SWEET – Shallow Water Equation Environment for Tests v1.0

Abstract. SWEET is an open-source software for numerical simulation of differential equations discretized with global spectral methods, both on the bi-periodic plane and the sphere. Although not directly restricted to it, its main focus is on numerical developments for the shallow water equations (SWE) since they play a crucial role in developing new numerical methods for climate and weather simulations.

SWEET's main purpose is to bridge the gap between the development of new time integration methods for atmospheric dynamical cores and high-performance computing. This is done by providing a fast and efficient environment for developing and analyzing time discretization methods for the SWE while reducing spatial errors to a minimum due to the utilization of global spectral methods. In addition, the performance of new time integration methods can be assessed on HPC systems. Regarding the numerics, this is achieved through a versatile implementation, allowing the user to quickly run and combine different time-stepping schemes, and flexibly choose the different terms of the governing equations (i.e., the different physical processes) to be considered in the time integration in a composable way through command line arguments, allowing a rapid exploration of time integration methods. Concerning HPC, SWEET supports various ways to explore parallel-in-time integration methods on large-scale HPC clusters. To analyze the results, SWEET also contains many benchmark tests, including standard test cases relevant to atmospheric modeling research. These features make SWEET a robust and powerful tool for researching temporal schemes for atmospheric circulation models.

This paper summarizes the main features of SWEET and provides some numerical examples illustrating its application.