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J. E. Williams - One of the best experts on this subject based on the ideXlab platform.
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Multi-model simulation of CO and HCHO in the Southern Hemisphere: comparison with observations and impact of Biogenic Emissions
Atmospheric Chemistry and Physics, 2015Co-Authors: Guang Zeng, J. E. Williams, Jenny A. Fisher, Louisa Emmons, Nicholas B. Jones, Olaf Morgenstern, John Robinson, Dan Smale, Clare Paton-walsh, David W. T. GriffithAbstract:Abstract. We investigate the impact of Biogenic Emissions on carbon monoxide (CO) and formaldehyde (HCHO) in the Southern Hemisphere (SH), with simulations using two different Biogenic Emission inventories for isoprene and monoterpenes. Results from four atmospheric chemistry models are compared to continuous long-term ground-based CO and HCHO column measurements at the SH Network for the Detection of Atmospheric Composition Change (NDACC) sites, the satellite measurement of tropospheric CO columns from the Measurement of Pollution in the Troposphere (MOPITT), and in situ surface CO measurements from across the SH, representing a subset of the National Oceanic and Atmospheric Administration's Global Monitoring Division (NOAA GMD) network. Simulated mean model CO using the Model of Emissions of Gases and Aerosols from Nature (v2.1) computed in the frame work of the Land Community Model (CLM-MEGANv2.1) inventory is in better agreement with both column and surface observations than simulations adopting the Emission inventory generated from the LPJ-GUESS dynamical vegetation model framework, which markedly underestimate measured column and surface CO at most sites. Differences in Biogenic Emissions cause large differences in CO in the source regions which propagate to the remote SH. Significant inter-model differences exist in modelled column and surface CO, and secondary production of CO dominates these inter-model differences, due mainly to differences in the models' oxidation schemes for volatile organic compounds, predominantly isoprene oxidation. While Biogenic Emissions are a significant factor in modelling SH CO, inter-model differences pose an additional challenge to constrain these Emissions. Corresponding comparisons of HCHO columns at two SH mid-latitude sites reveal that all models significantly underestimate the observed values by approximately a factor of 2. There is a much smaller impact on HCHO of the significantly different Biogenic Emissions in remote regions, compared to the source regions. Decreased Biogenic Emissions cause decreased CO export to remote regions, which leads to increased OH; this in turn results in increased HCHO production through methane oxidation. In agreement with earlier studies, we corroborate that significant HCHO sources are likely missing in the models in the remote SH.
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Multi-model simulation of CO and HCHO in the Southern Hemisphere: Biogenic Emissions and model uncertainties
Atmospheric Chemistry and Physics Discussions, 2015Co-Authors: Guang Zeng, J. E. Williams, Jenny A. Fisher, Louisa Emmons, Nicholas B. Jones, Olaf Morgenstern, John Robinson, Dan Smale, Clare Paton-walsh, David W. T. GriffithAbstract:Abstract. We investigate the impact of Biogenic Emissions on carbon monoxide (CO) and formaldehyde (HCHO) in the Southern Hemisphere (SH), with simulations using two different Biogenic Emission inventories for isoprene and monoterpenes. Results from four atmospheric chemistry models are compared to continous long-term ground-based CO and HCHO column measurements at SH NDACC sites, and to in situ surface CO measurements from across the SH, representing a subset of the NOAA GMD network. Simulated mean model CO using the CLM-MEGANv2.1 inventory is in good agreement with both column and surface observations, whereas simulations adopting LPJ-GUESS Emissions markedly underestimate measured column and surface CO at most sites. Differences in Biogenic Emissions cause large differences in CO in the source regions which propagate to the remote SH. Significant inter-model differences exist in modelled column and surface CO, due mainly to differences in the models' oxidation schemes for volatile organic compounds; secondary production of CO dominates these inter-model differences. While Biogenic Emissions are a significant factor in modelling SH CO, inter-model differences pose an additional challenge to constrain these Emissions. Corresponding comparisons of HCHO columns at two SH mid-latitude sites reveal that all models significantly underestimate the observed values by approximately a factor of 2. There is a much smaller impact on HCHO of the significantly different Biogenic Emissions in remote regions, compared to the source regions. Decreased Biogenic Emissions cause decreased CO export to remote regions, which leads to increased OH; this in turn results in increased HCHO production through methane oxidation. In agreement with earlier studies, we corroborate that significant HCHO sources are likely missing in the models in the remote SH.
