Some Comments on the Lindzen and Choi (2009) Feedback Study
by Roy W. Spencer, Ph. D.
I keep getting requests to comment on the recent GRL paper by Lindzen and Choi (2009), who computed how satellite-measured net (solar + infrared) radiation in the tropics varied with surface temperature changes over the 15 year period of record of the Earth Radiation Budget Satellite (ERBS, 1985-1999).
The ERBS satellite carried the Earth Radiation Budget Experiment (ERBE) which provided our first decadal-time scale record of quasi-global changes in absorbed solar and emitted infrared energy. Such measurements are critical to our understanding of feedbacks in the climate system, and thus to any estimates of how the climate system responds to anthropogenic greenhouse gas emissions.
The authors showed that satellite-observed radiation loss by the Earth increased dramatically with warming, often in excess of 6 Watts per sq. meter per degree (6 W m-2 K-1). In stark contrast, all of the computerized climate models they examined did just the opposite, with the atmosphere trapping more radiation with warming rather than releasing more.
The implication of their results was clear: most if not all climate models that predict global warming are far too sensitive, and thus produce far too much warming and associated climate change in response to humanity’s carbon dioxide emissions.
A GOOD METHODOLOGY: FOCUS ON THE LARGEST TEMPERATURE CHANGES
One thing I liked about the authors’ analysis is that they examined only those time periods with the largest temperature changes – whether warming or cooling. There is a good reason why one can expect a more accurate estimate of feedback by just focusing on those large temperature changes, rather than blindly treating all time periods equally. The reason is that feedback is the radiation change RESULTING FROM a temperature change. If there is a radiation change, but no temperature change, then the radiation change obviously cannot be due to feedback. Instead, it would be from some internal variation in cloudiness not caused by feedback.
But it also turns out that a non-feedback radiation change causes a time-lagged temperature change which completely obscures the resulting feedback. In other words, it is not possible to measure the feedback in response to a radiatively induced temperature change that can not be accurately quantified (e.g., from chaotic cloud variations in the system). This is the subject of several of my previous blog postings, and is addressed in detail in our new JGR paper — now in review — entitled, “On the Diagnosis of Radiative Feedbacks in the Presence of Unknown Radiative Forcing”, by Spencer and Braswell).
WHAT DO THE AMIP CLIMATE MODEL RESULTS MEAN?
Now for my main concern. Lindzen and Choi examined the AMIP (Atmospheric Model Intercomparison Project) climate model runs, where the sea surface temperatures (SSTs) were specified, and the model atmosphere was then allowed to respond to the specified surface temperature changes. Energy is not conserved in such model experiments since any atmospheric radiative feedback which develops (e.g. a change in vapor or clouds) is not allowed to then feed-back upon the surface temperature, which is what happens in the real world.
Now, this seems like it might actually be a GOOD thing for estimating feedbacks, since (as just mentioned) most feedbacks are the atmospheric response to surface forcing, not the surface response to atmospheric forcing. But the results I have been getting from the fully coupled ocean-atmosphere (CMIP) model runs that the IPCC depends upon for their global warming predictions do NOT show what Lindzen and Choi found in the AMIP model runs. While the authors found decreases in radiation loss with short-term temperature increases, I find that the CMIP models exhibit an INCREASE in radiative loss with short term warming.
In fact, a radiation increase MUST exist for the climate system to be stable, at least in the long term. Even though some of the CMIP models produce a lot of global warming, all of them are still stable in this regard, with net increases in lost radiation with warming (NOTE: If analyzing the transient CMIP runs where CO2 is increased over long periods of time, one must first remove that radiative forcing in order to see the increase in radiative loss).
So, while I tend to agree with the Lindzen and Choi position that the real climate system is much less sensitive than the IPCC climate models suggest, it is not clear to me that their results actually demonstrate this.
