Chemistry‐turbulence interactions and mesoscale variability influence the cleansing efficiency of the atmosphere

Kaser, L.; Karl, T.; Yuan, Bin; Mauldin, R. L.; Cantrell, C. A.; Patton, Edward G.; Weinheimer, A. J.; Knote, Christoph; Emmons, L. K.; Apel, E. C.; Hornbrook, R. S.; Shertz, Stephen; Ullmann, Kirk; Hall, Samuel R.; Graus, M.; Gouw, J. A. de; Zhou, Xianliang; Ye, Chunxiang

doi:10.1002/2015gl066641

Cited by 42 publications

(80 citation statements)

References 74 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Hereafter we use the notation

k^{normal ef f} \overset{[normalBVOC]}{false} (z)

to represent the sum of the three terms inside square brackets in equation and define a time scale associated with the ozone loss in the oxidation of the BVOCs as

τ_{normalchem} (z) = \frac{1}{k^{normal ef f} \overset{[normalBVOC]}{false} (z)} .

The intensity of segregation cannot be determined from the measurements available as this would require simultaneous, high‐frequency measurements of the two species involved. While the intensity of segregation between isoprene and OH may be significant [e.g., Kaser et al , ], the reactivity between ozone and terpenes is much lower (due to the much lower ambient levels of terpenes compared to isoprene) and segregation effects are expected to be much smaller [e.g., see Ouwersloot et al , ]. These effects are neglected hereafter and the approximation

k_{normal [A]}^{normal ef f} \approx k_{normal [A]}

is employed.…”

Section: Methodsmentioning

confidence: 99%

Turbulent mixing and removal of ozone within an Amazon rainforest canopy

et al. 2017

View full text Add to dashboard Cite

Simultaneous profiles of turbulence statistics and mean ozone mixing ratio are used to establish a relation between eddy diffusivity and ozone mixing within the Amazon forest. A one‐dimensional diffusion model is proposed and used to infer mixing time scales from the eddy diffusivity profiles. Data and model results indicate that during daytime conditions, the upper (lower) half of the canopy is well (partially) mixed most of the time and that most of the vertical extent of the forest can be mixed in less than an hour. During nighttime, most of the canopy is predominantly poorly mixed, except for periods with bursts of intermittent turbulence. Even though turbulence is faster than chemistry during daytime, both processes have comparable time scales in the lower canopy layers during nighttime conditions. Nonchemical loss time scales (associated with stomatal uptake and dry deposition) for the entire forest are comparable to turbulent mixing time scale in the lower canopy during the day and in the entire canopy during the night, indicating a tight coupling between turbulent transport and dry deposition and stomatal uptake processes. Because of the significant time of day and height variability of the turbulent mixing time scale inside the canopy, it is important to take it into account when studying chemical and biophysical processes happening in the forest environment. The method proposed here to estimate turbulent mixing time scales is a reliable alternative to currently used models, especially for situations in which the vertical distribution of the time scale is relevant.

show abstract

“…Hereafter we use the notation

k^{normal ef f} \overset{[normalBVOC]}{false} (z)

to represent the sum of the three terms inside square brackets in equation and define a time scale associated with the ozone loss in the oxidation of the BVOCs as

τ_{normalchem} (z) = \frac{1}{k^{normal ef f} \overset{[normalBVOC]}{false} (z)} .

k_{normal [A]}^{normal ef f} \approx k_{normal [A]}

is employed.…”

Section: Methodsmentioning

confidence: 99%

Turbulent mixing and removal of ozone within an Amazon rainforest canopy

et al. 2017

View full text Add to dashboard Cite

show abstract

“…Kaser et al . [] have recently shown that in addition to uncertainties in atmospheric chemistry schemes, the limited spatial resolution of models masks the true spatial covariability and spatial segregation of BVOC and atmospheric oxidants, which can result in up to 30% overestimation of isoprene oxidation rates. Figure depicts this process where two different air parcels over heterogeneous landscapes (cropland versus mixed oak forests) that are separated by a distance of just a few kilometers have very different concentrations of OH radicals and isoprene: one with high OH and low isoprene and the other with low OH and high isoprene.…”

