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At least 1,063 records · Page 59
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NASA NTRS1974

Infrared measurements of stratospheric composition

The observational techniques and results of IR measurements of the minor and trace molecular composition of the lower stratosphere are reviewed. Emphasis is given to those theoretical aspects of the formation of emission and absorption spectra which affect the quantitative interpretation of observational data in terms of the vertical distribution of observed molecular species. The principal experimental techniques currently being used are briefly reviewed, followed by a detailed summary of current knowledge of the abundances and spatial variability of the known minor constituents. The question of the determination of the minimum detectable concentration of a constituent molecule and its relationship to the instrumental parameters, the molecular transition intensities, and observation geometry is discussed; upper limit concentrations are given for some additional species of importance in current stratospheric studies.

Farmer, C. B.↗
NASA NTRS1975

Detection of fluorocarbons in the stratosphere

Infrared absorption spectral measurements are applied to selected balloon flight data to detect CF2Cl2 and CFCl3 in the stratosphere. Identification of the fluorocarbons from absorption spectra is described, and the results are compared with previous models of fluorocarbon content at 21 km. A volume mixing ratio is derived for CF2Cl3 and a probable ratio is estimated for CFCl3. An upper limit for HF in the lower stratosphere up to 30 km is set based on data from a balloon flight.

Murcray, D. G.↗
NASA NTRS1974

A general circulation model of stratospheric ozone

The paper reports on a general circulation model being developed with the ultimate objective of assessing the effect of SST operations on the atmospheric ozone distribution. The model variables are represented in the spectral domain using 79 spherical harmonics and 26 vertical levels between the ground and 70 km. Initial calculations have attempted to simulate the seasonal variations of the unperturbed global ozone distribution. The model shows the presence of a westerly stratospheric jet in the winter hemisphere with amplitudes similar to those observed in the polar night jet. Easterlies dominate in the summer hemisphere. The model also shows ozone to be transported polewards and downwards. Furthermore the annual cycle in ozone concentrations at mid-latitudes has been simulated. Preliminary comparisons are also made with other features of the dynamics and the ozone distribution in the stratosphere.

Cunnold, D. M.↗
NASA NTRS1975

A comparison of dustsonde and LIDAR measurements of stratospheric aerosols

This paper describes the results and analysis of an experiment to compare the stratospheric aerosol profiles as measured by a balloon-borne in situ particle counter and by the backscattered light from a ground-based laser radar (LIDAR) operating at a wavelength of 6943 A. The profile comparison agrees within the experimental errors for particles with radii greater than 0.25 micrometer and for altitudes between 15 and 28 kilometers. Following the calibration tests, the LIDAR was used to monitor the stratospheric aerosols at Hampton, Virginia. Enhanced backscatter appeared sporadically in November and December of 1974 over Hampton; scattering ratios averaged over altitude increments of 450 meters range from 1.10 at 20 kilometers in early November to 3.3 at 17 kilometers on December 18. The source of this enhanced backscattering is attributed to the aerosols associated with the eruption of the Fuego volcano in Guatemala in mid-October.

Remsberg, E. E.↗
NASA NTRS1975

Mean meridional circulation in the Southern Hemisphere stratosphere based on satellite information

Atmospheric structure derived from satellite multi-channel radiance data is used to calculate zonally-averaged vertical motions in the wintertime stratosphere of both hemispheres using a heat budget approach. The Northern Hemisphere calculations based on the satellite data are shown to compare favorably with a computation carried out with conventional data, and with results of previous studies. The mean Southern Hemisphere pattern for the month of July 1969 indicates a high-latitude cell with the axis of sinking motion at approximately 50 deg S, while the rising motion is centered at 70 deg S. Thus the Antarctic stratospheric jet stream is associated with an indirect cell. Two individual 10-day periods from July 1969 are also examined to compare the mean meridional circulation and eddy heat flux patterns in the Southern Hemisphere during a minor midwinter warming and during a quiet period.