ANOTHER VIEW OF THE ERBE DATA
Since I have been doing similar computations with the CERES satellite data, I decided to do my own analysis of the re-calibrated ERBE data that Lindzen and Choi analyzed. Unfortunately, the ERBE data are rather dicey to analyze because the ERBE satellite orbit repeatedly drifted in and out of the day-night (diurnal) cycle. As a result, the ERBE Team advises that one should only analyze 36-day intervals (or some multiple of 36 days) for data over the deep tropics, while 72-day averages are necessary for the full latitudinal extent of the satellite data (60N to 60S latitude).
Lindzen and Choi instead did some multi-month averaging in an apparent effort to get around this ‘aliasing’ problem, but my analysis suggests that the only way around the problem it is to do just what the ERBE Team recommends: deal with 36 day averages (or even multiples of that) for the tropics; 72 day averages for the 60N to 60S latitude band. So it is not clear to me whether the multi-month averaging actually removed the aliased signal from the satellite data. I tried multi-month averaging, too, but got very noisy results.
Next, since they were dealing with multi-month averages, Lindzen and Choi could use available monthly sea surface temperature datasets. But I needed 36-day averages. So, since we have daily tropospheric temperatures from the MSU/AMSU data, I used our (UAH) lower tropospheric temperatures (LT) instead of surface temperatures. Unfortunately, this further complicates any direct comparisons that might be made between my computations (shown below) and those of Lindzen and Choi.
Finally, rather than picking specific periods where the temperature changes were particularly large, like Lindzen and Choi did, I computed results from ALL time periods, but then sorted the results from the largest temperature changes to the smallest. This allows me to compute and plot cumulative average regression slopes from the largest to the smallest temperature changes, so we can see how the diagnosed feedbacks vary as we add more time intervals with progressively weaker temperature changes.
RESULTS
For the 20N-20S latitude band (same as that analyzed by Lindzen and Choi), and at 36-day averaging time, the following figure shows the diagnosed feedback parameters (linear regression slopes) tend to be in the range of 2 to 4 W m-2 K-1, which is considerably smaller than what Lindzen and Choi found, which were often greater than 6 W m-2 K-1. As mentioned above, the corresponding climate model computations they made had the opposite sign, but as I have pointed out, the CMIP models do not, and the real climate system cannot have a net negative feedback parameter and still be stable.
But since the Lindzen and Choi results were for changes on time scales longer than 36 days, next I computed similar statistics for 108-day averages. Once again we see feedback diagnoses in the range of 2 to 4 W m-2 K-1:
Finally, I extended the time averaging to 180 days (five 36-day periods), which is probably closest to the time averaging that Lindzen and Choi employed. But rather than getting closer to the higher feedback parameter values they found, the result is instead somewhat lower, around 2 W m-2 K-1.
In all of these figures, running (not independent) averages were computed, always separated by the next average by 36 days.
By way of comparison, the IPCC CMIP (coupled ocean-atmosphere) models show long-term feedbacks generally in the range of 1 to 2 W m-2 K-1. So, my ERBE results are not that different from the models. BUT..it should be remembered that: (1) the satellite results here (and those of Lindzen and Choi) are for just the tropics, while the model feedbacks are for global averages; and (2) it has not yet been demonstrated that short-term feedbacks in the real climate system (or in the models) are substantially the same as the long-term feedbacks.
WHAT DOES ALL THIS MEAN?
It is not clear to me just what the Lindzen and Choi results mean in the context of long-term feedbacks (and thus climate sensitivity). I’ve been sitting on the above analysis for weeks since (1) I am not completely comfortable with their averaging of the satellite data, (2) I get such different results for feedback parameters than they got; and (3) it is not clear whether their analysis of AMIP model output really does relate to feedbacks in those models, especially since my analysis (as yet unpublished) of the more realistic CMIP models gives very different results.
