How Radiative Forcing Decreases Static Stability

Implications for the efficiency of earth radiance.

Background

In the most recent posts, I shared using the Column Radiation Model (CRM) on atmospheric data from the Climate Forecast System (CFS) in order to reproduce the Radiative Forcing (RF) estimates used by the IPCC and to run that same calculation on the one degree CFS data. I came to the realization that RF represents a what if scenario and it occurs to me that further ‘What Ifs’ are applicable. Namely what if:

  • 2xCO2, Instantaneous – the given profiles with 2x preindustrial CO2.
  • 2xCO2, Strat Adjusted – 2x CO2 and stratospheric temperatures reduced until the stratospheric cooling rates approach zero ( the so called ‘adjusted’ forcing )
  • 2xCO2, Strat Adjusted, Trop Humidified – 2x CO2, adjusted, tropospheric temperatures unchanged, tropospheric humidities uniformly increased as for constant relative humidity of a 2.4C increased temperature
  • 2xCO2, Strat Adjusted, Trop Warmed – 2x CO2, adjusted, tropospheric temperatures uniformly increased 2.4C but humidities unchanged
  • 2xCO2, Strat Adjusted, Trop Warmed and Humidified – 2x CO2, adjusted, tropospheric temperatures uniformly increased 2.4C and tropospheric humidities uniformly increased as constant relative humidity

The scenarios applied below are for March 21, 2010, at 00Z. The results for other dates are similar.

Results

The results below include the RF, averaged by pressure level and latitude band,  in the left column. The RF is the difference from the baseline preindustrial CO2 scenario of the net of the upward and downward, longwave and shortwave radiative fluxes. The IPCC definition of RF is the difference of fluxes at the tropopause. The average tropopause height is indicated on the plots of RF as is the 600 millibar level. The spatially weighted mean of the midpoint between the tropopause and surface for this data is 592 millibars, so the 600 millibar level roughly defines the middle of the troposphere.

The layer RF is depicted for each scenario in the right column. The layer RF of the Upper Troposphere as a result of the scenario, is the RF at the tropopause level minus the RF at the 600 millibar level, and the layer RF of the Lower Troposphere, including flux at the surface, is the RF at the 600 millibar level.

  Net Radiance Upper & Lower RF

2xCO2,
Instantaneous



2xCO2,
Strat Adjusted



2xCO2,
Strat Adjusted,
Trop Humidifed



2xCO2,
Strat Adjusted,
Trop Warmed



2xCO2,
Strat Adjusted,
Trop Warmed,
& Trop Humidified



The results indicate two important features:

  1. for large regions of all cases, the layer RF of the upper troposphere is less than the layer RF of the lower troposphere
  2. for the cases of 2xCO2 with increased temperature and/or humidity, the upper troposphere retains less energy in absolute terms, that is there is implied cooling of the upper troposphere with warming in the lower troposphere.

The principle of RF implies warming of the troposphere as a whole because energy is retained as sampled at the tropopause. But by splitting the troposphere in two, we can see that most of the RF is imposed by the lower troposphere. This implies a reduction in the ‘static stability’ for the global mean, and an increase in the convective transport of energy from the lower to upper troposphere. Convection does not transport energy to space, but can transport energy higher within the troposphere where reduced average ambient water vapor means less obstructed emission to space relative to the lower levels.

Assumptions and Conditions

Bear in mind that this exercise assumes:

  • Uniformity of warming, humidifying – uniformity is arbitrary, but an illustrative test case
  • Static atmosphere – this is not a gcm but simply radiative calculations for the given atmosphere. The real dynamic atmosphere will respond to forcing and could produce very different cloud, temperature and humidity profiles.
  • Warming and humidifying of the upper troposphere theorized to occur with increased CO2 occur, of course, because of the very convection implied by the diferential RF.
  • The definition of the layer RF of the lower troposphere includes the net RF change at the surface level. This assumes the majority of surface flux returns to the lower troposphere in the form of sensible and latent heat convected from surface to lower troposphere.

Main Points

The two points I wish to emphasize again are:

  • The Radiative Forcing from increased CO2 appears to reduce static stability of the troposphere which implies a greater convective transport of energy from lower troposphere to upper troposphere.
  • The effect of warming and/or humidifying the troposphere appears to make the upper troposphere more effective at radiating energy to space.

Of course, these processes are included in great detail in the numerous general circulation models. But this exercise serves as a reminder that in addition to the effects of infrared obscurants, the net radiance from earth to space is in part determined by the motion of the atmosphere.