Adler, R. F.↗
NASA NTRS1975

Stratospheric effects

The mechanism of the destruction of ozone by fluorocarbons is described and models for predicting future levels of stratospheric ozone are discussed. Measurement of various stratospheric constituents, particularly ozone, fluorocarbons, and other chlorine compounds, is also considered. Industrial and governmental activities in this area are described.

Source record↗
NASA NTRS1976

A study of satellite remote measurements of stratospheric aerosol and gas parameters using the solar occultation technique

Satellite remote measurements of stratospheric aerosol and ozone profiles using the solar occultation approach were analyzed based on the known properties of the atmospheric parameters. Atmospheric refraction effects which are important in this experiment were determined analytically. Different inversion techniques were developed based on inverting simulated irradiance data. It was shown that aerosol and ozone profiles in the stratosphere can be inverted from the irradiance measurements to an accuracy of better than 10 percent.

Chu, W. P.↗
NASA NTRS1976

Stratospheric aerosol measurement experiment MA-007

The Apollo Soyuz Test Project Stratospheric Aerosol Measurement Experiment was flown to demonstrate that direct solar occultation measurements by photometers and photographs can be used for defining stratospheric aerosol concentrations. Supporting ground truth data were provided by laser radar and balloon borne dustsonde. Initial results show a significant difference in aerosol concentrations between the Northern and Southern Hemispheres.

Pepin, T. J.↗
NASA NTRS1975

Periodic variations in stratospheric-mesospheric temperature from 20-65 km at 80 N to 30 S

Results on large-scale periodic variations of the stratospheric-mesospheric temperature field based on Meteorological Rocket Network (MRN) measurements are reported for a long-term (12-year) mean, the quasi-biennial oscillation (QBO), and the first three harmonics of the annual wave (annual wave, semi-annual wave, and terannual wave or 4-month variation). Station-to-station comparisons are tabulated and charted for amplitude and phase of periodic variations in the temperature field. Masking and biasing factors, such as diurnal tides, solar radiation variations, mean monthly variations, instrument lag, aerodynamic heating, are singled out for attention. Models of the stratosphere will have to account for these oscillations of different periods in the thermal field and related properties of the wind fields, with multilayered horizontal stratification with height taken into account.-

Nastrom, G. D.↗
NASA NTRS1976

Curvature of the wind profile in the troposphere versus regions of CAT and non-CAT in the stratosphere

A discussion of the theoretical importance of the curvature of the wind profile to the amplitude of mountain waves is presented. Mechanisms favorable for clear air turbulence (CAT) are discussed in relation to such wave motions. It is shown that CAT encountered by the XB-70 aircraft in the stratosphere during expected mountain-wave conditions is related to the vertical gradient of curvature of the wind profile in the troposphere. Results indicate that 89% of the turbulent regions in the stratosphere occurred in expected mountain-wave areas and that 79% were located where the vertical gradient of curvature was positive in the 10-30,000 ft layer below. For the nonturbulent regions, 74% were outside expected mountain-wave areas and 98% of these occurred where the vertical gradient of curvature was negative. All the nonturbulent regions within expected mountain-wave areas occurred where the vertical gradient of curvature was negative.

Possiel, N.↗
NASA NTRS1976

Behavior of the sodium and hydroxyl nighttime emissions during a stratospheric warming

The behavior of the sodium and hydroxyl nighttime emissions during a stratospheric warming has been studied principally by use of data from the airglow photometers on the OGO 4 satellite. During the late stages of a major warming, both emissions increased appreciably, with the sodium emission returning to normal values prior to the decrease in the hydroxyl emission. The emission behaviors are attributed to temperature and density variations from 70 to 94 km, and a one-dimensional hydrostatic model for that altitude range is used to calculate the effects on the emissions and on the mesospheric ozone densities. These results support the existence of a warming in the upper part of the mesosphere that is correlated with a major stratospheric warming.