Of course, since the above analysis is not peer-reviewed and published, it might be worth no more than what you paid for it. But I predict that Lindzen and Choi will eventually be challenged by other researchers who will do their own analysis of the ERBE data, possibly like that I have outlined above, and then publish conclusions that are quite divergent from the authors’ conclusions.
In any event, I don’t think the question of exactly what feedbacks are exhibited by the ERBE satellite is anywhere close to being settled.
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P Wilson,
The 255K radiated temperature of the planet is the equivalent temperature of the radiation leaving the planet. If you examine it’s spectral components, it will have gaps caused primarily by water vapor, CO2 and O3. If you integrate the power over all wavelengths, the total energy will be less than that of an ideal BB without the spectral gaps. If you convert this total energy into an equivalent temperature with SB, you get 255K.
If you examine the spectral composition of the power leaving the planet, it’s peak amplitude is that of the Plank power distribution corresponding to warm surface temperatures, even though the total power is consistent with
a colder temperature.
George
co2isnotevil (George) says:
No…That would be a silly assumption to make and is not at all what it is based on. The 3.7 W/m^2 is how much less energy is emitted back out into space as a result of a doubling of CO2 (once stratospheric adjustment has occurred). The amount absorbed by GHGs is irrelevant in the sense that the radiation can be multiply-absorbed and emitted, which is why you need line-by-line radiation transfer codes to accurately compute the radiative forcing.
In fact, the water vapor feedback is needed to explain various data for changes in temperature. For example, it is needed to explain the temperature response to the Mt. Pinatubo eruption ( http://www.sciencemag.org/cgi/content/abstract/296/5568/727 ). It is needed to explain the data from satellites that probe the upper troposphere: http://www.sciencemag.org/cgi/content/abstract/sci;310/5749/841 (see also http://www.sciencemag.org/cgi/content/summary/323/5917/1020 ) And, it is apparently also need to explain the general climate variability ( http://citeseerx.ist.psu.edu/viewdoc/download?doi=10.1.1.143.6379&rep=rep1&type=pdf ).
Your statement about apehelion and perihelion is not correct (and your estimate of the forcing, once you account for albedo is a little high anyway…it is more like 15 W/m^2) because the climate system does not adjust instantaneously to a forcing. In particular, the oceans provide a large thermal inertia. So, yes, you are correct that the water vapor feedback operates on a timescale of days but that does not mean that the climate system re-establishes radiative balance (after a perturbation of that balance) on such a short timescale…In fact, it’s way longer than that.
I think the word you are looking at is “simplistic”, not “simple”. In fact, this is a way too simplistic way to calculate things. If only it were that easy, the calculation of climate sensitivity could have been settled a long time ago!
No…The effective radiating temperature of the earth is what matters for the top of the atmosphere radiative forcing…and that is the 255 K number.
Joel, what is being explained is that the human body is relatively warmer than its surroundings, that it generates up to 100w/m2, which is what it radiates. It certainly doesn’t absorb 400w/m2 from air or objects in a room. Contrarywise, central heating is used to reach a thermal equilibrium with the body – which always stays at an emission of 1-2 met
George: at 24C at an emission level of 100w/m2 from the floor surface, rising air cools, so the ceiling may be 20C or 17C in a poorly insulated room.
The SB says that at 59F, the energy of (lets say) a wall in a dark basement is 235W/m2 – which is what it emits. At 27C the wall in a room of the cambridge experiment it is 459 w/m2. At the basement, a human will emit what he generates – aroung 85w/m2 since he’s warmer than the walls or objects in that basement, so he can’t be receiving radiation from them. However, air being a poor conductor, its unlikely he will increase the dark room at 15C to his own temperature. If something is giving off radiation it is getting cooler. This basement at 235 w/m2 is the same as what the constant says the earth on average emits. My contention with Joel was that thermal imaging equipment shows that little radiation is given off by *normal* temperature matter.
Yeah…I guess so!
co2isnotevil (16:51:28) :
What is observed is that a uniform radiating surface of 100w/m2 produces 24C at the floor. Though this is the optimum.
