About

Development of the CHARM® Software began in 1981. At that time, personal computers were very limited in their capabilities. Because of the computer memory and speed restrictions, the first versions of CHARM contained a puff model for advection and dispersion calculations. A puff model simulates a continuous release as a series of discreet puffs. The number of puffs was restricted.

As computers became more capable, so did the model. Initially, the model was a DOS program. In 1990, the model was moved to the Windows environment. Throughout its development, continuous improvements and enhancements have been added as users requested them. Around the year 2000 a hybrid version of the model was made to try to simulate the effects of complex terrain on the wind field and dispersion of a release. It didn’t take long to discover that a hybrid was not the approach to take.

Once computers were capable of running in excess of about 1 GHz, a true complex terrain version of the model was developed to take advantage of the advancements. Rather than a puff model, the complex terrain version uses a 3 dimensional grid to perform the simulation. Two versions of CHARM then existed in parallel. The flat terrain version is fast and so can be used for screening and rapid “what if” simulations. The complex terrain version is slower but useful for detailed simulations. Besides considering terrain effects it can be used inside and around buildings. It will also calculate the dynamics of particles and air chemistry.

CHARM was developed and is being developed by Dr. Mark Eltgroth. Dr. Eltgroth has a B.S. in Physics (Caltech, 1974) and a Ph.D. in Atmospheric Physics (University of Washington, 1978). During its lifetime CHARM has been associated with a number of companies (Radian Corporation through its various names until acquired by URS Corporation). In 2008 the software was taken over solely by Dr. Eltgroth.