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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 325 records · Page 18
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NASA NTRS1977

Sources and sinks for atmospheric H2 - A current analysis with projections for the influence of anthropogenic activity

Oxidation of CH4 provides the major source for atmospheric H2, which is removed mainly by reaction with OH. Biological activity at earth's surface appears to represent at most a minor sink for H2. Anthropogenic activity is a significant source for both H2 and CO in the present atmosphere and may be expected to exert a growing influence in the future. Models are presented which suggest a rise in the mixing ratio of H2 from its present value of 5.6 ten-millionths to about 1.8 millionths by the year 2100. The mixing ratio of CO should grow from 9.7 hundred-millionths to 2.3 ten-millionths over the same time period, and there should be a rise in CH4 by about a factor of 1.5 associated with anthropogenically induced reductions in tropospheric OH.

Penner, J. E.↗
NASA NTRS1985

Global lower mesospheric water vapor revealed by LIMS observations

The Limb Infrared Monitor of the Stratospheric water vapor channel data analysis has been extended from the 1. mb level (about 48 km) to the .3 mb level (about 60 km) through a radiance averaging procedure and better understanding of systematic errors. The data show H2O mixing ratio peaks near the .5 mb level varying from 4 to 7 ppmv with latitude and season. Above this level the mixing ratio drops off quickly with altitude, but, due to experimental uncertainties, at an uncertain rate. The stratospheric results are virtually the same as determined from the archived LIMS results with a tropical hygropause and enhanced H2O concentration in the lower levels at high winter latitudes.

Gordley, L. L.↗
NASA NTRS1992

Water vapor variance measurements using a Raman lidar

Because of the importance of atmospheric water vapor variance, we have analyzed data from the NASA/Goddard Raman lidar to obtain temporal scales of water vapor mixing ratio as a function of altitude over observation periods extending to 12 hours. The ground-based lidar measures water vapor mixing ration from near the earth's surface to an altitude of 9-10 km. Moisture profiles are acquired once every minute with 75 m vertical resolution. Data at each 75 meter altitude level can be displayed as a function of time from the beginning to the end of an observation period. These time sequences have been spectrally analyzed using a fast Fourier transform technique. An example of such a temporal spectrum obtained between 00:22 and 10:29 UT on December 6, 1991 is shown in the figure. The curve shown on the figure represents the spectral average of data from 11 height levels centered on an altitude of 1 km (1 plus or minus .375 km). The spectra shows a decrease in energy density with frequency which generally follows a -5/3 power law over the spectral interval 3x10 (exp -5) to 4x10 (exp -3) Hz. The flattening of the spectrum for frequencies greater than 6x10 (exp -3) Hz is most likely a measure of instrumental noise. Spectra like that shown in the figure are calculated for other altitudes and show changes in spectral features with height. Spectral analysis versus height have been performed for several observation periods which demonstrate changes in water vapor mixing ratio spectral character from one observation period to the next. The combination of these temporal spectra with independent measurements of winds aloft provide an opportunity to infer spatial scales of moisture variance.

Evans, K.↗
NASA NTRS1994

Model study of atmospheric transport using carbon 14 and strontium 90 as inert tracers

The observed excess carbon 14 in the atmosphere from 1963 to 1970 provides unique, but limited, data up to an altitude of about 35 km for testing the air motions calculated by 11 multidimensional atmospheric models. Strontium 90 measurements in the atmosphere from 1964 to mid-1967 provide data that have more latitude coverage than those of carbon 14 and are useful for testing combined models of air motions and aerosol settling. Model calculations for carbon 14 begin at October 1963, 9 months after the conclusion of the nuclear bomb tests; the initial conditions for the calculations are derived by three methods, each of which agrees fairly well with measured carbon 14 in October 1963 and each of which has widely different values in regions of the stratosphere where there were no carbon 14 measurements. The model results are compared to the stratospheric measurements, not as if the observed data were absolute standards, but in an effort to obtain new insight about the models and about the atmosphere. The measured carbon 14 vertical profiles at 31 deg N are qualitatively different from all of the models; the measured vertical profiles show a maximum mixing ratio in the altitude range of 20 to 25 km from October 1963 through July 1966, but all modeled profiles show mixing ratio maxima that increase in altitude from 20 km in October 1963 to greater than 40 km by April 1966. Both carbon 14 and strontium 90 data indicate that the models differ substantially among themselves with respect to stratosphere-troposphere exchange rate, but the modeled carbon 14 stratospheric residence times indicate that differences among the models are small with respect to transport rate between the middle stratosphere and the lower stratosphere. Strontium 90 data indicate that aerosol settling is important up to at least 35 km altitude. Relative to the measurements, about three quarters of the models transport carbon 14 from the lower stratosphere to the troposphere too rapidly, and all models with all three sets of initial conditions appear to sweep carbon 14 out of the midstratosphere (above 28 km) much more slowly than was observed from 1963 to 1970. Atmospheric dynamicists should seriously consider that the carbon 14 measurements imply with respect to advection in the midstratosphere.

