GRL doi:10.1029/2011GL049236 Andy Dessler does not like Spencer and Braswell very much

UPDATE: Video (Thnx to Sou)

Andrew Dessler has a new, recently awaited take (open preprint) on Spencer and Braswell 2011 and Lindzen and Choi 2011. Skeptical Science goes over the cherry picking in SB. Basically, the former looked only at the models that were not very sensitive to El Nino and found them wanting in a comparison where El Nino dominated, and both made interesting choices of data. Skeptical Science goes through this in detail. You gotta get up early in the morning to beat them Aussies. UPDATE: Gavin has a measured take on the blowup @ Real Climate, more meta than not.

Eli is more interested in the setup. Dessler notices that when both LC and SB write an equation for the change in the ocean surface temperature on a short term basis, ∆T_sas a function of the heating of the climate system by the ocean, ∆F_ocean and the change in the TOA flux due to clouds,

C dT_s/dt=∆R_cloud+∆F_ocean−λ∆T_s

they bundle the feedbacks into λ, but this defines the clouds and oceans as the source of ∆T_s not as the result. SB specifically separate cloud forcing from response, AKA, they assume what they wish to prove which is not such a bad tactic if you want to show that the something you assumed is wrong, e.g. induce a contradiction, but it does not work as well in the other direction. However, are the oceans part of the climate system which SB and LC are modeling? If so the ∆F_ocean forcing term is driving changes in the temperature of the oceans, but if the ocean is part of the climate system then the ocean respond to changes in the system, i.e. this model confuses forcings and feeedbacks. Dessler puts it this way

The formulation of Eq. 1 is potentially problematic because the climate system is defined to include the ocean, yet one of the heating terms is flow of energy to/from the ocean (∆F_ocean). This leads to the contradictory situation where heating of their ocean, yet one of the heating terms is flow of energy to/from climate system by the ocean (∆F_ocean > 0) causes an increase of energy in the ocean (C(dTs/dt) > 0), apparently violating energy conservation. While it may be possible to define the terms so that Eq. 1 conserves energy, LC11 and SB11 do not provide enough information to show that they have actually done so.

One possible out is to claim that neither the oceans nor clouds are forced on a monthly time scale (which kinda says El Nino is external to the system, all flail down) or to jigger the constants C and λ which provides the freedom to pick the ratios of ∆R_cloud and ∆F_ocean

The issue of the specific heat is indicative. The standard value is ~168 W-month m^-2K^-1 which both LC and Dessler use (also see for example Schwartz). This is for a depth of ~100 m, but SB use 3 W-month m^-2K^-1 for a depth of 25 m. If you simply scale this it is equivalent to 12 W-month m^-2K^-1, still way low. However, this shallow ocean would respond faster to any changes in the system as SB discuss as justification for choosing such a low value, making the assumption of decoupling from the system even worse.

Still, Andy is a nice guy

However, to comprehensively evaluate the arguments of LC11 and SB11, I simply note this potential problem and assume in the rest of the paper that Eq. 1 is correct.

Which is where Skeptical Science comes in.

Eli? Eli is fond of conservation of energy.