Numerical modeling of the turbulent fluxes of chemically reactive trace gases in the atomospheric boundary layer
- Argonne National Laboratory, IL (United States)
Turbulent fluxes of chemically reactive trace gases in the neutral atmospheric boundary layer (ABL) were simulated with a one-dimensional, coupled diffusion-chemistry model. The effects of rapid chemical reactions were included with a suite of second-order turbulence equations in which additional chemical terms were used to describe contributions to flux by rapid chemical production and loss. A total of 69 chemical reactions were incorporated to describe basic atmospheric photochemistry coupled with chemistry for isoprene and its oxidation products. Daytime flux profiles of O{sub 3}, NO, NO{sub 2}, OH, isoprene, and other depositing gases were simulated with assumed rates of NO emission from soil, isoprene emission rates appropriate for a deciduous forest, and initial concentrations of various chemical species typical of a remote area. Results show that chemical reactions can influence vertical fluxes by producing sources of sinks in the atmosphere and by changing mean concentrations. Magnitudes of NO and NO{sub 2} fluxes decrease with height at a much greater rate than predicted by a nonreactive model. The NO emitted from soil can quickly be converted to NO{sub 2}, and the upward NO flux can decrease by as much as 80% at a height of 100 m. The magnitude of NO{sub 2} flux decreases sharply with height because of the NO-to-NO{sub 2} conversion, but NO{sub 2} deposition near the surface tends to be enhanced by an increase in NO{sub 2} concentration near the surface NO emission source. The profile of O{sub 3} flux simulated with forced entrainment at the top of the ABL closely matches the profile derived from a field experiment, and the flux throughout the ABL increases slightly because mean O{sub 3}, concentrations are increased by chemical production associated with isoprene emissions. Simulated profiles of isoprene flux closely agree with results of a nonreactive model. 34 refs., 11 figs., 3 tabs.
- OSTI ID:
- 432164
- Journal Information:
- Journal of Applied Meteorology, Vol. 33, Issue 7; Other Information: PBD: Jul 1994
- Country of Publication:
- United States
- Language:
- English
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