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Kenneth J. Davis, Principal Investigator

Modeling the Influence of Atmospheric Boundary Layer Processes on Biogenic Hydrocarbon Mixing and Chemistry

Research Group

Mary C. Barth, National Center for Atmospheric Research, Boulder, Colorado
Chin-Hoh Moeng, National Center for Atmospheric Research, Boulder, Colorado
Edward (Ned) G. Patton, Research Associate

An instantaneous x,z slice of the deviation from the instantaneous horizontal mean of the Da = 0.34 second-order species normalized by c* overlaid with the coincident velocity vectors normalized by u*. Contours with solid lines are positive, dotted lines are negative. In non-dimensional units, the contours range from -1.5 to 1.5 with an interval of 0.25. The maximum velocity vector corresponds with a non-dimensional magnitude of 4.2. The dashed-line is the top of the forest canopy

This work has been focused on publishing and analyzing past results and computations. A good deal of code has been recently ported to run on mixed distributed/shared memory machines at the Supercomputing Institute.

This code allows study on lower atmospheric turbulence and cloud formation influence ozone-hydrocarbon photochemistry. Focus is being placed on how cumulus clouds, a forest canopy, spatial variations in forest hydrocarbon emissions, and chemical lifetimes influence the chemistry of the lower atmosphere.

The model used to resolve turbulent motions within the PBL is the NCAR large eddy simulation (LES) model. This project has taken the newest version of the LES, which allows for multiple regions of grid nesting, and introduced the dynamical effects of a forest canopy into the fine resolution region located at the surface. This nested model can resolve canopy scales of motion and examine their influence on the full CBL. The coupled forest canopy-CBL LES is used to study the influence of the forest on biogenic hydrocarbon mixing in the CBL.

An updated version of the IMAGES model provides the chemical mechanism. Because the set of chemical reactions presents a stiff set of differential equations, an approximate solution technique, the Euler Backward Iterative (EBI), is used. This chemical mechanism, merged with the LES, helps study the influence of micro-scale mixing in the cloud-free CBL on ozone photochemistry.

This information is available in alternative formats upon request by individuals with disabilities. Please send email to alt-format@msi.umn.edu or call 612-624-0528.

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