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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.

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At least 73 records · Page 4
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NASA NTRS1983

Carbon monoxide mixing ratio inference from gas filter radiometer data

A new algorithm has been developed which permits, for the first time, real time data reduction of nadir measurements taken with a gas filter correlation radiometer to determine tropospheric carbon monoxide concentrations. The algorithm significantly reduces the complexity of the equations to be solved while providing accuracy comparable to line-by-line calculations. The method is based on a regression analysis technique using a truncated power series representation of the primary instrument output signals to infer directly a weighted average of trace gas concentration. The results produced by a microcomputer-based implementation of this technique are compared with those produced by the more rigorous line-by-line methods. This algorithm has been used in the reduction of Measurement of Air Pollution from Satellites, Shuttle, and aircraft data.

Wallio, H. A.↗
NASA NTRS1983

Effects of systematic errors on the mixing ratios of trace gases obtained from occulation spectra

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.

Shaffer, W. A.↗
NASA NTRS1984

Effects of systematic errors on the mixing ratios of trace gases obtained from occultation spectra

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 rely on externally supplied information.

Shaffer, W. A.↗
NASA NTRS1987

Spray Gun With Constant Mixing Ratio

Conceptual mechanism mounted in handle of spray gun maintains constant ratio between volumetric flow rates in two channels leading to spray head. With mechanism, possible to keep flow ratio near 1:1 (or another desired ratio) over range of temperatures, orifice or channel sizes, or clogging conditions.

Simpson, William G.↗
NASA NTRS1989

The mixing ratio of the stratospheric hydroxyl radical from far infrared emission measurements

Far infrared emission spectra of the stratosphere, measured with a 0.0033/cm resolution Fourier transform spectrometer using a limb scanning method, are analyzed in order to retrieve the vertical distribution of the hydroxyl radical (OH). The observations cover a time interval between 1300 and 2300 hours, showing a pronounced time decrease of the OH signals. Vertical profiles are obtained for the afternoon and sunset periods. An upper limit is derived from the small signals present in the night measurements. Three different methods of analysis have been applied to the same data set, and the results provided the basis for a critical discussion of the error sources. The results are compared with theoretical predictions and with the results of other experiments.

Carli, Bruno↗
NASA NTRS2012

Seasonal Variations in Titan's Stratosphere Observed with Cassini/CIRS: Temperature, Trace Molecular Gas and Aerosol Mixing Ratio Profiles

Titan's northern spring equinox occurred in August 2009. General Circulation Models (e.g. Lebonnois et al., 2012) predict strong modifications of the global circulation in this period, with formation of two circulation cells instead of the pole-to-pole cell that occurred during northern winter. This winter single cell, which had its descending branch at the north pole, was at the origin of the enrichment of molecular abundances and high stratopause temperatures observed by Cassini/CIRS at high northern latitudes (e.g. Achterberg et al., 2011, Coustenis et al., 2010, Teanby et al., 2008, Vinatier et al., 2010). The predicted dynamical seasonal variations after the equinox have strong impact on the spatial distributions of trace gas, temperature and aerosol abundances. We will present here an analysis of CIRS limb-geometry datasets acquired in 2010 and 2011 that we used to monitor the seasonal evolution of the vertical profiles of temperature, molecular (C2H2, C2H6, HCN, ..) and aerosol abundances.

Vinatier, S.↗
NASA NTRS2017

An 8-Year, High-Resolution Reanalysis of Atmospheric CO2 Mixing Ratios Based on OCO-2 and GOSAT-ACOS Retrievals

The NASA GMAO (Global Modeling and Assimilation Office) reanalysis blends OCO-2 (Orbiting Carbon Observatory 2) and GOSAT-ACOS (Greenhouse Gases Observing Satellite-Atmospheric Carbon Observations from Space) retrievals (top) with GEOS (Goddard Earth Observing System) model predictions (bottom) to estimate the full 3D (three-dimensional) state of CO2 every 3 hours (middle). This poster describes monthly atmospheric growth rates derived from the reanalysis and an application to aircraft data with the potential to aid bias correction.

