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At least 19 records
All sourcesNASA NTRSDOE OSTI
NASA NTRS1983

Correlative nature of ozone and carbon monoxide in the troposphere - Implications for the tropospheric ozone budget

The small-scale vertical variability of troposheric O3 and CO is examined using a set of simultaneous measurements obtained in July and August 1974 between 55 deg S and 67 deg N. From this set of vertical profiles, it is found that many of the fluctuations are coincident in both species, and a method is presented that quantifies the correlation between the observed O3 and CO variability. A two-dimensional depiction of the distribution of these O3-CO correlations reveals that there are regions in the troposphere where these trace gases are positively correlated and that, at the same time, there are preferred locations where these two species are primarily anticorrelated. The regions of anticorrelation are found to be consistent with the traditional picture of the tropospheric ozone cycle, suggesting that this gas is chemically unreactive in the troposphere. On the other hand, the location and magnitude of the region in which these two species are positively correlated indicates that there is considerable in situ production of tropospheric ozone.

Fishman, J.↗
NASA NTRS1979

Observational and theoretical evidence in support of a significant in-situ photochemical source of tropospheric ozone

The latitudinal and seasonal variation of ozone in the troposphere is discussed. Of particular interest is the asymmetrical behavior of this gas with respect to the two hemispheres. These asymmetries, when coupled with a diagnostic photochemical model of the troposphere, lends support to the view that ozone cannot be viewed as an inert tracer of stratospheric origin. In the calculations it is noted that it is likely that the budgets of carbon monoxide and tropospheric ozone may be quite dependent on each other and the calculations are discussed in light of the uncertainty which currently exists about representative global tropospheric background concentrations of the nitrogen oxides. In addition, the seasonal variation of excess (C-14)O2 (a stratospheric tracer) is examined and compared with the seasonal ozone variation during the same period of observations at the same location and altitudes. The distinct maxima for ozone found during the summer in the lower troposphere are not present for the (C-14)O2 data. This finding likewise suggests that photochemical processes taking place in the troposphere are an important source term for tropospheric ozone.

Fishman, J.↗
NASA NTRS1977

Non Urban Troposphere Composition Symposium, Hollywood, Fla., November 10-12, 1976, Proceedings

Papers are presented which originate from a conference on 'The Non-Urban Troposphere Composition', held in 1976. Attention is given to distributions of nitrous oxide in the atmosphere, and to tropospheric and stratospheric compositions which are perturbed by NO(x) emissions from high-altitude aircraft. Ozone is studied in terms of in situ measurements; various meteorological analyses of tropopause folding, ozone measurements in the Boston area, and ozone measurements in rural areas are presented. A one-dimensional model used to study tropospheric photochemistry numerically is presented as are vertical profiles of tropospheric and stratospheric molecular hydrogen. The oxidation of ammonia, methane, and hydrogen sulfide is assessed in nonurban tropospheres along with nonurban measurements of ethane and methane for various atmospheric conditions. With reference to the particle size distribution of chloride in the marine aerosol, organic and inorganic chlorine concentrations are evaluated, and measurements of sea-air CO2 flux by eddy correlation are investigated.

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NASA NTRS1978

Parametric modeling of low-frequency water-vapor-induced tropospheric path length fluctuations

Detailed wet tropospheric fluctuation information is presented in support of proposals to search for gravitational waves in ultra-precise Doppler data. The similarities between the solar wind and tropospheric effects on apparent signal path length are used to hypothesize a parametric model for low-frequency wet tropospheric path length fluctuation. Experimental observations of wet tropospheric signal delay fluctuations are interpreted as confirmation of this parametric form. The model is used to suggest the appropriate conditions for collection of experimental tropospheric fluctuation data.

Berman, A. L.↗
NASA NTRS1980

Simultaneous presence of O3 and CO bands in the troposphere

Vertical profiles of CO and O3 in the troposphere and lower stratosphere have been constructed during a series of flights conducted in July and August 1974 over the American continents between 53 deg S and 67 deg N. The mixing ratios of both gases show large fluctuations with altitude in the Northern Hemisphere. Most of the observed bands of O3 in the free troposphere are coexistent with elevated CO concentrations indicating that this O3 is probably not of stratospheric origin, but most likely produced in the troposphere. From the observations, it is not clear whether these high concentrations of ozone were produced in situ in the remote troposphere or had been transported out of a polluted boundary layer. Isentropic trajectory calculations likewise indicate that the air containing these elevated ozone and carbon monoxide concentrations had been situated in the troposphere for at least 72 h prior to being sampled.

