Evaluation of effects of stratospheric ozone to policy relevant background ozone
01 Jan 2011-
TL;DR: In this paper, the authors evaluate ozone in the United States, chemical transport modeling is required for simulating the condition of the where absence of North American (NA) anthropogenic emissions while including all the natural processes and nonNA emission influences.
Abstract: Policy Relevant Background (PRB) ozone was introduced for the purposes of informing decisions about the National Ambient Air Quality Standard (NAAQS) of ozone. It is defined by USEPA as the background ozone level in absence of anthropogenic emissions from continental North American. In other words, it represents the best achievable ozone condition and “how much controllable ozone is available through emission reduction”. In ambient environment, ozone is produced from both natural and anthropogenic processes. It is clear that many processes including local emission-induced ozone, longrange transport of air pollution, stratospheric ozone intrusion and photolysis are contributed to the overall tropospheric ozone in North America [He et al., 1999; Price et al., 2004; Wang et al., 2009]. To evaluate PRB ozone in the United States, chemical transport modeling is required for simulating the condition of the where absence of North American (NA) anthropogenic emissions while including all the natural processes and NonNA emission influences
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TL;DR: In this paper, the effects of aerosol impacts on NO 2 photolysis rates and ozone production in the troposphere were studied by applying a modern sensitivity analysis technique ADIFOR on a coupled transport/chemistry/radiative transfer model.
Abstract: Aerosol impacts on NO 2 photolysis rates and ozone production in the troposphere are studied by applying a modern sensitivity analysis technique ADIFOR on a coupled transport/chemistry/radiative transfer model. Four representative types of tropospheric aerosol (rural, urban, maritime, and desert) are evaluated in terms of loading strength and radiative characteristics. The effects of relative humidity (RH), aerosol vertical loading profile, and NO x (NO+NO 2 ) emission are also studied. The presence of absorbing aerosols in the boundary layer is found to inhibit near-ground ozone formation and to reduce ground level ozone by up to 70% in polluted environments. The presence of strongly scattering aerosols may increase ozone concentration in the lower boundary layer, but their effects vary with season, NO x , nonmethane hydrocarbon emission (NMHC), and temperature. Ozone production in the upper troposphere can be either enhanced or weakened, depending on the scattering and absorbing ability of aerosol particles and availability of NO x . In the lower troposphere, NO 2 photolysis and ozone production rates are most sensitive to urban aerosol, followed by rural, then desert, and finally, maritime aerosol. As expected, NMHC, and NO x emissions also are found to have a large influence on O 3 formation.
112 citations
TL;DR: In this article, the theoretical basis of three different methods to validate and intercompare satellite measurements of atmospheric composition, and apply them to tropospheric ozone retrievals from the Tropospheric Emission Spectrometer (TES) and the Ozone Monitoring Instrument (OMI).
Abstract: . We analyze the theoretical basis of three different methods to validate and intercompare satellite measurements of atmospheric composition, and apply them to tropospheric ozone retrievals from the Tropospheric Emission Spectrometer (TES) and the Ozone Monitoring Instrument (OMI). The first method (in situ method) uses in situ vertical profiles for absolute instrument validation; it is limited by the sparseness of in situ data. The second method (CTM method) uses a chemical transport model (CTM) as an intercomparison platform; it provides a globally complete intercomparison with relatively small noise from model error. The third method (averaging kernel smoothing method) involves smoothing the retrieved profile from one instrument with the averaging kernel matrix of the other; it also provides a global intercomparison but dampens the actual difference between instruments and adds noise from the a priori. We apply the three methods to a full year (2006) of TES and OMI data. Comparison with in situ data from ozonesondes shows mean positive biases of 5.3 parts per billion volume (ppbv) (10%) for TES and 2.8 ppbv (5%) for OMI at 500 hPa. We show that the CTM method (using the GEOS-Chem CTM) closely approximates results from the in situ method while providing global coverage. It reveals that differences between TES and OMI are generally less than 10 ppbv (18%), except at northern mid-latitudes in summer and over tropical continents. The CTM method further allows for CTM evaluation using both satellite observations. We thus find that GEOS-Chem underestimates tropospheric ozone in the tropics due to possible underestimates of biomass burning, soil, and lightning emissions. It overestimates ozone in the northern subtropics and southern mid-latitudes, likely because of excessive stratospheric influx of ozone.
105 citations
"Evaluation of effects of stratosphe..." refers methods in this paper
...In this study, the GEOS-Chem v8-02-03 global chemical transport model was used to evaluate the potential impacts of stratospheric ozone and longrange transport of air pollution to surface ozone [Zhang et al., 2010]....
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TL;DR: The authors used a global chemical transport model to quantify the effects of anthropogenic emissions from Canada, Mexico, and outside North America on daily maximum 8-hour average ozone concentrations in US surface air.
