Abstract

Much recent work in the Community Earth System Model (CESM) and its atmosphere component (CAM) has been devoted to developing higher resolution configurations, motivating new dynamical cores which can use unstructured quasi-isotropic grids. These dynamical cores also allow for variable resolution configurations in CAM , but making use of variable resolution (adaptive or statically refined grids) is difficult due to the strong resolution sensitivity of CAM ’s many subgrid physical parameterizations.

Here we will describe our work with statically refined grids in CAM , using CAM ’s spectral finite element dynamical core. This work is supporting the development of a model/observation “test bed”. Test-beds combine models, observations and uncertainty quantification methodologies in order to evaluate existing models, quickly develop and test new parameterizations and constrain parameters with observations. It is hoped that variable resolution can provide a 10-100 times more efficient way to calibrate and evaluate high-resolution configurations of CAM . Our initial focus is on central U.S. precipitation, using a global 14km grid and a variable resolution grid with 14km resolution over the central U.S., transitioning to 110km over most of the globe. For both configurations, we will present computational performance and compare precipitation related diagnostics.