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Title: A new and inexpensive non-bit-for-bit solution reproducibility test based on time step convergence (TSC1.0)

Abstract

A test procedure is proposed for identifying numerically significant solution changes in evolution equations used in atmospheric models. The test issues a fail signal when any code modifications or computing environment changes lead to solution differences that exceed the known time step sensitivity of the reference model. Initial evidence is provided using the Community Atmosphere Model (CAM) version 5.3 that the proposed procedure can be used to distinguish rounding-level solution changes from impacts of compiler optimization or parameter perturbation, which are known to cause substantial differences in the simulated climate. The test is not exhaustive since it does not detect issues associated with diagnostic calculations that do not feedback to the model state variables. Nevertheless, it provides a practical and objective way to assess the significance of solution changes. The short simulation length implies low computational cost. The independence between ensemble members allows for parallel execution of all simulations, thus facilitating fast turnaround. The new method is simple to implement since it does not require any code modifications. We expect that the same methodology can be used for any geophysical model to which the concept of time step  convergence is applicable.

Authors:
 [1];  [1];  [1];  [1];  [1];  [2]
  1. Pacific Northwest National Lab. (PNNL), Richland, WA (United States). Atmospheric Sciences and Global Change Division
  2. National Center for Atmospheric Research, Boulder, CO (United States). Climate and Global Dynamics Laboratory
Publication Date:
Research Org.:
Pacific Northwest National Lab. (PNNL), Richland, WA (United States)
Sponsoring Org.:
USDOE Office of Science (SC), Biological and Environmental Research (BER) (SC-23)
OSTI Identifier:
1342455
Alternate Identifier(s):
OSTI ID: 1344047
Report Number(s):
PNNL-SA-118076
Journal ID: ISSN 1991-9603; KP1703020
Grant/Contract Number:  
AC05-76RL01830; AC05-00OR22725
Resource Type:
Journal Article: Published Article
Journal Name:
Geoscientific Model Development (Online)
Additional Journal Information:
Journal Name: Geoscientific Model Development (Online); Journal Volume: 10; Journal Issue: 2; Journal ID: ISSN 1991-9603
Publisher:
European Geosciences Union
Country of Publication:
United States
Language:
English
Subject:
54 ENVIRONMENTAL SCIENCES; 58 GEOSCIENCES

Citation Formats

Wan, Hui, Zhang, Kai, Rasch, Philip J., Singh, Balwinder, Chen, Xingyuan, and Edwards, Jim. A new and inexpensive non-bit-for-bit solution reproducibility test based on time step convergence (TSC1.0). United States: N. p., 2017. Web. doi:10.5194/gmd-10-537-2017.
Wan, Hui, Zhang, Kai, Rasch, Philip J., Singh, Balwinder, Chen, Xingyuan, & Edwards, Jim. A new and inexpensive non-bit-for-bit solution reproducibility test based on time step convergence (TSC1.0). United States. doi:10.5194/gmd-10-537-2017.
Wan, Hui, Zhang, Kai, Rasch, Philip J., Singh, Balwinder, Chen, Xingyuan, and Edwards, Jim. Fri . "A new and inexpensive non-bit-for-bit solution reproducibility test based on time step convergence (TSC1.0)". United States. doi:10.5194/gmd-10-537-2017.
@article{osti_1342455,
title = {A new and inexpensive non-bit-for-bit solution reproducibility test based on time step convergence (TSC1.0)},
author = {Wan, Hui and Zhang, Kai and Rasch, Philip J. and Singh, Balwinder and Chen, Xingyuan and Edwards, Jim},
abstractNote = {A test procedure is proposed for identifying numerically significant solution changes in evolution equations used in atmospheric models. The test issues a fail signal when any code modifications or computing environment changes lead to solution differences that exceed the known time step sensitivity of the reference model. Initial evidence is provided using the Community Atmosphere Model (CAM) version 5.3 that the proposed procedure can be used to distinguish rounding-level solution changes from impacts of compiler optimization or parameter perturbation, which are known to cause substantial differences in the simulated climate. The test is not exhaustive since it does not detect issues associated with diagnostic calculations that do not feedback to the model state variables. Nevertheless, it provides a practical and objective way to assess the significance of solution changes. The short simulation length implies low computational cost. The independence between ensemble members allows for parallel execution of all simulations, thus facilitating fast turnaround. The new method is simple to implement since it does not require any code modifications. We expect that the same methodology can be used for any geophysical model to which the concept of time step  convergence is applicable.},
doi = {10.5194/gmd-10-537-2017},
journal = {Geoscientific Model Development (Online)},
number = 2,
volume = 10,
place = {United States},
year = {Fri Feb 03 00:00:00 EST 2017},
month = {Fri Feb 03 00:00:00 EST 2017}
}

Journal Article:
Free Publicly Available Full Text
Publisher's Version of Record at 10.5194/gmd-10-537-2017

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Cited by: 2 works
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