scholarly journals Tropospheric ozone changes, radiative forcing and attribution to emissions in the Atmospheric Chemistry and Climate Model Intercomparison Project (ACCMIP)

2013 ◽  
Vol 13 (6) ◽  
pp. 3063-3085 ◽  
Author(s):  
D. S. Stevenson ◽  
P. J. Young ◽  
V. Naik ◽  
J.-F. Lamarque ◽  
D. T. Shindell ◽  
...  
Keyword(s):  
Climate Change ◽  
Atmospheric Chemistry ◽  
Tropospheric Ozone ◽  
Climate Model ◽  
Anthropogenic Emissions ◽  
Model Intercomparison ◽  
A Value ◽  
Intercomparison Project ◽  
Column Ozone ◽  
Global Mean

Abstract. Ozone (O3) from 17 atmospheric chemistry models taking part in the Atmospheric Chemistry and Climate Model Intercomparison Project (ACCMIP) has been used to calculate tropospheric ozone radiative forcings (RFs). All models applied a common set of anthropogenic emissions, which are better constrained for the present-day than the past. Future anthropogenic emissions follow the four Representative Concentration Pathway (RCP) scenarios, which define a relatively narrow range of possible air pollution emissions. We calculate a value for the pre-industrial (1750) to present-day (2010) tropospheric ozone RF of 410 mW m−2. The model range of pre-industrial to present-day changes in O3 produces a spread (±1 standard deviation) in RFs of ±17%. Three different radiation schemes were used – we find differences in RFs between schemes (for the same ozone fields) of ±10%. Applying two different tropopause definitions gives differences in RFs of ±3%. Given additional (unquantified) uncertainties associated with emissions, climate-chemistry interactions and land-use change, we estimate an overall uncertainty of ±30% for the tropospheric ozone RF. Experiments carried out by a subset of six models attribute tropospheric ozone RF to increased emissions of methane (44±12%), nitrogen oxides (31 ± 9%), carbon monoxide (15 ± 3%) and non-methane volatile organic compounds (9 ± 2%); earlier studies attributed more of the tropospheric ozone RF to methane and less to nitrogen oxides. Normalising RFs to changes in tropospheric column ozone, we find a global mean normalised RF of 42 mW m−2 DU−1, a value similar to previous work. Using normalised RFs and future tropospheric column ozone projections we calculate future tropospheric ozone RFs (mW m−2; relative to 1750) for the four future scenarios (RCP2.6, RCP4.5, RCP6.0 and RCP8.5) of 350, 420, 370 and 460 (in 2030), and 200, 300, 280 and 600 (in 2100). Models show some coherent responses of ozone to climate change: decreases in the tropical lower troposphere, associated with increases in water vapour; and increases in the sub-tropical to mid-latitude upper troposphere, associated with increases in lightning and stratosphere-to-troposphere transport. Climate change has relatively small impacts on global mean tropospheric ozone RF.

scholarly journals Tropospheric ozone changes, radiative forcing and attribution to emissions in the Atmospheric Chemistry and Climate Model Inter-comparison Project (ACCMIP)

2012 ◽  
Vol 12 (10) ◽  
pp. 26047-26097 ◽  
Author(s):  
D. S. Stevenson ◽  
P. J. Young ◽  
V. Naik ◽  
J.-F. Lamarque ◽  
D. T. Shindell ◽  
...  
Keyword(s):  
Nitrogen Oxides ◽  
Atmospheric Chemistry ◽  
Tropospheric Ozone ◽  
Radiative Forcing ◽  
Climate Model ◽  
Lower Troposphere ◽  
Radiative Forcings ◽  
A Value ◽  
Intercomparison Project ◽  
Column Ozone

