Models Methods Software

Dan Hughes

Looks like we’re getting some Traction

This is interesting; Computational science: …Error. From Nature News, even. Comments allowed over there.

Related; Publish your computer code: it is good enough.

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October 17, 2010 Posted by | Calculation Verification, Documentation, Verification | , , , , , , , , , , | Leave a comment

Ensemble of Models

There’s a fundamental problem with the ensemble of GCM models approach used in climate science.

Updated 15 August 2010. See below.

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August 10, 2010 Posted by | Uncategorized | | Leave a comment

The Clausius-Clapeyron Equation

Much is made about the exponential dependency of the vapor pressure of water as a function of temperature. The implication being, as I understand it, that the Clausius-Clapeyron equation implies that there will be significant additional amounts of water vapor in the atmosphere as the so-called global-average surface temperature increases.

Updated November 27, 2010:
For some reasons unknown to me, this post has gotten a lot of hits. But, as noted back in September, nobody is saying anything. Maybe nobody actually reads the post ?? Maybe it’s completely wrong ??

Updated September 17, 2010. At end of the post.

Updated November 2, 2010:

Here’s a recent review of condensation of a vapor from a non-condensable plus vapor mixture: CONDENSATION FROM A VAPOR-GAS MIXTURE

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August 10, 2010 Posted by | Uncategorized | | 1 Comment

Validation; can’t ever do too much

A recent example.

July 27, 2010 Posted by | Uncategorized | , | Leave a comment

Hard Concepts

Boy, it’s difficult to get my mind around many of the concepts discussed in the post Tracking down the uncertainties in weather and climate prediction.

Updated July 10, 2010.

I have looked around but have not been successful in finding additional material from either the meeting or the presentation. I suspect all information presented at the meeting will eventually show up on the CCSM Web site.

Here’s a part that I find to be very unsettling. Starting at the 15th paragraph in the post.

And now, we have another problem: climate change is reducing the suitability of observations from the recent past to validate the models, even for seasonal prediction:

Figure Uncertainty2. Climate Change shifts the climatology, so that models tuned to 20th century climate might no longer give good forecasts

Hence, a 40-year hindcast set might no longer be useful for validating future forecasts. As an example, the UK Met Office got into trouble for failing to predict the cold winter in the UK for 2009-2010. Re-analysis of the forecasts indicates why: Models that are calibrated on a 40-year hindcast gave only 20% probability of cold winter (and this was what was used for the seasonal forecast last year). However, models that are calibrated on just the past 20-years gave a 45% probability. Which indicates that the past 40 years might no longer be a good indicator of future seasonal weather. Climate change makes seasonal forecasting harder!

The conclusion, “Climate change makes seasonal forecasting harder!” is basically unsupported. There are a very large number of critically important aspects between ‘Analysis” and “Changed climatology” that are simply skipped over.

Firstly, the Analysis has been conduced with models, methods, computer code, associated application procedures, and users, any one of which separately, or in combinations with the others, could contribute to the differences between the 40-year and 20-year hindcasts. Secondly, within each of these aspects there are many individual parts and pieces that could cause the difference; taken together the sum is enormous. Thirdly, relative to the time-scales for climate change in the physical world 20-years seems to be kind of short and maybe even 40 years is, too. Fourthly, no evidence has been offered to show that climatology has in fact changed sufficiently to contribute to the difference.

The presentation seems to have leapt from (1) there are differences, to (2) the climatology has changed. I find this very unsettling. The phrase, Jumping to conclusions, seems to be applicable.

With the given information, I think about all we can say is the the models, methods, code, application procedures, and users did not successfully calculate the data.

I don’t see that any ‘tracking down’ was done.

July 7, 2010 Posted by | Uncategorized | , , , | 2 Comments

Validation; Can’t ever do too much

A very recent case.

