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At least 1,081 records · Page 60
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NASA NTRS1977

Balloon stratospheric research flights, April 1976 to December 1976

These flights were designed to measure the vertical concentration profile of trace stratospheric species which form major links in the chlorine photochemical system of the upper atmosphere, to measure the vertical concentration profiles of atomic oxygen, the hydroxyl radical and ozone in the stratosphere. An overview of the scientific goals of the program, a statement of program management and support functions, a brief description of the instrumentation flown, pertinent engineering and payload operations data, and a summary of the scientific data obtained for four flights are presented.

Allen, N. C.↗
NASA NTRS1977

Monte Carlo analysis of uncertainty propagation in a stratospheric model. 2: Uncertainties due to reaction rates

A concise stratospheric model was used in a Monte-Carlo analysis of the propagation of reaction rate uncertainties through the calculation of an ozone perturbation due to the addition of chlorine. Two thousand Monte-Carlo cases were run with 55 reaction rates being varied. Excellent convergence was obtained in the output distributions because the model is sensitive to the uncertainties in only about 10 reactions. For a 1 ppby chlorine perturbation added to a 1.5 ppby chlorine background, the resultant 1 sigma uncertainty on the ozone perturbation is a factor of 1.69 on the high side and 1.80 on the low side. The corresponding 2 sigma factors are 2.86 and 3.23. Results are also given for the uncertainties, due to reaction rates, in the ambient concentrations of stratospheric species.

Stolarski, R. S.↗
NASA NTRS1977

Aerosol physical properties in the stratosphere (APPS) radiometer design

The measurement concepts and radiometer design developed to obtain earth-limb spectral radiance measurements for the Aerosol Physical Properties in the Stratosphere (APPS) measurement program are presented. The measurements made by a radiometer of this design can be inverted to yield vertical profiles of Rayleigh scatterers, ozone, nitrogen dioxide, aerosol extinction, and aerosol physical properties, including a Junge size-distribution parameter, and a real and imaginary index of refraction. The radiometer design provides the capacity for remote sensing of stratospheric constituents from space on platforms such as the space shuttle and satellites, and therefore provides for global measurements on a daily basis.

Gray, C. R.↗
NASA NTRS1976

Stratospheric air sampling platform/sensor tradeoffs

Results of a study are described in which in-situ and remote sensing instrumentation are considered for accommodation on airborne platforms capable of reaching stratospheric altitudes. The instrumentation measures trace species of importance to present concerns regarding stratospheric pollution and possible ozone depletion. The platforms examined were the U-2, modified U-2, balloon, rocket, F-15 flown in a zoom-climb maneuver, YF-12, and remotely piloted vehicle (RPV). The sensors and performance characteristics of the platforms are described and special problems of sensor-platform integration are discussed. A typical latitudinal sampling mission is utilized to describe platform logistics problems and how the platforms might perform such missions.

Arno, R. D.↗
NASA NTRS1977

Atomic and molecular fluorescence as a stratospheric species monitor

The results of an investigation are presented evaluating the potential of atomic and molecular fluorescence as a stratospheric monitor of the concentrations of any one of 18 minor species: Cl, Cl2, ClO, ClO2, CO, H2, HCHO, HCl, HNO2, HNO3, H2S, NH3, NO, NO2, N2O, O, OH, and SO2. All spectral regions from the vacuum ultraviolet through the infrared were included. It was found that suitable systems can be constructed for the stratospheric monitoring of CO (5 ppb), NO2 (less than 1 ppb), OH (0.2 ppt), and O (50-200 ppt). The fluorescence sensitivities for Cl (0.5-1.0 ppt), H2 (0.2 ppm at 10 torr) and SO2 (1-10 ppb) are marginally insufficient with current technology.

Schofield, K.↗
NASA NTRS1977

A study of the chemical degradation of ClONO2 in the stratosphere

The flash photolysis-resonance fluorescence system described by Davis et al. (1974) is used to measure the rate constants for the reactions of chlorine nitrate (ClONO2) with stratospheric O(3-P) and OH. Both reactions are examined in a pyrex cell with an internal volume of about 150 cu cm, where the reaction mixture was maintained at 245 K by circulating methanol from a thermostated circulation bath through the outer jacket of the reaction cell. The relative chemical degradation rates as a function of altitude for both reactions are tabulated, which shows that the chemical degradation pathways contribute less than 10% to the total rate of ClONO2 destruction at altitudes less than 30 km. Since the concentration of ClONO2 is calculated to be near its maximum around 25 km and drops off very significantly at higher altitudes, it is concluded that the photochemical decomposition of ClONO2 in the stratosphere is by far the most important degradation path for this molecule.

