TChem-atm (
https://github.com/PCLAeroParams/TChem-atm) is a performance-portable software library designed to support atmospheric chemistry applications, specifically computing source term Jacobian matrices. The software utilizes Kokkos as its portability layer, preparing it for next-generation computing architectures. The software interface employs a hierarchical parallelism design to leverage the massive parallelism available on modern computing platforms, including model parallelism, batch parallelism, and nested parallelism for each problem instance. Additionally, TChem-atm is designed to be coupled with third-party libraries that may be used to advance the state of gas and particle species over time, notably interfacing with the Tines, Kokkos-kernels, and Sundials libraries. We have tested TChem-atm in two scenarios: using a typical reaction mechanism in atmospheric science and an example involving multiple aerosol particles. This testing framework allows us to evaluate our code by varying the number of evaluations and the size of the source term (right-hand side). Finally, we report performance measurements using the CUDA, HIP, and OpenMP back ends.
