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A new procedure is outlined for the rapid calculation of transmittances of atmospheric gases in the infrared. A feature of the method is the relatively high accuracy (better than 1%) and the fact that any line shape can be handled. The highest gain in speed over direct line-by-line integration is in the low pressure region (Voigt or Doppler profiles).
A better detector system was developed for far infrared spectroscopy by usng cryogenic technology to cool bolometric detectors to approximately 0.4K. Technical assistance was provided to two submillimeter infrared balloon experiment (SIBEX) flights which demonstrated the diagnostic capability of far IR emission spectroscopy. It is estimated that more than a hundred spectral emission features were detected which are not due to the main emitting gases O3, O2, and H2O. The trace species sources for many features still remain unidentified and the spectra obtained during the SIBEX flights present a new source of information on stratospheric composition.
Measurements were made of the aerosol size, height and geographical distribution, their composition and optical properties, and their temporal variation with season and following large volcanic eruptions. Sulfur-bearing gases were measured in situ in the stratosphere, and studied of the chemical and physical processes which control gas-to-particle conversion were carried out in the laboratory.
A conservative flux difference splitting is presented for the hyperbolic systems of gasdynamics. The stable robust method is suitable for wide application in a variety of schemes, explicit or implicit, iterative or direct, for marching in either time or space. The splitting is modeled on the local quasi one dimensional characteristics system for multi-dimensional flow similar to Chakravarthy's nonconservative split coefficient matrix method; but, as the result of maintaining global conservation, the method is able to capture sharp shocks correctly. The embedded characteristics formulation is cast in a primitive variable the volumetric internal energy (rather than the pressure) that is effective for treating real as well as perfect gases. Finally the relationship of the splitting to characteristics boundary conditions is discussed and the associated conservative matrix formulation for a computed blown wall boundary condition is developed as an example. The theoretical development employs and extends the notion of Roe of constructing stable upwind difference formulae by sending split simple one sided flux difference pieces to appropriate mesh sites. The developments are also believed to have the potential for aiding in the analysis of both existing and new conservative difference schemes.
The rates and altitudes for the dissociation of atmospheric constituents on Titan are calculated for solar ultraviolet radiation, the solar wind, Saturn magnetospheric particles, the Saturn co-rotating plasma, and cosmic rays. Laboratory experiments show that a variety of simple gas phase organic molecules and more complex organic solids called tholins are produced by such irradiations of simulated Titanian atmospheres. Except for ultraviolet wavelengths longward of the methane photodissociation continuum, most dissociation events occur between about 3100 and 3600 km altitude, corresponding well to the region of EUV opacity detected by Voyager. For a wide variety of simple to moderately complex organic gases in the Titanian atmosphere, condensation occurs below the top of the main cloud deck at about 2825 km. It is proposed that such condensates, beginning with CH4 at about 2615 km, comprise the principal mass of the Titan clouds. There is a distinct tendency for the atmosphere of Titan to act as a fractional distillation device, molecules of greater complexity condensing out at higher altitudes.
Weekly air samples were collected at Cape Kumakahi (0 km) and at nearby Mauna Loa Observatory (3.4 km) which is above the boundary layer. EC/GC and GC/FID techniques were used to measure CH3I, CHCl3, CO and CH4 which are largely natural in origin, and C2Cl4, CCl4, CH3CCl3, (F-11), CCl2F2, (F-12), CHClF, (F-22) and C2F3Cl3 (F-113), which are due to anthropogenic (CCl3F) etc. activities. It was found that all these gases are significantly (alpha is equal to or less than 0.05) more abundant in the boundary layer than above it.
Estimates in excellent agreement with experimental values. Simple method proposed for estimating solubility of gases in electrolytes of lithium batteries using expressions for energy of vaporization and for molar volume.
In situ removal of SO2 in flue gases and fluidized-coal combustors, with no waste product possible using NaO/LiO as regenerable supported molten sorbent.
Nineteen stratospheric samples from the eruption plumes of Mount St. Helens were collected in five flight experiments. The plume samples were collected at various altitudes from 13.1 to 20.7 km by using the Ames cryogenic sampling system on board the NASA U-2 aircraft. The enriched, cryogenically collected samples were analyzed by chromatography. The concentrations of aerosols precursor gases (OCS, SO2, and CS2), CH3Cl, N2O, CF2Cl2, and CFCl3 were measured by gas chromatography. Large enhancement of the mixing ratio of SO2 and moderate enhancement of CS2 and OCS were found in the plume samples compared with similar measurement under pre-volcanic conditions. A fast decay rate of the SO2 mixing ratio in the plume was observed. Measurement of Cl(-), SO2(2-), and NO3(-) by ion chromatography was also carried out on water solutions prepared from the plume samples. The results obtained with this technique imply large mixing ratios of HCl, (NO + NO2 + HNO3), and SO2, in which these constituents are the respective sources of the anions. Measurement of the Rn222 concentration in the plume was made. Other stratospheric constituents in the plume samples, such as H2O, CO2, CH4, and CO, were also observed.
