An iterative time-stepping scheme for the Met Office's semi-implicit semi-Lagrangian non-hydrostatic model

A predictor -corrector time-stepping algorithm is used by the Met Office's semi-implicit semi-Lagrangian non-hydrostatic Unified Model. This scheme is here extended to include an iterative option, improving performance when large time steps are used in highly nonlinear situations. The scheme is described, and results from global model tests, which show improvements in forecast accuracy, are presented. (c) Crown Copyright 2007.