Islet: interpolation semi-Lagrangian element-based transport

Abstract. Advection of trace species, or tracers, also called tracer transport, in models the atmosphere and other physical domains is an important potentially computationally expensive part a model's dynamical core. Semi-Lagrangian (SL) advection methods are efficient because they permit time step much larger than advective stability limit for explicit Eulerian without requiring solution globally coupled system equations as implicit do. Thus, to reduce computational expense cores often use SL advect tracers. The class interpolation semi-Lagrangian (ISL) contains extremely methods. We describe finite-element ISL transport method that we call element-based (Islet) method, such with discretized using spectral element method. Islet uses three grids share grid: dynamics grid supporting, example, Gauss–Legendre–Lobatto basis degree three; physics parameterizations configurable number finite-volume subcells per element; supporting bases particular again configurable. This provides accurate excellent diagnostic values verification problems.