Dependence of the OH concentration on solar UV

Ehhalt, D. H.; Rohrer, Franz

doi:10.1029/1999jd901070

Cited by 142 publications

(158 citation statements)

References 12 publications

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“…cm −3 . These values are still slightly higher than measurements from George et al (1999) in recent polluted plumes and in better agreement with Ehhalt and Roher (2000). Moreover, since modelled J-values and O 3 agree well with the data we can have some confidence in OH results.…”

Section: Results: Chemistry Deposition and Mixingsupporting

confidence: 60%

Lagrangian analysis of low altitude anthropogenic plume processing across the North Atlantic

et al. 2008

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Abstract. The photochemical evolution of an anthropogenic plume from the New-York/Boston region during its transport at low altitudes over the North Atlantic to the European west coast has been studied using a Lagrangian framework. This plume, originally strongly polluted, was sampled by research aircraft just off the North American east coast on 3 successive days, and then 3 days downwind off the west coast of Ireland where another aircraft re-sampled a weakly polluted plume. Changes in trace gas concentrations during transport are reproduced using a photochemical trajectory model including deposition and mixing effects. Chemical and wet deposition processing dominated the evolution of all pollutants in the plume. The mean net photochemical O 3 production is estimated to be −5 ppbv/day leading to low O 3 by the time the plume reached Europe. Model runs with no wet deposition of HNO 3 predicted much lower average net destruction of −1 ppbv/day O 3 , arising from increased levels of NO x via photolysis of HNO 3 . This indicates that wet deposition of HNO 3 is indirectly responsible for 80% of the net destruction of ozone during plume transport. If the plume had not encountered precipitation, it would have reached Europe with Correspondence to: E. Real (elsa.real@aero.jussieu.fr) O 3 concentrations of up to 80 to 90 ppbv and CO between 120 and 140 ppbv. Photochemical destruction also played a more important role than mixing in the evolution of plume CO due to high levels of O 3 and water vapour showing that CO cannot always be used as a tracer for polluted air masses, especially in plumes transported at low altitudes. The results also show that, in this case, an increase in O 3 /CO slopes can be attributed to photochemical destruction of CO and not to photochemical O 3 production as is often assumed.

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Section: Results: Chemistry Deposition and Mixingsupporting

confidence: 60%

Lagrangian analysis of low altitude anthropogenic plume processing across the North Atlantic

et al. 2008

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“…The parameters of [Ehhalt and Rohrer, 2000] are a = 0.83, b = 0.19, a = 4.1 Â 10 9 , b = 140, c = 0.41, and d = 1.7, indicating a strong, slightly nonlinear dependence of OH on j O1 D and a small but highly nonlinear contribution from j NO 2 . This OH parameterization does not include an influence of isoprene and other VOC changing the OH concentration [e.g., Lelieveld et al, 2008].…”

Section: Warneke Et Al: Biogenic Emissions and Inventoriesmentioning

confidence: 99%

“…[27] OH was measured only during the ICARTT2004 mission, but the data quality and coverage were very low and instead a parameterization was used to estimate [OH] along the flight tracks [Ehhalt and Rohrer, 2000]. The parameterization makes use of photolysis frequency measurements of j O 1 D and j NO 2 as well as the measured NO 2 concentrations in ppbv,…”

Section: Warneke Et Al: Biogenic Emissions and Inventoriesmentioning

confidence: 99%

Biogenic emission measurement and inventories determination of biogenic emissions in the eastern United States and Texas and comparison with biogenic emission inventories

