An observational study on the effects of time and space averaging in photochemical models

Arellano, Jordi Vilì-Guerau de; Duynkerke, Peter G.; Jonker, Piet J.; Builtjes, P. J. H.

doi:10.1016/0960-1686(93)90109-c

Cited by 18 publications

(6 citation statements)

References 22 publications

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“…Therefore, the chemical sink term is modeled as

R_{normalchem} (z) = - ([], k_{[normalISOP]}^{normal ef f} \overset{[normalISOP]}{false} (z) + k_{normal [MT]}^{normal ef f} \overset{[normalMT]}{false} (z) + k_{[normalSQT]}^{normal ef f} \overset{[normalSQT]}{false} (z)) \overset{[{normalO}_{3}]}{false} (z),

where

\overset{[normalISOP]}{false}

\overset{[normalMT]}{false}

, and

\overset{[normalSQT]}{false}

are the mean mixing ratios of isoprene, monoterpenes, and sesquiterpenes, respectively. Additionally, the effective reaction rate constant for the reaction of the chemical species [A] with ozone is defined as

k_{[normalA]}^{normal ef f} = k_{[normalA]} (1 + I_{S, [A]}),

where k [A] is the true reaction rate constant for the reaction and

I_{S, [A]} = \overset{{[normalA]}^{'} {[{normalO}_{3}]}^{'}}{false} / (\overset{[normalA]}{false} \overset{[{normalO}_{3}]}{false})

is the intensity of segregation between spatial distributions of ozone and [A] [e.g., see Schumann , ; de Arellano et al , ]. The rate constants for the reactions of isoprene, monoterpenes, and sesquiterpenes with ozone are needed (see Table ).…”

Section: Methodsmentioning

confidence: 99%

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Turbulent mixing and removal of ozone within an Amazon rainforest canopy

et al. 2017

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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.

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“…Therefore, the chemical sink term is modeled as

R_{normalchem} (z) = - ([], k_{[normalISOP]}^{normal ef f} \overset{[normalISOP]}{false} (z) + k_{normal [MT]}^{normal ef f} \overset{[normalMT]}{false} (z) + k_{[normalSQT]}^{normal ef f} \overset{[normalSQT]}{false} (z)) \overset{[{normalO}_{3}]}{false} (z),

where

\overset{[normalISOP]}{false}

\overset{[normalMT]}{false}

, and

\overset{[normalSQT]}{false}

k_{[normalA]}^{normal ef f} = k_{[normalA]} (1 + I_{S, [A]}),

where k [A] is the true reaction rate constant for the reaction and

I_{S, [A]} = \overset{{[normalA]}^{'} {[{normalO}_{3}]}^{'}}{false} / (\overset{[normalA]}{false} \overset{[{normalO}_{3}]}{false})

Section: Methodsmentioning

confidence: 99%

“…is the intensity of segregation between spatial distributions of ozone and [A] [e.g., see Schumann, 1989;de Arellano et al, 1993]. The rate constants for the reactions of isoprene, monoterpenes, and sesquiterpenes with ozone are needed (see Table 2).…”

Section: Ozone Chemistry Time Scalementioning

confidence: 99%

Turbulent mixing and removal of ozone within an Amazon rainforest canopy

et al. 2017

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“…The boundary conditions in the horizontal directions are periodic. DALES 3.2 is extended with a chemistry module, thus allowing for simultaneous simulation of both boundary layer dynamics and chemistry (Vilà-Guerau de Arellano et al, 2005).…”

Section: Modelmentioning

confidence: 99%

“…This segregation of species was previously studied for idealized cases (Schumann, 1989;Sykes et al, 1992;Vilà-Guerau de Arellano et al, 1993). The inability of turbulence to uniformly mix the emitted and entrained species creates sub-regions where the species are non-uniformly distributed in a correlated or anti-correlated way, thereby modifying the mean chemical reaction rate in the boundary layer.…”

