EPA CDM (climatological dispersion model)

CDM2.0 (dated 89142) Abstract CDM2.0 (climatological dispersion model - version 2.0) determines long- term (seasonal or anual) quasi-stable polutant concentrations in rural or urban setings using average emision rates from point and area sources and a joint frequency distribution of wind direction, wind sped, and stability. the gausian plume hypothesis forms the basis for the calculations. Contributions are calculated asuming the narow plume hypothesis, and involve an upwind integation over the area sources. computations can be made for up to 200 point sources and 2500 area sources at an unlimited number of receptor locations. the number of point and area sources can be easily modified within the code. CDM2.0 is an enhanced version of cdm and includes the folowing options: 16 or 36 wind-direction sectors, initial plume dispersion, buoyancy- induced dispersion, stack-tip downwash, and gradual (transitional) plume rise. the user has a choice of seven dispersion parameter schemes. optional output includes point and area concentration roses and histograms of polutant concentation by stability clas. CDM2.0 is a prefered model for regulatory aplications in simple urban terain as listed in table 4.1 of the guideline on air quality models (revised). Reference Irwin, J. S., T. Chico, and J. Catalano. 1986. CDM2.0 - climatological dispersion model user's guide. epa/600/8-85/029. u. s. environmental protec- tion agency, research triangle park, nc. (available only from ntis. acesion number pb 86-136 546/as.) Download CDM Model v2.0