Abstract. Ozone (O3) from 17 atmospheric chemistry models taking part in the Atmospheric Chemistry and Climate Model Intercomparison Project (ACCMIP) has been used to calculate tropospheric ozone radiative forcings (RFs). We calculate a~value for the pre-industrial (1750) to present-day (2010) tropospheric ozone RF of 0.40 W m−2. The model range of pre-industrial to present-day changes in O3 produces a spread (±1 standard deviation) in RFs of ±17%. Three different radiation schemes were used – we find differences in RFs between schemes (for the same ozone fields) of ±10%. Applying two different tropopause definitions gives differences in RFs of ±3%. Given additional (unquantified) uncertainties associated with emissions, climate-chemistry interactions and land-use change, we estimate an overall uncertainty of ±30% for the tropospheric ozone RF. Experiments carried out by a subset of six models attribute tropospheric ozone RF to increased emissions of methane (47%), nitrogen oxides (29%), carbon monoxide (15%) and non-methane volatile organic compounds (9%); earlier studies attributed more of the tropospheric ozone RF to methane and less to nitrogen oxides. Normalising RFs to changes in tropospheric column ozone, we find a global mean normalised RF of 0.042 W m−2 DU−1, a value similar to previous work. Using normalised RFs and future tropospheric column ozone projections we calculate future tropospheric ozone RFs (W m−2; relative to 1850 – add 0.04 W m−2 to make relative to 1750) for the Representative Concentration Pathways in 2030 (2100) of: RCP2.6: 0.31 (0.16); RCP4.5: 0.38 (0.26); RCP6.0: 0.33 (0.24); and RCP8.5: 0.42 (0.56). Models show some coherent responses of ozone to climate change: decreases in the tropical lower troposphere, associated with increases in water vapour; and increases in the sub-tropical to mid-latitude upper troposphere, associated with increases in lightning and stratosphere-to-troposphere transport.

scholarly journals Pre-industrial to end 21st century projections of tropospheric ozone from the Atmospheric Chemistry and Climate Model Intercomparison Project (ACCMIP)

2012 ◽  
Vol 12 (8) ◽  
pp. 21615-21677 ◽  
Author(s):  
P. J. Young ◽  
A. T. Archibald ◽  
K. W. Bowman ◽  
J.-F. Lamarque ◽  
V. Naik ◽  
...  
Keyword(s):  
Atmospheric Chemistry ◽  
Tropospheric Ozone ◽  
Climate Model ◽  
Stratospheric Ozone ◽  
Climate Projections ◽  
Model Intercomparison ◽  
Intercomparison Project ◽  
High Bias ◽  
Ozone Column ◽  
Global Mean

Abstract. Present day tropospheric ozone and its changes between 1850 and 2100 are considered, analysing 15 global models that participated in the Atmospheric Chemistry and Climate Model Intercomparison Project (ACCMIP). The multi-model mean compares well against present day observations. The seasonal cycle correlates well, except for some locations in the tropical upper troposphere. Most (75%) of the models are encompassed with a range of global mean tropospheric ozone column estimates from satellite data, although there is a suggestion of a high bias in the Northern Hemisphere and a low bias in the Southern Hemisphere. Compared to the present day multi-model mean tropospheric ozone burden of 337 Tg, the multi-model mean burden for 1850 time slice is ~ 30% lower. Future changes were modelled using emissions and climate projections from four Representative Concentration Pathways (RCPs). Compared to 2000, the relative changes for the tropospheric ozone burden in 2030 (2100) for the different RCPs are: −5% (−22%) for RCP2.6, 3% (−8%) for RCP4.5, 0% (−9%) for RCP6.0, and 5% (15%) for RCP8.5. Model agreement on the magnitude of the change is greatest for larger changes. Reductions in precursor emissions are common across the RCPs and drive ozone decreases in all but RCP8.5, where doubled methane and a larger stratospheric influx increase ozone. Models with high ozone abundances for the present day also have high ozone levels for the other time slices, but there are no models consistently predicting large or small changes. Spatial patterns of ozone changes are well correlated across most models, but are notably different for models without time evolving stratospheric ozone concentrations. A unified approach to ozone budget specifications is recommended to help future studies attribute ozone changes and inter-model differences more clearly.

scholarly journals Preindustrial to present-day changes in tropospheric hydroxyl radical and methane lifetime from the Atmospheric Chemistry and Climate Model Intercomparison Project (ACCMIP)

