instantaneous photochemical rates in the global stratosphere

Starting with the average actual distribution of ozone (Dütsch [15]) and temperature in the stratosphere, we have calculated the solar intensity as a function of wavelength and the instantaneous rates (molecules cm^–3 sec^–1) for each Chapman reaction and for each of several reactions of the oxides of nitrogen. The calculation is similar to that ofBrewer andWilson [5]. These reaction rates were calculated independently in each volume element in spherical polar coordinates defined by R=1 km from zero to 50, =5° latitude, and ø=15° longitude (thus including day and night conditions). Calculations were made for two times: summer-winter (January 15) and spring-fall (March 22). As input data we take observed solar intensities (Ackerman [1]) and observed, critically evaluated. constants for elementary chemical and photochemical reactions; no adjustable parameters are employed. (These are not photochemical equilibrium calculations.) According to the Chapman model, the instantaneous, integrated, world-wide rate of formation of ozone from sunlight is about five times faster than the rate of ozone destruction, and locally (lower tropical stratosphere) the rate of ozone formation exceeds the rate of destruction by a factors as great as 1000. The global rates of increase of ozone are more than 50 times faster thanBrewer andWilson's [5] estimate of the average annual transfer rate of ozone to the troposphere. The rate constants of the Chapman reactions are believed to be well-enough known that it is highly improbable that these discrepancies are, due to erroneous rate constants. It is concluded that something else besides neutral oxygen species is very important in stratospheric ozone photochemistry. The inclusion of a uniform concentration of the oxides of nitrogen (NO_x as, NO and NO₂) averaging 6.6×10^–9 mole fraction gives a balance between global ozone formation and destruction rates. The inclusion of a uniform mole fraction of NO_x at 28×10^–9 also gives a global balance. These calculations support the hypethesis (Crutzen [10],Johnston [24]) that the oxides of nitrogen are the most important factor in the global, natural ozone balance. Several authors have recently evaluated the natural source strength of NO_x in the stratosphere; the projected fleets of supersonic transports would constitute an artificial source of NO_x about equal to the natural value, thus promising more or less to double an active natural stratospheric ingredient.     

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.     

Kinetics of ozone photochemistry

Summary The photolysis of ozone in the u.v. Hartley Band produces metastable oxygen atoms and molecules. At wavelengths shorter than 3100 Å the primary quantum yield is probably unity but greater uncertainty exists about its value at longer wavelengths. At 2500 Å, O₂(¹_g) is produced with near unit efficiency and there is some evidence that singlet O₂ is also a primary prduct at the short wavelenght end of the Huggins band. O₂(¹ _g ⁺ ) is not a primary photolytic product at 2500 Å but is produced as a secondary product from the rapid reaction of O(¹D) with ground state O₂. O(¹D) reacts rapidly with O₃ although the nature of the products of this reaction has not been unequivocally established and there is now strong evidence against the occurrence of energy chains in dry ozone. The reaction of O(³P) atoms with O₃ has been found to have an activation energy of 4.4 kcal mole^–1.     

Long-term variation of solar UVB (290–330 nm) observed at the earth's surface

During solar cycle 21 (1976–86), the primary solar irradiance at 300 nm was steady during 1980–82 and thereafter decreased until 1986 by only 2–3%. The stratospheric ozone in middle latitudes had a QBO of 3–4% in this interval but the long-term ozone trend was less than 3% per decade, which could result in a UVB increase of only 5–6% per decade. Thus, the combined effect of changes in primary solar irradiance and ozone changes could be an increase of 5–6% in UVB, observed at ground during 1977–81 and a steady level during 1981–86. During 1976–86, the average cloudiness changed by less than 5% indicating UVB changes of 5% or less on this count. The aerosol level was almost constant during 1976–82 and increased abruptly in 1982 due to the E1 Chichon eruption and decayed slowly unitl 1986. Thus, due to aerosols only, the UVB was expected to be constant during 1976–82, to decrease sharply in 1982 and to recoup slowly thereafter.Measurements of clear-sky solar UVB at ground made at Jungfraujoch (Swiss Alps, 47°N, 8°E) during 1981–89 and at Rockville, USA (39°N, 77°W) were not comparable between themselves and did not follow the above expected patterns. Neither did the all-day R-B meter UVB measurements at Philadelphia, USA (40°N, 75°W) and Minneapolis, USA (45°N, 93°W). We suspect that some of these measurements are erroneous. This needs further detailed scrutiny.     

