FORest Canopy Atmosphere Transfer (FORCAsT) 2.0: model updates and evaluation with observations at a mixed forest site

Abstract. The FORCAsT (FORest Canopy Atmosphere Transfer) model version 1.0 is updated to FORCAsT 2.0 by implementing five major changes, including (1) a change to the operator splitting, separating chemistry from emission and dry deposition, which reduces the run time of the gas-phase chemistry by 70 % and produces a more realistic in-canopy profile for isoprene; (2) a modification of the eddy diffusivity parameterization to produce greater and more realistic vertical mixing in the boundary layer, which ameliorates the unrealistic simulated end-of-day peaks in isoprene under well-mixed conditions and improves daytime air temperature; (3) updates to dry deposition velocities with available measurements; (4) implementation of the Reduced Caltech Isoprene Mechanism (RCIM) to reflect the current knowledge of isoprene oxidation; and (5) extension of the aerosol module to include isoprene-derived secondary organic aerosol (iSOA) formation. Along with the operator splitting, modified vertical mixing, and dry deposition, RCIM improves the estimation of first-generation isoprene oxidation products (methyl vinyl ketone and methacrolein) and some second-generation products (such as isoprene epoxydiols). Inclusion of isoprene in the aerosol module in FORCAsT 2.0 leads to a 7 % mass yield of iSOA. The most important iSOA precursors are IEPOX and tetrafunctionals, which together account for >86 % of total iSOA. The iSOA formed from organic nitrates is more important in the canopy, accounting for 11 % of the total iSOA. The tetrafunctionals compose up to 23 % of the total iSOA formation, highlighting the importance of the fate (i.e., dry deposition and gas-phase chemistry) of later-generation isoprene oxidation products in estimating iSOA formation.

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FORest Canopy Atmosphere Transfer (FORCAsT) 2.0: model updates and evaluation with observations at a mixed forest site

10.5194/gmd-2021-104 ◽

2021 ◽

Author(s):

Dandan Wei ◽

Hariprasad D. Alwe ◽

Dylan B. Millet ◽

Brandon Bottorff ◽

Michelle Lew ◽

...

Keyword(s):

Dry Deposition ◽

Forest Canopy ◽

Operator Splitting ◽

Vertical Mixing ◽

Oxidation Products ◽

Gas Phase Chemistry ◽

Isoprene Oxidation ◽

Aerosol Module ◽

Phase Chemistry ◽

Isoprene Oxidation Products

Abstract. The FORCAsT (FORest Canopy Atmosphere Transfer) model version 1.0 is updated to FORCAsT 2.0 by implementing five major changes, including (1) a change to the operator splitting, separating chemistry from emission and dry deposition, which reduces the run time of the gas-phase chemistry by 70 % and produces a more realistic in-canopy profile for isoprene; (2) a modification of the eddy diffusivity parameterization to produce greater and more realistic vertical mixing in the boundary layer, which ameliorates the unrealistic simulated end-of-day peaks in isoprene under well-mixed conditions and improves daytime air temperature; (3) updates to dry deposition velocities with available measurements; (4) implementation of the Reduced Caltech isoprene mechanism (RCIM) to reflect the current knowledge of isoprene oxidation; and (5) extension of the aerosol module to include isoprene-derived aerosol (iSOA) formation. Along with the operator splitting, modified vertical mixing and dry deposition, RCIM improves the estimation of first generation isoprene oxidation products (methyl vinyl ketone and methacrolein) and some second generation products (such as isoprene epoxydiols). Inclusion of isoprene in the aerosol module in FORCAsT 2.0 leads to a 7 % mass yield of iSOA. The most important iSOA precursors are IEPOX and tetrafunctionals, which together account for > 86 % of total iSOA. The iSOA formed from organic nitrates are more important in the canopy, accounting for 11 % of the total iSOA. The tetrafunctionals compose up to 23 % of the total iSOA formation, highlighting the importance of the fate (i.e. dry deposition and gas-phase chemistry) of later-generation isoprene oxidation products in estimating iSOA formation.

