Saturday, February 16, 2008

Redistribution of Enthalpy

Eli understands that the old guy is trying to trash him. Eli would be quite happy to talk it over with him, if the old guy wanted to have a discussion, but he appears to want to talk to others without others talking to him and the Rabett is not interested in that. OTOH, we have been hopping about the net and came across the figures for Mark Jacobson's books on Atmospheric Modeling and Atmospheric Pollution (look down at the bottom) and came across this interesting figure. Looking at it we see that the difference in absorbed incoming solar energy is about a factor of two higher at the equator than at the poles (100% difference) but the emitted outgoing IR radiation above the atmosphere is only about 25% higher at the equator than at the poles.

As near as we can make out the large units on the ordinate are 100 W/m^2, which agrees with these measurements of average solar insolation.

What first caught Eli's eye was the implication that radiation and convection move enthalpy from the tropics to the poles. No surprise there. It's called weather. This, of course, is averaged over the year, different cloud conditions and more.

So the bottom line is that even though the temperature difference between the poles and the equator is ~ 50 K, the solar insolation at the surface is a factor of two higher at the equator and the same is true of the emission from the surface as predicted by the Stefan-Boltzmann relation, the amount of energy emitted by the earth in the polar region is only about 25% less than at the equator. Hmm. Let the old guy chew on that.

37 comments:

Atmoz said...

The Encyclopedia of Earth offers a fairly good explaination of is - Earth's energy balance.

"The redistribution of energy across the Earth's surface is accomplished primarily through three processes: sensible heat flux, latent heat flux, and surface heat flux into oceans. Sensible heat flux is the process where heat energy is transferred from the Earth's surface to the atmosphere by conduction and convection. This energy is then moved from the tropics to the poles by advection, creating atmospheric circulation. As a result, atmospheric circulation moves warm tropical air to the polar regions and cold air from the poles to the equator. Latent heat flux moves energy globally when solid and liquid water is converted into vapor. This vapor is often moved by atmospheric circulation vertically and horizontally to cooler locations where it is condensed as rain or is deposited as snow releasing the heat energy stored within it. Finally, large quantities of radiation energy are transferred into the Earth's tropical oceans. The energy enters these water bodies at the surface when absorbed radiation is converted into heat energy. The warmed surface water is then transferred downward into the water column by conduction and convection. Horizontal transfer of this heat energy from the equator to the poles is accomplished by ocean currents."

Anonymous said...

Oh yeah??

You didn't hear about the predicted ice age?

http://www.dailytech.com/Article.aspx?newsid=10630&red=y#comments

wildmice

guthrie said...

*Yawn*
The sunspot cycle started again over a month ago. The cycle was later than "average", but not as late as many people were predicting, in starting.
As for the RUssians and their domm-mongering, I don't see that they have managed any publications out of it. Anyone got more than my pitifully small amount of information?

And the article resurects Svensmarks Zombie.
Thus, it is more fear mongering.

Anonymous said...

Yeah, but the skeptics are eating it up.

wildmice

John Mashey said...

BTW, I recommend perusal of Prof. Jacobson's list of papers at the bottom (PDFs provided). he is a sharp guy and does a *lot* of very interesting work.

Arthur said...

Hi Eli,

who's the "old guy"? Kramm? Or I'm missing something...

Anyway, I note that the figure is for thermal radiation at the *top of the atmosphere*. If you're looking for thermal radiation from the surface, I believe you'd see a graph with no "surplus" anywhere; it pushes the "emitted outgoing infrared" numbers up by over 60%...

Anonymous said...

Arthur, Eli is referring to Roger Pielke Sr. He uses the expression 'old guy' to indicate that RP is too old for his opinions to be of value, unlike Eli, who is young enough for his opinions to have value.

Eli thus continues the great tradition of AGW believers in trashing peoples ideas not because of they are wrong, but because they are asserted by people some of whose characteristics you do not care for. Like, they are too old. The wrong religion. Belong to the wrong political party. Write for the wrong paper. Etc etc.

Eli like many of his ilk has preserved the form of authoritarian political movements of the 20c while changing the detail of targets. To, in this case, the old. Whereas an equally irrelevant characteristic, skin color, would never be used.

It reminds you of that wonderful line in the Godard movie. The first thing we do, lets kill all the Jews and the bankers. Yes. Wait a minute, why the bankers?

The old black guy. Wait a minute, stop referring to him as black. Quite so.

bi said...

Anonymous 3:12 AM:

Wow, this is hilarious! You totally ignore the scientific points presented by Rabett, so that you can accuse him of being a bigot!

Anonymous 9:25 AM, guthrie:

And despite what the article insinuates, Tapping does think AGW is real. But who needs facts? Any scientist who says that AGW is real is obviously either part of the Scientific Inquisition, or has obviously been threatened by the Scientific Inquisition, or both.

bi said...

