Here we get into the nitty-gritty (as much as we can) of the energy coming off the planet. Looking at the spectrum of outgoing infrared we can learn a lot from the Nimbus data. In the graph below we can see a lot more energy comes from certain wavelengths, and given that the curve would follow the “grey” shape if it was a single body emitting, we can also see how some “pipes” are blocked.
The CO2 band shows a large obvious indentation, but don’t be fooled, most of that curve looks the same at much lower concentrations of CO2. As CO2 levels rise in our atmosphere there is little effect on the radiance of the coldest parts of the CO2 band, what changes is in the “wings”.
The hotter a thing is, the more energy it radiates, so in this graph the higher amounts of OLR (outgoing longwave radiation) are coming off the warmer surface or air closer to it. Turn things upside down in your mind, the high readings come from low-altitude places which are warm (like the surface), and as the readings get lower in radiance, they must be coming from colder spots at higher altitudes. The lowest part of the CO2 absorption band in the graph is in the stratosphere, where it’s very cold. The highest parts of the CO2 band in the graph are from CO2 low in the atmosphere. The “wings” represent emissions from CO2 all the way up and down the vertical air column.
…
In terms of “pipes” David has managed to estimate the comparative sizes of different pipes, with a table I haven’t seen elsewhere — which I’ve graphed here. (Though we expect the IPCC crew would have done this ).
This graphic below is roughly the size and height of the emissions escaping to space. (The CO2 height is the height of its “average” emitting temperature, which is not that useful, as most of the emissions are coming from lower down and further up rather than at the “average”. We don’t use that height in the analysis that follows.) See below how David calculated this and all his references. I’m surprised at how big the CO2 pipe is. A similar amount of energy is coming off CO2 molecules as is radiating from cloud tops or from the surface?
Don’t miss David’s figure 1 below, which is an important graph we will need to refer too. Those emission layers matter!
–Jo
A rough idea of how much energy is escaping through each pipe, and the average altitudes that the emissions come from. (Note that in the case of CO2 the average emission temperature is about 244 K, which corresponds to a height of 7 km in the troposphere, although the CO2 emissions layer is largely well over 20 km in the stratosphere.)
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14. Emission Layer Parameters
Dr David Evans, 21 October 2015, David Evans’ Basic Climate Models Home, Intro, Previous, Next, Nomenclature.
We are going to add a model of outgoing longwave radiation (OLR) to the sum-of-warmings model we completed in the last post. However before we can construct the OLR model we need some basic information about OLR — such as how much OLR comes from each emission layer. In this post we collect that information from various sources.
Introduction
We described how the greenhouse effect works in post 6, where we discussed emission layers and pipes. Most OLR is emitted by the four main emission layers — the CO2 emissions layer, the water vapor emission layer (WVEL), the cloud tops, and the surface. Nearly all OLR is emitted by the main four emission layers plus the ozone and methane emission layers, so in this post we are going to collect parameters on those six emission layers.
We are only concerned here with the average OLR, heights, and temperatures for each emission layer — averaged over area, time of day, time of year, and applicable wavelengths. What follows in this blog series is not terribly sensitive to these emission layer parameters, so we are a bit approximate. Several parameter values were estimated from ratios of areas on Nimbus spectra diagrams (such as Fig. 2 below). Overlaps in emission wavelengths were ignored when partitioning the Nimbus spectra between emission layers (at a given wavelength, the highest emission layer should apply). We assume that all the OLR comes from the main six emission layers.
We speak of “the emission layer” of a gas as its average, but bear in mind that the notion of the height of an emissions layer can be further refined to depend on wavelength. Viewed as wavelength-dependent, the CO2 emission layer descends from the lower stratosphere to the surface in the wide wings around 15 μm, because at wavelengths further away from an absorption line it takes a greater amount of CO2 to achieve a certain probability of absorption — see the Nimbus spectra, such as in Fig. 2 below, and note the sloping walls of the well centered on 15 μm as the temperature climbs (“the wings”). While some OLR comes from far below the emission layer (some emitted photons get lucky and escape to space despite long odds), and some from far above the emission layer (where the odds of a photon emitted upwards escaping to space are high), on average the emissions occur at about the height of the emissions layer, whose temperature and thus height we can estimate. Interestingly most of the significant changes in the emission spectrum due to increased CO2 occur in the wings of the 15 μm well, in emissions from the troposphere — see the last diagram on this page of the Barrett-Bellamy website.
Figure 1: The four main emission layers and their OLR. Most of the Earth’s OLR is emitted to space through the four pipes shown, where “pipe” is shorthand for the electromagnetic wavelengths at which a type of molecule absorbs and emits, and the associated emissions layer. (The CO2 emissions layer around the center of its blockage at 15 μm is in the lower stratosphere. But averaging by wavelength across the whole CO2 blockage gives an average temperature of about 244 K, corresponding to a height around 7 km. This is in the wings of the blockage, which also happens to be where the main changes due to increasing CO2 are occurring. Hence this depiction.)