Section: Biogenic Emissions and Soa Formationmentioning

confidence: 99%

Recent advances in understanding secondary organic aerosol: Implications for global climate forcing

Shrivastava

Cappa

Fan

et al. 2017

Reviews of Geophysics

695

668

View full text Add to dashboard Cite

Anthropogenic emissions and land use changes have modified atmospheric aerosol concentrations and size distributions over time. Understanding preindustrial conditions and changes in organic aerosol due to anthropogenic activities is important because these features (1) influence estimates of aerosol radiative forcing and (2) can confound estimates of the historical response of climate to increases in greenhouse gases. Secondary organic aerosol (SOA), formed in the atmosphere by oxidation of organic gases, represents a major fraction of global submicron‐sized atmospheric organic aerosol. Over the past decade, significant advances in understanding SOA properties and formation mechanisms have occurred through measurements, yet current climate models typically do not comprehensively include all important processes. This review summarizes some of the important developments during the past decade in understanding SOA formation. We highlight the importance of some processes that influence the growth of SOA particles to sizes relevant for clouds and radiative forcing, including formation of extremely low volatility organics in the gas phase, acid‐catalyzed multiphase chemistry of isoprene epoxydiols, particle‐phase oligomerization, and physical properties such as volatility and viscosity. Several SOA processes highlighted in this review are complex and interdependent and have nonlinear effects on the properties, formation, and evolution of SOA. Current global models neglect this complexity and nonlinearity and thus are less likely to accurately predict the climate forcing of SOA and project future climate sensitivity to greenhouse gases. Efforts are also needed to rank the most influential processes and nonlinear process‐related interactions, so that these processes can be accurately represented in atmospheric chemistry‐climate models.

show abstract

“…For midday conditions, the chemical tendency of isoprene can be estimated following Reynolds decomposition as

{\frac{\overset{\partial C_{5} H_{8}}{true}}{\partial t}|}_{chemistry} = prefix- \overset{k}{true} ([], \overset{C_{5} H_{8}}{true} \overset{normalO normalH}{true} prefix+ \overset{C_{5} H_{8}^{'} normalO H^{'}}{true}),

where k is the C 5 H 8 + OH reaction rate coefficient, the bars denote time and space averages, and the primes are deviations or fluctuations from the averages [e.g., Kaser et al ., ]. By discretizing the conservation equation on a grid, regional‐ and global‐scale models implicitly average over all motions smaller than the grid size.…”

Section: Introductionmentioning

confidence: 99%

Impact of turbulent mixing on isoprene chemistry

Kim

Barth

Trainer

2016

Geophysical Research Letters

View full text Add to dashboard Cite

Isoprene, a volatile organic compound that is mainly emitted from trees, rapidly reacts with hydroxyl radical (OH) during daytime and subsequently forms ozone and aerosols in the troposphere. The isoprene‐OH reaction can be affected by the interplay between chemistry and mixing because the two processes occur at a similar time scale. We investigate the impact of turbulent mixing on isoprene‐OH reactivity with large eddy simulations (LES) coupled with comprehensive chemistry. Our results show that the covariance of isoprene and OH causes ~20% decrease to ~10% increase of the horizontal average reaction rate, depending on nitrogen oxides (NOx = NO + NO2) abundances, compared to the rate that neglects the covariance. This wide range of effects on reaction rates is caused by the primary production and loss reactions of OH in each NOx regime. Our research promotes the use of LES for better understanding the role of turbulence in isoprene‐OH reaction and parameterizations in large‐scale models.

show abstract

Chemistry‐turbulence interactions and mesoscale variability influence the cleansing efficiency of the atmosphere

Cited by 42 publications

References 74 publications

Turbulent mixing and removal of ozone within an Amazon rainforest canopy

Turbulent mixing and removal of ozone within an Amazon rainforest canopy

Recent advances in understanding secondary organic aerosol: Implications for global climate forcing

Impact of turbulent mixing on isoprene chemistry

Contact Info

Product

Resources

About