GEOS-Carb↗
NASA NTRS1987

Three-dimensional analysis of potential vorticity associated with tropopause folds and observed variations of ozone and carbon monoxide

The usability and reliability of potential vorticity as a meteorological stratospheric tracer are evaluated. The concept of potential vorticity conservation during transport in which stratospheric and tropospheric air are mixing is tested. Aircraft data collected on April 20, 1984 in the western and southwestern U.S. are analyzed in order to derive potential vorticity data; vertical cross sections of constant-pressure data and temperature and wind speed gradients are examined. The tropopause fold observed during the April 20, 1984 aircraft flights is described. The potential vorticity, ozone mixing ratio, and carbon monoxide mixing ratio are compared; a positive correlation between potential vorticity and the ozone mixing ratio and a negative correlation between the potential vorticity and the carbon monoxide mixing ratio are detected. The data support the concepts of the conservation of potential vorticity, the entrainment and mixing of tropospheric air across the boundaries of the fold, and the applicability of potential vorticity as a stratospheric tracer.

Danielsen, Edwin F.↗
NASA NTRS2002

Ice Cloud Formation and Dehydration in the Tropical Tropopause Layer

Stratospheric water vapor is important not only for its greenhouse forcing, but also because it plays a significant role in stratospheric chemistry. Several recent studies have focused on the potential for dehydration due to ice cloud formation in air rising slowly through the tropical tropopause layer (TTL). Holton and Gettelman showed that temperature variations associated with horizontal transport of air in the TTL can drive ice cloud formation and dehydration, and Gettelman et al. recently examined the cloud formation and dehydration along kinematic trajectories using simple assumptions about the cloud properties. In this study, a Lagrangian, one-dimensional cloud model has been used to further investigate cloud formation and dehydration as air is transported horizontally and vertically through the TTL. Time-height curtains of temperature are extracted from meteorological analyses. The model tracks the growth, advection, and sedimentation of individual cloud particles. The regional distribution of clouds simulated in the model is comparable to the subvisible cirrus distribution indicated by SAGE II. The simulated cloud properties and cloud frequencies depend strongly on the assumed supersaturation threshold for ice nucleation. The clouds typically do not dehydrate the air along trajectories down to the temperature minimum saturation mixing ratio. Rather the water vapor mixing ratio crossing the tropopause along trajectories is 10-50% larger than the saturation mixing ratio. I will also discuss the impacts of Kelvin waves and gravity waves on cloud properties and dehydration efficiency. These simulations can be used to determine whether observed lower stratospheric water vapor mixing ratios can be explained by dehydration associated with in situ TTL cloud formation alone.

Jensen, Eric↗
NASA NTRS1993

An intercomparison of aircraft instrumentation for tropospheric measurements of carbonyl sulfide, hydrogen sulfide, and carbon disulfide

This paper reports results of NASA's Chemical Instrumentation and Test Evaluation (CITE 3) during which airborne measurements for carbonyl sulfide (COS), hydrogen sulfide (H2S), and carbon disulfide (CS2) were intercompared. Instrumentation included a gas chromatograph using flame photometric detection (COS, H2S, and CS2), a gas chromatograph using mass spectrometric detection (COS) and CS2), a gas chromatograph using fluorination and subsequent SF6 detection via electron capture (COS and CS2), and the Natusch technique (H2S). The measurements were made over the Atlantic Ocean east of North and South America during flights from NASA's Wallops Flight Center, Virginia, and Natal, Brazil, in August/September 1989. Most of the intercomparisons for H2S and CS2 were at mixing ratios less than 25 pptv and less than 10 pptv, respectively, with a maximum mixing ratio of about 100 pptv and 50 pptv, respectively. Carbonyl sulfide intercomparisons were at mixing ratios between 400 and 600 pptv. Measurements were intercompared from data bases constructed from time periods of simultaneous or overlapping measurements. Agreement among the COS techniques averaged about 5%, and individual measurements were generally within 10%. For H2S and at mixing ratio greater than 25 pptv, the instruments agreed on average to about 15%. At mixing ratios less than 25 pptv the agreement was about 5 pptv. For CS2 (mixing ratios less than 50 pptv), two techniques agreed on average to about 4 pptv, and the third exhibited a bias (relative to the other two) that varied in the range of 3-7 pptv. CS2 mixing ratios over the ocean east of Natal as measured by the gas chromatograph-mass spectrometer technique were only a few pptv and were below the detection limits of the other two techniques. The CITE 3 data are used to estimate the current uncertainty associated with aircraft measurements of COS, H2S, and CS2 in the remote troposphere.