Trace gases evolved from a polyimide film during its thermal curing stages have been studied using ion-induced nucleation mass spectrometry. The technique involved exposing the test gas sample to a low energy beta source and recording the masses of the ion-induced molecular clusters formed in the reaction chamber. On the basis of the experimentally observed molecular cluster spectra, it has been concluded that the dominant trace component had a molecular weight of 87 atomic mass units. This component has been identified as a molecule of dimethylacetamide (DMAC) which had been used as a solvent in the preparation of the test polyimide specimen. This identification has been further confirmed by comparing the spectra of the test gas sample and the DMAC calibration sample obtained with a conventional mass spectrometer. The advantages of the ion-induced nucleation mass spectrometer versus the conventional mass spectrometer are discussed.
The infrared absorption spectra of a number of gases found in planetary atmospheres were studied at high resolution. Absorption line measurements which can be of value for the interpretation of planetary spectra in terms of molecular abundances and conditions in the planetary atmospheres were provided. The high resolution spectra have yielded measurements of individual vibration rotation line parameters including positions, strengths, pressure broadened widths and, where assignments were unknown, the temperature sensitivity of the strengths. Such information allows the determinations of the absorption of a given molecular gas under planetary conditions of temperature and pressure and at the same time it provides the data necessary if the spectra are to be understood in terms of basic molecular theory. Thus this work has included spectral analysis in the form of line assignments as well as fitting of the data to Hamiltonian models. Such fitting is very useful in that it helps to confirm and extend the assignments.
In order to have all the thermal and caloric states of combustion gases accessible in a computer, closed mathematical approximation equations were established for the real factors, the enthalpy and the entropy of a real combustion gas. The equations approximate the various effects of molecular forces real gas influence and dissociation - at temperatures of 200 K to 6,000 K, pressures of 0.001 to 1,000 bar, and in the range from stoichiometric composition to air. A system of subprograms is listed in FORTRAN, by means of which thermodynamic calculations can be carried out in the same manner as with Mollier I,S diagrams.
CO2 lidar systems technology and signal processing requirements relevant to measurement needs and sensitivity are discussed. Doppler processing is similar to microwave radar, with signal reception controlled by a computer capable of both direct and heterodyne operations. Trace gas concentrations have been obtained with the NASA DIAL system, and trace gas transport has been determined with Doppler lidar measurements for wind velocity and turbulence. High vertical resolution measurement of trace gases, wind velocity, and turbulence are most important in the planetary boundary layer and in regions between the PBL and the lower stratosphere. Shear measurements are critical for airport operational safety. A sensitivity analysis for heterodyne detection with the DIAL system and for short pulses using a Doppler lidar system is presented. The development of transient injection locking techniques, as well as frequency stability by reducing chirp and catalytic control of closed cycle CO2 laser chemistry, is described.
In order to test the possibility that tunable diode laser (TDL) systems using topographic targets can be applied to the measurement of a variety of gases at concentrations and distances characteristic of industrial gas leaks, a single-ended TDL system was assembled for use with selected topographic targets to detect NO2 at atmospheric pressure and NO2 and NH3 at low pressures. In both cases, the intensity distribution of radiation backscattered from selected targets was found to be heavily weighted to a specular rather than a Lambertian distribution. A sensitivity of 5 ppm-m has been demonstrated for the case of NO2.
The present investigation is concerned with the application of a pressure modulated radiometer (PMR) to the remote sensing of trace amounts of gases in the atmospheres as well as to the direct measurement of upper atmospheric winds. The PMR operates as a gas correlation spectrometer. Compared to conventional gas correlation parameters, it has some advantages which are related to greater versatility and the employment of a simpler method for maintaining electrical/optical balance. The PMR has a high sensitivity in connection with its essentially very high effective resolution. It represents a passive system and emits no radiation. A PMR is flown on Nimbus 6 which was launched in 1975. The instrument has also been used on the Nimbus 7 satellite and the Tiros N satellite.
The influence of systematic errors in the parameters of the models describing the geometry and the atmosphere on the profiles of trace gases retrieved from simulated solar occultation spectra, collected at satellite altitudes, is investigated. Because of smearing effects and other uncertainties, it may be preferable to calibrate the spectra internally by measuring absorption lines of an atmospheric gas such as CO2 whose vertical distribution is assumed rather than to relay on externally supplied information.
A variety of experimentally established flame phenomena in premixed gases are interpreted by relating them to basic aerodynamic properties of the flow field. On this basis the essential mechanism of some well known characteristic features of flames stabilized in the wake of a bluff-body or propagating in ducts are revealed. Elementary components of the flame propagation process are shown to be: rotary motion, self-advancement, and expansion. Their consequences are analyzed under a most strict set of idealizations that permit the flow field to be treated as potential in character, while the flame is modelled as a Stefan-like interface capable of exerting a feed-back effect upon the flow field. The results provide an insight into the fundamental fluid-mechanical reasons for the experimentally observed distortions of the flame front, rationalizing in particular its ability to sustain relatively high flow velocities at amazingly low normal burning speeds.
The mechanism of deposition of Na2SO4 was studied under controlled laboratory conditions and the results have been compared to a recently developed comprehensive theory of vapor deposition. Thus Na2SO4, NaCl, NaNO3 and simulated sea salt solutions were injected into the combustor of a nominal Mach 0.3 burner rig burning jet fuel at constant fuel/air ratios. The deposits formed on inert collectors, rotation in the cross flow of the combustion gases, were weighed and analyzed. Collector temperature was uniform and could be varied over a large range by internal air cooling. Deposition rates and dew point temperatures were determined. Supplemental testing included droplet size measurements of the atomized salt solutions. These tests along with thermodynamic and transport calculations were utilized in the interpretation of the deposition results.