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.     

The importance of energetic particle precipitation on the chemical composition of the middle atmosphere

An assessment is made of the relative contribution of certain classes of energetic particle precipitation to the chemical composition of the middle atmosphere with emphasis placed on the production of odd nitrogen and odd hydrogen species and their subsequent role in the catalytic removal of ozone. Galactic cosmic radiation is an important source of odd nitrogen in the lower stratosphere but since the peak energy deposition occurs below the region where catalytic removal of O₃ is most effective, it is questionable whether this mechanism is important in the overall terrestrial ozone budget. The precipitation of energetic solar protons can periodically produce dramatic enhancement in upper stratospheric NO. The long residence time of NO in this region of the atmosphere, where catalytic interaction with O₃ is also most effective, mandates that this mechanism be included in future modelling of the global distribution of O₃. Throughout the mesosphere the precipitation of energetic electrons from the outer radiation belt (60°70°) can sporadically act as a major local source of odd hydrogen and odd nitrogen leading to observable O₃ depletion. Future satellite studies should be directed at simultaneously measuring the precipitation flux and the concomitant atmosphere modification, and these results should be employed to develop more sophisticated models of this important coupling.     

Do Solar Flares Affect Total Ozone?

An analysis of total ozone from Hradec Králové (50.25°N, 15.21°E) and of radio wave absorption in the lower ionosphere at 1539 kHz (reflection point 50.3°N, 11.8°E) shows that there is no detectable effect of strong solar flares in total ozone, no correlation between total ozone and absorption on a day-to-day time scale, and that strong solar flares do not affect this correlation. Thus the long-term correlation of monthly average values (Alberca et al., 1996) is not reproduced on a day-to-day time scale, and the effects of strong geomagnetic storms in total ozone (Latovika et al., 1992; Mlch and Latovika, 1996) have no counterpart in effects of strong solar flares.     

Total ozone measurements in cloudy weather

Obtaining an accurate, value for total ozone under a cloudy sky, especially when the sun is not high, is a major remaining problem associated with total ozone measurements. The Toronto spectrophotometer has been designed with this in mind. It has been fitted with a polarizing prism, and measures light at four wavelengths simultaneous which makes it possible to obtain two independent double ratios. Clouds produce two effects on ozone measurements; the first is purely an optical effect which causes an apparent increase in ozone, the second is most likely a real increase in ozone associated with large cumulus-type clouds. By considering the three following points it is possible to distinguish between these two cloud effects and probably measure the true total ozone for solar zenith angles less than 80°: 1. The multiply scattered component of polarized light is used to reduce optical cloud variance. This makes all skies appear like thick coulds. 2. A double difference similar to the AD method is used but the two ratios of the double difference are weighted inversely with(= ₁ - ₂ for a pair). This further reduces the optical effects of clouds. 3. Real ozone increases due to large clouds are verified by comparing the increase of ozone obtained from one double difference to that of another. Differences between this multiply, polarized curve and the direct sun curve will be given, and a technique to obtain an accurate value of total ozone under all sky conditions, provided that the solar zenith angle is less than 80°, will be given.     

Actinometric determination of turbidity parameters in India

Summary A study of the wavelength exponent of aerosol scattering in the Ångström relation for extinction by aerosol has been made from the ground-based measurments of direct solar radiation using Ångström pyrheliometer with and without Schott filters. It has been observed that in India, mainly for the middle part of the year this exponent is zero or even negative which means that the aerosol scattering is nearly neutral which is in marked contrast with the condition prevailing in middle latitudes. It is evident from the -values that the aerosol size distribution in India is far different from that prevailing in middle latitudes. At four representative stations in India, the values of the wavelength exponent and the atmospheric turbidity coefficient have been determined using the method introduced byÅngström [1,2]) and are discussed here.     

Turbidometric estimations in Mexico city using the Volz sun photometer

Summary Measuring, with the aid of two filters, the instantaneous intensity of the solar radiation in two wave lengths ( _B = 0.44 , _R = 0.64 ) by means of a sun photometer designed byVolz, we carried out determinations of the decadic turbidity coefficientB (=0.5 ) and the wave length exponent of the haze extinction for Mexico City. Observations were made for almost two and a half years (1960 to 1962 period). A seasonal size distribution in both parameters was found. Although the data thus obtained are provenient of a contaminated atmosphere, comparison of our data is made with those found for higher latitudes ofÅngström, Schüepp andVolz. The height of the homogeneous haze layerH _D was calculated showing pronounced variations for a given wind direction. The maximum and minimum values ofB enable us to get, by the first approximation, the aerosol size distribution ofJunge for our latitudes. However, for exceptional very clear days having maximum actinometric intensity of the solar radiation the sensitivity of the microamperimeter in theVolz sun photometer fails.     