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quantifying the uncertainty in simulating global tropospheric composition due to the variability in global Emission estimates of Biogenic volatile organic compounds
Atmospheric Chemistry and Physics, 2012Co-Authors: J. E. Williams, P. F. J. Van Velthoven, C A M BrenninkmeijerAbstract:Abstract. The Emission of organic compounds from Biogenic processes acts as an important source of trace gases in remote regions away from urban conurbations, and is likely to become more important in future decades due to the further mitigation of anthropogenic Emissions that affect air quality and climate forcing. In this study we examine the contribution of Biogenic volatile organic compounds (BVOCs) towards global tropospheric composition using the global 3-D chemistry transport model TM5 and the recently developed modified CB05 chemical mechanism. By comparing regional BVOC Emission estimates we show that Biogenic processes act as dominant sources for many regions and exhibit a large variability in the annually and seasonally integrated Emission fluxes. By performing sensitivity studies we find that the contribution of BVOC species containing between 1 to 3 carbon atoms has an impact on the resident mixing ratios of tropospheric O 3 and CO, accounting for ~2.5% and ~10.8% of the simulated global distribution, respectively. This is approximately a third of the cumulative effect introduced by isoprene and the monoterpenes. By examining an ensemble of 3-D global chemistry transport simulations which adopt different global BVOC Emission inventories we determine the associated uncertainty introduced towards simulating the composition of the troposphere for the year 2000. By comparing the model ensemble values against a composite of atmospheric measurements we show that the effects on tropospheric O 3 are limited to the lower troposphere (with an uncertainty between −2% to 10%), whereas that for tropospheric CO extends up to the upper troposphere (with an uncertainty of between 10 to 45%). Comparing the mixing ratios for low molecular weight alkenes in TM5 against surface measurements taken in Europe implies that the cumulative Emission estimates are too low, regardless of the chosen BVOC inventory. This variability in the global distribution of CO due to BVOC Emissions introduces an associated uncertainty in the tropospheric CO burden of 11.4%, which impacts strongly on the oxidative capacity of the troposphere, introducing an uncertainty in the atmospheric lifetime of the greenhouse gas CH 4 of ~3.3%. This study thus identifies the necessity of placing further constraints on non-CH 4 global Biogenic Emission estimates in large-scale global atmospheric chemistry models.
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The influence of Biogenic Emissions from Africa on tropical tropospheric ozone during 2006: a global modeling study
Atmospheric Chemistry and Physics, 2009Co-Authors: J. E. Williams, C. Galy-lacaux, M. P. Scheele, P. F. J. Van Velthoven, J.-p. Cammas, V. Thouret, A. Volz-thomasAbstract:Abstract. We have performed simulations using a 3-D global chemistry-transport model to investigate the influence that Biogenic Emissions from the African continent exert on the composition of the troposphere in the tropical region. For this purpose we have applied two recently developed Biogenic Emission inventories provided for use in large-scale global models (Granier et al., 2005; Lathiere et al., 2006) whose seasonality and temporal distribution for Biogenic Emissions of isoprene, other volatile organic compounds and NO is markedly different. The use of the 12 year average values for Biogenic Emissions provided by Lathiere et al. (2006) results in an increase in the amount of nitrogen sequestrated into longer lived reservoir compounds which contributes to the reduction in the tropospheric ozone burden in the tropics. The associated re-partitioning of nitrogen between PAN, HNO3 and organic nitrates also results in a ~5% increase in the loss of nitrogen by wet deposition. At a global scale there is a reduction in the oxidizing capacity of the model atmosphere which increases the atmospheric lifetimes of CH4 and CO by ~1.5% and ~4%, respectively. Comparisons against a range of different measurements indicate that applying the 12 year average of Lathiere et al. (2006) improves the performance of TM4_AMMA for 2006 in the tropics. By the use of sensitivity studies we show that the release of NO from soils in Africa accounts for between ~2–45% of tropospheric ozone in the African troposphere, ~10% in the upper troposphere and between ~5–20% of the tropical tropospheric ozone column over the tropical Atlantic Ocean. The subsequent reduction in OH over the source regions allows enhanced transport of CO out of the region. For Biogenic volatile organic C1 to C3 species released from Africa, the effects on tropical tropospheric ozone are rather limited, although this source contributes to the global burden of VOC by between ~2–4% and has a large influence on the organic composition of the troposphere over the tropical Atlantic Ocean.
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The influence of Biogenic Emissions from Africa on tropical tropospheric ozone during 2006: a global modeling study
Atmospheric Chemistry and Physics Discussions, 2009Co-Authors: J. E. Williams, C. Galy-lacaux, M. P. Scheele, P. F. J. Van Velthoven, J.-p. Cammas, V. Thouret, A. Volz-thomasAbstract:Abstract. We have performed simulations using a 3-D global chemistry-transport model to investigate the influence that Biogenic Emissions from the African continent exert on the composition of the tropopause in the tropical region. For this purpose we have applied two recently developed Biogenic Emission inventories provided for use in large-scale global models (Granier et al., 2005; Lathiére et al., 2006) whose seasonality and temporal distribution for isoprene, Biogenic NO and Biogenic volatile organic compounds is markedly different. The use of the climatological values for Biogenic Emissions provided by Lathiére et al. (2006) results in an increase in the amount of nitrogen sequestrated into longer lived reservoir compounds which contributes to the reduction in tropospheric ozone burden in the tropics. The associated re-partitioning of nitrogen between PAN, HNO3 and organic nitrates also results in a ~5% increase in the loss of nitrogen by wet deposition. At a global scale there is a reduction in the oxidizing capacity of the model atmosphere which increases the atmospheric lifetimes of CH4 and CO by ~1.5% and ~4%, respectively. By the use of sensitivity studies we show that the release of NO from soils in Africa accounts for between ~5–45% of tropospheric ozone in the African troposphere, ~10% in the upper troposphere and between ~5–20% of the tropical tropospheric ozone column over the tropical Atlantic Ocean. The subsequent reduction in OH over the source regions allows enhanced transport of CO out of the region. For Biogenic volatile organic C1 to C3 species released from Africa the effects on tropical tropospheric ozone are rather limited, although this source contributes to the global burden of VOC by between ~2–4% and has a large influence on the organic composition of the troposphere over the tropical Atlantic Ocean. Comparisons against a range of different measurements indicate that applying the climatology of Lathiére et al. (2006) improves the performance of TM4 for 2006 in the tropics.
