Technological advances continue to provide new opportunities to advance our understanding through enhanced observational studies/monitoring and through the modeling of complex geophysical flows/physics. It is now feasible to carry out storm/tornado simulations in unprecedented detail using horizontal resolutions of 10-20 m and vertical resolutions stretched starting at 5 m near the ground. In preparation for actually doing this, a distributed memory version of the COMMAS (Collaborative Model for Multiscale Atmospheric Simulation) called PCOMMAS is being built in a collaboration between Paul Woodward, Sarah Anderson, and David Porter at Minnesota, Rob Fowler at Rice, Lou Wicker at the NSSL, and Peckham, Wilhelmson, Shaw, and Straka at NCSA. One aspect of this restructuring is the reorganization of the COMMAS calculations to work from a small memory context entirely contained in the processor’s off-chip cache, performing many floating point operations from that memory context per word moved either from or to the main memory. Another is the utilization of Shared Memory on Disk (SHMOD) software for executing tiled codes on clusters. SHMOD was developed in the Woodward group and has been used successfully for turbulence and other simulations for very large simulations (up to 8 billion zones).

Results from the first high resolution PCOMMAS simulations will be presented at the conference. Constant horizontal grid resolution will be used throughout the storm and its environment. The simulations will provide the data for studying the detailed structure of supercells along with associated tornadogenesis. This approach will also be compared with the use of another version of COMMAS that utilizes stretched horizontal grids and which has also been submitted for presentation at the conference by Wicker, Wilhelmson, and Dowell.