2006-01-23

Dynamical amplification of polar warming

Polar amplification, again. RC recently had a post on this; though now I look again its a teensy bit vague about the actual *causes*. Which I've posted on before. Now along comes... Cai, M. (2005), Dynamical amplification of polar warming, Geophys. Res. Lett., 32, L22710, doi:10.1029/ 2005GL024481. Unfortunately, I have failed to do my duty, which is to carefully read and understand the paper. Maybe someone else will do that and comment. All I've done is skim it. But read on...

This paper presents theoretical and modeling evidence suggesting that the atmospheric poleward heat transport can lead to a polar warming amplification (i) by redistributing part of the extra energy intercepted by the low-latitude atmosphere to high latitudes, and (ii) by strengthening the water vapor feedback in high latitudes. For an anthropogenic radiative forcing of 4 Wm/2, we illustrate that the dynamical amplifier contributes to about 1/4 (1/10) of the total high-latitude (global) surface warming in winter in a simple coupled atmosphere-surface moist radiativetransportive climate model. Budget analysis of the radiation fluxes at the top of the atmosphere derived from IPCC AR4 CGCM climate simulations seems to support the dynamical amplifier theory for the larger warming in high latitudes.


The most interesting part of this is part (ii) - the strengthening of the WV feedback in high latitudes. Its interesting because although many people think its why polar amp occurs, this is the first paper I've seen to assert it. The least interesting is part (i), because thats been done already (and better, from a brief scan) by Alexeev in Cli Dyn (see my prev post). The problem is that Cai is using a 4-box coupled atmosphere-surface moist radiative-transportive climate model to illustrate the dynamical amplification of the high-latitude surface warming due to an anthropogenic forcing. And the WV feedback isn't done properly, The water vapor feedback has been crudely parameterized using an ad-hoc formula Equation 5 to mimic the strong dependency of the atmospheric absorption of longwave radiation to the amount of water vapor. Specifically, the total atmospheric effective emissivity in the model is made of two parts: a constant part e0 representing the absorption due to other gases, such as CO2, and a part that varies as a function of the total amount of water vapor in an atmosphere column. And worse than that, I can't see where they seperate out effects (i) and (ii), so at the end of it all I can't see where they say how important the WV feedback is (if we trusted their eq 5).

[Updated to fix funny char (ctrl-A?) in the Wm/2 that was doing naughty things to the feed, apparently]

3 Comments:

Blogger nige said...

Wow. I'm so ignorant I thought the air was so dry in polar regions, so this sort of thing could be discounted...

BTW, on subject of Lubos Motl, you might want to take a glance at http://www.math.columbia.edu/~woit/wordpress/?p=333

Motl is getting the worst of it from Woit, and responding to the failure of string theory by making feeble personal attacks on the number of citations Woit's papers have...

Wikipedia has an article about Woit here, but the Wikipedia article "Not Even Wrong" about Pauli's criticism of rubbish like Motl's ideas on string theory, was deleted.

It is a pity, because string theorists have no scientific answer to give to valid criticisms, but they refuse to admit that string theory is not based on facts and is untestable. Vague predictions of gravitons and superpartners, with no testable details, from extra dimensions isn’t useful science.

I think Peter is doing a very good job indeed. It is a shame that string theorists don’t concede defeat after 21 years of failure. (I worked a bit on alternative ideas, but nobody wants to read them while untestable speculation dominates the mainstream...)

12:40 pm  
Blogger Belette said...

Hmmm... I tend to leave string theory well alone (Lubos on climate change being a perfect example of why getting outside your field leaves you looking silly). And I've even asked Lubos's advice on Gravity on wikipedia. CIP teases Lubos about stringy things occaisionally.

9:09 pm  
Blogger nige said...

Gravity: what Lubos doesn't know

Lubos is prejudiced toward string theory crap, "predicting" the existence of unobservable gravitons without testable numbers, using extra dimensions!

Lee Smolin's Loop Quantum Gravity, specifically the Spin Foam Vacuum, is modelling the physics of known processes causing force. Smolin shows that the Feynman "sum over histories" is equivalent to summing graphs for the spatial topography of each interaction in the vacuum for Penrose's spin networks.

General relativity is the Newtonian law expressed as a field potential, with a special "contraction" term put in to make the whole thing self-consistent for energy conservation.

Newton's law: R = G

General relativity: R - r = G

where r is contraction. (Lubos thinks, wrongly, that GR = SR + gravity, whereas the framework os GR is entirely different to SR, implying a spacetime fabric to produce accelerations, which SR specifically excludes hence the twins paradox.)

Feynman showed the general relativity contraction of Earth's radius is (1/3)GM/c^2 = 1.5 mm

This contraction is radial (along gravitational field lines) only, not transverse, so circumference is unaffected. Hence the value of Pi (circumference of planet/diameter) would be increased due to gravity, if there are only 3 dimensions. By treating c.dt as fourth dimension, you keep Pi intact.

Why the contraction? Answer: by Einstein's equivalence principle between inertial and gravitational mass, the increase in inertial mass given by the Lorentz transformation can be related to that due to gravity. A simple physical argument using escape velocity and the equivalence principle shows that the Lorentz transformation can be applied to gravity, the result is the (1 - v2/c2)^1/2 transformation is converted to gravity by putting escape velocity into v, giving the gravitational contraction of general relativity, (1 - 2GM/(rc2))^1/2 (see http://feynman137.tripod.com).

So the spacetime fabric is the result of general relativity, and this is the unification with the Standard Model of quantum field theory (which postulates all mass of fundamental particles is due to a surrounding vacuum perfect fluid, the Higgs field).

Swiss theorist G.L. LeSage first put forward a physical pressure model of gravity in 1747, and was independently followed by a Russian, M.V. Lomonosov in 1848.

What really happens is that Feynman's interpretation of quantum field theory - gauge boson exchange causing force in Feynman diagrams - is literally correct, physically.

Masses exchange gauge bosons, which travel at light speed, hit masses, and exert pressure from all directions. The energy bounces back in the same direction it came from, like a reflection. Shielding by two masses nearby causes gravity.

LeSage and others are wrong to treat the gauge bosons as a gas, because there is no mutual interaction between them, but only interactions between them and mass.

By promoting extra dimensional speculation as truth, Lubos is destroying the chances of real research getting a look in:

1. Feynman diagrams, the physics behind the maths of quantum field theory, show that forces arise from the exchange of gauge bosons (coming from distances at light speed, hence coming from times in the past).
2. The big bang mass has an increasing speed, in our observable spacetime, from 0 toward speed of light c with times past of 0 toward 15 billion years (or distances of 0 to 15 billion light-years), giving outward force by Newton’s 2nd empirically based law: F = ma = m.dv/dt = m(c - 0) / (age of universe) = mcH, where H is Hubble’s constant (based on v = HR, where R is distance).
3. Newton’s 3rd empirically based law suggests equal inward implosion force, carried by gauge bosons, which shielded by mass, proves gravity and electromagnetism to within 1.65%

1:10 pm  

Post a Comment

Links to this post:

Create a Link

<< Home