Heterogeneous reactions on and in sulfate aerosols: Implications for the chemistry of the midlatitude tropopause region

Hendricks, Johannes; Lippert, Erich; Petry, H.; Ebel, A.

doi:10.1029/1998jd100098

Cited by 35 publications

(29 citation statements)

References 65 publications

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“…For reactions (R11) and (R12), the temperature and composition dependence of k II has not been measured. As done by Hendricks et al [1999], the single measurement of (R12) by Abbatt and Nowak [1997] has been extrapolated, assuming the behavior of (R12) is comparable to (R5). For (R11), a diffusion‐limited rate has been assumed, consistent with the data of Abbatt [1995].…”

Section: Model Descriptionmentioning

confidence: 99%

Microphysical modeling of the 1999–2000 Arctic winter 2. Chlorine activation and ozone depletion

Drdla

Schoeberl

2002

J. Geophys. Res.

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The effect of polar stratospheric clouds (PSCs) on ozone depletion during the 1999–2000 Arctic winter has been assessed using a coupled microphysical/photochemical model. Scenarios spanned a large range of denitrification levels, with up to 80% vortex‐averaged denitrification and localized dehydration. PSC composition was varied, exploring sensitivity to heterogeneous reaction rates. PSC formation during February was critical in causing severe ozone depletion below 500 K. Heterogeneous chemistry on these PSCs was able to continuously reactivate the newly produced ClONO2. Only 30–40% vortex‐averaged ozone loss would have occurred without this chlorine reactivation; with it, 21–32% more ozone loss is possible. During February (unlike earlier in the winter), chlorine reactivation and ozone loss were sensitive to heterogeneous chemistry: varying the reactivities altered ozone loss by 11%. An analysis of the critical temperatures for heterogeneous chemistry demonstrates the importance of temperatures near the nitric acid trihydrate condensation point, where many uncertainties influence heterogeneous reaction rates. Chlorine reactivation during February also prevented denitrification from enhancing ozone loss until March: 70% vortex‐averaged denitrification only enhanced ozone depletion by 3% on 10 March. The mid‐March vortex breakup probably limited the extent of ozone depletion; if the vortex had remained stable until 15 April, 16% ozone loss (out of a total 68% ozone loss) could be caused by 70% denitrification. Ozone loss intensifies nonlinearly with enhanced denitrification: in individual air parcels with 90% denitrification, 40% ozone loss in mid‐April can be attributed to denitrification alone.

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Section: Model Descriptionmentioning

confidence: 99%

Microphysical modeling of the 1999–2000 Arctic winter 2. Chlorine activation and ozone depletion

Drdla

Schoeberl

2002

J. Geophys. Res.

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“…The loss of N 2 O 5 on an aerosol is thus recognised as an important removal process for NO x in many regions of the atmosphere (Chartrand and McConnell, 1999;Hendricks et al, 1999;Evans and Jacob, 2005). The direct reduction in NO 3 and the indirect reduction of O 3 (due to repartitioning of NO x to NO y ) both impact on the oxidising power of the troposphere.…”

Section: Introductionmentioning

confidence: 99%

The interaction of N<sub>2</sub>O<sub>5</sub> with mineral dust: aerosol flow tube and Knudsen reactor studies

et al. 2008

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Abstract. The interaction of mineral dust with N 2 O 5 was investigated using both airborne mineral aerosol (using an aerosol flow reactor with variable relative humidity) and bulk samples (using a Knudsen reactor at zero humidity). Both authentic (Saharan, SDCV) and synthetic dust samples (Arizona test dust, ATD and calcite, CaCO 3 ) were used to derive reactive uptake coefficients (γ ). The aerosol experiments (Saharan dust only) indicated efficient uptake, with e.g. a value of γ (SDCV)=(1.3±0.2)×10 −2 obtained at zero relative humidity. The values of γ obtained for bulk substrates in the Knudsen reactor studies are upper limits due to assumptions of available surface area, but were in reasonable agreement with the AFT measurements, with: γ (SDCV)=(3.7±1.2)×10 −2 , γ (ATD)=(2.2±0.8)×10 −2 and γ (CaCO 3 )=(5±2)×10 −2 . The errors quoted are statistical only. The results are compared to literature values and assessed in terms of their impact on atmospheric N 2 O 5 .

