Sensitivity of the predicted CO‐OH‐CH4 perturbation to tropospheric NOx concentrations

Hameed, Sultan; Pinto, Joseph P.; Stewart, R. W.

doi:10.1029/jc084ic02p00763

Cited by 59 publications

(13 citation statements)

References 22 publications

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“…It is well known from clean tropospheric models (Liu, 1977;Hameed et al, 1979;Fishman et al, 1979;Logan et al, 1981) that these two reactions play key roles in controlling the concentration of hydroxyl radicals. When NOx is lower than approximately 1 ppbv, reaction (1) x × x x 7: increases with NOx.…”

Section: Discussionmentioning

confidence: 99%

A study of ozone in the Colorado mountains

et al. 1983

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The seasonal and diurnal variations of ozone mixing ratios have been observed at Niwot Ridge, Colorado. The ozone mixing ratios have been correlated with the NOx(NO +NO2) mixing ratios measured concurrently at the site. The seasonal and diurnal variations in 03 can be reasonably well understood by considering photochemistry and transport, In the winter there is no apparent systematic diurnal variation in the 03 mixing ratio because there is little diurnal change of transport and a slow photochemistry. In the summer, the 03 levels at the site are suppressed at night due to the presence of a nocturnal inversion layer that isolates ozone near the surface, where it is destroyed. Ozone is observed to increase in the summer during the day. The increases in ozone correlate with increasing NO~ levels, as well as with the levels of other compounds of anthropogenic origin. We interpret this correlation as in-situ or in-transit photochemical production of ozone from these precursors that are transported to our site. The levels of ozone recorded approach 100 ppbv at NOt mixing ratios of approximately 3 ppbv. Calculations made using a simple clean tropospheric chemical model are consistent with the NOxrelated trend observed for the daytime ozone mixing ratio. However, the chemistry, which does not include nonmethane hydrocarbon photochemistry, underestimates the observed 03 production.

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Section: Discussionmentioning

confidence: 99%

A study of ozone in the Colorado mountains

et al. 1983

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“…Previous studies of the CO-OH-CH4 cycle [Sze, 1977;Chameides et al, 1977] suggest that increases in CO, due to anthropogenic emissions, or CH,• may have significant consequences with regard to tropospheric 03 and OH, as well as stratospheric H20. Studies by Hameed et al [1979] suggest that the CO-OH-CH,• interactions are sensitive to the ambient NO,, levels. This is due to the behavior of OH as NO,, levels are raised from lower to higher values.…”

Section: Carbon Monoxide and Cfm Perturbationsmentioning

confidence: 99%

On the relationship between the greenhouse effect, atmospheric photochemistry, and species distribution

Callis¹,

Natarajan

Boughner

1983

J. Geophys. Res.

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A radiative‐convective‐photochemical model that extends from 0 to 53 km is used to examine the effect on atmospheric constituents and thermal structure of changes in the atmospheric levels of CO2, CFM's, CO, N2O, and combinations of these species. Calculations were carried out for two reference atmospheres, one with high (HINOX) and one with low (LONOX) levels of NOx. The HINOX atmosphere has a vertical distribution of NOx similar to that resulting from recently published measurements. Such a distribution requires an unrealistically large value for the integrated tropospheric source of NOx. This suggests that the HINOX profile, and the measurements from which it was drawn, are more characteristic of contaminated, rather than clean, air masses. The HINOX troposphere provides a net photochemical source of O3 and is not greatly sensitive to downward transport of O3 from the stratosphere. The LONOX troposphere is a photochemical sink for O3 and, as a result, is sensitive to such variations in downward transport. Results of this study suggest that (1) infrared opacity changes due to CO2 and CFM increases can cause significant changes in tropospheric O3, OH, CH4, CO, and other species through changes in tropospheric water vapor; (2) perturbation or sensitivity studies conducted with tropospheric photochemical models may be subject to significant errors due to the absence of modulating effects provided by the stratosphere; (3) the response to given perturbations is significantly dependent upon the tropospheric NOx distribution present in the model; (4) CO2 growth rates must be included in the calculation of CFM‐O3 time scenarios and must account for surface temperature changes, especially in the steady state; and (5) that thermal or chemical perturbations introduce a variety of coupling or interactive mechanisms which are significant and which may provide compensating effects.

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“…The photolysis of ozone initiates most tropospheric photochemistry, the global budget of ozone influences world climate via radiative interactions, and ozone is a serious urban and rural tropospheric pollutant. Second, the concentration of hydroxyl radicals in the troposphere depends critically on the NO x concentration [Liu, 1977;Hameed et al, 1979]. Hydroxyl radicals are the predominant sink for a variety of atmospheric species including CO, CH 4, and other hydrocarbons, as well as NOx itself [Levy, 1971].…”

Section: Introductionmentioning

confidence: 99%

Systematic variations in the concentration of NO_x (NO Plus NO₂) at Niwot Ridge, Colorado

Parrish¹,

Hahn²,

Fahey³

et al. 1990

J. Geophys. Res.

118

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Measurements of the concentrations of NO and NO2 were made in the rural troposphere during a year's period in 1980–1981, during the summers of 1983, 1984, and 1987, and during the fall of 1984. The field site was located near Niwot Ridge, Colorado, at an elevation of 3 km. NO was measured with a chemiluminescence instrument, and NO2 was photolyzed to NO and measured by the same instrument. The performance of this instrument is discussed in detail. Aspects of the NOx (sum of NO and NO2) concentrations discussed include the overall distribution, the seasonal and diurnal cycles, the interannual variations, and the correlation with meteorological parameters. The meteorological dependence of [NOx] elucidates the mechanisms that transport NOx to the site. Even though the Denver urban area lies downwind from the site with respect to the prevailing winds, it is NOx from that area that predominates and is responsible for the enhanced acidic deposition and elevated ozone levels at the site. The valley‐mountain flow that is primarily responsible for this transport also may be an important mechanism for transporting anthropogenic pollution from the planetary boundary layer to the free troposphere. The major photochemical loss processes of NOx are reaction of NO2 with hydroxyl radicals to form HNO3 and the formation of PAN (peroxyacetyl nitrate) and perhaps other organic nitrates in the summer and reaction of NO2 with O3 to form NO3, N2O5, and further oxidized species in the winter.

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Sensitivity of the predicted CO‐OH‐CH₄ perturbation to tropospheric NO_x concentrations

Cited by 59 publications

References 22 publications

A study of ozone in the Colorado mountains

A study of ozone in the Colorado mountains

On the relationship between the greenhouse effect, atmospheric photochemistry, and species distribution

Systematic variations in the concentration of NO_x (NO Plus NO₂) at Niwot Ridge, Colorado

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Sensitivity of the predicted CO‐OH‐CH4 perturbation to tropospheric NOx concentrations

Cited by 59 publications

References 22 publications

A study of ozone in the Colorado mountains

A study of ozone in the Colorado mountains

On the relationship between the greenhouse effect, atmospheric photochemistry, and species distribution

Systematic variations in the concentration of NOx (NO Plus NO2) at Niwot Ridge, Colorado

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Product

Resources

About

Sensitivity of the predicted CO‐OH‐CH₄ perturbation to tropospheric NO_x concentrations

Systematic variations in the concentration of NO_x (NO Plus NO₂) at Niwot Ridge, Colorado