J Williams - One of the best experts on this subject based on the ideXlab platform.
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a new marine Biogenic Emission methane sulfonamide msam dimethyl sulfide dms and dimethyl sulfone dmso 2 measured in air over the arabian sea
Atmospheric Chemistry and Physics, 2020Co-Authors: Achim Edtbauer, Christof Stonner, Eva Y Pfannerstill, Matias Berasategui, David Walter, J N Crowley, Jos Lelieveld, J WilliamsAbstract:Abstract. We present the first ambient measurements of a new marine Emission methane sulfonamide (MSAM: CH5NO2S ), along with dimethyl sulfide (DMS) and dimethyl sulfone ( DMSO2 ) over the Arabian Sea. Two shipborne transects (W → E, E → W) were made during the AQABA (Air Quality and Climate Change in the Arabian Basin) measurement campaign. Molar mixing ratios in picomole of species per mole of air (throughout this paper abbreviated as ppt) of DMS were in the range of 300–500 ppt during the first traverse of the Arabian Sea (first leg) and 100–300 ppt on the second leg. On the first leg DMSO2 was always below 40 ppt and MSAM was close to the limit of detection. During the second leg DMSO2 was between 40 and 120 ppt and MSAM was mostly in the range of 20–50 ppt with maximum values of 60 ppt. An analysis of HYSPLIT back trajectories combined with calculations of the exposure of these trajectories to underlying chlorophyll in the surface water revealed that most MSAM originates from the Somalia upwelling region, known for its high biological activity. MSAM Emissions can be as high as one-third of DMS Emissions over the upwelling region. This new marine Emission is of particular interest as it contains both sulfur and nitrogen, making it potentially relevant to marine nutrient cycling and marine atmospheric particle formation.
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a new marine Biogenic Emission methane sulfonamide msam dms and dmso 2 measured in air over the arabian sea
Atmospheric Chemistry and Physics, 2020Co-Authors: Achim Edtbauer, Christof Stonner, Eva Y Pfannerstill, Matias Berasategui, David Walter, J N Crowley, Jos Lelieveld, J WilliamsAbstract:Abstract. We present the first ambient measurements of a new marine Emission methane sulfonamide (MSAM), along with dimethyl sulfide (DMS) and dimethyl sulfone (DMSO2) over the Arabian Sea. Two shipborne transects (W to E, E to W) were made during the AQABA (Air Quality and Climate Change in the Arabian Basin) measurement campaign. DMS mixing ratios were in the range 0.3–0.5 ppb during the first traverse of the Arabian Sea (first leg) and 0.1 to 0.3 ppb in the second leg. In the first leg DMSO2 was always below 0.04 ppb and MSAM was close to the limit of detection. During the second leg DMSO2 was between 0.04–0.12 ppb and MSAM was mostly in the range 0.02–0.05 ppb with maximum values of 0.06 ppb. An analysis of HYSPLIT back trajectories combined with calculations of the exposure of these trajectories to chlorophyll a content in the water revealed that most MSAM originates from the Somalia upwelling region, known for its high biological activity. This new marine Emission is of particular interest as it contains both sulfur and nitrogen, making it potentially relevant to marine nutrient cycling and particle formation.