Section: Introductionmentioning

confidence: 99%

On the segregation of chemical species in a clear boundary layer over heterogeneous land surfaces

et al. 2011

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Abstract. Using a Large-Eddy Simulation model, we have systematically studied the inability of boundary layer turbulence to efficiently mix reactive species. This creates regions where the species are accumulated in a correlated or anti-correlated way, thereby modifying the mean reactivity. We quantify this modification by the intensity of segregation, I S , and analyse the driving mechanisms: heterogeneity of the surface moisture and heat fluxes, various background wind patterns and non-uniform isoprene emissions. The heterogeneous surface conditions are characterized by cool and wet forested patches with high isoprene emissions, alternated with warm and dry patches that represents pasture with relatively low isoprene emissions. For typical conditions in the Amazon rain forest, applying homogeneous surface forcings and in the absence of free tropospheric NO x , the isoprene-OH reaction rate is altered by less than 10 %. This is substantially smaller than the previously assumed I S of 50 % in recent large-scale model analyses of tropical rain forest chemistry. Spatial heterogeneous surface emissions enhance the segregation of species, leading to alterations of the chemical reaction rates up to 20 %. The intensities of segregation are enhanced when the background wind direction is parallel to the borders between the patches and reduced in the case of a perpendicular wind direction. The effects of segregation on trace gas concentrations vary per species. For the highly reactive OH, the differences in concentration averaged over the boundary layer are less than 2 % compared to homogeneous surface conditions, while the isoprene concentration is increased by as much as 12 % due to the reduced chemical reaction rates. These processes take place at the sub-grid scale of chemistry transport models and therefore need to be parameterized.

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“…For both the studies of Ouwersloot et al [2011] and Krol et al [2000], the chemical reaction is slowed down because the concentrations of the reacting chemicals anticorrelate in space. This segregation has been studied in idealized cases by Schumann [1989], Sykes et al [1992], and Vilà-Guerau de Arellano et al [1993b]. LES studies have also been performed on physical processes such as cloud formation [van Heerwaarden and Vilà-Guerau de Arellano, 2008].…”

Section: Introductionmentioning

confidence: 99%

A large‐eddy simulation of the phase transition of ammonium nitrate in a convective boundary layer

et al. 2013

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[1] Under warm and dry conditions, ammonium nitrate aerosol outgasses to form ammonia and nitric acid in the lower atmospheric boundary layer. In the upper boundary layer, where the temperature is lower and the relative humidity is higher, nitric acid and ammonia condense back to the aerosol phase. Measurements show that aerosol nitrate mixing ratios increase with altitude, confirming this phase transition. Since phase equilibrium is not reached instantaneously, updrafts transport aerosol-poor air from the surface to high altitudes and aerosol-rich air subsides from high altitudes to the surface under turbulent conditions. As a result, the partitioning deviates from equilibrium, so the horizontal and temporal variabilities of the aerosol nitrate mixing ratio are enhanced and a continuous downward aerosol nitrate flux emerges. We postulate that observations of this variability and flux should not be interpreted as instrument noise and deposition of nitrate. In an idealized large-eddy simulation (LES) experiment of a convective boundary layer, we find that the larger variability and flux occurred at about one third of the boundary layer height. Both are largest when the gas-aerosol partitioning time scale is assumed to be about half the time scale of turbulence. Our LES result shows negatively skewed nitrate mixing ratios. Under colder conditions, a smaller fraction of ammonium nitrate aerosol outgasses at the surface, so the absolute effect of nitrate repartitioning becomes smaller. However, dimensionless statistical properties do not change as long as the turbulent properties of the boundary layer remain similar. This indicates that the identified processes are also present under colder conditions. Citation: Aan de Brugh, J. M. J., H. G. Ouwersloot, J. Vila`-Guerau de Arellano, and M. C. Krol (2013), A large-eddy simulation of the phase transition of ammonium nitrate in a convective boundary layer,

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An observational study on the effects of time and space averaging in photochemical models

Cited by 18 publications

References 22 publications

Turbulent mixing and removal of ozone within an Amazon rainforest canopy

Turbulent mixing and removal of ozone within an Amazon rainforest canopy

On the segregation of chemical species in a clear boundary layer over heterogeneous land surfaces

A large‐eddy simulation of the phase transition of ammonium nitrate in a convective boundary layer

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