2013 ◽  
Vol 13 (10) ◽  
pp. 5277-5298 ◽  
Author(s):  
V. Naik ◽  
A. Voulgarakis ◽  
A. M. Fiore ◽  
L. W. Horowitz ◽  
J.-F. Lamarque ◽  
...  
Keyword(s):  
Carbon Monoxide ◽  
Hydroxyl Radical ◽  
Atmospheric Chemistry ◽  
Climate Model ◽  
Stratospheric Ozone ◽  
Regional Distribution ◽  
Model Intercomparison ◽  
Intercomparison Project ◽  
Concentration Changes ◽  
Global Mean

Abstract. We have analysed time-slice simulations from 17 global models, participating in the Atmospheric Chemistry and Climate Model Intercomparison Project (ACCMIP), to explore changes in present-day (2000) hydroxyl radical (OH) concentration and methane (CH4) lifetime relative to preindustrial times (1850) and to 1980. A comparison of modeled and observation-derived methane and methyl chloroform lifetimes suggests that the present-day global multi-model mean OH concentration is overestimated by 5 to 10% but is within the range of uncertainties. The models consistently simulate higher OH concentrations in the Northern Hemisphere (NH) compared with the Southern Hemisphere (SH) for the present-day (2000; inter-hemispheric ratios of 1.13 to 1.42), in contrast to observation-based approaches which generally indicate higher OH in the SH although uncertainties are large. Evaluation of simulated carbon monoxide (CO) concentrations, the primary sink for OH, against ground-based and satellite observations suggests low biases in the NH that may contribute to the high north–south OH asymmetry in the models. The models vary widely in their regional distribution of present-day OH concentrations (up to 34%). Despite large regional changes, the multi-model global mean (mass-weighted) OH concentration changes little over the past 150 yr, due to concurrent increases in factors that enhance OH (humidity, tropospheric ozone, nitrogen oxide (NOx) emissions, and UV radiation due to decreases in stratospheric ozone), compensated by increases in OH sinks (methane abundance, carbon monoxide and non-methane volatile organic carbon (NMVOC) emissions). The large inter-model diversity in the sign and magnitude of preindustrial to present-day OH changes (ranging from a decrease of 12.7% to an increase of 14.6%) indicate that uncertainty remains in our understanding of the long-term trends in OH and methane lifetime. We show that this diversity is largely explained by the different ratio of the change in global mean tropospheric CO and NOx burdens (ΔCO/ΔNOx, approximately represents changes in OH sinks versus changes in OH sources) in the models, pointing to a need for better constraints on natural precursor emissions and on the chemical mechanisms in the current generation of chemistry-climate models. For the 1980 to 2000 period, we find that climate warming and a slight increase in mean OH (3.5 ± 2.2%) leads to a 4.3 ± 1.9% decrease in the methane lifetime. Analysing sensitivity simulations performed by 10 models, we find that preindustrial to present-day climate change decreased the methane lifetime by about four months, representing a negative feedback on the climate system. Further, we analysed attribution experiments performed by a subset of models relative to 2000 conditions with only one precursor at a time set to 1860 levels. We find that global mean OH increased by 46.4 ± 12.2% in response to preindustrial to present-day anthropogenic NOx emission increases, and decreased by 17.3 ± 2.3%, 7.6 ± 1.5%, and 3.1 ± 3.0% due to methane burden, and anthropogenic CO, and NMVOC emissions increases, respectively.

scholarly journals Pre-industrial to end 21st century projections of tropospheric ozone from the Atmospheric Chemistry and Climate Model Intercomparison Project (ACCMIP)

2013 ◽  
Vol 13 (4) ◽  
pp. 2063-2090 ◽  
Author(s):  
P. J. Young ◽  
A. T. Archibald ◽  
K. W. Bowman ◽  
J.-F. Lamarque ◽  
V. Naik ◽  
...  
Keyword(s):  
Atmospheric Chemistry ◽  
Tropospheric Ozone ◽  
Climate Model ◽  
Stratospheric Ozone ◽  
Climate Projections ◽  
Model Intercomparison ◽  
Ensemble Mean ◽  
Intercomparison Project ◽  
High Bias ◽  
Ozone Precursor