June 24, 2010 Posted by | Uncategorized | , | Leave a comment

Testing Energy Balance and Budget

In this previous post, I mentioned the energy budget / balance for the Earth’s systems. Specifically, the fundamental hypothesis for AGW is that human activities have created an imbalance in the radiative-energy transport budget and that an increase in temperature will be obtained in order to return to some kind of, but practically undefined, equilibrium state. A true state of energy in-come = energy out-go is never attained for the Earth’s systems. The daily and yearly cyclic variations are observed easily by direct experience and instrumental means. Especially, neither the out-going infrared energy or the in-coming ultra-violet energy are constant, and are not monotonically increasing or decreasing.
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March 16, 2010 Posted by | Uncategorized | , | 4 Comments

Equilibrium, Energy Balances and Budgets, and Stuff

Recently I ran across the following comments on a blog. The comments are followed by my response.

1.

“The physics of the direct warming effects of increased concentrations of CO2 and other infrared-absorbing gasses is completely clear.”

Let me try, “The physics of radiative-energy transport phenomena and processes given changing compositions of CO2 and other infrared-absorbing gasses in a homogeneous mixture of gases is completely clear.”

In fact, I think this can be expanded to include all radiative-energy transport phenomena and processes, ( absorption, transmission, and reflectance ), for both ultra-violet and infrared radiation, so long as homogeneous mixtures of gases are the material.

For me, one question is, How does this relate to the Earth’s atmosphere, oceans, ice, and land, and all the materials in and on these, and all the phenomena and processes occurring within and between these?

2.

“So, yes, one must combine this measurement of anthropogenic CO2 with the simple radiative physics in the atmosphere to get the fact that we expect AGW.”

The radiative-energy transport phenomena and processes occurring in the Earth’s atmosphere are far from ‘simple’. If these were simple, I think the treatment of them in mathematical models could be fairly characterized as being based on the full and complete fundamental equations associated with these, depend solely on properties of the materials of interest free of any parameterizations, accurate numerical solution methods known and fully incorporated into all GCMs, and resolution of all temporal and spatial scales accurately resolved for every calculation.

So far as I am aware, none of these conditions are met. The parameterizations for some of the phenomena and processes associated with radiative-energy transport in the Earth’s atmosphere are in fact used to tune the GCMs when improvements in hindcasts are needed. The properties of materials as they appear in the fundamental equations for any phenomenon or process are never used as tuning knobs.

I’ll add now, that R. D. Cess, V. Ramanathan, G. E. Thomas, K. Stamnes and a few other people might be surprised to learn of the simplicity of radiative-energy transport calculations in the Earth’s atmosphere. The earth’s atmosphere is not a homogeneous mixture of gases; it’s far more complex. Some of the materials that make the Earth’s atmosphere a heterogeneous mixture of gases, vapor, liquid, and solids have critically important interactions with the radiative energy transport.

Recently, I also ran across this statement in an online kind-of textbook:

“To develop this understanding we must discuss various forms of energetic equilibria in which a physical system may reside. Earth (and the other terrestrial planets, Mercury, Venus, and Mars) are said to be in planetary radiative equilibrium because, on an annual timescale the solar energy absorbed by the Earth system balances the thermal energy emitted to space by Earth.”

My bold.

The writer has specified a time scale over which the in-come and out-go of radiative energy for the Earth’s systems are balanced; ‘annually’. In my opinion there is no foundation whatsoever for this statement. By the same token, I think that this is the first time that I’ve seen any temporal scale attached to the radiative-equilibrium hypothesis. This one is clearly unsupported, however. The Earth’s systems both receive and reject energy on all temporal and spatial scales. Yes, the Earth’s systems, at this very instance, are losing energy to deep space and this seems to be frequently overlooked.

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March 10, 2010 Posted by | Uncategorized | , , | 3 Comments

Validation is a Process

Why has global warming paused? Water vapor may be in the answer. And here.

Contrary to what seems to be the general impression, radiative energy transport in complex interacting media is not a slam-dunk given. Until the numerical values of the dominant driving potential for the Earth’s climate systems are pinned down, the uncertainties in the response of the systems will continue to be large.

January 30, 2010 Posted by | Uncategorized | , | 1 Comment

Validation is a Process

AOLBGCM validation is an ongoing process.
Can’t ever do too much of it.

October 9, 2009 Posted by | Uncategorized | , , | Leave a comment