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In-canopy gas-phase chemistry during CABINEX 2009: sensitivity of a 1-D canopy model to vertical mixing and isoprene chemistry

Atmospheric Chemistry and Physics ◽

10.5194/acp-12-8829-2012 ◽

2012 ◽

Vol 12 (18) ◽

pp. 8829-8849 ◽

Cited By ~ 39

Author(s):

A. M. Bryan ◽

S. B. Bertman ◽

M. A. Carroll ◽

S. Dusanter ◽

G. D. Edwards ◽

...

Keyword(s):

Atmospheric Chemistry ◽

Forest Canopy ◽

Deciduous Forest ◽

Vertical Mixing ◽

Field Studies ◽

Oxidation Products ◽

Base Case ◽

Emission Model ◽

Order Of Magnitude ◽

Phase Chemistry

Abstract. Vegetation emits large quantities of biogenic volatile organic compounds (BVOC). At remote sites, these compounds are the dominant precursors to ozone and secondary organic aerosol (SOA) production, yet current field studies show that atmospheric models have difficulty in capturing the observed HOx cycle and concentrations of BVOC oxidation products. In this manuscript, we simulate BVOC chemistry within a forest canopy using a one-dimensional canopy-chemistry model (Canopy Atmospheric CHemistry Emission model; CACHE) for a mixed deciduous forest in northern Michigan during the CABINEX 2009 campaign. We find that the base-case model, using fully-parameterized mixing and the simplified biogenic chemistry of the Regional Atmospheric Chemistry Model (RACM), underestimates daytime in-canopy vertical mixing by 50–70% and by an order of magnitude at night, leading to discrepancies in the diurnal evolution of HOx, BVOC, and BVOC oxidation products. Implementing observed micrometeorological data from above and within the canopy substantially improves the diurnal cycle of modeled BVOC, particularly at the end of the day, and also improves the observation-model agreement for some BVOC oxidation products and OH reactivity. We compare the RACM mechanism to a version that includes the Mainz isoprene mechanism (RACM-MIM) to test the model sensitivity to enhanced isoprene degradation. RACM-MIM simulates higher concentrations of both primary BVOC (isoprene and monoterpenes) and oxidation products (HCHO, MACR+MVK) compared with RACM simulations. Additionally, the revised mechanism alters the OH concentrations and increases HO2. These changes generally improve agreement with HOx observations yet overestimate BVOC oxidation products, indicating that this isoprene mechanism does not improve the representation of local chemistry at the site. Overall, the revised mechanism yields smaller changes in BVOC and BVOC oxidation product concentrations and gradients than improving the parameterization of vertical mixing with observations, suggesting that uncertainties in vertical mixing parameterizations are an important component in understanding observed BVOC chemistry.

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In-canopy gas-phase chemistry during CABINEX 2009: sensitivity of a 1-D canopy model to vertical mixing and isoprene chemistry

Atmospheric Chemistry and Physics Discussions ◽

10.5194/acpd-12-12801-2012 ◽

2012 ◽

Vol 12 (5) ◽

pp. 12801-12852 ◽

Cited By ~ 2

Author(s):

A. M. Bryan ◽

S. B. Bertman ◽

M. A. Carroll ◽

S. Dusanter ◽

G. D. Edwards ◽

...

Keyword(s):