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Diel and seasonal changes of Biogenic volatile organic compounds within and above an Amazonian rainforest
Atmospheric Chemistry and Physics, 2015Co-Authors: A. Yañez-serrano, J Williams, A. Nölscher, S. Wolff, E. Alves, G. Martins, E. Bourtsoukidis, J. Brito, K. Jardine, P. ArtaxoAbstract:The Amazonian rainforest is a large tropical ecosystem, which is one of the last pristine continental terrains. This ecosystem is ideally located for the study of diel and seasonal behaviour of Biogenic volatile organic compounds (BVOCs) in the absence of local human interference. In this study, we report the first atmospheric BVOC measurements at the Amazonian Tall Tower Observatory (ATTO) site, located in central Amazonia. A quadrupole proton-transfer-reaction mass spectrometer (PTR-MS), with seven ambient air inlets, positioned from near ground to about 80 m (0.05, 0.5, 4, 24, 38, 53 and 79 m above the forest floor), was deployed for BVOC monitoring. We report diel and seasonal (February–March 2013 as wet season and September 2013 as dry season) ambient mixing ratios for iso-prene, monoterpenes, isoprene oxidation products, acetalde-hyde, acetone, methyl ethyl ketone (MEK), methanol and acetonitrile. Clear diel and seasonal patterns were observed for all compounds. In general, lower mixing ratios were observed during night, while maximum mixing ratios were observed during the wet season (February–March 2013), with the peak in solar irradiation at 12:00 LT (local time) and during the dry season (September 2013) with the peak in temperature at 16:00 LT. Isoprene and monoterpene mixing ratios were the highest within the canopy with a median of 7.6 and 1 ppb, respectively (interquartile range (IQR) of 6.1 and 0.38 ppb) during the dry season (at 24 m, from 12:00 to 15:00 LT). The increased contribution of oxygenated volatile organic compounds (OVOCs) above the canopy indicated a transition from dominating forest Emissions during the wet season (when mixing ratios were higher than within the canopy), to a blend of Biogenic Emission, photochemical production and advection during the dry season when mixing ratios were higher above the canopy. Our observations suggest strong seasonal interactions between environmental (in-solation, temperature) and biological (phenology) drivers of leaf BVOC Emissions and atmospheric chemistry. Considerable differences in the magnitude of BVOC mixing ratios, as compared to other reports of Amazonian BVOC, demonstrate the need for long-term observations at different sites and more standardized measurement procedures, in order to better characterize the natural exchange of BVOCs between the Amazonian rainforest and the atmosphere.
A. Volz-thomas - One of the best experts on this subject based on the ideXlab platform.
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The influence of Biogenic Emissions from Africa on tropical tropospheric ozone during 2006: a global modeling study
Atmospheric Chemistry and Physics, 2009Co-Authors: J. E. Williams, C. Galy-lacaux, M. P. Scheele, P. F. J. Van Velthoven, J.-p. Cammas, V. Thouret, A. Volz-thomasAbstract:Abstract. We have performed simulations using a 3-D global chemistry-transport model to investigate the influence that Biogenic Emissions from the African continent exert on the composition of the troposphere in the tropical region. For this purpose we have applied two recently developed Biogenic Emission inventories provided for use in large-scale global models (Granier et al., 2005; Lathiere et al., 2006) whose seasonality and temporal distribution for Biogenic Emissions of isoprene, other volatile organic compounds and NO is markedly different. The use of the 12 year average values for Biogenic Emissions provided by Lathiere et al. (2006) results in an increase in the amount of nitrogen sequestrated into longer lived reservoir compounds which contributes to the reduction in the tropospheric ozone burden in the tropics. The associated re-partitioning of nitrogen between PAN, HNO3 and organic nitrates also results in a ~5% increase in the loss of nitrogen by wet deposition. At a global scale there is a reduction in the oxidizing capacity of the model atmosphere which increases the atmospheric lifetimes of CH4 and CO by ~1.5% and ~4%, respectively. Comparisons against a range of different measurements indicate that applying the 12 year average of Lathiere et al. (2006) improves the performance of TM4_AMMA for 2006 in the tropics. By the use of sensitivity studies we show that the release of NO from soils in Africa accounts for between ~2–45% of tropospheric ozone in the African troposphere, ~10% in the upper troposphere and between ~5–20% of the tropical tropospheric ozone column over the tropical Atlantic Ocean. The subsequent reduction in OH over the source regions allows enhanced transport of CO out of the region. For Biogenic volatile organic C1 to C3 species released from Africa, the effects on tropical tropospheric ozone are rather limited, although this source contributes to the global burden of VOC by between ~2–4% and has a large influence on the organic composition of the troposphere over the tropical Atlantic Ocean.
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The influence of Biogenic Emissions from Africa on tropical tropospheric ozone during 2006: a global modeling study
Atmospheric Chemistry and Physics Discussions, 2009Co-Authors: J. E. Williams, C. Galy-lacaux, M. P. Scheele, P. F. J. Van Velthoven, J.-p. Cammas, V. Thouret, A. Volz-thomasAbstract:Abstract. We have performed simulations using a 3-D global chemistry-transport model to investigate the influence that Biogenic Emissions from the African continent exert on the composition of the tropopause in the tropical region. For this purpose we have applied two recently developed Biogenic Emission inventories provided for use in large-scale global models (Granier et al., 2005; Lathiére et al., 2006) whose seasonality and temporal distribution for isoprene, Biogenic NO and Biogenic volatile organic compounds is markedly different. The use of the climatological values for Biogenic Emissions provided by Lathiére et al. (2006) results in an increase in the amount of nitrogen sequestrated into longer lived reservoir compounds which contributes to the reduction in tropospheric ozone burden in the tropics. The associated re-partitioning of nitrogen between PAN, HNO3 and organic nitrates also results in a ~5% increase in the loss of nitrogen by wet deposition. At a global scale there is a reduction in the oxidizing capacity of the model atmosphere which increases the atmospheric lifetimes of CH4 and CO by ~1.5% and ~4%, respectively. By the use of sensitivity studies we show that the release of NO from soils in Africa accounts for between ~5–45% of tropospheric ozone in the African troposphere, ~10% in the upper troposphere and between ~5–20% of the tropical tropospheric ozone column over the tropical Atlantic Ocean. The subsequent reduction in OH over the source regions allows enhanced transport of CO out of the region. For Biogenic volatile organic C1 to C3 species released from Africa the effects on tropical tropospheric ozone are rather limited, although this source contributes to the global burden of VOC by between ~2–4% and has a large influence on the organic composition of the troposphere over the tropical Atlantic Ocean. Comparisons against a range of different measurements indicate that applying the climatology of Lathiére et al. (2006) improves the performance of TM4 for 2006 in the tropics.