Abstract. Present day tropospheric ozone and its changes between 1850 and 2100 are considered, analysing 15 global models that participated in the Atmospheric Chemistry and Climate Model Intercomparison Project (ACCMIP). The ensemble mean compares well against present day observations. The seasonal cycle correlates well, except for some locations in the tropical upper troposphere. Most (75 %) of the models are encompassed with a range of global mean tropospheric ozone column estimates from satellite data, but there is a suggestion of a high bias in the Northern Hemisphere and a low bias in the Southern Hemisphere, which could indicate deficiencies with the ozone precursor emissions. Compared to the present day ensemble mean tropospheric ozone burden of 337 ± 23 Tg, the ensemble mean burden for 1850 time slice is ~30% lower. Future changes were modelled using emissions and climate projections from four Representative Concentration Pathways (RCPs). Compared to 2000, the relative changes in the ensemble mean tropospheric ozone burden in 2030 (2100) for the different RCPs are: −4% (−16%) for RCP2.6, 2% (−7%) for RCP4.5, 1% (−9%) for RCP6.0, and 7% (18%) for RCP8.5. Model agreement on the magnitude of the change is greatest for larger changes. Reductions in most precursor emissions are common across the RCPs and drive ozone decreases in all but RCP8.5, where doubled methane and a 40–150% greater stratospheric influx (estimated from a subset of models) increase ozone. While models with a high ozone burden for the present day also have high ozone burdens for the other time slices, no model consistently predicts large or small ozone changes; i.e. the magnitudes of the burdens and burden changes do not appear to be related simply, and the models are sensitive to emissions and climate changes in different ways. Spatial patterns of ozone changes are well correlated across most models, but are notably different for models without time evolving stratospheric ozone concentrations. A unified approach to ozone budget specifications and a rigorous investigation of the factors that drive tropospheric ozone is recommended to help future studies attribute ozone changes and inter-model differences more clearly.

scholarly journals Preindustrial to present day changes in tropospheric hydroxyl radical and methane lifetime from the Atmospheric Chemistry and Climate Model Intercomparison Project (ACCMIP)

2012 ◽  
Vol 12 (11) ◽  
pp. 30755-30804 ◽  
Author(s):  
V. Naik ◽  
A. Voulgarakis ◽  
A. M. Fiore ◽  
L. W. Horowitz ◽  
J.-F. Lamarque ◽  
...  
Keyword(s):  
Carbon Monoxide ◽  
Hydroxyl Radical ◽  
Northern Hemisphere ◽  
Atmospheric Chemistry ◽  
Climate Model ◽  
Stratospheric Ozone ◽  
Tropospheric Temperature ◽  
Model Intercomparison ◽  
Intercomparison Project ◽  
Global Mean

Abstract. We have analysed results from 17 global models, participating in the Atmospheric Chemistry and Climate Model Intercomparison Project (ACCMIP), to explore trends in hydroxyl radical concentration (OH) and methane (CH4) lifetime since preindustrial times (1850) and gain a better understanding of their key drivers. For the present day (2000), the models tend to simulate higher OH abundances in the Northern Hemisphere versus Southern Hemisphere. Evaluation of simulated carbon monoxide concentrations, the primary sink for OH, against observations suggests low biases in the Northern Hemisphere that may contribute to the high north-south OH asymmetry in the models. A comparison of modelled and observed methyl chloroform lifetime suggests that the present day global multi-model mean OH concentration is slightly overestimated. Despite large regional changes, the modelled global mean OH concentration is roughly constant over the past 150 yr, due to concurrent increases in OH sources (humidity, tropospheric ozone, and NOx emissions), together with decreases in stratospheric ozone and increase in tropospheric temperature, compensated by increases in OH sinks (methane abundance, carbon monoxide and non-methane volatile organic carbon (NMVOC) emissions). The large intermodel diversity in the sign and magnitude of OH and methane lifetime changes over this period reflects differences in the relative importance of chemical and physical drivers of OH within each model. For the 1980 to 2000 period, we find that climate warming and a slight increase in mean OH leads to a 4.3 ± 1.9% decrease in the methane lifetime. Analysing sensitivity simulations performed by 10 models, we find that preindustrial to present day climate change decreased the methane lifetime by about 4 months, representing a negative feedback on the climate system. Further, using a subset of the models, we find that global mean OH increased by 46.4 ± 12.2% in response to preindustrial to present day anthropogenic NOx emission increases, and decreased by 17.3 ± 2.3%, 7.6 ± 1.5%, and 3.1 ± 3.0% due to methane burden, and anthropogenic CO, and NMVOC emissions increases, respectively.