Kinnison, D. E.↗
NASA NTRS2009

First Global Observations of Atmospheric COClF from the Atmospheric Chemistry Experiment Mission

Carbonyl chlorofluoride (COClF) is an important reservoir of chlorine and fluorine in the Earth's atmosphere. Satellite-based remote sensing measurements of COClF, obtained by the Atmospheric Chemistry Experiment (ACE) for a time period spanning February 2004 through April 2007, have been used in a global distribution study. There is a strong source region for COClF in the tropical stratosphere near 27 km. A layer of enhanced COClF spans the low- to mid-stratosphere over all latitudes, with volume mixing ratios of 40-100 parts per trillion by volume, largest in the tropics and decreasing toward the poles. The COClF volume mixing ratio profiles are nearly zonally symmetric, but they exhibit a small hemispheric asymmetry that likely arises from a hemispheric asymmetry in the parent molecule CCl3F. Comparisons are made with a set of in situ stratospheric measurements from the mid-1980s and with predictions from a 2-D model.

Fu, Dejian↗
NASA NTRS2009

Appendix C: First Global Observations of Atmospheric COClF from the Atmospheric Chemistry Experiment Mission

Carbonyl chlorofluoride (COCIF) is an important reservoir of chlorine and Fluorine in the Earth's atmosphere. Satellite-based remote sensing measurements of COCIF, obtained by Received in revised form the Atmospheric Chemistry Experiment (ACE) for a time period spanning February 2004 through April 2007, have been used in a global distribution study. There is a strong Accepted 18 February 2009 source region for COCIF in the tropical stratosphere near 27 km. A layer of enhanced COCIF spans the low- to mid-stratosphere over all latitudes, with volume mixing ratios of 40-100 parts Per trillion by volume, largest in the tropics and decreasing toward the poles. The COCIF volume mixing ratio profiles are nearly zonally symmetric, but they exhibit a small hemispheric asymmetry that likely arises from a hemispheric asymmetry in the parent molecule CCl3F. Comparisons are made with a set of in situ stratospheric measurements from the mid-1980s and with predictions from a 2-D model.

Fu, Djian↗
NASA NTRS2010

First Global Observations of Atmospheric COCIF from the Atmospheric Chemistry Experiment Mission

Carbonyl chlorofluoride (COCIF) is an important reservoir of chlorine and fluorine in the Earth's atmosphere. Satellite-based remote sensing measurements of COCIF, obtained by the Atmospheric Chemistry Experiment (ACE) for a time period spanning February 2004 through April 2007, have been used in a global distribution study. There is a strong source region for COCIF in the tropical stratosphere near 27 km. A layer of enhanced COCIF spans the low- to mid-stratosphere over all latitudes, with volume mixing ratios of 40-100 parts per trillion by volume, largest in the tropics and decreasing toward the poles. The COCIF volume mixing ratio profiles are nearly zonally symmetric, but they exhibit a small hemispheric asymmetry that likely arises from a hemispheric asymmetry in the parent molecule CCl3 F. Comparisons are made with a set of in situ stratospheric measurements from the mid-1980s and with predictions from a 2-D model.

Fu, Dejian↗
NASA NTRS1980

Far infrared measurement of stratospheric HCl

Thermal emission from three rotational lines of H(Cl-35) and H(Cl-37) was observed with a Fourier transform spectrometer from a balloon platform at 28.9 km. The measured HCl line-of-sight density at 1.9 deg elevation above 28.9 km is 4.7 + or - 1.3 x 10 to the 15th/sq cm, implying an average volume mixing ratio of 0.8 + or - 0.2 x 10 to the -9th at the mean sampling altitude of 32.5 km. For a uniform mixing ratio model, this corresponds to a vertical column density of 2.4 + or - 0.6 x 10 to the 14th/sq cm. This result is in reasonable agreement with near infrared spectroscopic determinations and an abundance from a chemical sampling technique of HCl at this altitude; a pressure modulator radiometer measurement yields a significantly higher amount of HCl.

