The Spencer-Braswell & Dessler papers

This page is a collection of posts related to the controversy surrounding the Spencer and Braswell and Dessler papers regarding climate sensitivity and cloud feedback/forcing arguments.

Papers:

The Dessler (2011) paper is in press at Geophysical Research Letters.  Dessler et al. is a critique of Spencer and Braswell (2011), .

Spencer and Braswell (2011)  is a critique of  Dessler (2010).

Dessler (2010)  is a critique of Spencer and Braswell (2010).

Related: Lindzen and Choi (2011)

Stories:

The page is ordered newest at the top, oldest at the bottom.

Pielke Sr. on Skeptical Science’s attacks on Spencer and Christy

Dessler gets schooled by Spencer [Cartoon by Josh]

Dessler: “People who discount the science of climate change don’t do it because they’ve read the science”

The Good, The Bad, and The Ugly: My Initial Comments on the New Dessler 2011 Study [Roy Spencer]

Dessler’s GRL paper video

Hot off the press: Dessler’s record turnaround time GRL rebuttal paper to Spencer and Braswell

Monday mirthiness: Autumn – time to test fireworks [Cartoon by Josh]

Journal Deliverance: The True Story of the Climate Hillbillies [Les Johnson]

The science is scuttled: Abraham, Gleick, and Trenberth resort to libeling Spencer and Christy

The Spencer and Braswell story goes viral

BREAKING: Editor-in-chief of Remote Sensing resigns over Spencer & Braswell paper

Rise of the 1st Law Deniers [Roy Spencer]

Spencer and Braswell on Slashdot

Fallout from Our Paper: The Empire Strikes Back [Roy Spencer]

Pielke Sr. on new Spencer and Braswell paper [Roger Pielke Sr.]

Science has been sitting on his critique of Dessler’s paper for months”

The Dessler Cloud Feedback Paper in Science: A Step Backward for Climate Research

Spencer on water vapor feedback [Roy Spencer]

Congratulations (finally) to Spencer and Braswell on getting their new paper published

Related:

Climate Audit
Spencer on Cloud Feedback Dec. 30, 2007
Trenberth: “Unbelievable” Breakdown in Defensive Zone Coverage July 31, 2011
The Stone in Trenberth’s Shoe Sept. 6, 2011
Dessler Data
Spencer Data

The BlackBoard
CERES and the Shortwave Cloud Feedback

Climate Etc.
Spencer & Braswell’s new paper>Spencer & Braswell’s new paper
Update on Spencer & Braswell
Update on Spencer & Braswell: Part II
Spencer & Braswell: Part III

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7 Responses to The Spencer-Braswell & Dessler papers

  1. dahuang says:

    Please also pay attention to the Lindzen and Choi papers which are also criticized in Dessler (2011), because they are discussing basically the same problem, the cloud feedback using observational data. With Trenberth himself facing Lindzen, and Dessler assigned to scuffle with Spencer, this is really a spectacular fight.

    References:

    Lindzen, R. S., and Y.‐S. Choi (2009), On the determination of climate feedbacks from ERBE data, Geophys. Res. Lett., 36, L16705, doi:10.1029/2009GL039628.

    Trenberth, K. E., J. T. Fasullo, C. O’Dell, and T. Wong (2010), Relationships between tropical sea surface temperature and top‐of‐atmosphere radiation, Geophys. Res. Lett., 37, L03702,
    doi:10.1029/2009GL042314.

    Lindzen, R. S., and Y. S. Choi (2011), On the observational determination of climate
    sensitivity and its implications, Asia Pacific J. Atmos. Sci., 47, 377-390, doi: 10.1007/s13143-011-0023-x.

    Dessler, A. E. (2011), Cloud variations and the Earth’s energy budget, Geophys. Res. Lett., doi:10.1029/2011GL049236, in press.

  2. Paul Deacon says:

    Anthony – housekeeping point. The page appears in the drop-down menu for Reference Pages, but if you click on Reference Pages, this page does not appear in the list.

    All the best

    Reply: Fixed ~ ctm

  3. Theo Goodwin says:

    Anthony this is a wonderful innovation and it makes WUWT the leading education center for climate science blogs. Hats off to you, Sir.

  4. sophocles says:

    Perhaps the CLOUD experiment’s outputs should be tracked, too. They are evidentially relevant (IMHO) to this debate.

  5. Socratic says:

    What follows is a recap of three posts I made on on Dr. Spencer’s blog, concerning computation of the left-hand side of the main equation. You may recall that Dr. Spencer obtained 2.3 Wm^-2 and Dr. Dessler obtained 9 Wm^-2 for the LHS. The obvious differences between these papers were (a) Spencer used quarterly data, while Dessler used monthly data; (b) Spencer used a mixing layer depth of 25 meters while Dessler used a mixing layer depth of 100 meters.