P. F. J. Van Velthoven - One of the best experts on this subject based on the ideXlab platform.
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quantifying the uncertainty in simulating global tropospheric composition due to the variability in global Emission estimates of Biogenic volatile organic compounds
Atmospheric Chemistry and Physics, 2012Co-Authors: J. E. Williams, P. F. J. Van Velthoven, C A M BrenninkmeijerAbstract:Abstract. The Emission of organic compounds from Biogenic processes acts as an important source of trace gases in remote regions away from urban conurbations, and is likely to become more important in future decades due to the further mitigation of anthropogenic Emissions that affect air quality and climate forcing. In this study we examine the contribution of Biogenic volatile organic compounds (BVOCs) towards global tropospheric composition using the global 3-D chemistry transport model TM5 and the recently developed modified CB05 chemical mechanism. By comparing regional BVOC Emission estimates we show that Biogenic processes act as dominant sources for many regions and exhibit a large variability in the annually and seasonally integrated Emission fluxes. By performing sensitivity studies we find that the contribution of BVOC species containing between 1 to 3 carbon atoms has an impact on the resident mixing ratios of tropospheric O 3 and CO, accounting for ~2.5% and ~10.8% of the simulated global distribution, respectively. This is approximately a third of the cumulative effect introduced by isoprene and the monoterpenes. By examining an ensemble of 3-D global chemistry transport simulations which adopt different global BVOC Emission inventories we determine the associated uncertainty introduced towards simulating the composition of the troposphere for the year 2000. By comparing the model ensemble values against a composite of atmospheric measurements we show that the effects on tropospheric O 3 are limited to the lower troposphere (with an uncertainty between −2% to 10%), whereas that for tropospheric CO extends up to the upper troposphere (with an uncertainty of between 10 to 45%). Comparing the mixing ratios for low molecular weight alkenes in TM5 against surface measurements taken in Europe implies that the cumulative Emission estimates are too low, regardless of the chosen BVOC inventory. This variability in the global distribution of CO due to BVOC Emissions introduces an associated uncertainty in the tropospheric CO burden of 11.4%, which impacts strongly on the oxidative capacity of the troposphere, introducing an uncertainty in the atmospheric lifetime of the greenhouse gas CH 4 of ~3.3%. This study thus identifies the necessity of placing further constraints on non-CH 4 global Biogenic Emission estimates in large-scale global atmospheric chemistry models.
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The influence of Biogenic Emissions from Africa on tropical tropospheric ozone during 2006: a global modeling study
Atmospheric Chemistry and Physics, 2009Co-Authors: J. E. Williams, C. Galy-lacaux, M. P. Scheele, P. F. J. Van Velthoven, J.-p. Cammas, V. Thouret, A. Volz-thomasAbstract:Abstract. We have performed simulations using a 3-D global chemistry-transport model to investigate the influence that Biogenic Emissions from the African continent exert on the composition of the troposphere in the tropical region. For this purpose we have applied two recently developed Biogenic Emission inventories provided for use in large-scale global models (Granier et al., 2005; Lathiere et al., 2006) whose seasonality and temporal distribution for Biogenic Emissions of isoprene, other volatile organic compounds and NO is markedly different. The use of the 12 year average values for Biogenic Emissions provided by Lathiere et al. (2006) results in an increase in the amount of nitrogen sequestrated into longer lived reservoir compounds which contributes to the reduction in the tropospheric ozone burden in the tropics. The associated re-partitioning of nitrogen between PAN, HNO3 and organic nitrates also results in a ~5% increase in the loss of nitrogen by wet deposition. At a global scale there is a reduction in the oxidizing capacity of the model atmosphere which increases the atmospheric lifetimes of CH4 and CO by ~1.5% and ~4%, respectively. Comparisons against a range of different measurements indicate that applying the 12 year average of Lathiere et al. (2006) improves the performance of TM4_AMMA for 2006 in the tropics. By the use of sensitivity studies we show that the release of NO from soils in Africa accounts for between ~2–45% of tropospheric ozone in the African troposphere, ~10% in the upper troposphere and between ~5–20% of the tropical tropospheric ozone column over the tropical Atlantic Ocean. The subsequent reduction in OH over the source regions allows enhanced transport of CO out of the region. For Biogenic volatile organic C1 to C3 species released from Africa, the effects on tropical tropospheric ozone are rather limited, although this source contributes to the global burden of VOC by between ~2–4% and has a large influence on the organic composition of the troposphere over the tropical Atlantic Ocean.
