Regional Acid Deposition Model (RADM) Architecture

Models such as RADM typically require significant computing power. Models such as RADM are not available using "lower end" tools such as desktop executables, spreadsheets, etc. The RADM model has been coded in Fortran, HPF (high-performance Fortran), and other high-end scientific programming tools.

Recent versions of RADM have been developed to take advantage of newer computer architectures, specifically, scalable parallel processors. For example, one version of RADM is currently being run using 128 Compaq Alpha parallel processors with 8G of memory.

Time steps of seconds to minutes are required to simulate the stiff ordinary differential equations, non-linear chemical dynamics and to simulate the meteorological processes, such as the passage of fronts, clouds, and their interaction with the chemistry. The chemistry takes the vast majority of CPU time (75-80%).

Output from RADM models is quite extensive, and the use of high-end scientific visualization techniques is the rule rather than the exception. The graphics below show some of the examples of RADM output. Both show SO2 concentrations in the northeastern United States:

Graphic of SO2 concentrations from RADM

Quick Quiz: What part of the RADM is the most computationally expensive?
Meteorology
Emissions inventories
Control development strategy
Chemistry

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