    In his blog, Dr. Spencer recommended use of Levitus when computing the LHS. Levitus appears to be the World Ocean Atlas (WOA) which is available online in updated form, here:
    http://www.nodc.noaa.gov/OC5/WOA09/woa09data.html

    I found that mixing layer depth has already been computed by Levitus on a global grid, and available from NOAA, here: http://www.nodc.noaa.gov/OC5/WOA94/mix.html

    There are three criteria for ML in use: A) (most common definition) depth at which temp is .5 C lower than the surface; B) depth at which the density is .125 standard deviations greater than the surface; and C) depth at which the density is equal to what the density would be with a .5 C change. These three definitions give rather different results.

    After downloading all the data and running global weighted averages (weight = cosine[latitude]), the global average mixing layer depth for each definition was:
    A. 71.5 meters
    B. 57.2 meters
    C. 45.9 meters

    These numbers fall neatly between the depths used by Spencer and Dessler.

    Downloading quarterly data for temperature (objectively analyzed means) from WOA allows you to compute a weighted mean SST for the globe. The four weighted means thus computed were: JFM=18.293; AMJ=18.1672; JAS=18.128;OND=17.935, with a global annual mean of 18.130 C.
    The four differences between quarters are then ,358, -.131, -.034, and -.193, with a standard deviation of those values being .247 C.

    To compute heat capacity (and change thereof) I used the mean temp of 18.130 as a “before” value and a changed temp of 18.130+.247=18.377 as an “after” value. I computed density and heat capacity for both using a salinity of 35 g/kg and the equations of Sharqawy et.al. 2010. For a 1m x 1m x 25m column, I get mass=25634.58 kg (before), 25633.14 kg (after); HC=29854059 kJ (before), 29878463 kJ (after) for a quarterly change of 24404 kJ. The rate of change per quarter is therefore 2440384 J / 7889400 seconds = 3.1 Wm^-2. This is a bit higher than the 2.3 value given by Dr. Spencer. Note also that this value may be wrong; one could argue that we should be operating on a constant mass of water rather than a constant volume. Computing on that basis, the result would be 3.3 Wm^-2.

    But note that this was computed using a 25m ML depth. Using the Levitus ML depths gives for the LHS of the equation energy change rates of (A) 8.9 (B) 7.1 and (C) 5.7 Wm^-2 respectively. In other words, Dr. Spencer’s 2.3 Wm^-2 seems too low.

    Using monthly (rather than quarterly) WOA data, I find the global weighted-average SSTs by month: 18.176, 18.347, 18.357, 18.282, 18.147, 18.057, 18.134, 18.173, 18.078, 17.950, 17.871, 17.984 giving the same 18.13 average as in quarterly data.
    This gives Delta-Ts of: .192, .171, .010, -.075, -.135, -.090, .077, .038, -.094, -.128, -.078, .113, and the standard deviation of these is .117°C. Already we notice a major difference: if the SST is changing by typically .117 C in a month, we might expect it to change by .117 x 3 = .35 C per quarter. But the actual quarterly change is .25, which means that monthly data is more variable than quarterly data. Not a surprise, but here it is quantified.

    Now let’s repeat the same computations, but using Dr. Dessler’s assumptions. In this run I added a slight improvement: I also downloaded and used salinity data from WAO, which is a little less than the 35 I had been using (mean=34.586).

    Using T=18.130 as the “before” temp and 18.130+.117=18.246 as “after”, I find a “before” density of 1025.0639, and for a column 1×1×100 meters a mass of 102506.4 kg, specific heat of 4.001219 KJ/kg/K and heat capacity of 119468525 KJ. “After” density is 1025.0369, specific heat is 4.001262, and heat capacity is 119514517 KJ. The change over time is therefore 45991.5 KJ in 2629800 seconds, for 17.5 Wm^-2.

    Using the Levitus ML depths gives for the LHS of the equation energy change rates of (A) 12.5 (B) 10.0 and (C) 8.0 Wm^-2 respectively. In other words, Dr. Dessler’s use of 9 Wm^-2 seems about right, if used with a corrected ML depth, while Dr. Spencer’s LHS values are substantially too low.

    Frankly, I’m new at these equations and perhaps I’ve made a mistake somewhere. If so, I hope Dr. Spencer (or someone else) will correct me.

  6. plazaeme says:

    Estimation of the climate feedback parameter by using radiative fluxes from CERES EBAF

    P. Björnbom 2013

    However, the value found here agrees with the report by Spencer and Braswell (2010) that whenever linear striations were observed in their phase plane plots the slope was around 6Wm−2K−1. Spencer and Braswell (2010) used middle tropospheric temperature anomalies and although they did not consider any time lag they may have observed some feedback processes with negligible time lag considering that the tropospheric temperature is better correlated to the radiative flux than the surface air temperature. The value found in this study also agrees with Lindzen and Choi (2011) who also considered the effects of lead-lag relations.

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