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The influence of Biogenic Emissions from Africa on tropical tropospheric ozone during 2006: a global modeling study
Atmospheric Chemistry and Physics Discussions, 2009Co-Authors: J. E. Williams, C. Galy-lacaux, M. P. Scheele, P. F. J. Van Velthoven, J.-p. Cammas, V. Thouret, A. Volz-thomasAbstract:Abstract. We have performed simulations using a 3-D global chemistry-transport model to investigate the influence that Biogenic Emissions from the African continent exert on the composition of the tropopause in the tropical region. For this purpose we have applied two recently developed Biogenic Emission inventories provided for use in large-scale global models (Granier et al., 2005; Lathiére et al., 2006) whose seasonality and temporal distribution for isoprene, Biogenic NO and Biogenic volatile organic compounds is markedly different. The use of the climatological values for Biogenic Emissions provided by Lathiére et al. (2006) results in an increase in the amount of nitrogen sequestrated into longer lived reservoir compounds which contributes to the reduction in tropospheric ozone burden in the tropics. The associated re-partitioning of nitrogen between PAN, HNO3 and organic nitrates also results in a ~5% increase in the loss of nitrogen by wet deposition. At a global scale there is a reduction in the oxidizing capacity of the model atmosphere which increases the atmospheric lifetimes of CH4 and CO by ~1.5% and ~4%, respectively. By the use of sensitivity studies we show that the release of NO from soils in Africa accounts for between ~5–45% of tropospheric ozone in the African troposphere, ~10% in the upper troposphere and between ~5–20% of the tropical tropospheric ozone column over the tropical Atlantic Ocean. The subsequent reduction in OH over the source regions allows enhanced transport of CO out of the region. For Biogenic volatile organic C1 to C3 species released from Africa the effects on tropical tropospheric ozone are rather limited, although this source contributes to the global burden of VOC by between ~2–4% and has a large influence on the organic composition of the troposphere over the tropical Atlantic Ocean. Comparisons against a range of different measurements indicate that applying the climatology of Lathiére et al. (2006) improves the performance of TM4 for 2006 in the tropics.
Alex Guenther - One of the best experts on this subject based on the ideXlab platform.
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investigation on Emission properties of Biogenic vocs of landscape plants in shenzhen
Environmental Sciences, 2011Co-Authors: Aikui Huang, Alex Guenther, James A Greenberg, Brad Baker, Michael Graessli, Jianhui BaiAbstract:Isoprene and monoterpene Emissions were characterized using flow and enclosure sampling method and GC-MS in USA for 158 species of plants growing in Shenzhen, China. This survey was designed to include all of the dominant plants within the Shenzhen region as well as unique plants such as Cycads. These are the first measurements in a subtropical Asian metropolis. Substantial isoprene Emissions were observed from thirty-one species, including Caryota mitis, Adenanthera pavonina var. microsperma, Mangifera indica and Excoecoria agalloch. Monoterpene Emissions were observed from fifty-two species, including Passiflora edulis, Bambusa glaucescens cv. silverstripe as well as some primitive and rare Cycadaceae and Cyatheaceae plants. For the first time some of red plants have been measured, most of them have the ability of releasing terpene. These results will be used to develop Biogenic Emission model estimates for Shenzhen and the surrounding region that can be used as inputs for regional air quality models.
