Journal cover Journal topic
Geoscientific Model Development An interactive open-access journal of the European Geosciences Union
Geosci. Model Dev., 11, 697-711, 2018
https://doi.org/10.5194/gmd-11-697-2018
© Author(s) 2018. This work is distributed under
the Creative Commons Attribution 3.0 License.
Development and technical paper
26 Feb 2018
Nine time steps: ultra-fast statistical consistency testing of the Community Earth System Model (pyCECT v3.0)
Daniel J. Milroy1, Allison H. Baker2, Dorit M. Hammerling2, and Elizabeth R. Jessup1 1University of Colorado, Boulder, CO, USA
2The National Center for Atmospheric Research, Boulder, CO, USA
Abstract. The Community Earth System Model Ensemble Consistency Test (CESM-ECT) suite was developed as an alternative to requiring bitwise identical output for quality assurance. This objective test provides a statistical measurement of consistency between an accepted ensemble created by small initial temperature perturbations and a test set of CESM simulations. In this work, we extend the CESM-ECT suite with an inexpensive and robust test for ensemble consistency that is applied to Community Atmospheric Model (CAM) output after only nine model time steps. We demonstrate that adequate ensemble variability is achieved with instantaneous variable values at the ninth step, despite rapid perturbation growth and heterogeneous variable spread. We refer to this new test as the Ultra-Fast CAM Ensemble Consistency Test (UF-CAM-ECT) and demonstrate its effectiveness in practice, including its ability to detect small-scale events and its applicability to the Community Land Model (CLM). The new ultra-fast test facilitates CESM development, porting, and optimization efforts, particularly when used to complement information from the original CESM-ECT suite of tools.

Citation: Milroy, D. J., Baker, A. H., Hammerling, D. M., and Jessup, E. R.: Nine time steps: ultra-fast statistical consistency testing of the Community Earth System Model (pyCECT v3.0), Geosci. Model Dev., 11, 697-711, https://doi.org/10.5194/gmd-11-697-2018, 2018.
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Short summary
The Community Earth System Model Ensemble Consistency Test (CESM-ECT) suite was developed as an alternative to requiring bitwise identical output for quality assurance. We extend the CESM-ECT suite with an inexpensive and robust test for ensemble consistency that is applied to Community Atmospheric Model output after only nine model time steps. The new ultra-fast test facilitates CESM development, porting, and optimization efforts, and complements the original suite of tools.
The Community Earth System Model Ensemble Consistency Test (CESM-ECT) suite was developed as an...
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