摘要:

A model for reversible mass transport of HO2between the gas and aqueous phases of liquid water clouds is used to examine the coupling of reaction kinetics of this species in the two phases. The Henry's law coefficient of HO2necessary for this analysis is evaluated by means of a thermochemical cycle involving O2−(aq) to be (1–3) × 103Matm−1. The mass accommodation coefficient α for uptake of HO2by liquid water is not known and is treated as an adjustable parameter. Results are expressed in terms of yields of HNO3(g), H2O2(g) and H2O2(aq) relative to the initial photochemical generation rate of OH(g). For large values of α (≳10−3) aqueous‐phase H2O2formation may be a major radical sink process, but the rate of aqueous‐phase H2O2production decreases strongly with α ≲10−3. Substantial difference, e.g., a factor of as much as 50 in gas‐phase HO2concentration, is found between kinetic calculations where uptake of HO2by cloud droplets is treated reversibly versus irreversibly. Such differences demonstrate the need to treat the dissolution process as reversible, even for reacti

ISSN:0148-0227    

DOI:10.1029/JD089iD07p11589

年代:1984

数据来源: WILEY

摘要:

The concentrations of methane in the old and ancient atmospheres of the earth can be deduced by analyzing the air in bubbles embedded in polar ice cores. Upon analyzing some 80 ice core samples from the polar regions we found that the concentration of methane 250 years ago and earlier was only 700 (±30) ppbv, or about 45% of present levels. A rapid and significant increase of atmospheric methane started about 150 years ago. The rate of increase has escalated since then and is about 1.3%/yr at present. We also found that the concentration of methane in the atmosphere 250 years ago and earlier, when methane was not increasing, was 10% (±4%) higher in the Arctic as compared to the Antarctic. This finding is consistent with the expected ratio of about 1.07–1.11 obtained from a global mass balance model and the primarily land‐based natural sources of methane, estimated to be about 280 Tg/yr, which may have been the only sources several hundred years ago, when human activities did not contribute significantly to the global methane

ISSN:0148-0227    

DOI:10.1029/JD089iD07p11599

年代:1984

数据来源: WILEY

摘要:

The Bubble Interfacial Microlayer Sampler (BIMS) was used in the North Atlantic to determine the enrichment factors, relative to sodium and the ocean (EFsea), for a series of trace metals on bubble‐derived atmospheric sea salt particles. No enrichment was found for K and Mg within the analytical precision of ±10%. Mean EFseavalues determined for Al, Co, Cu, Fe, Mn, Pb, V, and Zn ranged from 10 to 20,000. Positive correlations were found between bubble generation depth and the EFseavalues for Fe, Pb, Sc, and Zn. Estimates suggest that the ocean is the primary global source of atmospheric K and Mg, that it is potentially a nontrivial (5–20% of the total) source of atmospheric Cu, V, and possibly Zn, and that it is an insignificant source of Al, Co, Fe, Mn, Pb, and Sc. In the remote North Pacific, during certain periods of the year, the ocean may be the primary source for all these elements present on aerosol particles with diameters greater than

ISSN:0148-0227    

DOI:10.1029/JD089iD07p11607

年代:1984

数据来源: WILEY

摘要:

Numerical results are presented for the diurnal variations of stratospheric species, including the chlorine species. The calculated diurnal variation of the column density of stratospheric chlorine monoxide (ClO) appears to be in good agreement with the recent measurement obtained from ground‐based millimeter‐wave spectroscopy. The observed large diurnal variation of the column density of ClO above 30 km can be understood in terms of various exchange processes between ClOx(Cl+ClO) and the temporary chlorine reservoirs (ClONO2and HOCl). The rapid early morning rise in the column density of ClO above 30 km is mainly attributed to photolysis of ClONO2, whereas its continual decrease during the nighttime may be attributed to the recombination of ClO with NO2, forming ClONO2as the major product. The predicted diurnal behavior of the upper stratospheric ClO, however, is mainly due to the exchange between ClOxand HOCl. Observation of the diurnal behavior of ClO in the upper stratosphere can place important constraints on the chemistry of H

ISSN:0148-0227    

DOI:10.1029/JD089iD07p11619

年代:1984

数据来源: WILEY

摘要:

