SEARCH · Engineering Papers

Results for “stratospheric”

Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

SourceResearch connectionFrom yearThrough year

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 703 records · Page 39

All sources NASA NTRS DOE OSTI

NASA NTRS1981

The formation and growth of sulfate aerosols in the stratosphere

The critical compositions, critical radii, and nucleation rates of sulfuric acid droplets formed through homogeneous heteromolecular nucleation process in the stratosphere under a variety of ambient conditions are calculated. Results are plotted as a function of H2SO4 concentration and H2O concentration so that characteristics of sulfate aerosols can be quickly estimated whenever environmental conditions are known. The effect of the uncertainty in the saturated vapor pressure of H2SO4 on the estimated properties of sulfate aerosols is elucidated. Plottings are presented that illustrate the relative importance of new particle formation by homogeneous nucleation vs growth by heteromolecular condensation on pre-existing nuclei in the stratosphere. The effects of ambient conditions, such as the concentrations of H2SO4 and H2O, the average stratospheric particle radius, and the number concentration of pre-existing nuclei on the relative importance of these two competing processes are discussed.

Yue, G. K.↗

NASA NTRS1981

Long-wave baroclinic instability in the troposphere and stratosphere with spherical geometry

The most unstable normal modes are obtained for a global, quasi-geostrophic and spectral-form atmospheric model that includes wavenumbers one through six. In a first set of model calculations, the basic state represents Northern Hemisphere winter solstice conditions, whose long waves are deep modes having maximum kinetic energy in the stratosphere. These internal modes exist even in the presence of a stratospheric wind minimum, but propagate vertically into the stratosphere only north of this minimum, at the latitudes of the polar jet. The basic state for a second set of calculations is the axisymmetric solution corresponding to radiative equilibrium, with large vertical wind shear and all modes being essentially external, tropospheric Charney modes.

Straus, D. M.↗

NASA NTRS1981

Nucleation and growth of stratospheric aerosols

Formation mechanisms and nucleation processes are examined, and nucleation in the stratosphere is considered, taking into account binary nucleation, ternary nucleation, binary heterogeneous nucleation, and heteromolecular nucleation. Attention is also given to the growth of aerosol particles, nucleation and growth in models, and the role of aerosols in the upper atmosphere. It is pointed out that various sampling studies and numerical models have provided evidence that the in situ oxidation of sulfur-bearing gases is responsible for the sulfate mass of the stratospheric aerosol. Data obtained by Castleman et al. (1974) suggest that there is a common source of sulfur compounds for the stratosphere of both the northern and southern hemispheres.

Castleman, A. W., Jr.↗

NASA NTRS1981

Latitudinal variations in Jovian stratospheric temperature

Ground-based observations of Jupiter show that the planet's stratospheric and tropospheric thermal emission are anticorrelated. The observations can possibly be explained by latitudinal variations in cloud altitude. These variations cause differential stratospheric heating by sunlight which is reflected off the clouds and then absorbed within the stratosphere by visible and near-infrared bands of methane.

Cess, R. D.↗

NASA NTRS1981

Numerical simulation of a sudden stratospheric warming with a three-dimensional, spectral, quasi-geostrophic model

An analysis of a sudden stratospheric warming which developed spontaneously during a winter simulation with a three-dimensional quasi-geostrophic model is described. Changes in the circulation and thermal structure of the winter polar stratosphere that occurred during the warming are shown to be in close agreement with observed behavior: enhanced vertical flux of eddy energy into the stratosphere, rapid temperature increase in high latitudes with a reversal of the zonal mean temperature gradient between midlatitude and pole, destruction of the circumpolar cyclonic vortex, and a marked deceleration of the westerly jet and the appearance of zonal mean easterlies. Energies of the warming are also consistent with observed characteristics. Many aspects of the dynamical development of the present model simulation are shown to agree with a previous model simulation, but there are also areas of disagreement.

Grose, W. L.↗

NASA NTRS1981

Chlorine monoxide radical, ozone, and hydrogen peroxide - Stratospheric measurements by microwave limb sounding

Profiles of stratospheric ozone and chlorine monoxide radical (ClO) have been obtained from balloon measurements of atmospheric limb thermal emission at millimeter wavelengths. The ClO measurements, important for assessing the predicted depletion of stratospheric ozone by chlorine from industrial sources, are in close agreement with present theory. The predicted decrease of ClO at sunset was measured. A tentative value for the stratospheric abundance of hydrogen peroxide was also determined.

Waters, J. W.↗

NASA NTRS1981

SAM 2 measurements of the polar stratospheric aerosol, volume 1: October to April 1979

Weekly averages of Antarctic and Arctic stratospheric aerosol data as well as corresponding temperature profiles for the time and place of each stratospheric aerosol measurement (SAM) II measurement during the first 6 months of satellite flight are presented. From the aerosol extinction profile data, contours of aerosol extinction as a function of altitude and longitude or time are plotted. Aerosol optical depths are calculated for each week. Polar stratospheric clouds at altitudes of about 22 km were observed during the Arctic winter at various times and locations. A representative sample of the first 6 months of data to be used in atmospheric and climatic studies is outlined.