Atmospheric ozone and flow field variations over Lisbon

The results of the observations of both total and layered ozone content of the atmosphere, the latter from C wavelength Umkehr observations, made in Lisbon (38° 46N; 09° 09W) during the period 1967 to 1971 by the Serviço Meteorológico Nacional, are analysed on a statistical basis in relation to the flow and temperature fields of the atmosphere, namely in relation to the position of the tropospheric jet axis and thê 100 mb air temperature.The preliminary results of the analysis show that the yearly mean variation of the total O₃ follow the very well-known trend as observed for other geographical coordinates, with a winter to spring maximum. In addition, the same parameter is positively correlated to the 100 mb temperature field for the seasons of the year, and it was found, both on a large time-scale and for synoptic distributions, that the total amount of O₃ is significantly higher a few hundreds of kilometres to the left of the jets looking downstream than to the right, so that mean cross-flow gradients of O₃ are field features to be taken into account.The time-height distributions of ozone from the Umkehr technique has revealed, in the long-term mean used, a descent of the level of the maximum of around 20 mb depth from the summer-winter period to spring, but this descent may be much more pronounced on occasions, as revealed by the preliminary analysis of a few days' period of important ozone changes in relation to the potential temperature and jet axis position. this showed, in addition, the existence of varying gradients along the stream, whereby differences in circulation along the jet complex may be implied.Work done for the Project LF2 of the IAC     

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.     

Solar activity dependence of ionospheric electron content and slab thickness using different solar indices

Ionospheric electron content (IEC) and slab thickness () data for the period 1977 to 1980 from Lunping (23.03°N; 121.90°E subionospheric) have been examined for their solar activity dependence. Local noontime monthly means as well as values for the 5 QQ days in a month have been examined separately with different solar indices, namely: solar EUV flux (170–190 Å),S _{10.7 cm} flux and sun spot number (SSN) on a seasonal basis. Both IEC and parameters exhibit better correlation with solar EUV andS _{10.7 cm} fluxes than with SSN for all seasons. IEC increases linearly with both EUV andS _{10.7 cm} flux whereas with SSN it shows a distinct nonlinear relationship during all seasons in both monthly mean and 5 QQ days' values. This study indicates that for correlating and predicting the variations (especially the medium term) in the ionospheric parameters, both EUV andS _{10.7 cm} fluxes have an advantage over SSN.     

Lunar and solar barometric tides at Rarotonga,Cook Islands

Lunar and solar atmospheric tidal oscillations have been determined with reasonable accuracy from a ten-year record of hourly mercury-barometer readings, corrected to mean-sea-level, at Rarotonga (Cook Islands), 21.2°S. For the lunar semidiurnal tide, the annual determination shows an amplitude (56 b) slightly lower and a phase (51°) much smaller than the values (58 b, 72°) that would be derived, for the position of Rarotonga, from the spherical harmonic analysis given byHaurwitz andCowley (1969). The seasonal variation of this oscillation, as given by the monthly and J, E, D values, shows most of the characteristic features found in world-wide determinations. In particular, the near equality of the J, D amplitudes at Rarotonga tends to support theHaurwitz andCowley (1969) suggestion of negative J-D values in southern middle latitudes. For the solar tides, the semidiurnal and terdiurnal oscillations at Rarotonga are similar to those found at other stations in the south-west Pacific region. However, for the diurnal oscillation, the annual amplitude (232 b) is only about half the value (465 b) indicated for the position of Rarotonga by the world maps of theS ₁(p) annual harmonic coefficients given byHaurwitz (1965). It thus seems likely that the relatively small area of lowS ₁(p) annual amplitude in the eastern part of the south Pacific, as indicated by these maps, is much more extensive than formerly supposed.     

