ISSN:0148-0227    

DOI:10.1029/JD091iD05p05321

年代:1986

数据来源: WILEY

摘要:

The total column abundance of NO3in the stratosphere at night has been measured for 5 years at 40°N, with additional observations at 19°, 31°, 51°, and 64°N. In this set of measurements the NO3abundance varied from slightly greater than 1014cm−2to below the detection limit of 1013cm−2. At low latitude the mean abundance appears to be in general agreement with a model based upon simple NOxchemistry, except that the summer values tend to be smaller than spring values. At mid‐latitude, the variation in abundance exceeds a factor of 5, which is greater than predicted. Large day‐to‐day variations in abundance are observed, especially in summer. The winter values mostly fall below the detection limit, which can be as low as 1013cm−2. The abundance appears to exhibit a close relation to the highest latitude experienced by stratospheric air prior to its arrival at mid‐latitude; the higher the latitude the lower is the NO3abundance. At 64°N the NO3abundance was below the detection limit of 1.5 × 1013cm−2, both in April and November. This is far below what is predicted, especially in April. These observations suggest that a scavenger of NO3is continually produced in the stratosphere, particularly at high latitude, and when there is a strong equatorward flow, the scavenger can at least reach mid‐latitude. The identity of the scavenger remains unknown, as does the importance of its role as a sink fo

ISSN:0148-0227    

DOI:10.1029/JD091iD05p05323

年代:1986

数据来源: WILEY

摘要:

The NO3radical in the aqueous phase is a strong oxidizing agent which reacts rapidly with a wide variety of inorganic and organic species. Within nighttime clouds the production of gaseous NO3from the reaction of NO2with O3followed by heterogeneous scavenging of NO3by cloud droplets can represent a significant source of these reactive radicals to cloud water. Model calculations indicate that in addition to leading to the production of NO3−in cloud water, this aqueous‐phase source of NO3can, under the appropriate conditions and depending upon the values for a number of uncertain rate constants, have a significant impact upon the rate of conversion of SO2to H2

ISSN:0148-0227    

DOI:10.1029/JD091iD05p05331

年代:1986

数据来源: WILEY

摘要:

The gas phase reactions of the NO3radical, a ubiquitous constituent of nighttime atmospheres with the reduced sulfur compounds COS, CS2, CH3SH, C2H5SH, and CH3SSCH3have been investigated. Using a relative rate technique and long path length Fourier transform infrared (FT‐IR) absorption spectroscopy, rate constants for these reactions have been determined at 297 ± 2 K in one atmosphere of air. The resulting rate constants (in units of 10−13cm3molecule−1s−1) are: COS,<0.0004; CS2,<0.008; CH3SH, 10 ± 3; C2H5SH, 12 ± 3; and CH3SSCH3, 0.42 ± 0.09. A number of products from these reactions were determined using FT‐IR absorption spectroscopy and combined gas chromatography/mass spectrometry. Atmospheric implications of these kinetic and product data

ISSN:0148-0227    

DOI:10.1029/JD091iD05p05338

年代:1986

数据来源: WILEY

摘要:

Kinetic studies have been made of the CH3CHO‐NO3reaction in dilute mixtures of CH3CHO, NO2, and N2O5in synthetic air at 700 torr and room temperature. During the course of the reaction, reactant and product analyses were made in situ, using long path length Fourier transform infrared spectroscopy. The major products of the reaction for these conditions are HONO2and CH3COO2NO2. All evidence suggests that the first step in the reaction sequence, NO3+ CH3CHO → HONO2+ CH3CO, proceeds with a rate constant,k= (2.1 ± 0.4) × 10−15cm3molecule−1s−1at 299 ± 1 K. These results, combined with other reaction rate data pertinent to tropospheric chemistry, are used to computer simulate the homogeneous chemistry of the polluted troposphere and to evaluate theoretically the nature of the nightti

ISSN:0148-0227    

DOI:10.1029/JD091iD05p05347

年代:1986

数据来源: WILEY

摘要:

The quantum yield for the production of NO3in the N2O5photolysis at 248 nm was measured to be unity. The concentration of NO3produced upon photolysis was measured using 662‐nm laser absorption. The quantum yields for O(3P) production in the photolysis of N2O5at 248 nm, 266 nm, 287 nm, and 289 nm were also measured using resonance fluorescence detection of O(3P). The quantum yield for O(3P) decreased from 0.7 at 248 nm to 0.15 at 289 nm. It is postulated that N2O5photolysis at wavelengths less than 298 nm yields NO3+ NO + O(3P)in addition to NO3+ NO

ISSN:0148-0227    

DOI:10.1029/JD091iD05p05355

年代:1986

数据来源: WILEY

摘要:

The photostationary state (PSS) involving NO, NO2, and O3has been studied at a site located in the Colorado mountains. During the daytime in summer the concentration of NO2relative to the concentration of NO is greater than expected from the PSS. These results indicate that an additional oxidantOXother than O3is converting NO to NO2. The level ofOXdepends on season, NOx(NO + NO2) concentration, and solar UV intensity. The maximumOXlevels occur for an NOxmixing ratio of about 0.4 parts per billion by volume (ppbv). For NOxmixing ratios below 0.1 ppbv, no substantial imbalance in the PSS is observed. For NOxconcentrations between 0.25 and 1.0 ppbv, theOXlevel depends linearly on solar UV intensity. In the winter the level ofOXis much lower than in the summer for all NOxconcentrations and solar UV intensities. The nature ofOX, as indicated from the NOx‐catalyzed formation of O3, is examine

ISSN:0148-0227    

DOI:10.1029/JD091iD05p05361

年代:1986

数据来源: WILEY

摘要:

Tunable diode laser absorption spectroscopy has been applied to the determination of gas phase hydrogen peroxide in ambient air with sub‐ppbv (parts per billion by volume) detection limits for measurement times of the order of minutes. The methods for calibrating the instrument and for assuring the absence of spectroscopic and sampling interferences at the level of our present detection limits are described. Ambient air monitoring with our system indicates that the hydrogen peroxide mixing ratio is often<0.3 ppbv. Five‐minute average mixing ratios of up to 2.9 ppbv have been measured at sites in southwestern Ontario, Canada, during the summer months of 1984 and 1985, while the highest 1‐hour average value observed was 2.1

ISSN:0148-0227    

DOI:10.1029/JD091iD05p05371

年代:1986

数据来源: WILEY

摘要:

The concentrations of HNO3and NO3−particulates have been measured simultaneously with NO and NO2concentrations at a nonurban field site in the Colorado mountains during a 5‐year period. Seasonal and diurnal trends of these species are presented. Correlations of HNO3and NO3−levels with each other and with NOx(NO + NO2) levels elucidate atmospheric chemical processes. Generally, the measurements agree with the widely accepted views of odd nitrogen chemical cycles in the atmosphere, with the exception that fast surface deposition of nitric acid replaces rain out as the primary loss mechanism. Local anthropogenic sources of odd nitrogen are primarily responsible for the airborne nitrate in the air samples at this rural mountain

ISSN:0148-0227    

DOI:10.1029/JD091iD05p05379

年代:1986

数据来源: WILEY

摘要:

It is argued on the basis of a two‐dimensional stratospheric model that upward transport of oxides of nitrogen produced by lightning in the tropical troposphere can significantly enhance the concentrations of NOY, the composite of all forms of odd nitrogen, in the lower stratosphere. The impact can be as large as a factor of 10 at 22 km near the equator, dropping to less than 50% above 30 km. Inclusion of the lightning source of NOY in the model results in improved agreement with available satellite data for the sum of NO2and HNO3. Lightning is important even if only 5% of the nitrogen oxides produced enters the stratosphere. This amounts to ∼2 × 105t N yr−1and is equivalent to about one third of the global production from in situ photochemical reaction of N2O with

ISSN:0148-0227    

DOI:10.1029/JD091iD05p05395

年代:1986

数据来源: WILEY