By making the Yinit and Angle parameters optional, the area source input data for the previous versions of ISC that were limited to square areas with a north-south orientation can still be used with the new algorithm. The aspect ratio (i.e., length/width) for area sources should be less than 10 to 1. If this is exceeded, then the area should be subdivided to achieve a 10 to 1 aspect ratio (or less) for all subareas.
The optional Szinit parameter may be used to specify an initial vertical dimension to the area source plume, similar to the use of the Szinit parameter for volume sources. This parameter may be important when the area source algorithm is used to model mechanically generated emission sources, such as mobile sources. In these cases, the emissions may be turbulently mixed near the source by the process that is generating the emissions, and therefore occupy some initial depth. For more passive area source emissions, such as evaporation or wind erosion, the Szinit parameter may be omitted, which is equivalent to using an initial sigma-z of zero.
An example of a valid SRCPARAM input card for a rectangular area source is given below:
where the source ID is SLAGPILE, the emission rate is 0.0015 g/(s-m2), the release height is 5.0 m, the X-dimension is 50.0 m, the Y-dimension is 100.0 m, and the orientation angle is 30.0 degrees clockwise from North. Note that if the orientation angle is zero, the Y-dimension is North and the X-dimension is east, which is the standard convention.
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castellano: DIS CUS DES RAD english: DIS CUS DES RAD
português: DIS CUS DES RAD italiano: DIS CUS DES RAD
français: DIS CUS DES RAD