Changes of Ozone Content at Middle Latitudes During Forbush Decreases in Cosmic Rays

The variations of total ozone at Alma-Ata (43°N, 76 °E) and ozone profiles obtained by balloon sounding at Tateno (36°N, 140°E), Wallops Island (38°N, 75°W) and Cagliari (39°N, 9°E) in the periods of Forbush decreases (FD) in galactic cosmic rays have been analysed. A decrease of total ozone was observed in the initial stage of the FD and an increase 10–11 days later. The average total deviations calculated using the superposed epoch method for 9 FD events are equal to 30 D. U. in the positive and to –18 D. U. in the negative phase. The changes of average ozone profiles, associated with 26 FD events, are more significant in the lower stratosphere and upper troposphere. The decrease of the partial ozone pressure at a height of 12–15 km is about 30 mb. These vertical variations of ozone coincide with the average changes of the respective temperature profiles. A cooling, on the average, of 3°C was observed at 12–15 km, and a heating of 4°C below this level.     

A self-consistent estimate of O+ + N2– rate coefficient and total EUV solar flux with λ < 1050 Å using EISCAT observations

There are differences between existing models of solar EUV with < 1050 Å and between laboratory measurements of the O⁺ + N₂ – reaction rate coefficient, both parameters being crucial for the F2-region modeling. Therefore, indirect aeronomic estimates of these parameters may be useful for qualifying the existing EUV models and the laboratory measured O⁺ + N₂ – rate coefficient. A modified self-consistent method for daytime F2-region modeling developed by Mikhailov and Schlegel was applied to EISCAT observations (32 quiet summer and equinoctial days) to estimate the set of main aeronomic parameters. Three laboratory measured temperature dependencies for the O⁺ + N₂ – rate coefficient were used in our calculations to find self-consistent factors both for this rate coefficient and for the solar EUV flux model from Nusinov. Independent of the rate coefficient used, the calculated values group around the temperature dependence recently measured by Hierl et al. in the 850–1400 K temperature range. Therefore, this rate coefficient may be considered as the most preferable and is recommended for aeronomic calculations. The calculated EUV flux shows a somewhat steeper dependence on solar activity than both, the Nusinov and the EUVAC models predict. In practice both EUV models may be recommended for the F2-region electron density calculations with the total EUV flux shifted by ±25% for the EUVAC and Nusinov models, correspondingly.     

The magnetic properties and morphology of metallic iron produced by subsolidus reduction of synthetic Apollo 11 composition glasses

Metallic iron has been precipitated from a synthetic high-iron, high-titanium Apollo 11 composition glass powder in a furnace with the oxygen fugacity controlled by gas mixing techniques. Measurable quantities of iron, as determined with a vibrating sample magnetometer capable of detecting 0.01 wt% iron in the absence of ferromagnetic minerals, were produced in experiments at temperatures between 700°C and 1045°C, with run times between 3 hr and 95 hr, and oxygen fugacities between 1 and 2 orders of magnitude below the iron-wustite (IW) buffer curve. Such conditions of ?_O2 and T are probably not greatly different from those occurring in a large lunar ejecta blanket. The oxygen fugacity determines the amount of iron produced for a given time and temperature, with about 1% produced if log ?_O2 is 1.4 units below the IW buffer curve and about 3.5% produced if log ?_O2 is 1.7 units below at 990°C. Above 950°C essentially all the iron is multidomain (>300Å) while below 950°C as much as 15% is single domain (150Å–300Å) and an appreciable quantity remains even smaller. Compaction of the sample slows the rate of reduction but does not influence the grain size of metal. The quantities and size distribution of the reduced iron in a number of the experimental runs are strongly analogous to certain lunar soils and breccias and indicate that reduction in an ejected blanket could partly account for the excess iron of lunar soils and breccias relative to the igneous rocks.     

High resolution analysis of the sun's radiation received at the ground from 9 μ to 11.6 μ

Summary A brief report on the instrumentation for observations, at the ground, in the 9 to 11.6 spectral region, in the absorption of solar radiation through the terrestrial atmosphere and of the results thus obtained for the H₂O, O₃ and HNO₃ molecules.The observations have been made at Montlouis, in the south of France, at 1650 m above sea-level. Here the pollution of the atmosphere is very low because there is no industry and very little local domestic activity.The chief aim ofM. Dionne [1], who is mainly responsible for this work, was to study the weak absorption of the terrestrial atmosphere around and beyond 10 , so observation had to be made with large air masses. For if there were excess water vapour the very weak lines might disappear through the background, owing to the water vapour itself; hence the need to observe during cold weather. Great air masses and cold weather can be obtained only on fine winter days, at about sunset. The configuration of Montlouis makes it difficult to observe at sunrise, so the time of observation was very limited.Laboratoire de Physique Moléculaire et d'Optique Atmosphérique, Station de Montlouis.     

