Global models are desirable in many ways. For example, they do not depend on boundary updating and do not inherit potential inaccuracies from the driving model(s). Also, undesirable artifacts from traditional nested modelling strategies, such as step changes at the boundaries and relatively coarse time sampling, can be avoided. On the other hand, high-resolution models are also desirable, as...
The Common Community Physics Package (CCPP) consists of a repository of physics schemes that adhere to a well-defined set of rules governing their data interface and a software framework for auto-generating "caps" that function as drivers for user-selectable collections (or suites) of compliant physics schemes. The intent and design of this package is to allow physics schemes to be...
While counterexamples can be found, running atmosphere models at fine resolution generally leads to better simulation of several aspects of the observed climate, e.g. the spatial distribution of precipitation. This can be attributed in part to tendency errors introduced by physical parameterizations at coarse resolution. At AI2 we have developed an approach that uses nudging to diagnose...
Atmospheric models consist of two main parts: dynamical core and physical parameterizations. Traditionally, dynamical cores and physical parameterizations have been engineered in isolation for the sake of tractability (Gross et al. 2018, and references therein). These two independent components are coupled and are integrated using the same time step, following either parallel splitting or...
Gravity waves (GWs) in the stratosphere contribute to the driving of the quasi-biennial oscillation and to the deceleration of the polar vortices and the subtropical jets. Global ECMWF IFS simulations with horizontal grid-spacings of 1 km, 4 km and 9 km are used to assess resolved gravity wave forcing (GWF) from larger-scale (with horizontal wavelengths 2000-100 km) and smaller-scale (with...
Most coupling problems result from using an overly long timestep. As an example, numerically accurate microphysics in version 1 of the Energy Exascale Earth System Model (E3SMv1) is shown to require a timestep which is an order of magnitude shorter than what is used in climate models today. Given this, how can we afford to perform accurate simulations? The answer lies at the intersection...
