Reliable low precision simulations in land surface models

Journal article

Abstract:: Weather and climate models must continue to increase in both resolution and complexity in order that forecasts become more accurate and reliable. Moving to lower numerical precision may be an essential tool for coping with the demand for ever increasing model complexity in addition to increasing computing resources. However, there have been some concerns in the weather and climate modelling community over the suitability of lower precision for climate models, particularly for representing processes that change very slowly over long time-scales. These processes are difficult to represent using low precision due to time increments being systematically rounded to zero. Idealised simulations are used to demonstrate that a model of deep soil heat diffusion that fails when run in single precision can be modified to work correctly using low precision, by splitting up the model into a small higher precision part and a low precision part. This strategy retains the computational benefits of reduced precision whilst preserving accuracy. This same technique is also applied to a full complexity land surface model, resulting in rounding errors that are significantly smaller than initial condition and parameter uncertainties. Although lower precision will present some problems for the weather and climate modelling community, many of the problems can likely be overcome using a straightforward and physically motivated application of reduced precision.

Files:: Dawson2018_Article_ReliableLowPrecisionSimulation.pdf

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Language:: English
Keywords:: single precision arithmetic

numerical precision

climate models

land surface models

deep soil processes

floating-point arithmetic
Pubs id:: pubs:812639
UUID:: uuid:7c524a82-70ef-4a89-a14d-bff05896ca5d
Local pid:: pubs:812639
Source identifiers:: 812639
Deposit date:: 2019-02-13

Copyright holder:: Dawson et al
Notes:: © The Author(s) 2017. This article is distributed under the terms of the Creative Commons Attribution 4.0 International License (http://creativecommons.org/licenses/by/4.0/), which permits unrestricted use, distribution, and reproduction in any medium, provided you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons license, and indicate if changes were made.

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