The development of new solar indices for use in thermospheric density modeling

New solar indices have been developed to improve thermospheric density modeling for research and operational purposes. Out of 11 new and 4 legacy indices and proxies, we have selected 3 (F_10.7, S_10.7, and M_10.7) for use in the new JB2006 empirical thermospheric density model. In this work, we report on the development of these solar irradiance indices. The rationale for their use, their definitions, and their characteristics, including the IS 21348:2007 spectral category and sub-category, wavelength range, solar source temperature region, solar source feature, altitude region of terrestrial atmosphere absorption at unit optical depth, and terrestrial atmosphere thermal processes in the region of maximum energy absorption, are described. We also summarize for each solar index the facility and instrument(s) used to observe the solar emission, the time frame over which the data exist, the measurement cadence, the data latency, and the research as well as operational availability. The new solar indices are provided in forecast as well as real time and historical time frames (http://SpaceWx.com JB2006 Quicklink). We describe the forecast methodology, compare results with actual data for active and quiet solar conditions, and compare improvements in F_10.7 forecasting with legacy HASDM and NOAA SWPC forecasts.     

Elektronenproduktion,Rekombination, Elektronendichte und Absorption in der ionosphärischenD-Region und ihre jahreszeitlichen Variationen

Zusammenfassung Es wird die Gleichung für die Elektronenproduktionq(z) abgeleitet, die die meteorologischen Elemente der Mesosphäre berücksichtigt. Nach Angaben über die mit Satelliten und Raketen gemessene Röntgenstrahlung mit 8 Å wird das Differentialspektrum des ionisierenden Energieflusses für eine mittlere Sonnenaktivität konstruiert. Auf dieser Grundlage und nach der bekannten Intensität der Strahlung Ly- sowie nach Angaben über dieElektronenproduktion der kosmischen Strahlung werden die Profileq _Rö(z),q _Ly-(z) undq _CR(z) für mittlere geographische Breiten und Standardatmosphäre entwickelt. Nach eingehender Analyse der vollständigen Gleichung für den effektiven Rekombinationskoeffizienten wird für die Verhältnisse in der tiefen Ionosphäre der Beitrag jeder einzelnen Komponente der Gleichung bestimmt. ist eine recht veränderliche Grösse, die von den aeronomischen und meteorologischen Verhältnissen und der Sonnenzenitdistanz abhängt. Aus den fürq(z) und (z) erhaltenen Angaben werden zwei ElektronendichteprofileN(z) für =30° und 75° erhalten. Das ProfilN(z) bei =30° wird mit dem gemittelten Profil einer umfangreichen Gruppe experimentell gefundener VerteilungenN(z) verglichen; das Profil bei =75° wird durch Messung der deviativen und nondeviativen Absorption für eine längere Zeitperiode überprüft. In beiden Fällen hat sich die Richtigkeit der theoretisch erhaltenen Profile bestätigt. Die jahreszeitlichen Variationen der nondeviativen Absorption in derD-Region sind ausschliesslich durch die Variationen der meteorologischen Parameter im Bereich der Mesopause bei konstantem Energiefluss der ionisierenden Strahlung bedingt.

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Summary An equation about the electron production is deduced in which the meteorological elements of the mesosphere are taken into account. The differential spectrum of the ionizing energy flux with 3 Å for average solar activity is constructed on evidence from rocket and satelitc measurements. The profilesq _Rö(z),q _Ly-(z) andq _CR(z) for mean geographical latitudes and standard atmosphere are plotted on that basis as well as on data fot the known intensity of the Ly- emission and the electron production of the cosmic rays. An exhaustive analysis is made of the full equation for the effective recombination coefficient and the contribution of all its components at lower ionosphere conditions is determined. is a rather variable quantity, dependent on the aeronomical and meteorological condition of the area under consideration, as well as on the solar zenith angle. Two profiles for the electron concentrationN(z) at =30° and 75° are drawn on the basis of data forq(z) and (z). The profileN(z) at =30° is compared with the averaged profile of a large group experimentally obtained distributionsN(z); the profile at =75° is checked by measurements of the deviative and nondeviative absorption taken for a lengthy period. Both checks are in good agreement with the theoretically obtained profiles. The seasonal variations of the nondeviative absorption in theD region could be completely explained with the variations of the meteorological parameters in the mesopause area at constant energy flux of the ionizing radiation.