Walker, J. D.↗
NASA NTRS1976

Stratospheric aluminum oxide

Balloons and U-2 aircraft were used to collect micrometer-sized stratospheric aerosols. It was discovered that for the past 6 years at least, aluminum oxide spheres have been the major stratospheric particulate in the size range from 3 to 8 micrometers. The most probable source of the spheres is the exhaust from solid-fuel rockets.

Brownlee, D. E.↗
NASA NTRS1976

The absolute concentration of OH/X 2 Pi/ in the earth's stratosphere

The letter reports two recent in-situ measurements of OH in the stratosphere between altitudes of 29 and 43 km using a resonance fluorescence technique that was previously employed for the measurement of ground-state atomic oxygen. The experimental technique is described in detail along with the photon detector and the absolute-calibration procedure. The results are found to indicate OH concentrations that approach the maximum predicted by current stratospheric photochemical theory.

Anderson, J. G.↗
NASA NTRS1976

Sensitivity of surface temperature and atmospheric temperature to perturbations in the stratospheric concentration of ozone and nitrogen dioxide

A radiative-convective model is proposed for estimating the sensitivity of the atmospheric radiative heating rates and atmospheric and surface temperatures to perturbations in the concentration of O3 and NO2 in the stratosphere. Contribution to radiative energy transfer within the atmosphere from H2O, CO2, O3, and NO2 is considered. It is found that the net solar radiation absorbed by the earth-atmosphere system decreases with a reduction in O3; if the reduction of O3 is accompanied by an increase in NO2, there is a compensating effect due to solar absorption by NO2. The surface temperature and atmospheric temperature decrease with decreasing stratospheric O3. Another major conclusion is the strong sensitivity of surface temperature to the vertical distribution of O3 within the atmosphere. The results should be considered as reflecting the sensitivity of the proposed model rather than the sensitivity of the actual earth-atmosphere system.

Ramanathan, V.↗
NASA NTRS1976

Radiative transfer within the earth's troposphere and stratosphere - A simplified radiative-convective model

A radiative transfer model of the troposphere and stratosphere is presented which includes both long-wave cooling and solar heating due to H2O, CO2 and O3 and has a simplified formulation which facilitates the inclusion of Doppler broadening, H2O continuum bands, hot and minor isotopic bands of CO2, and overlap of H2O bands with CO2 and O3 bands. The radiative model is used to develop an accurate radiative-convective model for studying the global surface temperature, stratospheric thermal structure and the net outgoing long-wave flux.

Ramanathan, V.↗
NASA NTRS1976

A numerical study of the radiative-dynamic interaction in the stratosphere by a time-dependent zonal mean circulation model

The response of a zonal mean circulation model was compared to different heating functions used to simulate the interannual climate cycle. Two heating functions were used: A simple Newtonian heating function and a sophisticated heating function (Ramanathan, 1976). The emphasis was on the coupling between radiative transfer and the circulation in the stratosphere. The model was formulated in terms of primitive equations with 10 deg latitudinal resolution and 18 levels in pressure. Eddy transport of heat in the stratosphere was treated by the Reed and German (1965) formulation, while Stone's (1973) formulation is used in the troposphere. Momentum eddy fluxes are specified by climate statistics after Harwood and Pyle (1975). The model dynamics resulting from the two runs are compared to demonstrate the benefits of using detailed heating functions.

Turner, R. E.↗
NASA NTRS1976

A preliminary investigation of downward coupling of the stratosphere and the troposphere

Potential relationships between anomalies in the stratosphere and later anomalies at the surface at the same station are identified. The anomaly of October precipitation at mid and high latitude stations appears related to the date the fall reversal of zonal wind occurs; and the magnitude of the anomaly of surface temperature five or six months following a key month appears related to the stratospheric zonal wind speed during the key month. Both relations are statistically significant at the five percent level, and require more detailed analysis for possible use in long range forecasting.

Nastrom, G. S.↗