Coupling simple dry physics to a dynamically adaptive global atmosphere model

Adaptive global circulation models (GCMs) have the potential to significantly improve the computational efficiency and accuracy of climate simulations by dynamically adjusting the local grid resolution to ensure a specified numerical tolerance or to track features of interest.  We have developed the global dynamical cores WAVETRISK-ATMOSPHERE and WAVETRISK-OCEAN to explore the strengths and weaknesses of dynamical GCMs. 

The main open challenge of adaptive climate modelling is how to appropriately couple the dynamical core to the physics. The physics should ideally be “scale-aware”: adjusting the parameterization as necessary based on the current local resolution (or disabling it entirely if the physical phenomenon becomes fully resolved).  A related question is whether the grid adaptation criteria should be based on the physics as well as the dynamics. Such scale-aware physics parameterizations remain poorly understood.  In this talk we report on initial progress in coupling WAVETRISK-ATMOSPHERE to Hourdin’s (1992) “simple dry physics”.

A better understanding of scale-aware physics will also improve non-adaptive climate modelling, since such models currently require extensive tuning each time the resolution is increased. An additional goal of this project is to develop a set of test cases for the simple physics that could be used to compare dynamical cores using a well-understood and standardized physics package.

This is joint work with Gabrielle Ching-Johnson (MSc student, McMaster University, Canada) and Thomas Dubos (LMD, École Polytechnique, France)