There are two approaches to modeling more complex
emission scenarios. The first is an extension of the use of the
CONTROL file in creating an emission matrix using three locations,
the first two representing the lower left and upper right grid corners, respectively,
and the third point representing the grid spacing, similar to what was
done for the trajectory error example shown previously.
In this case we will start sources every 0.5 degrees between the grid
corners (27.0, -82.0) and (30.0, -79.0). The model is then run from the Concentration /
Special Simulations / Run Matrix menu. Run with all the settings from
the previous example for Florida except change the output to a 6 hour average concentration
instead of a snapshot.
|Prior to executing the model, the initial 3-location
CONTROL file is automatically rewritten to a new CONTROL file
showing 49 locations. From the Concentration Display menu turn off the source location
labeling (see graphic below) before creating the 6-h average concentration graphic (bottom left) for
each of the 49 source locations. This graphic may be too noisy for some applications so there
is an option to remove the black contour lines from the graphic. Set the contour outlines to
none in the Concentration Display menu and execute the
display to create a considerably simplified graphic (below right).
The modified CONTROL file could also be
edited manually to customize the emission rate.
Another approach is to define an emissions file, which
tabulates hourly emission rates by location. An emission
text file, defines the grid to which those emissions
data will be accumulated. A simulation using this approach for
the same case is shown to the right. The CONTROL file must define
the lower left and upper right corners of the desired emission
domain, which may be larger or smaller than the data available. The
results shown here are almost identical to the control file emission run. The
MESSAGE file shows
that 49 sources were simulated using the emission file. Due to
the continuous emissions at many locations, these simulations
may require the maximum number of particles be increased from the default value. Information
on the format of the emissions file and the emission text file can
be found in the
HYSPLIT User's Guide
under Advanced / Special Topics (S441).