A numerical model employing the residual Eulerian formulation and small eddy diffusivity coefficients is used to calculate the distributions of chemical tracers and chlorine species. The predicted densities of nitrous oxide, methane, and chlorocarbons are shown to be in good agreement with available observations and to exhibit strong latitude gradients. Computed spatial variations in methane produce large variations in the HCl and ClO densities. In particular, a pronounced local minimum in HCl is obtained near 40 km for certain latitudes and seasons, with a corresponding maximum in ClO, primarily as a result of transport of atmospheric methane. It is suggested that spatial and short‐term temporal variability in methane has potentially important consequences for the HCl and ClO distributions in the atmosphere, and their variability, and for the chlorine‐catalyzed destruction of stratospheric oz

ISSN:0148-0227    

DOI:10.1029/JD089iD07p11633

年代:1984

数据来源: WILEY

摘要:

Spectra obtained by balloon‐borne Michelson interferometers over South Australia in 1977 and New Mexico in 1978 have been analyzed to obtain HF mixing ratios using a recently developed, sensitive analysis method for Fourier transform spectroscopy. The stratospheric HF mixing ratio appears to be significantly larger in the northern hemisphere than in the southern hemisphere for similar respective latitudes with the profiles having a similar vertical shape: the HF mixing ratio increases from 20 to 25 km, stays approximately constant between 25 and 35 km, and increases upward from 35 km. A brief discussion is given of possible causes for the HF profile shap

ISSN:0148-0227    

DOI:10.1029/JD089iD07p11645

年代:1984

数据来源: WILEY

摘要:

We present measurements of an altitude‐dependent upper limit for stratospheric hydrogen peroxide that is substantially lower than previously determined limits. The data were obtained with a remote‐sensing far‐infrared spectrometer during a balloon flight on 23 January 1983. Our 2 sigma upper limit is 0.05 ppbv near 26.5 km, and is larger above and below that altitude. This new upper limit is compared with two currently available modelling calculations for H2O2; in the neighborhood of 32 km, it is slightly lower than, but comparable to these theoretical profiles. The implications for measurement of H2O2at different latitudes and seasons are briefly disc

ISSN:0148-0227    

DOI:10.1029/JD089iD07p11655

年代:1984

数据来源: WILEY

摘要:

The ultraviolet absorption cross sections for molecular oxygen have been determined for wavelengths between 205 and 225 nm, for temperatures between 206 and 327 K, and at a pressure from 100 to 750 torr. No temperature effect on the O2cross sections was observed in the Herzberg continuum. It was necessary to separate the extremely weak O2absorption from the stronger collision‐induced absorption. These experimental data and similar data by others were interpreted in terms of a theoretical expression for the shape of the Herzberg continuum absorption spectrum. The O2absorption cross sections are in good agreement with the values measured in the stratosphere by Herman and Mentall (1982

ISSN:0148-0227    

DOI:10.1029/JD089iD07p11661

年代:1984

数据来源: WILEY

摘要:

The Angström coefficient profiles deduced from 93 SAGE Satellite observations in July 1980 between 50°N and 70°N have been used to study the variation of the aerosol size distribution in the Mount St. Helens aerosol layer. In most cases a layer of large particles corresponding to the maximum extinction at 18–20 km is topped by a layer of small particles. The study of profiles averaged over 10° latitude bands for May to November 1980 have confirmed the extent of this situation, which contrasts with a rather constant size distribution within the unperturbed stratosphere in 1979. Assuming an equivalent log‐normal size distribution with an effective variance of 0.250, the logarithmic mode radius is found around 0.20 μm for the large‐particle layer and around 0.06 μm for the top layer. The inferred mass density profile is strongly influenced by thi

ISSN:0148-0227    

DOI:10.1029/JD089iD07p11666

年代:1984

数据来源: WILEY

摘要:

The ozone density of the earth's mesosphere in the 1.0–0.1 mbar (48 to 70 km) region has been measured at sunlit latitudes for the period from December 1981 until the present by an ultraviolet spectrometer on the Solar Mesosphere Explorer satellite. Results for 1982 are reported. The ozone mixing ratios are found to be highly variable in time and place, with maxima occurring in the winter hemispheres. The results show complex time variations at all pressure levels, with annual and semiannual variations apparent at most pressures and latitudes. A relative maximum occurs in July at the equato

ISSN:0148-0227    

DOI:10.1029/JD089iD07p11677

年代:1984

数据来源: WILEY