90 citations
"Evaluation of effects of stratosphe..." refers background in this paper
...It is clear that many processes including local emission-induced ozone, longrange transport of air pollution, stratospheric ozone intrusion and photolysis are contributed to the overall tropospheric ozone in North America [He et al., 1999; Price et al., 2004; Wang et al., 2009]....
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Journal Article•
TL;DR: In this paper, the authors identified 11 transpacific long-range transport (LRT) episodes, which contain significantly elevated levels of CO, O 3, and aerosol scattering.
Abstract: On the basis of observations from the 1997-2002 Photochemical Ozone Budget of the Northeast Pacific (PHOBEA) experiments, we have identified 11 transpacific long-range transport (LRT) episodes, which contain significantly elevated levels of CO, O 3 , and aerosol scattering. The LRT episodes were determined from aircraft and ground-based observations of CO, O 3 , aerosol scattering coefficient, and 281 whole air samples analyzed for nonmethane hydrocarbons (NMHC). The ratio of excess O 3 to excess CO (ΔO 3 /ΔCO) for the 11 LRT episodes ranged from -0.06 to 1.52. Lower ΔO 3 /ΔCO ratios ( 0.50) are found in LRT episodes transported higher in the free troposphere and are probably due to a mixing of LRT pollution plumes with ozone-rich upper tropospheric air. Using PHOBEA observations, backward trajectories, and data from other experiments in the North Pacific (TRACE-P, ACE-Asia, PEM-West B) we calculate OH concentrations using two different methods. For the LRT episodes we obtain mean OH concentrations between 1.9 x 10 5 and 1.3 × 10 6 molecules cm -3 . We also present a method using dispersion models and observations to calculate the rate of dilution, k dil , with background air during LRT. A low k dil indicates less mixing with background air during transport, while a high value represents more entrainment with background air. For the April 2001 LRT episode we calculate a mean k dil of 0.010 ± 0.004 hr -1 and an OH radical concentration of 2 x 10 5 molecules cm -3 . On the basis of these calculations we find that the large mineral dust transport episode, which took place in April 2001, was associated with the lowest OH concentration of the 11 episodes considered, implicating a strong role for heterogeneous chemistry during LRT.
68 citations
TL;DR: Price et al. as mentioned in this paper identified 11 transpacific long-range transport (LRT) episodes, which contain significantly elevated levels of CO, O3, and aerosol scattering.
Abstract: [1] On the basis of observations from the 1997–2002 Photochemical Ozone Budget of the Northeast Pacific (PHOBEA) experiments, we have identified 11 transpacific long-range transport (LRT) episodes, which contain significantly elevated levels of CO, O3, and aerosol scattering. The LRT episodes were determined from aircraft and ground-based observations of CO, O3, aerosol scattering coefficient, and 281 whole air samples analyzed for nonmethane hydrocarbons (NMHC). The ratio of excess O3 to excess CO (DO3/DCO) for the 11 LRT episodes ranged from � 0.06 to 1.52. Lower DO3/DCO ratios ( 0.50) are found in LRT episodes transported higher in the free troposphere and are probably due to a mixing of LRT pollution plumes with ozone-rich upper tropospheric air. Using PHOBEA observations, backward trajectories, and data from other experiments in the North Pacific (TRACE-P, ACE-Asia, PEM-West B) we calculate OH concentrations using two different methods. For the LRT episodes we obtain mean OH concentrations between 1.9 � 10 5 and 1.3 � 10 6 molecules cm � 3 . We also present a method using dispersion models and observations to calculate the rate of dilution, kdil, with background air during LRT. A low kdil indicates less mixing with background air during transport, while a high value represents more entrainment with background air. For the April 2001 LRT episode we calculate a mean kdil of 0.010 ± 0.004 hr � 1 and an OH radical concentration of 2 � 10 5 molecules cm � 3 .O n the basis of these calculations we find that the large mineral dust transport episode, which took place in April 2001, was associated with the lowest OH concentration of the 11 episodes considered, implicating a strong role for heterogeneous chemistry during LRT. INDEX TERMS: 0305 Atmospheric Composition and Structure: Aerosols and particles (0345, 4801); 0340 Atmospheric Composition and Structure: Middle atmosphere—composition and chemistry; 0341 Atmospheric Composition and Structure: Middle atmosphere—constituent transport and chemistry (3334); 0368 Atmospheric Composition and Structure: Troposphere—constituent transport and chemistry; KEYWORDS: long-range transport, photochemistry, Pacific Citation: Price, H. U., D. A. Jaffe, O. R. Cooper, and P. V. Doskey (2004), Photochemistry, ozone production, and dilution during long-range transport episodes from Eurasia to the northwest United States, J. Geophys. Res., 109, D23S13,
67 citations