Atmospheric Chemistry ◽

Forest Canopy ◽

Deciduous Forest ◽

Vertical Mixing ◽

Field Studies ◽

Oxidation Products ◽

Base Case ◽

Emission Model ◽

Order Of Magnitude ◽

Phase Chemistry

Abstract. Vegetation emits large quantities of biogenic volatile organic compounds (BVOC). At remote sites, these compounds are the dominant precursors to ozone and secondary organic aerosol (SOA) production, yet current field studies show that atmospheric models have difficulty in capturing the observed HOx cycle and concentrations of BVOC oxidation products. In this manuscript, we simulate BVOC chemistry within a forest canopy using a one-dimensional canopy-chemistry model (Canopy Atmospheric CHemistry Emission model; CACHE) for a mixed deciduous forest in northern Michigan during the CABINEX 2009 campaign. We find that the base-case model, using fully-parameterized mixing and the simplified biogenic chemistry of the Regional Atmospheric Chemistry Model (RACM), underestimates daytime in-canopy vertical mixing by 50–70% and by an order of magnitude at night, leading to discrepancies in the diurnal evolution of HOx, BVOC, and BVOC oxidation products. Implementing observed micrometeorological data from above and within the canopy substantially improves the diurnal cycle of modeled BVOC, particularly at the end of the day, and also improves the observation-model agreement for some BVOC oxidation products and OH reactivity. We compare the RACM mechanism to a version that includes the Mainz isoprene mechanism (RACM-MIM) to test the model sensitivity to enhanced isoprene degradation. RACM-MIM simulates higher concentrations of both primary BVOC (isoprene and monoterpenes) and oxidation products (HCHO, MACR + MVK) compared with RACM simulations. Additionally, the revised mechanism alters the OH concentrations and increases HO2. These changes generally improve agreement with HOx observations yet overestimate BVOC oxidation products, indicating that this isoprene mechanism does not improve the representation of local chemistry at the site. Overall, the revised mechanism yields smaller changes in BVOC and BVOC oxidation product concentrations and gradients than improving the parameterization of vertical mixing with observations, suggesting that uncertainties in vertical mixing parameterizations are an important component in understanding observed BVOC chemistry.

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Emissions of putative isoprene oxidation products from mango branches under abiotic stress

Journal of Experimental Botany ◽

10.1093/jxb/ert202 ◽

2013 ◽

Vol 64 (12) ◽

pp. 3669-3679 ◽

Cited By ~ 35

Author(s):

Kolby J. Jardine ◽

Kimberly Meyers ◽

Leif Abrell ◽

Eliane G. Alves ◽

Ana Maria Yanez Serrano ◽

...

Keyword(s):

Abiotic Stress ◽

Oxidation Products ◽

Isoprene Oxidation ◽

Isoprene Oxidation Products

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EVOLUTION OF SELECTED ISOPRENE OXIDATION PRODUCTS IN DARK AQUEOUS AMMONIUM SULFATE

10.37099/mtu.dc.etds/868 ◽

2014 ◽

Author(s):

D.M. Ashraf Ul Habib

Keyword(s):

Ammonium Sulfate ◽

Oxidation Products ◽

Isoprene Oxidation ◽

Isoprene Oxidation Products

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Secondary organic aerosol yields from cloud-processing of isoprene oxidation products

Geophysical Research Letters ◽

10.1029/2007gl031828 ◽

2008 ◽

Vol 35 (2) ◽

Cited By ~ 203

Author(s):

Barbara Ervens ◽

Annmarie G. Carlton ◽

Barbara J. Turpin ◽

Katye E. Altieri ◽

Sonia M. Kreidenweis ◽

...

Keyword(s):

Secondary Organic Aerosol ◽

Organic Aerosol ◽

Oxidation Products ◽

Cloud Processing ◽

Isoprene Oxidation ◽

Isoprene Oxidation Products

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Repeated Exposure to Isoprene Oxidation Products Causes Enhanced Respiratory Tract Effects in Multiple Murine Strains

Inhalation Toxicology ◽

10.1080/713857303 ◽

2003 ◽

Vol 15 (12) ◽

pp. 1191-1207 ◽

Cited By ~ 1

Author(s):

Annette Rohr ◽

Stephanie Shore ◽

John Spengler

Keyword(s):

Respiratory Tract ◽

Repeated Exposure ◽

Oxidation Products ◽

Isoprene Oxidation ◽

Isoprene Oxidation Products

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NO<sub>x</sub> emissions, isoprene oxidation pathways, vertical mixing, and implications for surface ozone in the Southeast United States

10.5194/acp-2016-110 ◽

2016 ◽

Cited By ~ 8

Author(s):

Katherine R. Travis ◽

Daniel J. Jacob ◽

Jenny A. Fisher ◽

Patrick S. Kim ◽

Eloise A. Marais ◽

...