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“…In contrast to the polar vortex, the prevailing temperatures in the midlatitude lowermost stratosphere are too high for PSCs to form. It has nevertheless been demonstrated by box model studies that heterogeneous reactions on background liquid aerosols lead to chemical ozone loss in the midlatitude lowermost stratosphere [ Kotamarthi et al , 1997; Drdla et al , 1999; Hendricks et al. , 1999, 2000].…”

Section: Introductionmentioning

confidence: 99%

Chemical ozone loss in the tropopause region on subvisible ice clouds, calculated with a chemistry‐transport model

2002

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[1] A global chemistry-transport model has been used to investigate the role of subvisible ice clouds in chemical ozone loss in the tropopause region. The three-dimensional subvisible cloud representation is based on 6-hourly European Centre for Medium-Range Weather Forecasts high cloud fields, assuming observed cloud particle radii and densities. The resulting seasonal average subvisible cloud occurrence agrees well with that observed by the Stratospheric Aerosol and Gas Experiment (SAGE) II instrument. The clouds are located along cold and warm fronts, associated with cyclonic activity. On the ice clouds, heterogeneous reactions occur similarly as on polar stratospheric clouds. The calculated chemical perturbations show high spatial variability, owing to the relatively detailed cloud representation. Halogen activation occurs only when the clouds are located at or above potential vorticity levels of 2- 3 PVU. The cloud-induced chlorine activation is stronger in June than in December with maximum ClO levels close to 100 pptv. Consequently, the calculated chemical ozone loss is stronger in June than in December with local maxima of similar to4%. The calculated chlorine activation is significantly lower compared to previous model results and shows an opposite seasonal behavior. Changing the cloud composition to a mix of liquid and ice reduces the chlorine activation even further. This illustrates the strong sensitivity to cloud properties. In addition, the reactive gas uptake on the ice cloud surfaces is poorly described for midlatitude tropopause conditions. Although these uncertainties prevent an accurate calculation of chemical ozone loss, it seems unlikely that heterogeneous chemistry on subvisible clouds can explain the observed negative ozone trends in the midlatitude lowermost stratosphere. Nevertheless, the ozone loss cannot be neglected, being of comparable magnitude as ozone formation by NOx from commercial air traffic

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Heterogeneous reactions on and in sulfate aerosols: Implications for the chemistry of the midlatitude tropopause region

Cited by 35 publications

References 65 publications

Microphysical modeling of the 1999–2000 Arctic winter 2. Chlorine activation and ozone depletion

Microphysical modeling of the 1999–2000 Arctic winter 2. Chlorine activation and ozone depletion

The interaction of N<sub>2</sub>O<sub>5</sub> with mineral dust: aerosol flow tube and Knudsen reactor studies

Chemical ozone loss in the tropopause region on subvisible ice clouds, calculated with a chemistry‐transport model

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Heterogeneous reactions on and in sulfate aerosols: Implications for the chemistry of the midlatitude tropopause region

Cited by 35 publications

References 65 publications

Microphysical modeling of the 1999–2000 Arctic winter 2. Chlorine activation and ozone depletion

Microphysical modeling of the 1999–2000 Arctic winter 2. Chlorine activation and ozone depletion

The interaction of N&lt;sub&gt;2&lt;/sub&gt;O&lt;sub&gt;5&lt;/sub&gt; with mineral dust: aerosol flow tube and Knudsen reactor studies

Chemical ozone loss in the tropopause region on subvisible ice clouds, calculated with a chemistry‐transport model

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The interaction of N<sub>2</sub>O<sub>5</sub> with mineral dust: aerosol flow tube and Knudsen reactor studies