Chance, K. V.↗
NASA NTRS1989

Ground-based infrared measurements of tropospheric source gases over Antarctica during the 1986 austral spring

Simultaneous measurements of the atmospheric burdens of CH4, N2O, CO2, CF2Cl2, and CO above McMurdo Station, Antarctica, have been derived from solar absorption spectra obtained by the Jet Propulsion Laboratory high-resolution Fourier transform spectrometer. In all cases the burdens are smaller than midlatitude values. Furthermore, retrievals of N2O and CH4 indicate that the tropospheric mixing ratios were normal and that the depletion of the burdens can best be accounted for by a downward shift of the volume mixing ratio profiles by some 6-8 km. This rules out the possibility of large-scale upwelling of ozone-poor tropospheric air into the stratosphere being the cause of the Antarctic springtime ozone depletion.

Toon, G. C.↗
NASA NTRS2000

Solar Energy Deposition Rates in the Mesosphere Derived from Airglow Measurements: Implications for the Ozone Model Deficit Problem

We derive rates of energy deposition in the mesosphere due to the absorption of solar ultraviolet radiation by ozone. The rates are derived directly from measurements of the 1.27-microns oxygen dayglow emission, independent of knowledge of the ozone abundance, the ozone absorption cross sections, and the ultraviolet solar irradiance in the ozone Hartley band. Fifty-six months of airglow data taken between 1982 and 1986 by the near-infrared spectrometer on the Solar-Mesosphere Explorer satellite are analyzed. The energy deposition rates exhibit altitude-dependent annual and semi-annual variations. We also find a positive correlation between temperatures and energy deposition rates near 90 km at low latitudes. This correlation is largely due to the semiannual oscillation in temperature and ozone and is consistent with model calculations. There is also a suggestion of possible tidal enhancement of this correlation based on recent theoretical and observational analyses. The airglow-derived rates of energy deposition are then compared with those computed by multidimensional numerical models. The observed and modeled deposition rates typically agree to within 20%. This agreement in energy deposition rates implies the same agreement exists between measured and modeled ozone volume mixing ratios in the mesosphere. Only in the upper mesosphere at midlatitudes during winter do we derive energy deposition rates (and hence ozone mixing ratios) consistently and significantly larger than the model calculations. This result is contrary to previous studies that have shown a large model deficit in the ozone abundance throughout the mesosphere. The climatology of solar energy deposition and heating presented in this paper is available to the community at the Middle Atmosphere Energy Budget Project web site at http://heat-budget.gats-inc.com.

Mlynczak, Martin G.↗
NASA NTRS1999

Observations of Middle Atmosphere CO from the UARS ISAMS during the Early Northern Winter 1991/92

Structure and kinematics of carbon monoxide in the upper stratosphere and lower mesosphere (10-0.03 hPa) are studied for the early northern winter 1991/92 using the Upper Atmosphere Research Satellite Improved Stratospheric and Mesospheric Sounder (ISAMS) measurements. The study is aided by data from a 6-week parameterized-chemistry run of the Goddard Space Flight Center 3D Chemistry and Transport Model (CTM), initialized on 8 December 1991. Generally, CO mixing ratios increase with height due to the increasing source contribution from CO, photolysis. In the tropical upper stratosphere. however, a local maximum in CO mixing ratio occurs. A simple photochemical model is used to show that this feature results largely from methane oxidation. In the extratropics the photochemical lifetime of CO is long, and therefore its evolution is dictated by large-scale motion of air. evidenced by strong correlation with Ertel potential vorticity. This makes CO one of the few useful observable tracers at the stratopause level and above. Thus CO maps are used to study the synoptic evolution of the polar vortex in early January 1992. Modified Lagrangian mean mixing diagnostics are applied to ISAMS and CTM data to examine the strength of the mixing barrier at the polar vortex edge. It is demonstrated that planetary wave activity weakens the barrier. promoting vortex erosion. The vortex erosion first appears in the lower mesosphere and subsequently descends through the upper stratosphere. and is attributed to effects of planetary wave dissipation. Agreement between ISAMS and CTM is good in the horizontal distribution of CO throughout the examined period, but vertical CO gradients in the CTM weaken with time relative to the ISAMS observations.

Allen, D. R.↗
NASA NTRS1990

Simultaneous, in situ measurements of OH, HO2, O3, and H2O - A test of modeled stratospheric HO(x) chemistry

Simultaneous, in situ measurements of OH, HO2, H2O, and O3 from 37-23 km are reported. The partitioning between OH and HO2 and the total HO(x) concentration are compared with expected steady-state values. The ratio of HO2 to OH varies from less than 2 at 36 km to more than 3 at 25 km; in the lower stratosphere this ratio is nearly a factor of two less than predicted. The data are used to calculate HO(x) production and loss rates. The measured HO(x) mixing ratio is consistent with production dominated by the reaction of O(1D) with H2O, and loss controlled by NOy below 28 km and HO(x) above 30 km. The steady-state concentration of H2O2 is inferred from the measured HO2 concentration and calculated photolysis rate. The maximum H2O2 mixing ratio (at 33 km) is predicted to be less than 0.2 ppb.

