Upgrading photolysis in the p-TOMCAT CTM: model evaluation and assessment of the role of clouds

Voulgarakis, Apostolos; Savage, Nick; Wild, Oliver; Carver, G. D.; Clemitshaw, Kevin C.; Pyle, J. A.

doi:10.5194/gmd-2-59-2009

Cited by 36 publications

(37 citation statements)

References 48 publications

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“…Figure 2 summarizes the main findings of that study which compared local observations with model calculations employing both a box model and a three-dimensional global chemical transport model. Ozone from the Cambridge global model p-TOMCAT [42,43] considerably overestimates observations, as discussed further below. The diurnal behaviour of NO 2 in p-TOMCAT is broadly consistent with the data, but the model completely fails to capture the observed behaviour between midnight and dawn; observed NO 2 drops but it increases in the model.…”

Section: Local -Regional -Global Modellingmentioning

confidence: 97%

The impact of local surface changes in Borneo on atmospheric composition at wider spatial scales: coastal processes, land-use change and air quality

Pyle

Warwick

Harris

et al. 2011

Phil. Trans. R. Soc. B

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We present results from the OP3 campaign in Sabah during 2008 that allow us to study the impact of local emission changes over Borneo on atmospheric composition at the regional and wider scale. OP3 constituent data provide an important constraint on model performance. Treatment of boundary layer processes is highlighted as an important area of model uncertainty. Model studies of land-use change confirm earlier work, indicating that further changes to intensive oil palm agriculture in South East Asia, and the tropics in general, could have important impacts on air quality, with the biggest factor being the concomitant changes in NO x emissions. With the model scenarios used here, local increases in ozone of around 50 per cent could occur. We also report measurements of short-lived brominated compounds around Sabah suggesting that oceanic (and, especially, coastal) emission sources dominate locally. The concentration of bromine in short-lived halocarbons measured at the surface during OP3 amounted to about 7 ppt, setting an upper limit on the amount of these species that can reach the lower stratosphere.

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Section: Local -Regional -Global Modellingmentioning

confidence: 97%

The impact of local surface changes in Borneo on atmospheric composition at wider spatial scales: coastal processes, land-use change and air quality

Pyle

Warwick

Harris

et al. 2011

Phil. Trans. R. Soc. B

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“…Snow salinity in the Arctic is derived by extrapolating measured Antarctic salinity and monthly seaice coverage follows satellite observations [Comiso, 1990[Comiso, , updated 2005. Previous studies have demonstrated that the model is generally capable of simulating lower and middle tropospheric ozone with a relatively small bias [Voulgarakis et al, 2009a]. The addition of the bromine mechanism leads to reductions in ozone concentrations and to the successful simulation of bromine explosion events as seen at high latitudes from satellites.…”

Section: Model Description and Experimental Set-upmentioning

confidence: 99%

“…[5] We use the Cambridge p-TOMCAT CTM as described by Voulgarakis et al [2009a]. Detailed ozone budget calculations, which explore the radiative effect of clouds on oxidants, are described by Voulgarakis et al [2009b].…”

Section: Model Description and Experimental Set-upmentioning

confidence: 99%

How different would tropospheric oxidation be over an ice‐free Arctic?

Voulgarakis

Yang

Pyle

2009

Geophysical Research Letters

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[1] Climate projections suggest that a complete Arctic seaice retreat is likely in the future during summer. Less ice will cause less light reflection and slower tropospheric photolysis. We use a tropospheric chemistry model to examine how oxidation may differ over an ice-free Arctic. We find that late-summer OH concentrations can decrease by 30 -60% at polar latitudes, while effects on local ozone and global oxidant abundances are small. Ozone changes become larger in the more extreme case where sea-ice is also removed in spring and early summer. In this case, we find large spring ozone increases (up to 50-60%) over the Arctic, and even over inhabited high latitude regions (up to 20%), due mainly to a reduction in the impact of bromine chemistry, caused by the sea-ice retreat. Annual mean ozone also increases in the run with the summer/spring sea-ice removal, but not in the simulation including only latesummer sea-ice removal. Citation: Voulgarakis, A., X. Yang, and J. A. Pyle (2009), How different would tropospheric oxidation be over an ice-free

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“…The model used for the experiments is the updated version of the p-TOMCAT tropospheric CTM described in Voulgarakis et al (2009a). A detailed description of the ozone budget as calculated in the model is described in Voulgarakis et al (2009b).…”

Section: Model Set-up and Validation Of Its Ability To Capture Interamentioning

confidence: 99%

Interannual variability of tropospheric composition: the influence of changes in emissions, meteorology and clouds

et al. 2010

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Abstract.We have run a chemistry transport model (CTM) to systematically examine the drivers of interannual variability of tropospheric composition during 1996-2000. This period was characterised by anomalous meteorological conditions associated with the strong El Niño of 1997-1998 and intense wildfires, which produced a large amount of pollution. On a global scale, changing meteorology (winds, temperatures, humidity and clouds) is found to be the most important factor driving interannual variability of NO 2 and ozone on the timescales considered. Changes in stratospheretroposphere exchange, which are largely driven by meteorological variability, are found to play a particularly important role in driving ozone changes. The strong influence of emissions on NO 2 and ozone interannual variability is largely confined to areas where intense biomass burning events occur. For CO, interannual variability is almost solely driven by emission changes, while for OH meteorology dominates, with the radiative influence of clouds being a very strong contributor. Through a simple attribution analysis for 1996-2000 we conclude that changing cloudiness drives 25% of the interannual variability of OH over Europe by affecting shortwave radiation. Over Indonesia this figure is as high as 71%. Changes in cloudiness contribute a small but nonnegligible amount (up to 6%) to the interannual variability of ozone over Europe and Indonesia. This suggests that future assessments of trends in tropospheric oxidizing capacity should account for interannual variability in cloudiness, a factor neglected in many previous studies.

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Upgrading photolysis in the p-TOMCAT CTM: model evaluation and assessment of the role of clouds

Cited by 36 publications

References 48 publications

The impact of local surface changes in Borneo on atmospheric composition at wider spatial scales: coastal processes, land-use change and air quality

The impact of local surface changes in Borneo on atmospheric composition at wider spatial scales: coastal processes, land-use change and air quality

How different would tropospheric oxidation be over an ice‐free Arctic?

Interannual variability of tropospheric composition: the influence of changes in emissions, meteorology and clouds

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