Fishman, J.↗
NASA NTRS1980

Iodine - Its possible role in tropospheric photochemistry

A detailed study of the photochemistry of iodine and its oxides indicates that iodine species may play an important role in the tropospheric photochemical system. Methyl iodide, often observed in the marine troposphere with an average concentration of 5-10 ppt, is photolyzed and thereby produces I atoms. Chemical interactions with O3, HxOy, and NOx cause I to be converted to other inorganic compounds such as IO, HOI, IONO2, and I2. The production of these species and their subsequent recycling back to I can lead to the catalytic removal of tropospheric O3, the enhancement of the NO2/NO ratio, the destruction of HxOy free radicals, and the conversion of HO2 to OH. Ultimately, tropospheric inorganic iodine is removed by heterogeneous processes. Calculations using a numerical model to simulate tropospheric photochemistry indicate that iodine may have a strong impact upon the atmospheric O3-NOx-HxOy system. The magnitude of these effects is dependent upon the value of several uncertain rate constants and the primary source distributions of CH3I and other organic and inorganic iodine compounds.

Chameides, W. L.↗
NASA NTRS1981

On the warming of the polar troposphere during the stratospheric warming of January 1977

In January 1977, a warming of the polar troposphere occurred following a major stratospheric warming. The temperature increase in the polar troposphere is found to be larger below 400 mb than in the upper troposphere. Analysis of the heat budget of the polar troposphere shows that the eddy heat flux convergence is the major factor responsible for the tropospheric warming.

Hansen, A. R.↗
NASA NTRS1982

Ammonia and the NOx budget of the troposphere

Liu et al. (1980) suggested that NOx transported from the stratosphere, as opposed to the anthropogenic source of NOx, may be the dominant source that controls the distribution of NOx in the global troposphere. These ideas require a reinvestigation, and, in particular, an assessment of the role of the oxidation of ammonia as a source of NOx. Attention is given to the results of an ammonia measurement program, in which the vertical distribution of ammonia in the troposphere and lower stratosphere could be studied with the aid of the Infrared Heterodyne Radiometer (IHR), a solar-viewing remote sensor. A one-dimensional photochemical model of the troposphere reported by Levine et al. (1980) was employed to study the chemical and physical processes that control the loss of ammonia in the troposphere. The results of the considered investigation suggest that the oxidation of ammonia may indeed be a significant source of NOx in the troposphere.

Levine, J. S.↗
NASA NTRS1982

Airborne lidar investigations of ozone and aerosols in the nonurban troposphere

A description is presented of the first application of an airborne optical radar (lidar) to measurements of ozone and aerosol profiles in regional and global tropospheric investigations. It is pointed out that high spatial resolution measurements of ozone and aerosols are important in studying the relative contribution of chemistry and transport in large scale atmospheric processes. The investigation makes use of an airborne differential absorption optical radar system, which has been developed for the remote profiling of O3 and aerosols in the troposphere. Attention is given to lower tropospheric measurements and upper tropospheric measurements. The obtained results demonstrate the capability of the considered system to measure O3 and aerosol profiles in the troposphere and lower stratosphere.

Browell, E. V.↗
NASA NTRS1983

NASA Global Tropospheric Experiment

The rationale and program design for the NASA Global Tropospheric Experiment (GTE) are described. The GTE is intended to characterize the global tropospheric chemistry and its interaction with the stratosphere, the land, and the ocean. The program emphasis is laid on the potential global impact of human activities, particularly those which release CH4, N2O, and chlorofluorocarbons into the atmosphere. Specific tasks defined thus far include characterizing the tropospheric gas-phase chemistry of OH, NO, and NO2, determining concentrations and distributions of CO, CH4, O3, and N2O, as well as halogens, trace metals, and reduced sulfur species. Techniques are needed for measuring the chemical fluxes between earth surface sources and sinks, the boundary layer, the free troposphere, and the stratosphere. The first phase of the GTE will be to test and develop techniques and assay the detection limits for OH, NO, and NO2 and assess the reliability of laboratory calibrations. Improvements in modelling global-scale tropospheric processes will also be pursued.