Here are some indicative temperature differences, ΔT, for the individual
floor thicknesses, based on an output of70 W/m2, and normal operating output of 50 W/m2.
Output: 70W/m2: ΔT for: [°C]
22 mm boards: +9
20.5 mm wide boards: +8
14 mm boards: +6
Output: 50W/m2: ΔT for: [°C]
22 mm boards: +6
20.5 mm wide boards: +6
14 mm boards: +4
Example: With a surface temperature
on the boards of 27°C and output of 70
W/m2 the surface temperature of the
concrete for a 14 mm clip system laid
on Polyfilt (UK: PolyLay) can be calculated
as:
27+ (Σ md x 70) = 37.5 °C,
where Σ md = 0.15 m2 ºK/W.
oh as for the insulation of clothes , there are quite a few experiments that measure human radiative output in the nude
recognizing misconceptions is one of the job requirements here.
co2isnotevil,
read through my post. While the average required T is 255, the emission for clear skies turns out to be about 270w/m^2 not 239. Also, the atmosphere blocks about 1/3 of outgoing radiation from the surface.
cba says:
Not really…I think that you are confused on this. The distinction is between the “instantaneous” and “adjusted” radiative forcings. The “instantanous” is the value before the stratosphere has responded at all to the change. The “adjusted” value means the value once the stratosphere (and above) has adjusted, which occurs relatively rapidly and is usually what is discussed. For the adjusted case, the values at the tropopause and top-of-the-atmosphere are equal by definition, since if there was net radiation into or out of the stratosphere, further adjustment would occur.
Here are the numbers according to “Global Warming: The Hard Science” by L.D. Danny Harvey (which I recommend for a nice basic grounding in these and other issues): The instantaneous forcing is ~4.3 W/m^2 at the tropopause and 2.4 W/m^2 at the top of the atmosphere. After stratospheric adjustment (i,e., it cools), the values are reduced to ~3.8 W/m^2 at both the tropopause and the top of the atmosphere. (All these numbers are good to about +/-10%.)
As an interesting sidelight, both both and after adjustment, the additional radiation at the surface is only 1.4 W/m^2, which in fact is further evidence that the 3.7 W/m^2 number is not the value that finds its way back to the surface. Of course, the temperature at the surface can’t just be calculated based on this additional radiative amount because the tropospheric temperature distribution is determined by a combination of radiation, convection, and evapotranspiration / condensation. That is why scientists tend to focus on the top-of-the-atmosphere forcing (which, as noted above, is also the forcing at the tropopause when we speak of the forcing after stratospheric adjustment).
The point is that the earth radiates as a blackbody at an effective temperature of 255 K and it is this temperature that is thus relevant in computing the radiative forcing. However, the difference between 11 and 13 W/m^2 is barely outside of error bars on the accuracy to which radiative forcings can be calculated (and well inside of errorbars for estimates of the climate sensitivity), so I don’t think it is worth a lot of argument. Still, my estimate that the central value for equilibrium climate sensitivity of 3 C/(W/m^2) is approximately a factor of 3 larger than the value of ~1.0 C in the absence of feedbacks is what is generally agreed upon…The 11 W/m^2 being about 3X the 3.7 W/m^2.
A couple corrections to my last post:
“both both and after adjustment” should read “both before and after adjustment”.