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improved land cover and Emission factors for modeling Biogenic volatile organic compounds Emissions from hong kong
Atmospheric Environment, 2010Co-Authors: Dennis Y C Leung, P Wong, B K H Cheung, Alex GuentherAbstract:Atmospheric Environment 44 (2010) 1456e1468 Contents lists available at ScienceDirect Atmospheric Environment journal homepage: www.elsevier.com/locate/atmosenv Improved land cover and Emission factors for modeling Biogenic volatile organic compounds Emissions from Hong Kong D.Y.C. Leung a, * , P. Wong b , B.K.H. Cheung b , A. Guenther c a Department of Mechanical Engineering, the University of Hong Kong, Pokfulam Road, Hong Kong, China Air Science Group, Environmental Protection Department, Hong Kong Special Administrative Region Government, Hong Kong, China c National Center for Atmospheric Research, USA b a r t i c l e i n f o a b s t r a c t Article history: Received 12 September 2009 Received in revised form 11 January 2010 Accepted 13 January 2010 This paper describes a study of local Biogenic volatile organic compounds (BVOC) Emissions from the Hong Kong Special Administrative Region (HKSAR). An improved land cover and Emission factor database was developed to estimate Hong Kong Emissions using MEGAN, a BVOC Emission model developed by Guenther et al. (2006). Field surveys of plant species composition and laboratory measurements of Emission factors were combined with other data to improve existing land cover and Emission factor data. The BVOC Emissions from Hong Kong were calculated for 12 consecutive years from 1995 to 2006. For the year 2006, the total annual BVOC Emissions were determined to be 12,400 metric tons or 9.82 10 9 g C (BVOC carbon). Isoprene Emission accounts for 72%, monoterpene Emissions account for 8%, and other VOCs Emissions account for the remaining 20%. As expected, seasonal variation results in a higher Emission in the summer and a lower Emission in the winter, with Emission predominantly in day time. A high Emission of isoprene occurs for regions, such as Lowest Forest-NT North, dominated by broadleaf trees. The spatial variation of total BVOC is similar to the isoprene spatial variation due to its high contribution. The year to year variability in Emissions due to weather was small over the twelve-year period (1.4%, 2006 to 1995 trendline), but an increasing trend in the annual variation due to an increase in forest land cover can be observed (þ7%, 2006 to 1995 trendline). The results of this study demonstrate the importance of accurate land cover inputs for Biogenic Emission models and indicate that land cover change should be considered for these models. O 2010 Elsevier Ltd. All rights reserved. Keywords: BVOC Emission Isoprene Monoterpene Other VOCs 1. Introduction Volatile Organic Compounds (VOCs) in the troposphere react photochemically with oxides of nitrogen (NO x ) in the presence of solar radiation to form smog which contains various secondary air pollutants such as ozone and peroxyacetyl nitrate (PAN). This smog causes adverse impact on human health, plants and agricultural products. Atmospheric VOCs come from two sources, anthropo- genic and natural sources. Petrochemical plants, motor vehicles, and industrial/commercial use of paints, thinners and dry cleaning solvents are some examples of anthropogenic sources while vege- tation (trees, grasses and marshes) is an important source of natural Biogenic VOC. These Biogenic sources emit a significant amount of VOCs into our atmosphere with a composition, including isoprene and terpenes, which is considerably more reactive than anthropo- genic VOCs. Biogenic VOC studies enhance our knowledge of * Corresponding author. Tel.: þ86 852 2859 7911; fax: þ86 852 2858 5415. E-mail address: ycleung@hku.hk (D.Y.C. Leung). 1352-2310/$ e see front matter O 2010 Elsevier Ltd. All rights reserved. doi:10.1016/j.atmosenv.2010.01.012 Biogenic Emissions and the production of secondary air pollutants. They also provide useful inputs for air quality modeling and provide information for the government to develop effective environmental strategies associated with large scale tree planting and urban greening programs. BVOC Emission modeling is a multi-disciplinary research topic, which involves knowledge in botanical science, scientific computing, atmospheric science, and geography. The topic is an important and growing area of research that has been studied and reviewed in the literature by many researchers. Fuentes et al. (2000) reviewed the science of biosynthesis, transport, and chemical transportation of hydrocarbons emitted by the terrestrial biosphere and examined the integration of Biogenic hydrocarbon kinetics and atmospheric physics into quantitative modeling systems. Kesselmeier and Staudt (1999) reviewed the knowledge of Biogenic Emission of some VOCs and discussed biosynthesis, Emission inventories, relations between Emission and plant physiology and temperature, radiation, and ecophysiological functions. An extended summary of standard Emission factors with data related to plant genus and species is included for isoprene and monoterpenes in the paper.
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response of isoprene Emission to ambient co2 changes and implications for global budgets
Global Change Biology, 2009Co-Authors: Colette L Heald, M Wilkinson, Russell K Monson, Clement Alo, Guiling Wang, Alex GuentherAbstract:We explore the potential role of atmospheric carbon dioxide (CO2) on isoprene Emissions using a global coupled land–atmosphere model [Community Atmospheric Model–Community Land Model (CAM–CLM)] for recent (year 2000, 365ppm CO2) and future (year 2100, 717ppm CO2) conditions. We incorporate an empirical model of observed isoprene Emissions response to both ambient CO2 concentrations in the long-term growth environment and short-term changes in intercellular CO2 concentrations into the MEGAN Biogenic Emission model embedded within the CLM. Accounting for CO2 inhibition has little impact on predictions of present-day global isoprene Emission (increase from 508 to 523TgCyr � 1 ). However, the large increases in future isoprene Emissions typically predicted in models, which are due to a projected warmer climate, are entirely offset by including the CO2 effects. Projected global isoprene Emissions in 2100 drop from 696 to 479TgCyr � 1 when this effect is included, maintaining future isoprene sources at levels similar to present day. The isoprene Emission response to CO2 is dominated by the long-term growth environment effect, with modulations of 10% or less due to the variability in intercellular CO2 concentration. As a result, perturbations to isoprene Emissions associated with changes in ambient CO2 are largely aseasonal, with little diurnal variability. Future isoprene Emissions increase by more than a factor of two in 2100 (to 1242TgCyr � 1 ) when projected changes in vegetation distribution and leaf area density are included. Changing land cover and the role of nutrient limitation on CO2 fertilization therefore remain the largest source of uncertainty in isoprene Emission prediction. Although future projections suggest a compensatory balance between the effects of temperature and CO2 on isoprene Emission, the enhancement of isoprene Emission due to lower ambient CO2 concentrations did not compensate for the effect of cooler temperatures over the last 400 thousand years of the geologic record (including the Last Glacial Maximum).
