Diurnal variability of isoprene and hydroxyl radical over tropical forests

J. Vilà-Guerau de Arellano, E.G. Patton, T. Karl, C.L.A.M. van den Dries, M.C. Barth, J.J. Orlando, H.G. Ouwersloot

Research output: Contribution to conferenceAbstractAcademic

Abstract

We investigate diurnal variability of isoprene and related chemical species in the Amazonian region. The dynamics and chemistry of an atmospheric boundary layer are reproduced by a large-eddy simulation code and a mixed-layer model. These numerical experiments are constrained and evaluated with atmospheric dynamics and chemistry observations available for the same area. The main features of isoprene and methyl-vinyl-ketone are reproduced well, but their evolution raises questions regarding the role of different physical and chemical processes contributing to daily variability. We systematically examine the role of: a) the exchange of thermodynamic variables between the free troposphere and the atmospheric boundary layer (entrainment), b) surface isoprene and nitric oxide emissions, and c) recently proposed modifications to the chemical degradation scheme of isoprene resulting in more efficient recycling of HOx. The entrainment flux of isoprene and a lumped chemical species (methyl-vinyl-ketone+methacrolein) is found to be equally important as surface isoprene emissions. Varying the initial relationship between the initial isoprene mixing ratio in the boundary layer and that in the overlying free troposphere in the early morning results in a 50% increase/decrease of daytime isoprene mixing ratio within the atmospheric boundary layer. An OH concentration maximum is found during the morning transition, where the magnitude of this peak depends on: a) the onset of surface isoprene emission, b) OH photolysis reaction rates and, c) dilution of boundary layer concentrations through entrainment. The introduction of an OH recycling path increases midday OH concentration variation. Our findings suggest that atmospheric dynamics and chemistry are equally important for interpreting reactant observations and for local and region-scale modeling efforts where turbulence need to be parameterized.

Conference

ConferenceAGU Fall Meeting, San Francisco, California, USA
Period13/12/1017/12/10

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isoprene
hydroxyl radical
tropical forest
boundary layer
entrainment
atmospheric dynamics
atmospheric chemistry
ketone
mixing ratio
troposphere
recycling
large eddy simulation
nitric oxide
photolysis
chemical process
reaction rate
mixed layer
dilution
thermodynamics
turbulence

Cite this

Vilà-Guerau de Arellano, J., Patton, E. G., Karl, T., van den Dries, C. L. A. M., Barth, M. C., Orlando, J. J., & Ouwersloot, H. G. (2010). Diurnal variability of isoprene and hydroxyl radical over tropical forests. Abstract from AGU Fall Meeting, San Francisco, California, USA, .
Vilà-Guerau de Arellano, J. ; Patton, E.G. ; Karl, T. ; van den Dries, C.L.A.M. ; Barth, M.C. ; Orlando, J.J. ; Ouwersloot, H.G. / Diurnal variability of isoprene and hydroxyl radical over tropical forests. Abstract from AGU Fall Meeting, San Francisco, California, USA, .
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Vilà-Guerau de Arellano, J, Patton, EG, Karl, T, van den Dries, CLAM, Barth, MC, Orlando, JJ & Ouwersloot, HG 2010, 'Diurnal variability of isoprene and hydroxyl radical over tropical forests' AGU Fall Meeting, San Francisco, California, USA, 13/12/10 - 17/12/10, .

Diurnal variability of isoprene and hydroxyl radical over tropical forests. / Vilà-Guerau de Arellano, J.; Patton, E.G.; Karl, T.; van den Dries, C.L.A.M.; Barth, M.C.; Orlando, J.J.; Ouwersloot, H.G.

2010. Abstract from AGU Fall Meeting, San Francisco, California, USA, .

Research output: Contribution to conferenceAbstractAcademic

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AU - Vilà-Guerau de Arellano, J.

AU - Patton, E.G.

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AU - Orlando, J.J.

AU - Ouwersloot, H.G.

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N2 - We investigate diurnal variability of isoprene and related chemical species in the Amazonian region. The dynamics and chemistry of an atmospheric boundary layer are reproduced by a large-eddy simulation code and a mixed-layer model. These numerical experiments are constrained and evaluated with atmospheric dynamics and chemistry observations available for the same area. The main features of isoprene and methyl-vinyl-ketone are reproduced well, but their evolution raises questions regarding the role of different physical and chemical processes contributing to daily variability. We systematically examine the role of: a) the exchange of thermodynamic variables between the free troposphere and the atmospheric boundary layer (entrainment), b) surface isoprene and nitric oxide emissions, and c) recently proposed modifications to the chemical degradation scheme of isoprene resulting in more efficient recycling of HOx. The entrainment flux of isoprene and a lumped chemical species (methyl-vinyl-ketone+methacrolein) is found to be equally important as surface isoprene emissions. Varying the initial relationship between the initial isoprene mixing ratio in the boundary layer and that in the overlying free troposphere in the early morning results in a 50% increase/decrease of daytime isoprene mixing ratio within the atmospheric boundary layer. An OH concentration maximum is found during the morning transition, where the magnitude of this peak depends on: a) the onset of surface isoprene emission, b) OH photolysis reaction rates and, c) dilution of boundary layer concentrations through entrainment. The introduction of an OH recycling path increases midday OH concentration variation. Our findings suggest that atmospheric dynamics and chemistry are equally important for interpreting reactant observations and for local and region-scale modeling efforts where turbulence need to be parameterized.

AB - We investigate diurnal variability of isoprene and related chemical species in the Amazonian region. The dynamics and chemistry of an atmospheric boundary layer are reproduced by a large-eddy simulation code and a mixed-layer model. These numerical experiments are constrained and evaluated with atmospheric dynamics and chemistry observations available for the same area. The main features of isoprene and methyl-vinyl-ketone are reproduced well, but their evolution raises questions regarding the role of different physical and chemical processes contributing to daily variability. We systematically examine the role of: a) the exchange of thermodynamic variables between the free troposphere and the atmospheric boundary layer (entrainment), b) surface isoprene and nitric oxide emissions, and c) recently proposed modifications to the chemical degradation scheme of isoprene resulting in more efficient recycling of HOx. The entrainment flux of isoprene and a lumped chemical species (methyl-vinyl-ketone+methacrolein) is found to be equally important as surface isoprene emissions. Varying the initial relationship between the initial isoprene mixing ratio in the boundary layer and that in the overlying free troposphere in the early morning results in a 50% increase/decrease of daytime isoprene mixing ratio within the atmospheric boundary layer. An OH concentration maximum is found during the morning transition, where the magnitude of this peak depends on: a) the onset of surface isoprene emission, b) OH photolysis reaction rates and, c) dilution of boundary layer concentrations through entrainment. The introduction of an OH recycling path increases midday OH concentration variation. Our findings suggest that atmospheric dynamics and chemistry are equally important for interpreting reactant observations and for local and region-scale modeling efforts where turbulence need to be parameterized.

M3 - Abstract

ER -

Vilà-Guerau de Arellano J, Patton EG, Karl T, van den Dries CLAM, Barth MC, Orlando JJ et al. Diurnal variability of isoprene and hydroxyl radical over tropical forests. 2010. Abstract from AGU Fall Meeting, San Francisco, California, USA, .