And, my phrase “the values are reduced to ~3.8 W/m^2 at both the tropopause and the top of the atmosphere” is poorly worded since the 3.8 W/m^2 final value corresponds to a reduction of the value at the tropopause (from ~4.3 W/m^2) but an increase of the value at the top of the atmosphere (from ~2.4 W/m^2).
co2isnotevil (17:09:15)
i understand the concept although it doesn’t match with temperatures, since the greenhouse effect occurs in the lower troposphere where it hits the peaks of the spectra – some 3-7 and 12-70 microns for vapour and 13.4-16 for c02. radiation leaving averages 10 microns at 15C, though at 15microns its very cold energy being absorbed. Although the SB says that 235w/m2 is emitted from matter at 255k. not only is the equation overstated but the attempt to argue that energy is emitted into space at -19C looks spurious. It seems that if these figures for energy expressed in watts are divided by 10, we might have a good appraisal of the basic numbers involved, but they still don’t equate with the actual temperatures, which go from 288k at the surface to as low as 193k at the top.
so i don’t see the sb constant as having value for climatology since it juggles so many mathematics when what appears to occur is no change in the heat that ghgs “trap” or absorb
Joel says:
“Here are the numbers according to “Global Warming: The Hard Science” by L.D. Danny Harvey (which I recommend for a nice basic grounding in these and other issues): The instantaneous forcing is ~4.3 W/m^2 at the tropopause and 2.4 W/m^2 at the top of the atmosphere. After stratospheric adjustment (i,e., it cools), the values are reduced to ~3.8 W/m^2 at both the tropopause and the top of the atmosphere. (All these numbers are good to about +/-10%.)”
have you seen the data regarding stratospheric cooling due to infrared being trapped by ghg’s?
http://www.nsstc.uah.edu/data/msu/t4/tlsglhmam_5.1
there doesn’t seem to be a cooling trend to me.
Another case of “if it were not for global warming it would have been even colder?”
P Wilson: 255 K is the effective blackbody temperature for the earth radiating into space. It is not the temperature at some simple specific location such as the surface or the top of the troposphere because it represents the temperature of an effective radiating level that lies somewhere in between. Of course, the actual way it works is that the radiation that escapes into space comes from a distribution of different levels of the atmosphere (including some that even escapes directly from the surface, an amount equal to about 10% of what the surface emits or about 17% of what the earth / atmosphere system as a whole emits to space, as shown here: http://www.windows.ucar.edu/earth/Atmosphere/images/radiation_budget_kiehl_trenberth_2008_big.jpg ).
Whoops, in my (17:39:06) post, in the sentence that reads, “Still, my estimate that the central value for equilibrium climate sensitivity of 3 C/(W/m^2) …”, that number should be 3 C per CO2 doubling, not 3 C/(W/m^2). The corresponding value in C/(W/m^2) is (roughly) 0.75 C/(W/m^2). [If the climate sensitivity were really 3 C/(W/m^2), we’d really be hosed!]
Joel,
I have done the line by line spectral analysis using the latest HITRAN_2008 spectra. When CO2 is increased from 280ppm to 560ppm, the open loop amount of additional surface power captured by the atmosphere increases by about 3.6 W/m^2. That is, 3.6 W/m^2 less surface power is leaving planet. This power is captured by the atmosphere, mostly within the first km. Considering this a thin shell, half of the captured power is redirected up and half down. Now, whether this is kinetic energy of motion passed by collisions or emission by photons, it really doesn’t matter, the energy is still directed up and down and only the energy directed down heats the surface. The reduction in power leaving the planet is 1.8 W/m^2 and the increase in surface forcing is 1.8 W/m^2. The equilibrium surface temperature, given 1.8 W/m^2 of additional surface forcing, increases by about 0.33C. This produces 1.8 W/m^2 of new surface energy, about 1/2 of which is absorbed by the atmosphere while half passes through. Of the half thats absorbed, half of this goes up and half goes down. The total reduction in output power is decreased to 0.45 W/m^2 (1.8 – .9 – .45), while surface energy increased to 2.25 W/m^2 (1.8 + 0.45). Continuing the series, the net change in the power leaving the planet ultimately becomes zero, while the surface energy ultimately increases by 2.6 W/m^2, resulting in a net surface temperature increase of about 0.5C. A more precise analysis gives 0.55C.
George
Joel,
I’ve seen references to these 10%/17% numbers in many places that support AGW, but they are absolutely incorrect.