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5 Responses to How Radiative Forcing Decreases Static Stability

  1. Ron Graf says:

    Eddie, nice job, very clear and succinct. It is the feeling of some others and myself that the GCMs may be underestimating the degree of increased radiative efficiency in feedback the tropical daylight, or in tropical storms. These brief and concentrated atmospheric heat emissions may not fit well in the GCM 60sq km grid points, even with parameter corrections. Also with the troposphere being thicker in the tropics there may be an advantage of increased convection, aided by cloud condensation at heights that are still well below the effective radiative heights for 12um wavelength radiation, the band most enhanced by CO2 pressure. Thus the positive effect of CO2’s aid in convection perhaps more than offsets its tropopause insulating effect in special cases.

    Another possible area of interest is what happens to 2XCO2’s delta RF of the TOA in high noon sunlight until late afternoon. It seems plausible that while CO2’s warming effects are well understood because they occur in the relative stability of night and polar regions but the feedbacks against solar forcing and convection responses are less understood or appreciated.

    Do you have any familiarity with Entropy flux density at the TOA? There is unquestionably positive delta entropy in a situation when the highly vectored solar photon gas is being scattered, absorbed and remitted enumerable times before leaving the atmosphere in all directions, the thinner the layer of effective height, the more omnidirectional the outgoing photon gas. One must remember that increased entropy is outgoing energy just as heat is.

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  2. I think you may be of a different opinion but what else is new when it comes to the climate. Time will tell but how long does one have to wait before the realization comes that what AGW theory is calling for is not taking place?

    This is the data ,this is what it shows, and the evidence for what it shows as most likely being correct when contrasted to AGW theory.

    http://www.sciencemag.org/content/337/6096/809.summary

    Below , is a quote from the article, NASA satellite data shows a decline in water vapor.

    The quote is radiosonde data shows that upper atmosphere water vapor declines with warming.

    Now data from the Patriot Post Article called, Evidence That Demands a Verdict shows quite clearly two items of data of importance one being there has been no warming in the tropical atmosphere at the 12km level or 18 km level and that all the deviations in the upper tropical troposphere atmosphere temperatures are correlated with the temperature in Nino region 3.4.

    Data also showing thus far no lower tropospheric hot spot has materialized.

    What the data is saying if one tries to incorporate all of this, is first of all it appears that the temperature in the tropical troposphere is correlated to ENSO. When ENSO in in an El Nino phase the temperature in the tropical troposphere increases and vice versa with no long term change in the temperature of the tropical troposphere overall. In addition radiosonde data is indicating that water vapor concentrations are inversely correlated with the temperature of the atmosphere and from the article I posted it said one of the ways in which water vapor may get into the stratosphere outside of the tropics is via convection. Then in addition, with data still showing no tropical tropospheric hot spot here are the objective conclusions that have to be drawn based upon the data.

    The conclusions I take away from all of this is first the temperature of the tropical troposphere is controlled by ENSO not CO2 and that the concentrations of water vapor irrespective of if water vapor is or is not inversely correlated to the temperature of the upper atmosphere is going to be tied to ENSO, not CO2.
    In addition it looks like sea surface temperatures(PDO) /convection may have much to do with the amounts of water vapor which eventually reach the stratosphere all of which destroy AGW theory which said the amounts of water vapor which will reside in the tropical troposphere will be DIRECTLY tied into the strong positive feedback between CO2 and water vapor which would result in two distinct trends developing in the tropical troposphere which would be a steady increase in water vapor which would be in tandem with a steady increasing temperature trend in the tropical troposphere which would be more pronounced with altitude relative to the lower levels, and that this steady increase in water vapor /temperature trend which would be evolving would cause a tropical tropospheric hot spot to evolve, due to an ever increasing negative lapse rate.

    Data however shows no such negative lapse rate trend evolving and no correlation between CO2 and the tropical tropospheric temperature profile, nor no correlation with CO2 and tropical troposphere water vapor profile. Instead data shows the temperature and water vapor characteristics of the tropical troposphere seem to be correlated with ENSO ,and indicate in the case of water vapor (according to radiosonde data) an inverse relationship to temperature all things being equal, but this could be obscured by convection changes in the tropics due to sea surface temperature changes and atmospheric circulation changes all of which AGW theory does not address to any degree whatsoever when it comes to the temperature profile and water vapor profile of the tropical troposphere.

