Models, Methods, Software

The focus on this previous post was the fact that approximations made at the continuous-equation level mean that the model’s mass and energy budgets are different from the mass and energy budgets of the physical system. Note that there are very significant additional issues associated with the discrete approximations applied to the continuous equations and the numerical solutions of these. These issues in the discrete domain, in my opinion, have the potential to far outweigh issues in the continuous domain. Accurate integration of the discrete approximations over the enormous times scales of interest is a very tough problem.

The present post looks at some more issues associated with energy conservation in the discrete domain.

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it is not even viscous dissipation. There is also an energy imbalance in the NASA/GISS ModelE code due to the error in the ‘viscous dissipation’. The energy imbalance is about the same magnitude as the imbalance associated with increased concentrations of CO2 in the atmosphere.

Updated January 14, 2009, down near the end.

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This post is a continuation of discussions of the modeling of viscous dissipation in GCMs. The issue has recently come up again over at Lucia’s Blog in this thread. The thread at Lucia’s is related to the posts on this Blog here, here, and here. I have also in the past commented on the issue at Climate Audit, Professor Pielke Sr.’s Climate Science, and Real Climate. The dissipation questions come up now and then in several Blogs.

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While pursing the NASA/GISS ModelE coding as part of getting back to the dissipation questions that have come up on Lucia’s Blog in this thread, I ran across yet even more interesting coding. The thread at Lucia’s is related to the posts on this Blog here, here, and here. The dissipation questions come up now and then in several Blogs.

But first, a short diversion.
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Some time ago it was suggested to me something to the effect that most of the people in the Climate Change Community to whom I suggest V&V and SQA issues are critical and require significant attention don’t even know what I’m talking about. Here’s some information that lends support to that observation.

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