A 1-D modelling of climatic and chemical effects of greenhouse gases

Vupputuri, R. K. R.; Higuchi, Kaz; Hengeveld, Henry

doi:10.1007/bf00864039

Cited by 3 publications

(3 citation statements)

References 31 publications

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“…Several sensitivity studies have been conducted previously to elucidate the impact of temperature on OH (Stevenson et al, 2000;Wild, 2007;O'Connor et al, 2009). None of these studies separately assessed the impacts of the kinetics and photolysis effects of temperature on OH.…”

Section: Oh Sensitivity To Temperature Biasesmentioning

confidence: 99%

“…None of these studies separately assessed the impacts of the kinetics and photolysis effects of temperature on OH. Wild (2007) applied a globally uniform temperature rise of 5 K that led to a larger OH abundance and an around 10 % decrease in the CH 4 lifetime. O'Connor et al (2009) showed a small impact on global OH abundances due to temperature biases; this may be because either the temperature biases in their model were both positive and negative, in different regions, leading to some cancellation of the impact on global OH, or to low OH sensitivity to temperature biases.…”

Section: Oh Sensitivity To Temperature Biasesmentioning

confidence: 99%

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Assessing the sensitivity of the hydroxyl radical to model biases in composition and temperature using a single-column photochemical model for Lauder, New Zealand

López-Comí¹,

Morgenstern²,

Zeng³

et al. 2016

Preprint

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Abstract. We assess the major factors contributing to local biases in the hydroxyl radical (OH) as simulated by a global chemistry-climate model, using a single-column photochemical model (SCM) analysis. The SCM has been constructed to represent atmospheric chemistry at Lauder, New Zealand, which is representative of the background atmosphere of the Southern Hemisphere (SH) mid-latitudes. We use long-term observations of variables essential to tropospheric OH chemistry, i.e. ozone (O3), water vapour (H2O), methane (CH4), carbon monoxide (CO), and temperature, and assess how using these measurements affect OH calculated in the SCM, relative to a reference simulation only using modelled fields. The analysis spans 1994 to 2010. Results show that OH responds approximately linearly to correcting biases in O3, H2O, CO, CH4, and temperature. The biggest impact on OH is due to correcting H2O, using radiosonde observations. This is followed by correcting O3. Its impact is decomposed into a kinetics effect and a photolysis effect; both are of similar magnitude. The OH sensitivity to correcting CH4 and CO biases is inversely related to the relative changes applied to these two species. The work demonstrates the feasibility of quantitatively assessing OH sensitivity to biases in longer-lives species, which can help to explain differences in simulated OH between global chemistry models and relative to observations. In addition to clear-sky simulations, we have performed idealised sensitivity simulations to assess the impact of clouds (ice and liquid) on OH. The results indicate that the impacts on the ozone photolysis rate and OH are substantial, with a general decrease of OH below the clouds relative to the clear-sky situation, and an increase above. The effects of liquid and ice clouds are less-than-additive. Using the SCM simulation we calculate recent OH trends at Lauder. For the period of 1994 to 2010, all trends are insignificant, in agreement with previous studies.

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Section: Oh Sensitivity To Temperature Biasesmentioning

confidence: 99%

Section: Oh Sensitivity To Temperature Biasesmentioning

confidence: 99%

Assessing the sensitivity of the hydroxyl radical to model biases in composition and temperature using a single-column photochemical model for Lauder, New Zealand

López-Comí¹,

Morgenstern²,

Zeng³

et al. 2016

Preprint

View full text Add to dashboard Cite

show abstract

“…However, their analyses only pertain to polluted environments not representative of much of the global atmosphere and only take in episodic and surface measurements. Single-column models have been applied to modelling the atmospheric boundary layer (Mihailovic et al, 2005;Cuxart et al, 2006), diabatic processes (Randall et al, 2003;Bergman and Sardeshmukh, 2004), clouds and aerosols (Kylling et al, 2005;Lebassi-Habtezion and Caldwell, 2015;Dal Gesso et al, 2015), the impacts of GHGs on climate change (Vupputuri et al, 1995), and the chemistry of halogen compounds (Piot and von Glasow, 2008;Joyce et al, 2014). Tropospheric OH chemistry of the remote atmosphere has not been assessed in a single-column model framework before.…”

mentioning

confidence: 99%

Assessing the sensitivity of the hydroxyl radical to model biases in composition and temperature using a single-column photochemical model for Lauder, New Zealand

et al. 2016

View full text Add to dashboard Cite

Abstract. We assess the major factors contributing to local biases in the hydroxyl radical (OH) as simulated by a global chemistry-climate model, using a single-column photochemical model (SCM) analysis. The SCM has been constructed to represent atmospheric chemistry at Lauder, New Zealand, which is representative of the background atmosphere of the Southern Hemisphere (SH) mid-latitudes. We use long-term observations of variables essential to tropospheric OH chemistry, i.e. ozone (O 3 ), water vapour (H 2 O), methane (CH 4 ), carbon monoxide (CO), and temperature, and assess how using these measurements affect OH calculated in the SCM, relative to a reference simulation only using modelled fields. The analysis spans 1994 to 2010. Results show that OH responds approximately linearly to correcting biases in O 3 , H 2 O, CO, CH 4 , and temperature. The biggest impact on OH is due to correcting an overestimation by approximately 20 to 60 % of H 2 O, using radiosonde observations. Correcting this moist bias leads to a reduction of OH by around 5 to 35 %. This is followed by correcting predominantly overestimated O 3 . In the troposphere, the model biases are mostly in the range of −10 to 30 %. The impact of changing O 3 on OH is due to two pathways; the OH responses to both are of similar magnitude but different seasonality: correcting in situ tropospheric ozone leads to changes in OH in the range −14 to 4 %, whereas correcting the photolysis rate of O 3 in accordance with overhead column ozone changes leads to increases of OH of 8 to 16 %. The OH sensitivities to correcting CH 4 , CO, and temperature biases are all minor effects. The work demonstrates the feasibility of quantitatively assessing OH sensitivity to biases in longerlived species, which can help explain differences in simulated OH between global chemistry models and relative to observations. In addition to clear-sky simulations, we have performed idealized sensitivity simulations to assess the impact of clouds (ice and liquid) on OH. The results indicate that the impacts on the ozone photolysis rate and OH are substantial, with a general decrease of OH below the clouds of up to 30 % relative to the clear-skies situation, and an increase of up to 15 % above. Using the SCM simulation we calculate recent OH trends at Lauder. For the period of 1994 to 2010, all trends are insignificant, in agreement with previous studies. For example, the trend in total-column OH is 0.5 ± 1.3 % over this period.

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