And by the way, Tapping did not predict an ice age:

"If there is a cooling due to the solar activity cycle laying off for a bit, then the a period of solar cooling could be a much-needed respite giving us more time to attack the problem of greenhouse gases, with the caveat that if we do not, things will be far worse when things turn on again after a few decades."

Now feel free to write that off as the result of Coercion by the Scientific Inquisition.

-- bi, http://zompower.tk/

Anonymous said...

Come now Anon, be a little kind to our Rabett.

He has left his goof of sums a few posts down, so he does want us to see how ignorant he is, particularly funny when he said he knew what he was doing.

The old guy and friends turn up, start talking real sums, and Rabett and T disappear real quick. Kinda funny that Rabbet now says the old guy doesn't want to talk to him.

Rabett and sundry mice, have fun throwing rabbet poo at the Courtneys of the world. Funny thing is, the poo tends to stick to the fingers of the thrower rather than on the throwee.

Anyway Rabett, the ice, it grows.

JohnS

bi said...

JohnS talks about "sums" without doing any sums at all.

And the sums without sums show us that "the ice, it grows".

Never mind that the lack of sums doesn't sum up! Being a denialist means never having to do sums.

-- bi, http://zompower.tk/

EliRabett said...

Bi,

Given that Eli is now about one chair election from retirement he is not much impressed by trolls. Been there, seen that.

Anonymous said...

Perhaps as a retirement gift we could chip in and purchase a visit to your site by a real high-class troll? The action that you're getting from your local talent is the troll equivalent of a furtive caress in an airport restroom.

-spilgard

Anonymous said...

Wait!

Eli has an ilk?

Are there photographs?

Anonymous said...

What a bunch of Rabbet Pellets. Let's do the "old guy" math:

Roger Pielke Sr. Born October 1946, is now 61 years old.

Al Gore, born in March 1948, will be 60 years old next month.

So I'll look forward to Eli ignoring Gore's wisdom when he reaches "old guy" age next month.

Anonymous said...

Pielke jr is the young guy and sr is the old guy. and john s and the dumber anonymice on this thread are the dumb guys.

-- wise guy

Lazar said...

S/he probably meant to write elk.

Horatio Algeranon said...

Is all the brouhaha about emission Much ado about nothing?

I'd have to say "yes".

As Joan Rivers used to say, "Can we calculate"?

bi said...

Anonymous 12:30 PM hath impressed me with his cutting-edge denialist "science".

Pielke Sr. is old, Gore is old, Rabett says Pielke Sr. is old, ergo the ice sheets are growing. QED.

-- bi, http://zompower.tk/

Anonymous said...

http://climatesci.org/2008/02/18/spatial-variations-in-gmst-ii-eli-rabett-vs-dr-pielke-sr-guest-weblog-by-lucia-liljegren/

any comment....

~Bob

Anonymous said...

Come now, all those anon friends of Rabett must know what ilk stands for- ignorant luddite knutters(the silent k nutters- worse than ordinary nutters and trolls) An easy swap for faithwarmers.

JohnS

Anonymous said...

Shit. Don't take the latest Killfile update. It's quit working. I'd forgotten the density gradient that shows up here.

Cynthia said...

Prof. Rabett,

If you're a hare's breath away from retirement, does this mean that all of your bunny projects will come to an end, too?

Spilgard said...

Ohmygawds it's hilarious to learn that being in favor of altering business-as-usual via an industrial/technological push towards enhanced efficiency makes me a Luddite, inasmuch as the Luddites were crusading against the industrial/technological push towards enhanced efficiency which threatened to alter business-as-usual.

-Spilgard

Horatio Algeranon said...

I first integrated radiative emission over one day at a location having an average temperature for that day of 275K and a total diurnal variation of 20K, assuming that temperature varies sinusoidally over the day. This result deviated by only 0.4% from the result obtained by assuming that the emission for the entire day occurred at the average temp (275K).

I next integrated "change in radiative emission for a 1K change in temperature" over the entire earth's surface, assuming that temperature varies sinusoidally with latitude, from 250K at the pole to 300K at the equator. The answer I got deviated by only 4% from the answer one would get by assuming that every location on the earth's surface was radiating at the global mean temperature (288K).

More details here.

Flavius Collium said...

So, why do Lucia and Horatio get so different results, 17% vs 0.6%?

http://climatesci.org/2008/02/18/spatial-variations-in-gmst-ii-eli-rabett-vs-dr-pielke-sr-guest-weblog-by-lucia-liljegren/

vs

http://halgeranon.blogspot.com/2008/02/much-ado-about-nothing.html

Horatio Algeranon said...

First, i should make it clear that the 0.6% result was based on the very (perhaps overly) simplistic function i used to represent the temperature vs latitude, so it should be taken with a grain (or probably block) of salt.

It is certainly possible that the difference between the result i found and that found by others is due entirely to an oversimplification on my part.

But i am somewhat (though by no means completely) reassured that i am not completely off the mark by the fact that the temperature variation function I used gives a value for global mean temperature that is within 2% of the actual value.