scholarly journals Observational constraints on ozone radiative forcing from the Atmospheric Chemistry Climate Model Intercomparison Project (ACCMIP)

2012 ◽  
Vol 12 (9) ◽  
pp. 23603-23644 ◽  
Author(s):  
K. Bowman ◽  
D. Shindell ◽  
H. Worden ◽  
J. F. Lamarque ◽  
P. J. Young ◽  
...  
Keyword(s):  
Standard Deviation ◽  
Atmospheric Chemistry ◽  
Tropospheric Ozone ◽  
Radiative Forcing ◽  
Climate Models ◽  
Climate Model ◽  
Longwave Radiation ◽  
Model Intercomparison ◽  
Ensemble Mean ◽  
Intercomparison Project

Abstract. We use simultaneous observations of ozone and outgoing longwave radiation (OLR) from the Tropospheric Emission Spectrometer (TES) to evaluate ozone distributions and radiative forcing simulated by a suite of chemistry-climate models that participated in the Atmospheric Chemistry and Climate Model Intercomparison Project (ACCMIP). The ensemble mean of ACCMIP models show a persistent but modest tropospheric ozone low bias (5–20 ppb) in the Southern Hemisphere (SH) and modest high bias (5–10 ppb) in the Northern Hemisphere (NH) relative to TES for 2005–2010. These biases lead to substantial differences in ozone instantaneous radiative forcing between TES and the ACCMIP simulations. Using TES instantaneous radiative kernels (IRK), we show that the ACCMIP ensemble mean has a low bias in the SH tropics of up to 100 m W m−2 locally and a global low bias of 35 ± 44 m W m−2 relative to TES. Combining ACCMIP preindustrial ozone and the TES present-day ozone, we calculate an observationally constrained estimate of tropospheric ozone radiative forcing (RF) of 399 ± 70 m W m−2, which is about 7% higher than using the ACCMIP models alone but with the same standard deviation (Stevenson et al., 2012). In addition, we explore an alternate approach to constraining radiative forcing estimates by choosing a subset of models that best match TES ozone, which leads to an ozone RF of 369 ± 42 m W m−2. This estimate is closer to the ACCMIP ensemble mean RF but about a 40% reduction in standard deviation. These results point towards a profitable direction of combining observations and chemistry-climate model simulations to reduce uncertainty in ozone radiative forcing.

scholarly journals Tropospheric ozone in CMIP6 simulations

2021 ◽  
Vol 21 (5) ◽  
pp. 4187-4218
Author(s):  
Paul T. Griffiths ◽  
Lee T. Murray ◽  
Guang Zeng ◽  
Youngsub Matthew Shin ◽  
N. Luke Abraham ◽  
...  
Keyword(s):  
Atmospheric Chemistry ◽  
Tropospheric Ozone ◽  
Climate Models ◽  
Climate Model ◽  
Decadal Variability ◽  
Stratospheric Ozone ◽  
Ozone Production ◽  
Model Intercomparison ◽  
Chemical Production ◽  
Intercomparison Project