Mccormick, M. P.↗

NASA NTRS1981

An advective model for two-dimensional transport of stratospheric trace species

A parameterization of two-dimensional transport is applied to photochemical models of stratospheric trace species. It is shown that in a first approximation, tracer transport in the meridional plane may be treated as an advective rather than a diffusive process. The concept of residual mean meridional circulation (Andrews and McIntyre, 1976; Boyd, 1976) is used in the model and shown to be a modified Eulerian mean, a good approximation to the Lagrangian mean motion. A simple example in which the equilibrium distribution is computed for a tracer with a uniform tropospheric source and a stratospheric sink proportional to the local mixing ratio demonstrates the potential of the proposed parameterization. The resulting distribution is found to agree qualitatively with the observed stratospheric distribution of trace species whose sources are in the troposphere.

Holton, J. R.↗

NASA NTRS1982

Stratospheric aerosol effects from Soufriere Volcano as measured by the SAGE satellite system

During its April 1979 eruption series, Soufriere Volcano produced two major stratospheric plumes that the SAGE (Stratospheric Aerosol and Gas Experiment) satellite system tracked to West Africa and the North Atlantic Ocean. The total mass of these plumes, whose movement and dispersion are in agreement with those deduced from meteorological data and dispersion theory, was less than 0.5 percent of the global stratospheric aerosol burden; no significant temperature or climate perturbation is therefore expected.

Mccormick, M. P.↗

NASA NTRS1981

Ground-based detection of stratospheric ClO and average column density measurement over 17 days of observation

A very sensitive mm-wave heterodyne receiver of a type originally developed for radio astronomy is used in combination with a broadband filter bank spectrometer to detect and measure the 204-GHz rotational transition of stratospheric ClO. Data is acquired in the form of a dimensionless ratio and is converted to units expressing signal intensity. Computed line shapes are matched against the data for a comparison with theoretical stratospheric models and previous measurements. The ClO distribution in the stratosphere measured at 42 deg N latitude in early spring is significantly different from that expected based on existing theoretical models. There is much less ClO at latitudes below about 36 km than predicted, and average ClO column density found for 42 deg N is 20-30% less than that from existing balloon flight measurements at 32 deg N.

Dezafra, R.↗

NASA NTRS1982

Polar stratospheric cloud sightings by SAM II

The functions and data gained regarding stratospheric cloud sightings by the stratospheric aerosol measurement (SAM) II experiment on board the Numbus 7 spacecraft are reported. SAM II comprises a single channel sun photometer centered at 1.0 micron wavelength for measuring the solar intensity when the sun descends below an apparent 300 km altitude until the sun is occulted by clouds or the horizon. Readings are also made during sunrise in an opposite fashion. Transmission profiles are developed from the data and used to construct profiles of aerosol extinction with a 1 km resolution. Polar stratospheric clouds have been observed in more than 90% of the cases when the minimum temperature is 185 K or less, and 45% of the time when the temperature is 193 K or less. The clouds were more prevalent in the Antarctic winter than during the Arctic winter, and cloud height was lower than indicated by previous data.

Mccormick, M. P.↗

NASA NTRS1982

A simple method to compute the change in earth-atmosphere radiative balance due to a stratospheric aerosol layer

A computer code was developed in terms of a three-layer model for the earth-atmosphere system, using a two-stream approximation for the troposphere and stratosphere. The analysis was limited to variable atmosphere loading by solar radiation over an unperturbed section of the atmosphere. The scattering atmosphere above a Lambertian ground layer was considered in order to derive the planar albedo and the spherical albedo. Attention was given to the influence of the aerosol optical thickness in the stratosphere, the single scattering albedo and asymmetry factor, and the sublayer albedo. Calculations were performed of the zonal albedo and the planetary radiation balance, taking into account a stratospheric aerosol layer containing H2SO4 droplets and volcanic ash. The resulting ground temperature disturbance was computed using a Budyko (1969) climate model. Local decreases in the albedo in the summer were observed in high latitudes, implying a heating effect of the aerosol. An accompanying energy loss of 23-27 W/sq m was projected, which translates to surface temperature decreases of either 1.1 and 0.45 C, respectively, for background and volcanic aerosols.