Then again, that too could just be a coincidence. :)

I would nonetheless find it almost amazing if scientists had actually overlooked an error as great as 17%, but it is certainly possible.

At any rate, the resolution can only come by integrating radiative emission over the earth's surface using actual temperature data for the whole surface (or at least most of it) .

I did the exploration more out of curiosity than anything else. I'm not a climate scientist and certainly make no claims to being one.

flavius collium said...

I guess it can be seen from the top level that temperature grows easier at high latitudes and in the winter since they don't push as much energy out via the T^4 radiation if the temp grows by a absolute set amount of Kelvins as they started from a lower lever already.

The rate of the wattage increase with temperature increase is of course relative to T^3. So at around 300 K the difference of 20 K is about 7% and that means 20% difference in the wattage derivative (or one might even call it "sensitivity").
Ie 280^3/300^3 ~= 1.2 .

Looking at Eli's graph from an update to an earlier post that would mean the derivative is different in the early part than in the late part.

With the whole averaging business the "sensitivity" error could drop to around half.

So my estimate is 10% :) :) . IANAC.

raypierre said...

A lot of you guys are getting somewhat led up a garden path. There's no business about "scientists missing an error of 17%" going on no matter how you do the arithmetic. Climate models DO NOT CALCULATE THE ENERGY BUDGET USING A SINGLE GLOBAL MEAN TEMPERATURE, so Pielke Senior's "criticism" is pointless, absolutely incoherent. Climate models do a radiative transfer calculation several times a day at each gridpoint, incorporating the full variation of temperature.

The sort of thing you guys are talking about only tell you how big the errors are in the most primitive blackboard-type zero-dimensional climate calculation, where indeed you do do the energy budget in terms of a global average temperature. The fact that the errors made by doing so are so small is in fact why you can get pretty far with such simple calculations, especially on a planet like Earth or Venus with a thick atmosphere and or ocean to redistribute heat and make temperature more uniform.

Horatio Algeranon said...

Raypierre says "A lot of you guys are getting somewhat led up a garden path."

But how sweet those flowers do smell.

flavius collium said...

Of course raypierre, this is just gauging the result difference between two simplification levels.

Sort of zero dim vs one dim (latitude) "model" calculation.

Anonymous said...

Professor RP Sr nowhere says GCMs use a single temperature to calculate radiative energy transport.

You have introduced that incorrect characterization, not Professor Pielke. As you are solely responsible I suggest that you should make the correction.

You also say, " ... in the most primitive blackboard-type zero-dimensional climate calculation ... "

And I think that is exactly one of Professor Pielke's points. A very primitive "model" is used to develop a metric that is widely reported in the climate change literature. And there is an error associated with the approach that is not insignificant.

bi said...

Anonymous 9:25 AM,

"Professor RP Sr nowhere says GCMs use a single temperature to calculate radiative energy transport. [...] And I think that is exactly one of Professor Pielke's points. A very primitive `model' is used to develop a metric [...]"

You, Sir, are full of garbage.

Here on my web site is everything one needs to know about climate models. Prove me wrong.

-- bi, http://zompower.tk/

Anonymous said...

bi:

If your models are primitive, I'm all for it.

Me Tarzan!

Horatio Algeranon said...

I goofed big time!! I did not include the uncertainty estimate in my answer, which turns out to be on the order of 12.5% (or perhaps even bigger)! This changes my conclusion about the significance of the difference. The difference may indeed be significant. I can’s say for sure because the error bars on the temperature vs latitude graph from which I estimated the radiative emission as a function of temp across the globe are too big.

To settle the question, one needs to do the integral with actual temperatures from across the globe

raypierre said...

I'm glad you're all having fun with this, but I'll repeat that the answer to the calculation Horatio Algernon is trying to get right has no bearing whatever on the use of global mean temperature as a summary statistic. It has a bearing on the question of how well you can calculate the temperature of a planet using a globally averaged radiation balance parameterized in terms of a single global mean temperature. To do that calculation right, of course you also need to take into account the effect of the atmosphere on OLR, and not just use sigma Tsurf**4.

That's an interesting question but I repeat it has nothing to do with what is going on in general circulation models. Pielke Sr. seems to be implying that the global mean temperature is only useful if you can use it to do a global mean energy balance model, but what does that have to do with anything? The global mean temperature is just one of many summary statistics used to represent climate. Naturally, you can't capture all the interesting aspects of climate change by looking at one global statistic. That's why all climate modelers, and all the IPCC reports, give regional averages, as well as maps of how temperature changes are distributed across the globe.

Pielke Sr.'s claim about global mean temperature "overestimating" global warming is not something that you can prove to be "right" or "wrong" by a calculation, because the question he posed never made sense in the first place. It's like asking whether two kilograms is greater than three seconds. Makes no more sense than that question.

Marion Delgado said...

they should write an Encylopedia of Pseudoscience. Include Tim "Who's Archimedes?" Ball.

nowadays outright denialism is pretty far in the weeds. But this is laughable. bluff bravado and wrong ifo.