Gregory, Gerald L.↗
NASA NTRS2007

Liquid Water Oceans in Ice Giants

Aptly named, ice giants such as Uranus and Neptune contain significant amounts of water. While this water cannot be present near the cloud tops, it must be abundant in the deep interior. We investigate the likelihood of a liquid water ocean existing in the hydrogen-rich region between the cloud tops and deep interior. Starting from an assumed temperature at a given upper tropospheric pressure (the photosphere), we follow a moist adiabat downward. The mixing ratio of water to hydrogen in the gas phase is small in the photosphere and increases with depth. The mixing ratio in the condensed phase is near unity in the photosphere and decreases with depth; this gives two possible outcomes. If at some pressure level the mixing ratio of water in the gas phase is equal to that in the deep interior, then that level is the cloud base. The gas below the cloud base has constant mixing ratio. Alternately, if the mixing ratio of water in the condensed phase reaches that in the deep interior, then the surface of a liquid ocean will occur. Below this ocean surface, the mixing ratio of water will be constant. A cloud base occurs when the photospheric temperature is high. For a family of ice giants with different photospheric temperatures, the cooler ice giants will have warmer cloud bases. For an ice giant with a cool enough photospheric temperature, the cloud base will exist at the critical temperature. For still cooler ice giants, ocean surfaces will result. A high mixing ratio of water in the deep interior favors a liquid ocean. We find that Neptune is both too warm (photospheric temperature too high) and too dry (mixing ratio of water in the deep interior too low) for liquid oceans to exist at present. To have a liquid ocean, Neptune s deep interior water to gas ratio would have to be higher than current models allow, and the density at 19 kbar would have to be approx. equal to 0.8 g/cu cm. Such a high density is inconsistent with gravitational data obtained during the Voyager flyby. In our model, Neptune s water cloud base occurs around 660 K and 11 kbar, and the density there is consistent with Voyager gravitational data. As Neptune cools, the probability of a liquid ocean increases. Extrasolar "hot Neptunes," which presumably migrate inward toward their parent stars, cannot harbor liquid water oceans unless they have lost almost all of the hydrogen and helium from their deep interiors.

Wiktorowicz, Sloane J.↗
NASA NTRS1985

The photochemistry of biogenic gases in the early and present atmosphere

The distribution of gases in the prebiologial paleoatmosphere is investigated using photochemical models. A chart of the photochemical and chemical reactions and reaction rates for CH4, NH3, H2S, N2O, and CO atmospheric gases is given. Mixing ratios and surface mixing ratios for CH4, NH3, CO, and N2O are obtained using thermodynamic equilibrium calculations; an increase in CH4 and N2O is observed. The reactions, which explain the photochemistry of the gases studied, are presented. The sources of these gases and their concentration with regards to altitude are examined. Graphs of the vertical distribution of CH4, NH3, H2S, CO, O2, and N2O in prebiological paleoatmosphere are provided. The data reveals the presence of only N2, CO2, and N2O in the early atmosphere; with the evolution of life, sources of atmospheric gases increased and their influence on the photochemistry of the troposphere and stratosphere increased.

Levine, J. S.↗