AERMOD performs several quality assurance checks on data when it begins processing inputs. As part of these checks, the model will write several warning and informational messages to the output file for the user to reference. One common message bears the warning code W320.
SO W320 PPARM:Input Parameter May Be Out-of-Range for Parameter
One of several different parameters may be the cause for this message:
Stack Temperature (TS)
Exit Velocity (VS)
Release Height (HS; volume or area source only)
Initial Lateral Dimension (SY; volume or area source only)
Initial Vertical Dimension (SZ; volume or area source only)
The bounds for this warning are coded directly into the model. You will see W320 if your source parameters exceed the following bounds:
Any parameter < 0
TS > 2000 K
VS > 50 m/s
HS > 100 m
SY or SZ > 200 m
Despite the warning, AERMOD will not change values which exceed the upper bounds of those parameters. For example, if a modeler inputs an exit velocity of 100 m/s, AERMOD will perform calculations with the assigned exit velocity. The message is simply to warn the user that the input value was outside expected bounds.