Wennberg, P. O.↗
NASA NTRS1972

Water vapor in the atmosphere of Venus.

Infrared spectra of Venus produced by a Fourier spectrometer flown aboard the NASA CV 990 jet aircraft were analyzed for water-vapor content by comparison with calculated model spectra. The reflecting layer model gave an abundance of 1.6 plus or minus 0.4 micron of precipitable water for the two-way transmission of the Venus atmosphere. The scattering model resulted in a value of 0.25 plus or minus 0.10 micron of water per scattering mean free path. Neither is regarded as a definitive model, but derived mixing ratios will not be significantly in error. An abundance of CO2 using a number of bands, was determined for both models. The volume mixing ratios of H2O to CO2 obtained were 0.0000006 and 0.000001 for the reflecting layer and scattering model, respectively.

Fink, U.↗
NASA NTRS1981

Krypton and xenon in the atmosphere of Venus

The paper reports a determination by the Pioneer Venus large probe neutral mass spectrometer of upper limits to the concentration of krypton and xenon along with most of their isotopes in the atmosphere of Venus. The upper limit to the krypton mixing ratio is estimated at 47 ppb, with a very conservative estimate at 69 ppb. The probable upper limit to the sum of the mixing ratios of the isotopes Xe-128, Xe-129, Xe-130, Xe-131, and Xe-132 is 40 ppb by volume, with a very conservative upper limit three times this large.

Donahue, T. M.↗
NASA NTRS1982

Gaseous infrared absorption in the lower atmosphere of Venus

Possibly important sources of infrared opacity in the Venusian atmosphere was identified. It is shown that which is the major atmospheric constituent comprising about 97 percent of the atmosphere, is the dominant infrared opacity source. Not shown is N2 which comprises about 3 percent of the atmosphere. The mixing ratio of water vapor varies considerably with altitude but falls in the range of about 20 to 200 parts per million (ppm). The mixing ratio of SO2 falls in the range of 100-200 ppm. This number is about 5000 times larger than estimates obtained earlier via Earth-based observations. The abundance of some of the other minor constituents is also shown.

Chackerian, C., Jr.↗
NASA NTRS1982

SAGE - European ozonesonde comparison

Between February and December 1979, 30 correlative comparisons were conducted of ozone profiles derived from the satellite sensor SAGE and those derived from balloon-borne ozonesondes launched in Europe. The mean absolute differences between SAGE and the European sondes when ozone mixing ratio is used as the basis of comparison are listed, and ozone comparisons made at four stations in Europe are plotted as ozone mixing ratio versus altitude. The agreement is considered quite reasonable. Also shown is an April 2, 1979 Garmisch comparison where the time and space differences were very small. The agreement is found to be remarkable. For example, the ratio of SAGE to ozonesonde values at 13 out of 17 levels between 12.5 and 28.5 km lies in the range 0.92-1.06.

Reiter, R.↗
NASA NTRS1988

Trace gas measurements from whole air samples collected over the Antarctic continent

Whole air samples collected aboard the NASA DC-8 and ER-2 aircraft as part of the Airborne Antarctic Ozone Experiment (AAOE) were analyzed in a field laboratory set up at Punta Arenas, Chile, in August and September, 1987. Mixing ratios obtained from gas chromatographic analyses of these samples are presented for N2O, CFCl3, CFCl2, C2F3Cl3, CH3CCl3, CH4, and CO. Variations in the mixing ratios of these gases along the individual flight paths of the aircraft are used as tracers to indicate the history of air masses over and near the Antarctic continent.

Heidt, L. E.↗
NASA NTRS1990

An intercomparison of airborne nitric oxide measurements - A second opportunity

Results are reported from a comparison of three tropospheric NO measurement instruments during the NASA Global Tropospheric Experiment Chemical Instrumentation Test and Evaluation 2 (CITE 2) in summer 1986. The instruments tested were those used in CITE 1 (Hoell et al., 1987): a two-photon LIF system and two chemiluminescence systems. It is found that the mixing ratios obtained with the three systems agreed to within 15-20 parts per trillion volume (pptv) for sampling perods of 1-6 min at mixing ratios less than 20 pptv; the average difference between pairs of measurements was 5-7 pptv, which is considered to be the uncertainty in state-of-the-art ambient NO measurements.

Gregory, Gerald L.↗