Alternative small scale meteorology input to a chemical transport ...

educes eventual inconsistencies in the meteorological data input to CMAQ. An additional
subroutine was included in the package to bypass the unnecessary computations of PBL and
surface layer parameters. This alternative way uses PBL height, friction velocity, Monin-
Obukhov length, and land use data from CALMET to compute other necessary parameters,
such as sensible heat flux, moisture flux, albedo, roughness length, convective velocity scale, net
radiation. A printout of the code PBLSUP.F can be found in Appendix A.
A comparison between the two meteorological data inputs to CMAQ was made. To
illustrate the similarities and differences between the two meteorological inputs, one snapshot
was chosen in the four-day scenario - July 12, 1995, 19Z (or 2:00 pm EST).This time was
selected for the following reasons:
(i) Early afternoons (around 2pm local solar time) are times of great contrasts and if any
major differences occur, they should be most pronounced during these times;
(ii) Early afternoons are also times of maximum observed and modeled ozone
concentrations;
(iii) Other snapshots at night, early morning, and late evening were compared and no
substantially different information was drawn from these comparisons.
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