Keyword(s):

Boundary Layer ◽

Surface Ozone ◽

Vertical Mixing ◽

Satellite Observations ◽

Oxidation Products ◽

Large Contribution ◽

Nox Emissions ◽

Tropospheric No2 ◽

Isoprene Oxidation ◽

Southeast Us

Abstract. Ozone pollution in the Southeast US involves complex chemistry driven by emissions of anthropogenic nitrogen oxide radicals (NOx ≡ NO + NO2) and biogenic isoprene. Model estimates of surface ozone concentrations tend to be biased high in the region and this is of concern for designing effective emission control strategies to meet air quality standards. We use detailed chemical observations from the SEAC4RS aircraft campaign in August and September 2013, interpreted with the GEOS-Chem chemical transport model (CTM) at 0.25°×0.3125° horizontal resolution, to better understand the factors controlling surface ozone in the Southeast US. We find that the National Emission Inventory (NEI) for NOx from the US Environmental Protection Agency (EPA) is too high in the Southeast and nationally by 50 %. This is demonstrated by SEAC4RS observations of NOx and its oxidation products, by surface network observations of nitrate wet deposition fluxes, and by OMI satellite observations of tropospheric NO2 columns. Upper tropospheric NO2 from lightning makes a large contribution to the satellite observations that must be accounted for when using these data to estimate surface NOx emissions. Aircraft observations of upper tropospheric NO2 are higher than simulated by GEOS-Chem or expected from NO-NO2-O3 photochemical stationary state. NOx levels in the Southeast US are sufficiently low that only half of isoprene oxidation proceeds by the high-NOx pathway to produce ozone; this fraction is only moderately sensitive to changes in NOx emissions because isoprene and NOx emissions are spatially segregated. GEOS-Chem with reduced NOx emissions provides an unbiased simulation of ozone observations from the aircraft and from ozonesondes, and reproduces the observed ozone production efficiency in the boundary layer as derived from a regression of ozone and NOx oxidation products. However, the model is still biased high by 8 ± 13 ppb relative to observed surface ozone in the Southeast US. Ozonesondes launched during midday hours show a 7 ppb ozone decrease from 1.5 km to 0.2 km altitude, whereas GEOS-Chem has no such gradient because of efficient boundary layer mixing. We conclude that model biases in simulating surface ozone over the Southeast US may be due to a combination of excessive NOx emissions and excessive boundary layer vertical mixing.

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Marine aerosol production: a review of the current knowledge

Philosophical Transactions of The Royal Society A Mathematical Physical and Engineering Sciences ◽

10.1098/rsta.2007.2043 ◽

2007 ◽

Vol 365 (1856) ◽

pp. 1753-1774 ◽

Cited By ~ 444

Author(s):

Colin D O'Dowd ◽

Gerrit de Leeuw

Keyword(s):

Sulphuric Acid ◽

Current Knowledge ◽

Oxidation Products ◽

Marine Aerosol ◽

Aerosol Formation ◽

Multistep Process ◽

Isoprene Oxidation ◽

Iodine Oxides ◽

20 Nm ◽

Isoprene Oxidation Products

The current knowledge in primary and secondary marine aerosol formation is reviewed. For primary marine aerosol source functions, recent source functions have demonstrated a significant flux of submicrometre particles down to radii of 20 nm. Moreover, the source functions derived from different techniques up to 10 μm have come within a factor of two of each other. For secondary marine aerosol formation, recent advances have identified iodine oxides and isoprene oxidation products, in addition to sulphuric acid, as contributing to formation and growth, although the exact roles remains to be determined. While a multistep process seems to be required, isoprene oxidation products are more likely to participate in growth and sulphuric acid is more likely to participate in nucleation. Iodine oxides are likely to participate in both nucleation and growth.

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