28 February 2019

NCAR Release of CAM-SE in CESM2.0: A Reformulation of the Spectral Element Dynamical Core in Dry-Mass Vertical Coordinates With Comprehensive Treatment of Condensates and Energy

Summary

This paper provides comprehensive documentation of the new NCAR version of the spectral element (SE) dynamical core as part of the Community Earth System Model (CESM2.0) release. This version is a split from the previous version of SE, and resides in the CAM (Community Atmosphere Model) repository rather than being imported from the High‐Order Methods Modeling environment (HOMME) as an external code. The new version differs from previous releases of the SE dynamical core in several ways. Most notably the hybrid sigma vertical coordinate is based on dry air mass, the condensates are dynamically active in the thermodynamic and momentum equations (also referred to as condensate loading), and the continuous equations of motion conserve a more comprehensive total energy that includes condensates. The hyperviscosity operators and the vertical remapping algorithms have also been modified. The code base has been significantly reduced, sped up, and cleaned up. This paper also shows these computational advances. Several simulations demonstrate the features of the updated dynamical core.

Contact
Peter Lauritzen
National Center for Atmospheric Research (NCAR)
Publications
Lauritzen, P, R Nair, A Herrington, P Callaghan, S Goldhaber, J Dennis, J Bacmeister, B Eaton, C Zarzycki, MA Taylor, P Ullrich, T Dubos, A Gettelman, R Neale, B Dobbins, K Reed, C Hannay, B Medeiros, J Benedict, and J Tribbia.  2019.  "NCAR Release of CAM-SE in CESM2.0: A Reformulation of the Spectral Element Dynamical Core in Dry-Mass Vertical Coordinates With Comprehensive Treatment of Condensates and Energy."  Journal of Advances in Modeling Earth Systems 10(7): 1537-1570, pp. 1537-1570.  https://doi.org/10.1029/2017ms001257.