1 Department of Chemistry, University of Toronto 2 Climate and - - PowerPoint PPT Presentation
Sarah C. Kavassalis 1 , Jennifer G. Murphy 1 , Allison L. Steiner 2 1 Department of Chemistry, University of Toronto 2 Climate and Space Science and Engineering, University of Michigan September 13 th , 2017 6th Annual IACPES Symposium on
Sarah C. Kavassalis1, Jennifer G. Murphy1, Allison L. Steiner2
1 Department of
Chemistry, University of Toronto
2 Climate and Space
Science and Engineering, University of Michigan September 13th, 2017 6th Annual IACPES Symposium on Atmospheric Chemistry and Physics
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NO2
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Diel plots of the number and average duration of coherent (s) showing campaign median, 25th/75th, and 5th/95th quantiles.
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29m 21m 13m 5m 34m
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Diel plots of the number and average duration of coherent (s) showing campaign median, 25th/75th, and 5th/95th quantiles.
Diel plot of the fractional contribution of coherent structures to kinematic heat flux showing campaign median, 25th/75th, and 5th/95th quantiles.
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Diel plot of the fractional contribution of coherent structures to kinematic heat flux showing campaign median, 25th/75th, and 5th/95th quantiles.
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Forkel et al., 2006. Bryan et al., 2012. Ashworth et al., 2015.
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FORCAsT (Ashworth et al., 2015) was constrained by PROPHET-AMOS observations and used to model the campaign chemistry. In FORCAsT, mass fluxes are calculated by solving the continuity equation: 𝜖𝑑 𝜖𝑢 = 𝜖 𝑨 𝐿𝐼 𝜖𝑑 𝜖𝑨 + 𝑇𝑑 + 𝐷 Where c is the mixing ratio of the species of interest, KH is the turbulence exchange coefficient, SC includes contributions from emissions, deposition, and advection, and C represents chemical production and loss.
Forkel et al., 2006. Bryan et al., 2012. Ashworth et al., 2015.
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We define and observed 𝐿𝐼 following Makar et al. (1999)
2 0.3ℎ 𝑣∗
Where h is the height, 𝑣∗ is the friction velocity, and 𝜏𝑥 is the standard deviation of the vertical velocity.
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Fraction of heat flux attributable to coherent structures = 0.45 Campaign average 0.52±0.07
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July 20th, 2016 July 23rd, 2016 Fraction of heat flux attributable to coherent structures = 0.62 36m (12m above canopy height)
Fraction of heat flux attributable to coherent structures = 0.45 Campaign average 0.52±0.07
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July 20th, 2016 July 23rd, 2016 Fraction of heat flux attributable to coherent structures = 0.62 36m (12m above canopy height)
July 20th, 2016 July 23rd, 2016 36m (12m above canopy height)
July 20th, 2016 July 23rd, 2016 36m (12m above canopy height)
Slow Chemistry Fast Chemistry (Tturb/Tchem)
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Ratio of B to B+C, Tchem, A = 0.1s Above canopy sonic assimilation only
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Ratio of B to B+C, Tchem, A = 0.1s Full vertical sonic assimilation
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𝐶 𝐶+𝐷 ratio going from only top of canopy
➢We can model heat flux and chemical mixing ratios with reasonable accuracy in a 1D column model without explicit coherent structure representation (despite the large contribution coherent structures make to fluxes) so long as we fix KH by observations ➢Model preference is best when the fractional contribution of coherent structures to fluxes is the lowest ➢Constraining the subcanopy mixing in our model is important for chemical compounds with Damköhler numbers near 1 ➢By knowing the conditions in which our model recreates vertical exchange the most accurately, we can begin to probe other aspects of the model (like choice of chemical mechanism and dry deposition parametrization)
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