Abstract. The evolution of tropospheric ozone from 1850 to 2100 has been studied using data from Phase 6 of the Coupled Model Intercomparison Project (CMIP6). We evaluate long-term changes using coupled atmosphere–ocean chemistry–climate models, focusing on the CMIP Historical and ScenarioMIP ssp370 experiments, for which detailed tropospheric-ozone diagnostics were archived. The model ensemble has been evaluated against a suite of surface, sonde and satellite observations of the past several decades and found to reproduce well the salient spatial, seasonal and decadal variability and trends. The multi-model mean tropospheric-ozone burden increases from 247 ± 36 Tg in 1850 to a mean value of 356 ± 31 Tg for the period 2005–2014, an increase of 44 %. Modelled present-day values agree well with previous determinations (ACCENT: 336 ± 27 Tg; Atmospheric Chemistry and Climate Model Intercomparison Project, ACCMIP: 337 ± 23 Tg; Tropospheric Ozone Assessment Report, TOAR: 340 ± 34 Tg). In the ssp370 experiments, the ozone burden increases to 416 ± 35 Tg by 2100. The ozone budget has been examined over the same period using lumped ozone production (PO3) and loss (LO3) diagnostics. Both ozone production and chemical loss terms increase steadily over the period 1850 to 2100, with net chemical production (PO3-LO3) reaching a maximum around the year 2000. The residual term, which contains contributions from stratosphere–troposphere transport reaches a minimum around the same time before recovering in the 21st century, while dry deposition increases steadily over the period 1850–2100. Differences between the model residual terms are explained in terms of variation in tropopause height and stratospheric ozone burden.

scholarly journals Tropospheric ozone in CCMI models and Gaussian emulation to understand biases in the SOCOLv3 chemistry-climate model

2018 ◽  
Author(s):  
Laura E. Revell ◽  
Andrea Stenke ◽  
Fiona Tummon ◽  
Aryeh Feinberg ◽  
Eugene Rozanov ◽  
...  
Keyword(s):  
Atmospheric Chemistry ◽  
Tropospheric Ozone ◽  
Climate Models ◽  
Climate Model ◽  
Coupled Model ◽  
Ozone Monitoring Instrument ◽  
Data Set ◽  
Gaussian Process Emulation ◽  
Intercomparison Project ◽  
Column Ozone

Abstract. Previous multi-model intercomparisons have shown that chemistry-climate models exhibit significant biases in tropospheric ozone compared with observations. We investigate annual-mean tropospheric column ozone in 15 models participating in the SPARC/IGAC (Stratosphere-troposphere Processes and their Role in Climate/International Global Atmospheric Chemistry) Chemistry-Climate Model Initiative (CCMI). These models exhibit a positive bias, on average, of up to 40–50 % in the Northern Hemisphere compared with observations derived from the Ozone Monitoring Instrument and Microwave Limb Sounder (OMI/MLS), and a negative bias of up to ~ 30 % in the Southern Hemisphere. SOCOLv3.0 (version 3 of the Solar-Climate Ozone Links CCM), which participated in CCMI, simulates global-mean tropospheric ozone columns of 40.2 DU – approximately 33 % larger than the CCMI multi-model mean. Here we introduce an updated version of SOCOLv3.0, SOCOLv3.1, which includes an improved treatment of ozone sink processes, and results in a reduction in the tropospheric column ozone bias of up to 8 DU, mostly due to the inclusion of N2O5 hydrolysis on tropospheric aerosols. As a result of these developments, tropospheric column ozone amounts simulated by SOCOLv3.1 are comparable with several other CCMI models. We apply Gaussian process emulation and sensitivity analysis to understand the remaining ozone bias in SOCOLv3.1. This shows that ozone precursors (nitrogen oxides (NOx, carbon monoxide, methane and other volatile organic compounds) are responsible for more than 90 % of the variance in tropospheric ozone. However, it may not be the emissions inventories themselves that result in the bias, but how the emissions are handled in SOCOLv3.1, and we discuss this in the wider context of the other CCMI models. Given that the emissions data set to be used for phase 6 of the Coupled Model Intercomparison Project includes approximately 20 % more NOx than the data set used for CCMI, further work is urgently needed to address the challenges of simulating sub-grid processes of importance to tropospheric ozone in the current generation of chemistry-climate models.

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