Ravishankara, A. R.↗
NASA NTRS1976

Examples of synoptic changes in ozone and circulation in the stratosphere

The Backscatter Ultraviolet (BUV) experiment on board the Nimbus 4 polar orbiting satellite has been measuring the total ozone content and high-level atmospheric ozone profiles since early 1970. Synoptic type analyses of these data are now being accomplished and compared with appropriate constant-pressure analyses of stratospheric circulation. Ozone changes during a stratospheric warming of early 1971 are investigated by comparison with circulation changes in the layer between 30 mb (24 km) and 2 mb (42 km). A general increase in ozone concentrations, more pronounced in the higher latitudes, is noted during the warming period. Plans for future investigation are discussed, including analysis of ozone observations beginning from 1970 on every two-day basis for comparison with constant-pressure height, temperature, and wind charts analyzed with the aid of radiosonde, rocketsonde, and satellite data.

Finger, F. G.↗
NASA NTRS1976

Monitoring stratospheric ozone and aerosols using orbiting photoelectric detectors

Application of slightly modified off-the-shelf automatic celestial navigation systems ('star trackers') is considered for the purposes of monitoring variations in the optical depth of the stratospheric aerosol and ozone layers. The basic principle of the technique is to observe stars from an orbiting station as they are occulted by the stratospheric aerosol layer. Since molecular and refraction extinction are directly calculable, total extinction measurements using a dual-sensor (S4 and S20) approach allows us to directly solve for ozone and aerosol extinction and look for correlations between these two parameters. The technique appears promising for remotely monitoring aerosol and ozone optical depth in the 15-25 km region over selected locations and is independently accurate if aerosol composition and relative size distribution are invariant.

Matloff, G. L.↗
NASA NTRS1977

Mass spectrometer beam system for applications in the stratosphere

A special gas inlet system is required for reduction of high ambient pressures to ion source operating pressures for mass spectrometer investigations in the stratosphere for the determination of the abundance of minor constituents. A system has been designed which combines a mass spectrometer and a gas inlet system reducing pressure by differential pumping using high-speed liquid helium pumps and small orifices. The gas particles are formed into a neutral beam with a flag mechanism proceeding into the mass spectrometer ion source where they are ionized for subsequent mass separation. A laboratory model has been tested under conditions simulating stratospheric pressures. It was shown that the process is able to identify gases with abundances below 10 to the -8th. Some of the problems associated with gas analysis of trace constituents have been alleviated, and other applications of the system have been identified, such as pollution control and medicine.

Mauersberger, K.↗
NASA NTRS1976

Variations including possible solar cycle variations of stratospheric ozone over central Switzerland

The annual variation of the total amount of ozone over central Switzerland and the partial pressures in each of 7 layers from the surface to 7.8 m zeta shows the pattern representative of mid-latitude ozone: summer maximum in the troposphere, spring maximum in the lower stratosphere up to 30 mb and summer maximum in the middle stratosphere up to approx. mb. It was also shown that at the level of the ozone maximum the ozone partial pressure has a pronounced period of about 26 months. Total ozone and the ozone concentration in the different layers have marginally significant (at plus or minus sigma) correlations with relative sunspot number. The time lag for these correlations is long in the troposphere (about 36 months) but decreases with height to the level of ozone maximum (to about 2 months). A similar analysis of the data derived from the ozonesonde program at Hohenpeissenberg, Germany (GFR) gave completely consistent results with those discussed above.

London, J.↗
NASA NTRS1977

The inversion of stratospheric aerosol and ozone vertical profiles from spacecraft solar extinction measurements

The inversions of multi-channel solar extinction measurements have been analyzed for the 0.35-1.0 micron wavelength region to retrieve stratospheric aerosol and ozone vertical profiles using both the constrained linear inversion scheme and the iterative scheme. The inversions of the multi-wavelength solar extinction data obtained from spacecraft have been analyzed based on the inversion of computer simulated data using various atmospheric models with differing amounts of aerosol and ozone in the stratosphere. The sensitivities of the inversion schemes to different experimental errors are discussed in terms of accuracy and resolution of the retrieved profiles.

Chu, W. P.↗
NASA NTRS1978

Stratospheric ozone measurement with an infrared heterodyne spectrometer

A stratospheric ozone absorption line in the 10 microns band was measured and resolved completely, using an infrared heterodyne spectrometer with spectral resolution of 5 MHz (0.000167 cm to -1 power). The vertical concentration profile of stratospheric ozone was obtained through an analytical inversion of the measured spectral line profile. The absolute total column density was 0.34 cm atm with a peak mixing ratio occurring at approximately 24 km. The (7,1,6) to (7,1,7) O3 line center frequency was found to be 1043.1775 + or - 0.00033 cm to toe -1 power, or 430 + or - 10 MHz higher than the P(24) CO2 laser line frequency.

