Environmental Engineering Reference
In-Depth Information
vertical winds adjustment with concentration renormalization under strong vertical
wind shear conditions. Recall that renormalization is not mass conservative there-
fore some mass conservation errors are introduced but the trajectory deviations are
smaller than those seen in pure vertical wind adjustment methods.
Acknowledgments
This research was supported by the San Joaquin Valleywide Air Pollution
Study Agency under contract number 05-4CCOS
References
Hu, Y., Odman, M.T., Russell, A.G.:
Mass conservation in the Community Multiscale Air
Quality model. Atmos. Environ.
40
, 1199-1204 (2006).
Bott, A.: A
positive definite advection scheme obtained by nonlinear renormalization of the
advective fluxes. Mon. Wea. Rev.
117
, 1006-11015 (1989).
5. Questions and Answers
Jim Wilczak:
Are all of the problems with mass consistency completely mitigated
by the use of a fully coupled, on-line model that uses identical grids for chemistry
and meteorology.
Answer:
For mass consistency, the models must use the same grids, the same time
steps, and the same finite difference forms. Recently, we see more and more
applications where meteorology and chemistry-transport models share the same
grid. In an on-line model, it is much easier to use the same time steps. In addi-
tion, if the density is a prognostic variable in the meteorology model and if the
continuity equation and the species continuity equation are discretized using
the same finite difference forms (e.g., upwind differencing), then mass consistency
should no longer be a problem.