et al. 2010

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During the NOAA Southern Oxidant Study 1999 (SOS1999), Texas Air Quality Study 2000 (TexAQS2000), International Consortium for Atmospheric Research on Transport and Transformation (ICARTT2004), and Texas Air Quality Study 2006 (TexAQS2006) campaigns, airborne measurements of isoprene and monoterpenes were made in the eastern United States and in Texas, and the results are used to evaluate the biogenic emission inventories BEIS3.12, BEIS3.13, MEGAN2, and WM2001. Two methods are used for the evaluation. First, the emissions are directly estimated from the ambient isoprene and monoterpene measurements assuming a well‐mixed boundary layer and are compared with the emissions from the inventories extracted along the flight tracks. Second, BEIS3.12 is incorporated into the detailed transport model FLEXPART, which allows the isoprene and monoterpene mixing ratios to be calculated and compared to the measurements. The overall agreement for all inventories is within a factor of 2 and the two methods give consistent results. MEGAN2 is in most cases higher, and BEIS3.12 and BEIS3.13 lower than the emissions determined from the measurements. Regions with clear discrepancies are identified. For example, an isoprene hot spot to the northwest of Houston, Texas, was expected from BEIS3 but not observed in the measurements. Interannual differences in emissions of about a factor of 2 were observed in Texas between 2000 and 2006.

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“…A value of 0.73 ± 0.21 (Jefferson et al, 1997) is adopted for γ . Because OH is not measured in this work, the OH concentration is estimated according to Ehhalt and Rohrer (2000),…”

Section: H 2 So 4 Measurementsmentioning

confidence: 99%

Measurements of gaseous H<sub>2</sub>SO<sub>4</sub> by AP-ID-CIMS during CAREBeijing 2008 Campaign

Zheng

Zhang

et al. 2011

Atmos. Chem. Phys.

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Abstract. As part of the 2008 Campaign of Air Quality Research in Beijing and Surrounding Regions (CAREBeijing 2008), measurements of gaseous sulfuric acid (H2SO4) have been conducted at an urban site in Beijing, China from 7 July to 25 September 2008 using atmospheric pressure ion drift – chemical ionization mass spectrometry (AP-ID-CIMS). This represents the first gaseous H2SO4 measurements in China. Diurnal profile of sulfuric acid is strongly dependent on the actinic flux, reaching a daily maximum around noontime and with an hourly average concentration of 5 × 106 molecules cm−3. Simulation of sulfuric acid on the basis of the measured sulfur dioxide concentration, photolysis rates of ozone and nitrogen dioxide, and aerosol surface areas captures the trend of the measured H2SO4 diurnal variation within the uncertainties, indicating that photochemical production and condensation onto preexisting particle surface dominate the observed diurnal H2SO4 profile. The frequency of the peak H2SO4 concentration exceeding 5 × 106 molecules cm−3 increases by 16 % during the period of the summer Olympic Games (8–24 August 2008), because of the implementation of air quality control regulations. Using a multivariate statistical method, the critical nucleus during nucleation events is inferred, containing two H2SO4 molecules (R2 = 0.85). The calculated condensation rate of H2SO4 can only account for 10–25 % of PM1 sulfate formation, indicating that either much stronger sulfate production exists at the SO2 source region or other sulfate production mechanisms are responsible for the sulfate production.

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Dependence of the OH concentration on solar UV

Cited by 142 publications

References 12 publications

Lagrangian analysis of low altitude anthropogenic plume processing across the North Atlantic

Lagrangian analysis of low altitude anthropogenic plume processing across the North Atlantic

Biogenic emission measurement and inventories determination of biogenic emissions in the eastern United States and Texas and comparison with biogenic emission inventories

Measurements of gaseous H<sub>2</sub>SO<sub>4</sub> by AP-ID-CIMS during CAREBeijing 2008 Campaign

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Dependence of the OH concentration on solar UV

Cited by 142 publications

References 12 publications

Lagrangian analysis of low altitude anthropogenic plume processing across the North Atlantic

Lagrangian analysis of low altitude anthropogenic plume processing across the North Atlantic

Biogenic emission measurement and inventories determination of biogenic emissions in the eastern United States and Texas and comparison with biogenic emission inventories

Measurements of gaseous H&lt;sub&gt;2&lt;/sub&gt;SO&lt;sub&gt;4&lt;/sub&gt; by AP-ID-CIMS during CAREBeijing 2008 Campaign

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Measurements of gaseous H<sub>2</sub>SO<sub>4</sub> by AP-ID-CIMS during CAREBeijing 2008 Campaign