Mcneal, R. J.↗
NASA NTRS1977

Tropospheric ozone - Coupling transport and photochemistry

The budget of tropospheric ozone is re-examined in the light of lower observed nitrogen oxide densities and revised reaction rates. To estimate the relative importance of transport and photochemistry, model calculations are presented which determine one-dimensional vertical ozone profiles at midlatitudes for equinoctial conditions. These calculations imply that both photochemistry and transport are important in controlling the abundance of tropospheric ozone. It is estimated that photochemical processes produce about 0.6 times 10 to the eleventh and destroy about 1.4 times 10 to the eleventh tropospheric ozone molecules per sq cm per sec, while mixing processes transport about 1.4 times 10 to the eleventh ozone molecules per sq cm per sec from the stratosphere into the troposphere and ground level fluxes destroy about 0.6 times 10 to the eleventh ozone molecules per sq cm per sec. The sensitivity of our model calculations to transport parameters, key rate coefficients, and nitrogen oxide densities are discussed.

Chameides, W. L.↗
NASA NTRS1978

The origin of ozone in the troposphere

Examination of the distribution of tropospheric ozone indicates that surface destruction in the Northern Hemisphere (NH) should be about three times larger than in the Southern Hemisphere (SH). If, according to the traditional understanding of ozone, this species were a passive tracer in the troposphere, a threefold larger flux out of the stratosphere should exist in the NH than in the SH. However, meteorological analyses fail to support such pronounced hemispheric differences in stratosphere-troposphere exchange. Alternatively, therefore, it is hypothesized that photochemical synthesis of ozone in the troposphere may be particularly important in the NH because of asymmetries in the sources and distribution of carbon monoxide, hydrocarbons and nitric oxide.

Fishman, J.↗
NASA NTRS1980

Planetary wave coupling between the troposphere and the middle atmosphere as a possible sun-weather mechanism

The possibility of planetary wave coupling between the troposphere and solar-induced alterations in the upper atmosphere providing a viable mechanism for giving rise to sun-weather relationships is investigated. Some of the observational evidence for solar-activity-induced effects on levels of the upper atmosphere ranging from the thermosphere down to the lower stratosphere are reviewed. It is concluded that there is evidence for such effects extending down to the middle stratosphere and below. Evidence is also reviewed that these effects are due to changes in solar ultraviolet emission during disturbed solar conditions. A theoretical planetary wave model is then used to see at what levels in the upper atmosphere moderate changes in the mean zonal wind state would result in tropospheric changes. It is concluded that changes in the mean zonal flow of about 20% at levels in the vicinity of 35 km or below would give rise to changes in the tropospheric planetary wave pattern that are less than but on the same order as the observed interannual variability in the tropospheric wave pattern at middle and high latitudes.

Geller, M. A.↗
NASA NTRS1981

Effects of multiple scattering and surface albedo on the photochemistry of the troposphere

The effect of treatment of incoming solar radiation on the photochemistry of the troposphere is discussed. A one dimensional photochemical model of the troposphere containing the species of the nitrogen, oxygen, carbon, hydrogen, and sulfur families was developed. The vertical flux is simulated by use of the parameterized eddy diffusion coefficients. The photochemical model is coupled to a radiative transfer model that calculates the radiation field due to the incoming solar radiation which initiates much of the photochemistry of the troposphere. Vertical profiles of tropospheric species were compared with the Leighton approximation, radiative transfer, matrix inversion model. The radiative transfer code includes the effects of multiple scattering due to molecules and aerosols, pure absorption, and surface albedo on the transfer of incoming solar radiation. It is indicated that significant differences exist for several key photolysis frequencies and species number density profiles between the Leighton approximation and the profiles generated with, radiative transfer, matrix inversion technique. Most species show enhanced vertical profiles when the more realistic treatment of the incoming solar radiation field is included

Augustsson, T. R.↗
NASA NTRS1982

Applying modeling Results in designing a global tropospheric experiment

A set of field experiments and advanced modeling studies which provide a strategy for a program of global tropospheric experiments was identified. An expanded effort to develop space applications for trospheric air quality monitoring and studies was recommended. The tropospheric ozone, carbon, nitrogen, and sulfur cycles are addressed. Stratospheric-tropospheric exchange is discussed. Fast photochemical processes in the free troposphere are considered.

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