摘要:

Ground‐based measurements of the concentration of14CO are reported. The data exhibit a well‐defined seasonal variation at mid‐latitudes with a maximum of 25 ± 2 molecule cm−3during winter and a minimum of 11 ± 1 molecule cm−3during summer. The measurements also indicate a strong latitudinal variation, with the lower concentrations occurring in the tropics. The data are interpreted using a 2‐D time‐dependent model. To balance the sources of both14CO and12CO, an average tropospheric OH concentration of (6.5‐2+3) × 105molecule cm−3is required. In addition, the12CO production rate from biological processes including the oxidation of nonmethane hydrocarbons is found to be

ISSN:0148-0227    

DOI:10.1029/JC086iC06p05163

年代:1981

数据来源: WILEY

摘要:

Careful measurements by GC/MS techniques on atmospheric carbon tetrafluoride confirm that its concentration in 1979 was constant at about 69.9 pptv (standard deviation is 7.2 pptv). It is almost certainly produced entirely by emissions from the aluminium industry. Other compounds in the atmosphere containing the CF3group have been identified by GC/MS as C2F6, CF3Cl, CF3Br, and C2F5Cl. The concentrations of the first pair are about 4 pptv, and the latter two are about 0.7 pptv and 4 pptv, respectively. The C2F6is produced simultaneously with CF4in the manufacture of aluminium. CF3Cl, CF3Br, and C2F5Cl are probably produced by the chemical industry. The environmental importance of these compounds is discussed in the context of two papers on CF4recently published by Cicerone (1979) and by Wang et al. (1980).

ISSN:0148-0227    

DOI:10.1029/JC086iC06p05172

年代:1981

数据来源: WILEY

摘要:

Vertical profiles of H2, CH4, CO, N2O, CFCl3, and CF2Cl2resulting from gas chromatographic analysis of air samples collected from altitudes between 1.5 and 35.3 km at a latitude of about 44°N are presented. Ten balloon flights were performed with a neon‐cooled cryogenic air sampler designed to collect large air samples at eight different stratospheric heights. Supplementary tropospheric air samples were taken aboard a chartered aircraft. Vertical profiles from 1978 and 1979 are compared with those derived from fights in 19

ISSN:0148-0227    

DOI:10.1029/JC086iC06p05179

年代:1981

数据来源: WILEY

摘要:

Extensive new information on the daytime column abundance of atmospheric OH is presented from Spectroscopic observations of sunlight absorption by theP1(I)A2Σ+– X2π(0, 0) transition of OH at 3081.7 Å, taken with a Pepsios spectrometer. The observations were made from the NOAA Aeronomy Observatory at Fritz Peak, Colorado, between December 1976 and December 1979. An overall seasonal dependence on the depth of penetration of the solar ultraviolet flux, which is believed to initiate the photochemistry of daytime OH, was found. The overall averaged data is represented by an empirical curve,N(sec χ), where χ is the solar zenith angle, showing an overhead sun maximum abundance of 7.1 × 10l3/cm2, decreasing to 4.9 × 1013/cm2at sec χ = 2.0. The OH abundance and the sec χ variation agree reasonably well with predictions given by recent theoretical models of the stratosphere and mesophere and with the analysis of earlier in situ measurements of stratospheric and mesospheric OH by Anderson. An OH abundance increase of about 1 × 1013/cm2per year is found for the 1976–1979 period. There was a seasonal variation in 1978 with a 25–30% decrease from a springtime maximum to a fall minimum. The 1978 abundances also show a 30–40% diurnal oscillation whose cause is as yet undetermined. This effect is shown to be dependent on solar flux on both a diurnal and an annual basis, and the 1978–1979 observations exhibit additional long‐term changes, possibly related to the solar cycle, which will be mon

ISSN:0148-0227    

DOI:10.1029/JC086iC06p05185

年代:1981

数据来源: WILEY

摘要:

An analysis of the photodissociation of water vapor has been made for mesospheric conditions. The simultaneous action of two spectral ranges, namely the Lyman‐alpha radiation and the O2Schumann‐Runge bands, must be considered. The H2O photodissociation frequency owing to Lyman‐alpha is represented byJ(H2O, Ly‐α) =J∞ exp [−4.17 × 10−19N0.917], whereNis the total number of O2absorbing molecules, and J∞ = (3.5 ± 1.0) × 10−6s−1for quiet sun conditions and reaches (1.25 ± 0.35) × 10−5s−1for very active sun conditions. The H2O photodissociation frequency resulting from the O2Schumann‐Runge band spectral range is represented byJ(H2O, SRB) =J∞(H2O, SRB) exp [−4.8 × 10−10N0.466] forN≤ 1020cm−2, andJ(H2O, SRB) =J∞(H2O, SRB) exp [−4.6 × 10−8N0.366] for 1020

ISSN:0148-0227    

DOI:10.1029/JC086iC06p05203

年代:1981

数据来源: WILEY

摘要:

Tropospheric OH is believed to play a major role in atmospheric photochemistry, and, via its chemical interactions, OH ultimately may affect the climate, stratospheric ozone levels, and the pH of rain. A valuable tool for predicting the global OH abundance as a function of latitude and altitude is the two‐dimensional diagnostic model for tropospheric OH. This model can also be applied to budget studies of species which interact with OH, such as CH4, CO, and O3. In addition to laboratory‐obtained kinetic data, important variables, including the rate constants for several reactions, the rate of heterogeneous removal of soluble species, and the global abundance and spatial variability in H2O, O3, CO, and NOx. The uncertainties in these parameters imply over a factor of 3 variability in the calculated global OH concentration as well as significant uncertainties in the latitudinal and vertical OH distribut

ISSN:0148-0227    

DOI:10.1029/JC086iC06p05209

年代:1981

数据来源: WILEY

摘要:

Combination of the chemical continuity equation for odd oxygen with the second law of thermodynamics yields analytic solutions which describe the coupled behavior of temperature and ozone perturbations in response to an externally specified forcing. The results appear in a form which allows easy physical interpretation of the coupling between radiative and photochemical processes. When the forcing is chosen to mimic a planetary scale wave, the theory shows that photochemical acceleration of radiative damping reduces the amplitude of the temperature perturbation by an amount which increases with the wave period. Although ozone fluctuations are anti‐correlated with those in temperature, minima in ozone do not coincide exactly in longitude with temperature maxima. The percentage variation in ozone increases upward and is always larger than that in temperature at the same pressure. This demonstrates that variations in ozone on constant pressure surfaces may serve as a sensitive indicator of wave activity in the mesospher

ISSN:0148-0227    

DOI:10.1029/JC086iC06p05224

年代:1981

数据来源: WILEY

摘要:

Exceptionally high ozone ground level concentrations (>200 ppb) observed in Denver, Colorado, on the afternoon of March 4, 1978, are explained in terms of enhanced photochemistry combined with isentropic transport of ozone from the stratosphere. The maximum ozone concentrations observed on March 4 is the highest recorded for the 1975–1978 period. Inspection of the local pollutant and meteorological data shows high early morning accumulation of precursor gases and enhanced potential for afternoon photochemical activity. Objective cross‐sectional analysis and trajectories on isentropic surfaces indicate that some air parcels that mixed into the boundary layer over the city on the afternoon of March 4 were derived from a stratospheric intrusion 3 days earlier. It is concluded that a combination of these factors resulted in the exceptionally high ozone concentrati

ISSN:0148-0227    

DOI:10.1029/JC086iC06p05231

年代:1981

数据来源: WILEY

摘要:

The annual cycles of sea level and surface pressures and the atmospheric pressure owing to water vapor have been analyzed in detail. Global sea level pressures undergo an annual cycle of 0.5 mbar range with a maximum in the northern winter. Global surface pressures, which represent the total mass of the atmosphere, also undergo an annual cycle of 0.5 mbar range but with the maximum in the southern winter. The changes in water vapor concentrations are responsible for the latter—water vapor has a maximum in the southern winter. The constancy of the mass of dry air is used as a check on the accuracy of computations. The total mass of the atmosphere is 513.7 × 1016kg with a standard error of 0.02 × 1016kg and an annual cycle of amplitude 0.1 × 1016kg. The corresponding global mean surface pressure of the atmosphere is 984.68 mbar. The mean total mass of water vapor is 1.3 × 1016kg which corresponds to 2.53 cm of precipitable water or 12906 km3of water at 0°C. The distribution of pressure and mass as a function of latitude are also presented. A substantial annual exchange of mass occurs between the hemispheres amounting to 0.7 × 1016kg of dry air (2.7 mbar range in hemispheric averaged pressure). Maximum pressures occur in winter, and the summer loss of mass is partially compensated for by increased water vapor amounts. The maximum net meridional flow occurs across 5°N in the transition seasons. In the northern hemisphere, water vapor undergoes an annual cycle with a range of 1.5 mbar (area averaged) and a summer maximum, and the sea level pressure owing to dry air undergoes an annual cycle of range 5 mbar and a winter maximum. Of this, 54% is due to exchanges with the southern hemisphere and 46% is due to changes in the artificial atmospheric mass used to correct from the surface to s

ISSN:0148-0227    

DOI:10.1029/JC086iC06p05238

年代:1981

数据来源: WILEY

摘要:

Infrared emission from thev3band of ozone near 9.6 μm has been observed in the COCHISE cryogenic chemical reactor/spectrometer. Vibrationally excited O3, formed principally by recombination of O2with discharge‐produced oxygen atoms at 1 torr and 80–120 K, is expanded into a low‐pressure (∼3 mtorr) environment where its infrared radiation is observed without interference from infrared background effects. The observed spectral distributions are interpreted by using a least squares/spectral synthesis method, in which the vibrational state populations and spectroscopic parameters are adjusted in computed spectra so as to provide the best fits to the observed spectra. The (001) → (000) transition is responsible for most of the observed intensity; however, (Δυ3= 1) emission from higher vibrational levels is also seen, extending to ∼11 μm (υ3′ ∼ 6). Although the observed spectral distributions are affected by collisional deactivation occurring in the discharge region, the apparent degree of vibrational excitation observed in these experiments should have considerable bearing on investigations of infrared radiation in

ISSN:0148-0227    

DOI:10.1029/JC086iC06p05247

年代:1981

数据来源: WILEY