Microphysics and chemistry of sulphate aerosols at warm stratospheric temperatures

Drdla, K.; Pueschel, R. F.; Strawa, A. W.; Cohen, R. C.; Hanisco, T. F.

doi:10.1029/1999jd900406

Cited by 9 publications

(6 citation statements)

References 58 publications

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“…[15] The gas-phase chemistry [Drdla et al, 1999] incorporates 58 species, grouped into 29 families. 188 gas-phase reactions (41 of which are photodissociations) are considered, using rates from the work of Sander et al [2000].…”

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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“…Lightning can produce large amounts of NO [ Jeker et al , 2000], and NO x can be oxidized to HNO 3 over a period of several days by the daytime reaction with OH [ Jaegle et al , 1998]. To evaluate this possibility at tropical tropopause conditions, a chemical trajectory box model [ Drdla et al , 1999] was used to simulate the conversion of lightning‐produced NO to HNO 3 . An initial injection of 3 ppbv NO was assumed, consistent with past observations [ Stith et al , 1999; Jeker et al , 2000].…”

Section: Nitric Acid Concentrations At the Tropical Tropopausementioning

confidence: 99%

Nitric acid concentrations near the tropical tropopause: Implications for the properties of tropical nitric acid trihydrate clouds

Jensen

Drdla

2002

Geophysical Research Letters

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[1] In situ measurements of NO y , NO x , and temperature confirm that nitric acid trihydrate (NAT) particles could form at the tropical tropopause. The HNO 3 mixing ratio near the tropical tropopause is typically no larger than about 0.2-0.3 ppbv, and the corresponding equilibrium mass of nitric acid trihydrate (NAT) is no larger than 0.3 mg m À3. Considerably larger NAT condensed masses are required to explain the HALOE extinctions; however, localized regions of enhanced HNO 3 produced by oxidation of lightning-generated NO might exist. NAT layers would only be identified as clouds by SAGE II if the particle diameters are in the optimum range of about 0.6 to 2 mm and the condensed NAT mass is larger than about 0.2 mg m À3. The SAGE II extinction ratio measurements (0.5 mm/1.0 mm) cannot distinguish NAT clouds from mixtures of optically thin ice clouds and background aerosols.

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“…These were the data from UARS, multiyear observations of column abundance of NO 2 and HNO 3 from the surface, and high spatial resolution in situ measurements of NO y from balloons and aircraft. Extensive model‐measurement comparison were done by several research groups [ Morris et al , 1997; Sen et al , 1998; Danilin et al , 1999; Drdla et al , 1999; Gao et al , 1999]. It was found that NO x /NO y ratios and the NO 2 abundance predicted by the atmospheric models were substantially less than their observed values in the 30 to 7 mbar region.…”

Section: Introductionmentioning

confidence: 99%

A modeling study of the stratospheric NO_x/NO_y and NO_x/HNO₃ ratios: Single‐ versus dual‐channeled mode of OH, NO₂ association

Prasad

2003

J. Geophys. Res.

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[1] UARS observations bearing upon the NO x /NO y and NO x /HNO 3 ratios were revisited within the framework of advances in laboratory studies that were spurred by the findings, around 1999, of considerable model underestimation of the observations. The objective was to study the two models of the OH, NO 2 association reaction, one that considers the single HNO 3 product channel and the other that considers dual HNO 3 and HOONO products channels. Rate coefficients of the OH + HNO 3 and the single-channeled OH + NO 2 ! HNO 3 reactions recommended in JPL00-3 produce remarkably improved agreement between the modeled and observed NO x /HNO 3 and NO x /NO y , compared to the case with the recommendations in JPL-97. This agrees with the results of other previous studies, such as those using the Photochemistry of Ozone Loss in the Arctic Region in Summer and MkIV data. The consumption of OH, NO 2 pair in the lower stratosphere via the three-body association occurs at almost the same rate (within ±5%) whether the singleor the double-channeled version of that process is used with rate coefficients from JPL00-3. However, only 70-80% of this consumption yields HNO 3 in the dual-channeled version, compared to 100% in the case of the single-channeled version. Consequently, the dualchanneled model of HNO 3 formation performs better than the single-channeled model in predicting NO x /HNO 3 and NO x /NO y ratios. At 46.4 mbar, for example, the mean percentage difference between the modeled and the observed NO x /HNO 3 equals about À10%, if HOONO is included. The corresponding number is about À19% when HOONO is excluded. Because laboratory experiments on OH, NO 2 association that directly detect HOONO isomer are still maturing, further studies are needed. Further studies are also needed to understand the intriguing tendency of the model-measurement differences to maximize around 20 mbar.INDEX TERMS: 0317 Atmospheric Composition and Structure: Chemical kinetic and photochemical properties; 0322 Atmospheric Composition and Structure: Constituent sources and sinks; 0340 Atmospheric Composition and Structure: Middle atmosphere-composition and chemistry; KEYWORDS: OH, NO 2 association reaction, NO x /NO y ratio, HOONO channel, HOONO conformers, HNO 3 formation mechanism, NO x /HNO 3 ratio Citation: Prasad, S. S., A modeling study of the stratospheric NO x /NO y and NO x /HNO 3 ratios: Single-versus dual-channeled mode of OH, NO 2 association,

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Microphysics and chemistry of sulphate aerosols at warm stratospheric temperatures

Cited by 9 publications

References 58 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

Nitric acid concentrations near the tropical tropopause: Implications for the properties of tropical nitric acid trihydrate clouds

A modeling study of the stratospheric NO_x/NO_y and NO_x/HNO₃ ratios: Single‐ versus dual‐channeled mode of OH, NO₂ association

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Microphysics and chemistry of sulphate aerosols at warm stratospheric temperatures

Cited by 9 publications

References 58 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

Nitric acid concentrations near the tropical tropopause: Implications for the properties of tropical nitric acid trihydrate clouds

A modeling study of the stratospheric NOx/NOy and NOx/HNO3 ratios: Single‐ versus dual‐channeled mode of OH, NO2 association

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A modeling study of the stratospheric NO_x/NO_y and NO_x/HNO₃ ratios: Single‐ versus dual‐channeled mode of OH, NO₂ association