Intermediate-Range Grid Model and User's Guide for Atmospheric Sulfur Dioxide and Sulfate Concentrations and Depositions - Wisconsin Power Plant Impact Study

摘要

The UWATM-SOX computer model was developed to address the acid rain problem on a mesoscale. It predicts sulfur dioxide (SO2) and sulfate (SO4) ambient air concentrations and ground level dry and wet (rain or snow) depositions given certain emission and meteorological input data. It is a time-dependent, cell-type model which numerically solves coupled SO2 and SO4 conservation and mass equations described in an exterior frame of reference for a dilute species in the atmospheric boundary layer. Significant features of the model include: Handling arbitrary wind directions; inputting hourly meteorological data; fully computerized processing of meteorological tapes obtained from the National Climate Center; simulataneous handling of point, line, and area sources; accounting for the lofting condition of point source plumes; describing the atmospheric boundary layer by vertically variable but horizontally uniform wind and diffusivity profiles; handling dry deposition by means of a deposition velocity which accounts for terrain and net condition; and handling wet deposition by means of a non-linear cold cloud precipitation model developed by Battelle Pacific Northwest Labs. The model is written in ASCII Fortran and has been applied to the Rainy Lake Watershed in northern Minnesota and southern Ontario. A 1-yr simulation with an 11 x 13 x 6 cell structure and hourly meteorological data changes required 50K core space and took 6 h of computer up (CPU) time.