The amount of surface energy that leaves the planet under clear sky conditions is about 50%. Do the line by line HITRAN simulations and you will see this. The amount surface energy that leaves from under clouds is only the few percent that leaks through. However, you mustn’t forget that clouds are also radiating energy into space and must be considered part of the radiative system. Clouds are subject to less atmospheric absorption for ienergy directed up, primarily because there’s no water vapor above clouds. About 75% of the energy emitted by clouds and pointed up makes it off the planet.
The Earth is about 66% covered in clouds. The total surface + cloud energy fraction that leaves the planet is about 66% (0.33 * 0.5 + 0.66 * 0.75 = 0.66). Now, .33 * 0.5 is about 0.17 and this is probably where the 17% number comes from.
George
Just as a general philosophical comment: There is probably no one right way to make the calculations that we are arguing about. I.e., one could in principle consider the heat balance at the surface rather than at the top of the atmosphere. However, the problem with that is that it is much more difficult to do so because that involves lots of complex issues like how the convective and evapotranspiration processes change and so forth.
The nice thing about the top-of-the-atmosphere (after stratospheric adjustment) viewpoint is that it makes the calculation of the heat balance simpler…and it in some sense represents what is most important since the overall energy balance of the earth-atmosphere system depends on that value (and the heat exchange into and out of the earth-atmosphere system is due essentially solely to radiation) and also because temperature distribution in the troposphere is determined by the strong mixing that occurs within the troposphere and not so much by the details of where the radiative-only effects of the changing greenhouse gas concentrations (or other changes that cause radiative forcings) occur.
Of course, the complexity doesn’t disappear from the whole picture when one looks at the top-of-the-atmosphere radiative balance…But now it is relegated to the role of feedbacks and, hence, in determining how the final surface temperature depends on the radiative forcings themselves.
co2isnotevil says:
No. You are not correct in what the 3.6 W/m^2 number represents. And, furthermore, your estimate of the increase in radiative energy at the surface is not correct either…It is actually an overestimate! As I noted, it is actually only about 1.4 W/m^2 increase in radiation at the surface. However, it is also incorrect to calculate the resulting temperature change based on this value since the troposphere is tightly coupled and its temperature distribution is thus not simply determined by the radiative effects. That is why the more fundamental radiative forcing numbers are those at the top-of-the-atmosphere.
As I noted to cba, it is worth reading a textbook like “Global Warming: The Hard Science” by L.D. Danny Harvey. It helped explain clearly to me a lot of things that were kind of fuzzy in my mind before I read it. When you approach a field of science that is new to you, it is always useful to get a good solid grounding from those in the field who have come before you. They may not have everything right; however, unless you are absolutely brilliant beyond belief, they have the advantage of a lot more cumulative brainpower invested in gaining the current understanding…and it is necessary to come to grips with that current understanding before you challenge it. Having said this, my only regret is that I myself didn’t take this advice as seriously as I should have and it was not until recently that I went beyond the IPCC reports and recent scientific literature and actually started actually reading textbooks like Danny Harvey’s or Dennis Hartmann’s “Global Physical Climatology” (which I am still only part-way through.
Unfortunately, in this modern age, it is often easier to do calculations than it is to correctly interpret what they mean and I am afraid this applies to whatever you have done using the HITRAN spectra. (Although it isn’t quite clear to me if the problem is that you did the calculation incorrectly or interpreted the result incorrectly.)