Abbas, M. M.↗
NASA NTRS1978

Stratospheric warmings: Synoptic, dynamic and general-circulation aspects

Synoptic descriptions consist largely of case studies, which involve a distinction between major and minor warmings. Results of energetics studies show the importance of tropospheric-stratospheric interaction, and the significance of the pressure-work term near the tropopause. Theoretical studies have suggested the role of wave-zonal flow interaction as well as nonlinear interaction between eddies, chemical and photochemical reactions, boundary forcing, and other factors. Numerical models have been based on such considerations, and these are discussed under various categories. Some indication is given as to why some of the models have been more successful than others in simulating warnings. The question of ozone and its role in warmings is briefly discussed. Finally, a broad view is taken of stratospheric warmings in relation to man's activities.

Mcinturff, R. M.↗
NASA NTRS1978

SAM-2 ground-truth plan: Correlative measurements for the Stratospheric Aerosol Measurement-2 (SAM 2) sensor on the Nimbus G satellite

The SAM-2 will fly aboard the Nimbus-G satellite for launch in the fall of 1978 and measure stratospheric vertical profiles of aerosol extinction in high latitude bands. The plan gives details of the location and times for the simultaneous satellite/correlative measurements for the nominal launch time, the rationale and choice of the correlative sensors, their characteristics and expected accuracies, and the conversion of their data to extinction profiles. The SAM-2 expected instrument performance and data inversion results are presented. Various atmospheric models representative of polar stratospheric aerosols are used in the SAM-2 and correlative sensor analyses.

Russell, P. B.↗
NASA NTRS1978

Albedo enhancement and perturbation of radiation balance due to stratospheric aerosols

The effect of stratospheric aerosols on the earth's monthly zonal radiation balance is investigated using a model layer consisting of 75% H2SO4, which is the primary constituent of the background aerosol layer. The reduction in solar energy absorbed by the earth-atmosphere system is determined through the albedo sensitivity, defined here as the change in albedo per unit mid-visible optical depth of the aerosol layer. The optically thin approximation is used in conjunction with the Henyey-Greenstein phase function for scattering to simplify computations. Satellite derived planetary albedos are used as the frame of reference about which the change in albedo is computed. An infrared radiative transfer model is used to estimate the increased greenhouse effect attributed to the aerosol layer. The infrared heating tends to compensate for the albedo effect in altering the radiation balance. The results indicate that the dominant influence of the thin model stratospheric aerosol layer is an increased reflection of solar energy all over the globe except for the polar-winter region, but the change in the radiation balance is seen to be uniform and small equatorwards of 50%.

HARSHVARDHAN↗
NASA NTRS1978

The capability of satellite borne remote sensors to measure stratospheric trace constituents. Volume 2: Ozone and aerosol related missions

Stratospheric trace constituent measurement requirements are separated into two somewhat overlapping areas. In the first area, it is assumed that the only problem of interest is ozone; its chemistry chain, environmental effects and measurement requirements. In like manner, in the second area it is assumed that the only problem of interest is stratospheric aerosols; their chemistry, effects and measurement requirements.

Keitz, E. L.↗
NASA NTRS1978

The capability of satellite borne remote sensors to measure stratospheric trace constituents. Volume 3: Supporting material

Contained in this volume is material of a supportive nature not considered to be of sufficient importance to be included in the other two previous volumes. This material is of two types:(1) information and numerical evaluations used in the development of mission evaluations for stratospheric trace constituent measurement;and (2) various spatial and temporal distributions for those stratospheric trace species having sufficient measurements available to warrant their presentation.

Keitz, E. L.↗
NASA NTRS1977

A comparison of estimated and directly measured turbulent heat fluxes in the lower stratosphere

The contribution of small-scale motions to the vertical heat flux in the lower stratosphere is determined from wind and temperature fluctuation statistics obtained during the High Altitude Clear Air Turbulence investigation. Analysis of the cospectra suggests a horizontal wavelength of 3 km as the appropriate long-wave cutoff of small-scale motion. With this scale restriction, the measured vertical heat fluxes are in good agreement with the values of heat flux estimated by Lilly et al. (1974) from the kinetic energy dissipation rate. Hence, the hypothesis of Lilly et al. for estimating heat flux from the dissipation rate is considered to be reliable. It follows that, in the lower stratosphere, subsynoptic vertical transport is small compared to large-scale transport.

Heck, W.↗