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Future land use and land cover influences on regional Biogenic Emissions and air quality in the United States
Atmospheric Environment, 2009Co-Authors: Jack Chen, Alex Guenther, Christine Wiedinmyer, J. Avise, Eric P. Salathé, Robert B. Jackson, Brian LambAbstract:A regional modeling system was applied with inputs from global climate and chemistry models to quantify the effects of global change on future Biogenic Emissions and their impacts on ozone and Biogenic secondary organic aerosols (BSOA) in the US. Biogenic Emissions in the future are influenced by projected changes in global and regional climates and by variations in future land use and land cover (LULC). The modeling system was applied for five summer months for the present-day case (1990–1999, Case 1) and three future cases covering 2045–2054. Individual future cases were: present-day LULC (Case 2); projected-future LULC (Case 3); and future LULC with designated regions of tree planting for carbon sequestration (Case 4). Results showed changing future meteorology with present-day LULC (Case 2) increased average isoprene and monoterpene Emission rates by 26% and 20% due to higher temperature and solar insolation. However when LULC was changed together with climate (Case 3), predicted isoprene and monoterpene Emissions decreased by 52% and 31%, respectively, due primarily to projected cropland expansion. The reduction was less, at 31% and 14% respectively, when future LULC changes were accompanied by regions of tree planting (Case 4). Despite the large decrease in Biogenic Emission, future average daily maximum 8-h (DM8H) ozone was found to increase between þ8 ppbv and þ10 ppbv due to high future anthropogenic Emissions and global chemistry conditions. Among the future cases, changing LULC resulted in spatially varying future ozone differences of � 5 ppbv to þ5 ppbv when compared with present-day case. Future BSOA changed directly with the estimated monoterpene Emissions. BSOA increased by 8% with current LULC (Case 2) but decreased by 45%–28% due to future LULC changes. Overall, the results demonstrated that on a regional basis, changes in LULC can offset temperature driven increases in Biogenic Emissions, and, thus, LULC projection is an important factor to consider in the study of future regional air quality.
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evaluating the performance of pyrogenic and Biogenic Emission inventories against one decade of space based formaldehyde columns
Atmospheric Chemistry and Physics, 2008Co-Authors: Trissevgeni Stavrakou, Jeanfrancois Muller, Isabelle De Smedt, Luisa Giglio, Guido R. Van Der Werf, Michel Van Roozendael, Alex GuentherAbstract:A new one-decade (1997-2006) dataset of formaldehyde (HCHO) columns retrieved from GOME and SCIAMACHY is compared with HCHO columns simulated by an updated version of the IMAGES global chemical trans- port model. This model version includes an optimized chem- ical scheme with respect to HCHO production, where the short-term and final HCHO yields from pyrogenically emit- ted non-methane volatile organic compounds (NMVOCs) are estimated from the Master Chemical Mechanism (MCM) and an explicit speciation profile of pyrogenic Emissions. The model is driven by the Global Fire Emissions Database (GFED) version 1 or 2 for biomass burning, whereas bio- genic Emissions are provided either by the Global Emissions Inventory Activity (GEIA), or by a newly developed inven- tory based on the Model of Emissions of Gases and Aerosols from Nature (MEGAN) algorithms driven by meteorolog- ical fields from the European Centre for Medium-Range Weather Forecasts (ECMWF). The comparisons focus on tropical ecosystems, North America and China, which expe- rience strong Biogenic and biomass burning NMVOC emis- sions reflected in the enhanced measured HCHO columns. These comparisons aim at testing the ability of the model to reproduce the observed features of the HCHO distribu- tion on the global scale and at providing a first assessment of the performance of the current Emission inventories. The high correlation coefficients ( r>0.7) between the observed and simulated columns over most regions indicate a good consistency between the model, the implemented inventories and the HCHO dataset. The use of the MEGAN-ECMWF inventory improves the model/data agreement in almost all regions, but biases persist over parts of Africa and Australia. Although neither GFED version is consistent with the data over all regions, a better agreement is achieved over Indone- sia and Southern Africa when GFEDv2 is used, but GFEDv1 succeeds better in getting the correct seasonal patterns and intensities of the fire episodes over the Amazon basin, as re- flected in the significantly higher correlations calculated in this region. Although the uncertainties in the HCHO re- trievals, especially over fire scenes, can be quite large, this study provides a first assessment about whether the improved methodologies and input data implemented in GFEDv2 and MEGAN-ECMWF lead to better results in the comparisons of modelled with observed HCHO column measurements.