A Thread Parallel Sparse Matrix Chemistry Algorithm for the Community Multiscale Air Quality Model

HiPERiSM Consulting, LLC, USA

Abstract: This reports on integration of a new Chemistry Transport Model (CTM) sparse matrix algorithm (FSparse) as a replacement of the legacy JSparse algorithm in the U.S. EPA Community Multiscale Air Quality (CMAQ) model. This has been implemented in both Rosenbrock and Gear methods for aqueous chemistry in a hybrid MPI and OpenMP implementation. Both methods are well suited for an OpenMP thread-parallel version. For a 24 hour scenario, execution performance results for both MPI and OpenMP thread parallel scaling are presented with the CMAQ5.3b release on a heterogeneous cluster of 10 nodes with a total of 128 cores. The FSPARSE version of CMAQ typically provides significant speedup over the standard EPA release with similar precision in predicted species concentration values.