#L02 Composable solvers for multiphysics problems in ALM

Abstract

Land surface models (LSMs), which are key components of Earth System Models (ESMs), simulate mass, energy, and nutrient cycles at the surface of the Earth. LSMs are routinely used to study the impact of human activities via land-cover change and increasing CO2 emissions on global climate. Over recent decades, there has been a tremendous growth in the number and complexity of processes incorporated in current generation LSMs. Traditionally, the various physics formulations in LSMs are solved as loosely coupled system of equations, but the importance of solving fully coupled multiphysics problems (e.g., soil-plant-atmosphere continuum, conservation of mass-energy in soil, etc.) is now well recognized. In this work, we develop a framework for solving tightly coupled multi physics problems (MPP). Our framework is built on top of the Portable, Extensible Toolkit for Scientific Computation’s (PETSc’s) multi-physics coupling capability (DMComposite). One of the main advantages of the MPP  framework is the reuse of existing code when adding support for new physics formulations that are solved as a single fully coupled model. Numerical results from a range of multiphysics land surface process representations integrated in the ACME Land Model (ALM) are presented.