Lenoble, J.↗

NASA NTRS1983

Stratospheric sulfuric acid fraction and mass estimate for the 1982 volcanic eruption of El Chichon

The stratospheric sulfuric acid fraction and mass for the 1982 volcanic eruptions of El Chichon are investigated using data from balloon soundings at Laramie (41 deg N) and in southern Texas (27-29 deg N). The total stratospheric mass of these eruptions is estimated to be approximately 8 Tg about 6.5 months after the eruption with possibly as much as 20 Tg in the stratosphere about 45 days after the eruption. Observations of the aerosol in Texas revealed two primary layers, both highly volatile at 150 C. Aerosol in the upper layer at about 25 km was composed of an approximately 80 percent H2SO4 solution while the lower layer at approximately 18 km was composed of a 60-65 percent H2SO4 solution aerosol. It is calculated that an H2SO4 vapor concentration of at least 3 x 10 to the 7th molecules/cu cm is needed to sustain the large droplets in the upper layer. An early bi-modal nature in the size distribution indicates droplet nucleation from the gas phase during the first 3 months, while the similarity of the large particle profiles 2 months apart shows continued particle growth 6.5 months after the explosion.

Hofmann, D. J.↗

NASA NTRS1982

Climatic influence of background and volcanic stratosphere aerosol models

A simple modelization of the earth atmosphere system including tropospheric and stratospheric aerosols has been derived and tested. Analytical expressions are obtained for the albedo variation due to a thin stratospheric aerosol layer. Also outlined are the physical procedures and the respective influence of the main parameters: aerosol optical thickness, single scattering albedo and asymmetry factor, and sublayer albedo. The method is applied to compute the variation of the zonal and planetary albedos due to a stratospheric layer of background H2SO4 particles and of volcanic ash.

Deschamps, P. Y.↗

NASA NTRS1982

Periodic and aperiodic ozone variations in the middle and upper stratosphere

Umkehr, ozonesonde and satellite observations are used to determine the height/latitude distribution of the amplitude and phase of the periodic components of the variation in the ozone mixing ratio in the middle and upper stratosphere. The amplitude of the first (annual) harmonic is found to be small in the subtropics and to increase to a maximum at polar latitudes. In addition, it increases with height in the mid and upper stratosphere to an apparent maximum just below the stratosphere. The second (semi-annual) harmonic possesses an amplitude that is largest in tropical regions and in subpolar regions at a level of about 40 km. Very little ozone variation is seen above 30 km with dominant periods close to the quasi-biennial period of total ozone observed in the tropics. The percentage of the total variance of the ozone mixing ratio accounted for by the first harmonic is found to be larger than 60 percent at all heights from 20 deg to 60 deg latitude in both hemispheres (except near 40 km in the Northern Hemisphere).

London, J.↗

NASA NTRS1982

Mass spectrometry in the stratosphere

A gas expansion system incorporating a mass spectrometer that has been successfully flown in the stratosphere is described. Neutral gas particles are formed into a molecular beam that traverses the ion source of the mass spectrometer without wall interactions. It is noted that vertical profiles of such constituents as H2O, CO2, and O3 have been measured in the altitude range of 20 to 40 km during balloon descents. Isotopes of important gases (N2, O2, Ar) provided in-flight calibration standards. Before each flight the mass spectrometer system is calibrated in the laboratory for many gases of interest, including ozone. Mixing ratios of ozone established from recent flights have accuracies of better than 5 percent. The sensitivity of the system is sufficient to detect as well the heavy isotope of ozone at mass 50. A noticeable enhancement of heavy ozone in the upper stratosphere has been found. The mass spectrometer system is seen as providing a unique opportunity to perform in situ measurements in the stratosphere in combination with isotopic studies.

Mauersberger, K.↗

NASA NTRS1983

Troposphere-stratosphere (surface-55 km) monthly winter general circulation statistics for the Northern Hemisphere Four year averages

In response to theoretically predicted anthropogenic depletion of stratospheric ozone, there has been, in recent years, an increased effort in stratospheric modeling. For comparison between models and observations, it is not sufficient to only compare the morphology of model-generated parameters with observed parameter values. Model-generated statistics should also be compared with observation. It is one of the objectives of the present investigation to discuss a data set which can be used for this purpose for the Northern Hemisphere troposphere and stratosphere. However, the investigation is mainly concerned with a presentation of some of the general circulation statistics derived with the aid of the data set. Attention is given to winter monthly general circulation statistics which were derived from four years of daily 1200 GMT NOAA/NMC Northern Hemisphere analyses.

Geller, M. A.↗

NASA NTRS1982

Sferics in the stratosphere

Experimental and theoretical work on describing the propagation of sferics (electromagnetic waves) in the stratosphere is reviewed. Measurements are made with a double Langmuir probe that measures the potential difference between two identical, separated conductors, thereby permitting calculation of the electric field. The probe is usually mounted on a balloon floated up to the stratosphere. Data are presented that were taken over a thunderstorm and a theory of sferic propagation is developed, including defined relationships among the source, the propagation medium, and the detected signal. It is demonstrated that the signals recorded by the balloon instrumentation can be used to define the upper limit of the current density and total current in the stratosphere when a sferic is propagating.

Holzworth, R. H.↗