The contention, Joel and c02 isnot evil, is that if the constant exagerratess by 10 times the radiative properties of ghg’s and is corrected in line with *recorded* energy emitted from the terrestrial surface, then the surface emits 37w/m2 to the 1st km altitude, the 2nd 34w/m2 until at the stratosphere, cooling with height it decreases to 4w/m2, assuming all along that the change in air pressure increases the distance in which ghg’s absorb and re-emit radiation. C02 then ceases to absorb at it peak of 15 and goes down to the shoulders, but that occurs even if the SB equation is introduced. With or without SB, this is normal radiative activity, so no ghg’s are needed to explain the norm, as they do what they do on their own properties, and so do not change the location of heat/energy , given their ability to emit in all directions.
in a terrestial surface attaining to equilibrium with the incoming solar radiation, very little radiation is given off – most atmospheric radiation is convection, conduction and as you say evaporation, which accounts for the majority of the 235 w/m2 (If that is adirect measurement than an inference from an equation). That leaves 37 w/m2 for ghg’s to delay – and explains the data above from NSTC. I’ve tried to go through the examples of other thermal magnitudes at certain temps, such as underfloor heating as a comparison, and the *human generator* at 15C and 27C – there are many more, although the reason its brough up here is the SB constant is brought in as it exagerrates the effect of ghgs, and normal temperature matter tenfold. this is accepted by both AGW and *sceptics* alike, although they are not responsible for it, since its borrowed directly from physics. Normal temp matter equilibriates with air so it doesn’t need to give off much radiation.
It is possible, given that heat is not a constant, that it is absorbed by land and disaippates, and oceans where it can be stored, end of the affair. This land and oceans can cool or give off heat according to their own thermodynamics. What for example happens to the heat in a kiln when the kiln is turned off for good? Does it vanish or does it somehow transfer itself to other places? There is a strong argument that it naturally thermalises/cools with the immediate environment without adding the sum total of its heat content to its environment. It is natural that poor emitters, that increase in molecular density due to heat treatment lose velocity and absorb heat without re-emitting it. For most things, the exponent of the SB would have to be changed from a fixed radiative factor of 4, to much lower depending on its molecular structure: As the 2 pan experiment from CBA shows: non metals give off much less radiation a a given temperature than metals. THe SB works very well for incandescent metals
**Bump**
Joel says:
“Here are the numbers according to “Global Warming: The Hard Science” by L.D. Danny Harvey (which I recommend for a nice basic grounding in these and other issues): The instantaneous forcing is ~4.3 W/m^2 at the tropopause and 2.4 W/m^2 at the top of the atmosphere. After stratospheric adjustment (i,e., it cools), the values are reduced to ~3.8 W/m^2 at both the tropopause and the top of the atmosphere. (All these numbers are good to about +/-10%.)”
have you seen the data regarding stratospheric cooling due to infrared being trapped by ghg’s?
http://www.nsstc.uah.edu/data/msu/t4/tlsglhmam_5.1
It even shows a warming trend
Joel,
I don’t know about Harvey. He seems to be Canada’s Hansen. Someone who’s built a career on AGW and who’s ego would never handle being wrong about it. I’m sure he can spin a good yarn though.
George
addendum on borrowing from physics: Physics tends not to do an analysis of conception, unlike biology, medicine, or chemistry largely due to the abstract nature of it and this is what makes physics unaccountable – so its possible to have people like Eddington or James Jeans arguing for a mathematical deity that can be proven by physics, or even such arguments as made today that the universe is expanding (How can infinity expand on itself, and what is is expanding into). Is it a big bang or is it a steady state?
they (we) don’t know, so formulate equations to expedite the answer according to what is thought the desirable end..often out of relationship to what is observed. When physics is used in technology however, then these musings can’t be afforded. Its possible to argue with physics that 100 gentle taps on the head with a pencil will produce the same effect as a whack with a mallet, although in reality, something else happens. AGW is very much in Aristotle’s camp of logic -that a ten pount shot will reach the gound 10 times more quickly than a 1 pound shot from the same height. With exceptions, there has been little escape from deductive logic in physics at this level.