    In conclusion not only does the resultant tropical hot spot as called for by AGW theory not appear but data shows in addition the reasons why it does not appear are because it is not CO2 which governs how the tropical tropospheric temperature/water vapor profile may evolve but rather it is ENSO phases and sea surface temperature changes (PDO phases) along with convection changes in the tropics due to atmospheric circulation changes, that govern the tropical troposphere temperature/water vapor profile.

    This all showing that the central theme of AGW theory which is a strong positive feedback between CO2 and water vapor resulting in a tropical tropospheric temperature/water vapor profile which would give rise to a tropical hot spot is flawed. Hence the theory is flawed

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    • Well, I tend to agree that the missing hot spot is significant and indicates what’s been known all along – atmospheric motions, which determine the distribution of heat and humidity within the atmosphere, are not predictable beyond a few days. Imagining ( though not actually modeling ) the instability imposed by CO2 and H2O in these scenarios leads me to believe that motions will oppose the water vapor feedback. And to this date, the temperature trends do indicate warming, but closer to the theorized CO2 forcing alone than to CO2 plus H2O.

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  3. Hello, TE! Landed on your web site to find out what Steve Mosher was talking about when he demanded a yes or no answer from you. If he had not been a co-author of a book about the hockey stick I would totally ignore him because he has yet to produce any coherent comments. I see that you regard radiative forcing as a what-if, along with five other what-ifs involving doubled CO2. I have to tell you that any what-if that involves doubling, tripling, or even quadrupling of CO2 is simply a what-not. This may be a shock to you because you have not been taught the relevant science. Start with greenhouse gases in the atmosphere. As a percentage of total atmospheric greenhouse gas amount, water vapor makes up 95 percent of it and carbon dioxide only 3 percent. (I get that from Tim Ball.) But the Arrhenius greenhouse theory used by the IPCC uses only carbon dioxide to make predictions. This leaves the innfluence of 95 percent of atmospheric greenhouse gases totally unknown and unaccounted for. Right there is one reason to distrust all their climate models that have been written since Hansen first introduced them. All the models have been dead wrong but the program has been kept alive and is used to feed misinformation to politicians. IPCC has taken advantage of this absence of water vapor in the Arrhenius and claims, without any scientific backing, that water vapor increases the amount of greenhouse warming produced by carbon dioxide alone. But there is another greenhouse theory that actually does make use of both carbon dioxide and atmospheric water vapor. It is MGT, the Miskolczi greenhouse theory, that came out in 2007 [1]. It was immediately rejected by IPCC as soon as they found out what was in it. According to MGT, carbon dioxide and water vapor in the atmosphere create a joint optimal absorption window in the infrared whose optical thickness is 1.87. If you now add carbon dioxide to the atmosphere it will start to absorb in the IR, just as Arrhenius says. But this will increase the optical thickness. And as soon as this happens, water vapor will start to diminish, rain out, and the original optical thickness of the window is restored. The added carbon dioxide will of course keep absorbing but the reduction of water vapor has reduced total absorptivity to the background level and no greenhouse warming is possible. An observer will notice from the side that carbon dioxide keeps increasing but there is no parallel increase of atmosapheric temperature. That is because reduction of water vapor has suppressed the greenhouse warming that Arrhenius theory predicts. And that is exactly what is happening to us now, and has been happening for the last 18-plus years: atmospheric carbon dioxide steadily increases but global temperature does not. This pause or stand-still of global warming has been given the name “hiatus” in the hope that it is temporary. I am afraid it is not temporary but permanent. You know of course that the greenhouse warming that Arrhenius predicts is used as a justification for spending trillions to stop warming. This is actually amazing conbsidering that it has never been experimentally verified. Hansen knew that and attempted to verify it by presenting a 100 year warming curve to the U.S. Senate in 1988. Checking his curve I found that it did not have 100 years of warming in it. All those trillions pledged to eliminate global warming are just down the drain because there is no warming to stop. If this sounds over the top, consider this: the Keeling curve that records the the amount of carbon dioxide in the air absolutely refuses to follow the increase and decrease of observed global temperature changes. And this goes back as far as we have records of. And same with its extension by ice cores from Antarctica. The existence of the hiatus is sufficient of and by itself to invalidate the Arrhenius greenhouse theory and to deny that any greenhouse warming exists. Global warming advocates are well aware of this and that is why they claim that the hiatus does not exist. This was announced in a paper in Science by Karl et al. last year. More conscionable climate scientists then came out with a new paper by Fife et al. in Nature Climate Change and proved that Karl et al. are wrong. There the matter rests now. I have provided the information you need to make up your own mind about it.

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