Models Methods Software

Dan Hughes

Viscous Dissipation in the NASA/GISS ModelE Code is Wrong …

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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January 13, 2009 Posted by | Verification | , , | 17 Comments

More on NASA/GISS ModelE Viscous Dissipation: The Units

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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January 10, 2009 Posted by | Uncategorized | , | 4 Comments

Yet Even More NASA/GISS ModelE Coding

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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January 10, 2009 Posted by | Verification | , , , | 1 Comment

The Fundamental Issue

The Intergovernmental Panel for Climate Change (IPCC) Fourth Assessment Report (AR4, IPCC, 2007) states:

“A major advance of this assessment of climate change projections compared with the TAR is the large number of simulations available from a broader range of models. Taken together with additional information from observations, these provide a quantitative basis for estimating likelihoods for many aspects of future climate change.” [ My bolding. ]

Do the numbers from these “large number of simulations available from a broader range of models” GCM calculations have any Meaning. My answer is No.

One crucial and necessary first step is that application of Verification procedures have shown that the numbers produced by the software accurately reflect both (1) the original intent of the continuous equations for the models, and (2) the numerical solution methods applied to the discrete approximations to the continuous equations. That is, Verification shows that the equations have been solved right. Do the numbers actually satisfy the Verified-to-be-correct-as-coded discrete equations and do the solutions of the discrete equations converge to solution of the continuous equations. Neither of these has been demonstrated for any GCM. I will be pleased to be shown to be wrong on this point.

All software can be Verified. Objective technical criteria and associated success metrics can be developed and applied in a manner that provides assurances about the correctness of the coding of the equations and their numerical solutions. Lack of Verification leaves open the potential that the numbers from the software are simply results of “bugs” in the coding.

The present-day software development community, in all kinds of applications and organizations, is keenly aware that lack of SQA policies and procedures, and successful applications of these to the software, leaves open a significant potential for problems to exist in the software. So far as I am aware, there are no precedents whatsoever for public policy decisions to be based on software for which no SQA procedures have been applied.

December 8, 2008 Posted by | Calculation Verification, Verification | , , , | Leave a comment

Letters to NASA Quality Assurance Staff

On Tuesday November 11, 2008 at about 11:45 am I sent copies of the following letter to several NASA Quality Assurance personnel. The date has proven to be quite a coincidence as subsequent, and continuing, events have shown. I had started writing the letter a few days before I sent it.

I’ve heard nothing back yet; none of the recipients has acknowledged that the letter was received.

I have not yet located similar Quality Assurance offices in NOAA. All pointers will be appreciated.

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November 17, 2008 Posted by | Verification | , | 11 Comments

GISS/NASA: We Don’t Verify. We Calculate, you Verify.

Another example of the lack of even the most basic concerns with verification of calculations has been discovered in GISS/NASA work.

The response by GISS/NASA employees is extremely disconcerting. That response seems to me to say that if the application procedure simply produces numbers, we’re ok with that. Verification of the numbers is left to others.

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November 12, 2008 Posted by | Calculation Verification, Verification | , , | 1 Comment

Pattern Matching in GISS/NASA ModelE Coding

In a previous post I gave an illustration of how GISS/NASA employees have implemented new and innovative ways to produce inactive code using the capabilities provided by F90/95. I had run across the following statements in routine DIAG.f:

EWATER(J)=EWATER(J)+EL !+W*(SHV*T(I,J,L)*PK(L,I,J)+GRAV
! * *HSCALE*LOG(P(I,J)/PMID(L,I,J)))

The ‘!’ in the first line is going to be very difficult to remember it exists and correctly maintain. Someone might come along and say, “I wonder what that’s doing in the middle of an executable statement.” and promptly un-do the comment. Or un-do the comment of the second line while overlooking the comment in the first line. That would make a screw up on several levels.

Today I have found many more examples of innovative coding by employees of GISS/NASA. It is clear that the NASA Software Quality Assurance procedures are ignored by GISS/NASA. It is equally clear that there are no Software Quality Assurance procedures being applied to the GISS/NASA ModelE code. None.

Update November 2, 2008 down near the end.

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October 31, 2008 Posted by | Verification | , , , , | 7 Comments

“an extra thousand code checkers”

Well, GISS/NASA employee Dr. Gavin Schmidt has done it again. He has given direct proof that the fundamental concepts of software Verification and Validation and other Software Quality Assurance procedures are not in the work universe of GISS/NASA.

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September 10, 2008 Posted by | Uncategorized | , , , | 8 Comments

Journal of Computational Physics Special Issue

The journal of Computational Physics has a special issue that might be of interest to many here, Predicting weather, climate and extreme events.

This is a review article.

And Elsevier, aka Big Science Publishing, has kindly provided links to 8244 related articles.

July 16, 2008 Posted by | Uncategorized | , , | Leave a comment

Another NASA/GISS ModelE Code Fragment

Using the NASA/GISS ModelE code browser I ran across the MODULE CONSTANT in which several constants are setup as parameters.

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January 7, 2008 Posted by | Uncategorized | , , , | 15 Comments