PS i still think my fried bacon analogy is a good one
In the time I had this morning, I checked on some number runs using more common values. I still use 384ppm as a co2 baseline for doubling and halvings though. At 12km as the start of the stratosphere (I use the basic1976 US std atm), the absorption at the bottom is about 0.85W/m^2 absorption per km. This is for both the baseline co2 and 2x co2 (initial conditions. The difference between absorption at 50km is less than 1/100 W/m^2 per km with a total absorption at 50km of 0.45W/m^2 per km. At the upper end of the stratosphere, 50km, the outgoing power intensity is about 3.25 W/m^2 greater than the incoming for the 2x co2 and about 1.5 W/m^2 greater than incoming for the 1x co2. These are your initial conditions.
You do need to be careful using the term ‘adjusted’. Apparently, you mean a temperature equilibrium condition has been reached. In climate science, ‘adjusted’ has degenerated into being a synonym of ‘fudged’.
As I’m not a climatologist and the model I use was not designed for that task, doing things like adjusting temperatures to an equilibrium condition is not easy. In fact, running the model at even a low resolution like 1 nm over a reasonably large range is quite time consuming. What I found in attempting an equilibrium recalculation was that the differences in absorption were so low as to be in what would be expected to be the noise.
As to some of the later posts, I haven’t had time to read them properly. Your comment to surface radiation escaping being 17% doesn’t ring right although I don’t distinguish between what would be called re-emission and the original surface emission as radiative transfer is radiative transfer. What I find is that 70% of the power amount emitted at the surface makes it to the 70km mark. By that time, one starts to see other problems potentially begin to emerge, like the loss of local thermodynamic equilibrium.
from your computer model then, do we have 50 days to save the world, or can catastrophe be postponed until next year?
70%, 41% 17% radiation are all figures from different math flowcharts of energy budgets. Radiation from earth is calculated by adding the amount radiated into the atmosphere from earth to the amount radiated durectly into space then dividing it by the percentage reflected from earth and clouds to give 41% in the case of NASA’s flowchart.
These are math equations that don’t simulate what happens. In fact there are many wildly different math results for radiation according to different stories/simulations. If it were a real number it would be easy to measure by virtue of measurement of objective reality and we’d all be able to use it. Normal temperature matter at earth equilibrium doesn’t give off that much radiation. Its a figure generated to balance the mathbooks or energy budget ledger. 99% heat leaves by evaporation and convection – whilst that puts radiation at 1%, of this 1%, c02 intervenes with less than 8%, although most normal matter in equilibrium gives off little radiation anyway. It needs to be understood that the radiation something gives off is a function of its temperature and nothing else.
cba says:
The term “adjusted radiative forcing” is the standard terminology. See, for example, http://books.nap.edu/catalog.php?record_id=11175 for a lot more discussion on radiative forcings (which I have only briefly glanced at myself).
Yes…I was talking about original surface emission that has escaped from through the atmosphere without being absorbed at all. If you look at Kiehl and Trenberth’s diagram ( http://www.windows.ucar.edu/earth/Atmosphere/images/radiation_budget_kiehl_trenberth_2008_big.jpg ), you see that about 60% of the surface radiation eventually makes it out of the atmosphere when one includes absorption and re-emission within the atmosphere. I am not sure where you are getting 70% from; it is true that this escaping IR radiation is ~70% of the incoming solar radiation (although, since we have radiative balance to a good approximation, this is really just equivalent to saying that the earth system’s albedo is ~30%).
P Wilson: I think it goes without saying that you continue to spout utter and complete nonsense here. The split in energy leaving the earth’s surface is that ~4% leaves via thermals, ~16% via evapotranspiration, and ~80% via radiation, as Kiehl and Trenberth’s diagram shows. And, it is simply wrong to claim that there is no observational evidence to support these numbers. There are lots of measurements of radiation…and even the evapotranspiration number can be obtained simply by knowing the latent heat associated with the phase change from liquid to vapor (and vice versa) along with the average amount of precipitation (or, equivalently, the average amount of evaporation) over the surface of the earth.
Joel
*real* measurements of radiation!
please link to them