Implementation of new diffusion/filtering operators in the CAM-FV dynamical core

• Published in: The International Journal of High Performance Computing Applications
• Other Authors: Lauritzen, Peter (author), Mirin, Arthur (author), Truesdale, John (author), Raeder, Kevin (author), Anderson, Jeffrey (author), Bacmeister, Julio (author), Neale, Richard (author)
• Format: Article in Journal/Newspaper
• Language: English
• Published: Sage Publications, Inc. 2012
• Subjects: Diffusion filtering; CAM-FV; Dynamical core; DART; Laplacian damping; polar night
• Online Access: http://nldr.library.ucar.edu/repository/collections/OSGC-000-000-001-729; https://doi.org/10.1177/1094342011410088

Two new filtering/diffusion operators have been implemented in the Community Atmosphere Model finite-volume dynamical core (CAM-FV). First, a fourth-order divergence damping operator has been added to optionally replace the second-order version that has traditionally been used. This provides more scale selective dissipation of divergent modes that can generate gridscale noise in CAM-FV if not damped properly. For example, data-assimilation runs using CAMFV DART (Data Assimilation Research Testbed) have revealed potential noise problems at the grid scale that can be alleviated significantly using higher-order divergence damping. Second, a .‘Laplacian’-type damping operator has been implemented to increase the explicit momentum dissipation in the top-of-atmosphere sponge layers. This helps control the excessive polar night jets that have been observed in ultra-high resolution CAM-FV simulations. Results from stand-alone CAM-FV and CAM-FV DART are presented in this paper along with details on the implementation of the new operators.