The Parameters
| Emission Layer | Symbol subscript | Average Temperature | Average Height | Clear Sky OLR | Overcast Sky OLR | All Sky OLR |
| Units | K | km | W m−2 | W m−2 | W m−2 | |
| Symbol | i | Ti | hi | Ri | ||
| CO2 | C | 244 1 | 7 | 48 7 | 48 8 | 48 |
| Surface 9 | S | 288 | 0 | 119 7 | 0 8 | 45 9 |
| Cloud tops | U | 267 | 3.3 2 | 0 | 77 8 | 48 9 |
| Water vapor | W | 236 3 | 8 | 79 7 | 79 8 | 79 |
| Ozone | Z | > 15 | 14 7 | 14 8 | 14 | |
| Methane | M | 268 10 | 3 | 5 7 | 5 8 | 5 |
| Average or total | 255 4 | 4.8 | 265 6 | 223 | 239 6 |
Table 1: Parameters of the OLR emission layers. Superscripts refer to the notes below. Blue cells are calculated from average temperature or height using a lapse rate of 6.5 °C per km and a surface temperature of 288 K. Orange cells were calculated from clear and overcast skies using a cloud fraction of 62% (note 5).
Notes:
- The temperature at the base of the CO2 indentation/well/blockage in the Nimbus clear sky emission spectrum (Fig. 2) from 14.4 to 15.8 μm is ~215 K, consistent with emissions from the lower stratosphere. However the emissions from the “wings” of the indentation come from lower in the atmosphere, reaching close to the surface at 13 μm and 18 μm. The average temperature, formed by weighting the temperature at each frequency by the radiance of emission in the tropical Pacific Ocean Nimbus spectrum (surface temperature ~295 K) (Glickstein 2011 [1]), is approximately 244 K — this temperature and the corresponding height is not used in the calculations here; it is included only for completeness.
- The cloud-top height is from the study by Davies and Molloy in 2012 [2]. Roger Davies (personal communications, 2014) explained that the value depends on measurement technique and definition, such as whether very thin clouds are included.
- The WVEL temperature is estimated from 18 to 25 μm of the tropical Pacific Ocean Nimbus clear sky emission spectrum. The jaggedness of this part of the spectrum may arise from a combination of surface and narrow water-vapor emission bands. The temperature is presumably a mean of surface and WVEL temperatures, but the contribution from each layer is uncertain because of insufficient instrumental resolution in wavelength. The spectrum cools as wavelength increases beyond 25 μm: for instance a MODTRAN simulated emission spectra (Barrett) decreases to 220 K at a wavelength of 67 μm. Accordingly the WVEL temperature is more than 220 K but less than 260 K. The average WVEL temperature is taken here as 236 K, the minimum temperature (at ~24 μm) in the Nimbus spectra in wavelengths over 18 μm.
- The mean temperature of the emission layers is the Earth’s radiating temperature, namely 255 K.
- Kiehl and Trenberth 1997 [3], hereafter KT97, give the cloud fraction as 62% on p.200. Their model consists of randomly overlapped low clouds (1 – 2 km) covering 49%, midlevel clouds (5 – 6 km) covering 6%, and high clouds (10 – 11 km) covering 20% of the surface.
- KT97 (Table 2) gives the clear-sky OLR as 265 W m−2 and the all-sky OLR as 235 W m−2. Trenberth, Fasullo, and Kiehl (2009) [4] updated the all-sky OLR to 239 W m−2.
- Using the average of the areas under the Nimbus spectrum for the tropical Pacific Ocean (Fig. 7) (clear, daytime, surface temperature ~295 K) and the Niger Valley (clear, daytime, surface temperature adjusted down from 320 K to an assumed nighttime temperature of 300 K) below 25 μm, and the MODTRAN curve (note 3) above 25 μm, the ratios of OLR from CO2 emissions (taken to be 13–18 μm) to OLR from the surface (10–13 μm and 8.0–9.3 μm) to OLR from water vapor emissions (18–67 μm and 6.6–7.5 μm but not more than 236 K (see note 3)) to OLR from ozone (9.3–10 μm) to OLR from methane (7.5–8.0 μm) were estimated, then used to partition the total clear sky OLR in those ratios. Both surface temperatures in the Nimbus spectra were a little higher than the global mean of 288 K, so the surface OLR will be a little high by this method. See also note 9.
- Because the OLR from the CO2 emission layer depends only on the layer’s temperature, the clear-sky and overcast emissions are the same. Similarly for the water vapor, ozone, and methane emission layers. We follow KT97 in assuming the OLR from the surface is zero in overcast skies. Thus the difference in total OLR between clear and overcast skies is the same as the difference between OLR from the surface and the cloud tops.
- KT97 (p.206) give the OLR in the atmospheric window as 99 W m−2 under clear skies (so that OLR must originate near the surface), and 80 W m−2 under all-sky (so 38 W m−2 from near the surface under clear sky, and the remaining 42 W m−2 from cloud tops). Costa & Shine (2012) [5] show that the KT97’s clear sky OLR of 99 W m−2 consists of 66 W m−2 from the surface itself and the rest from the water-vapor continuum near the surface. However, “surface” may conveniently be taken to include the near surface because the two layers undergo the same temperature changes and because the water-vapor continuum emission altitude is determined chiefly by pressure and is invariant. Finally, KT97 take the atmospheric window as 8–12 μm, but in the Nimbus diagrams it appears to be 8–13 μm. The OLR figures from the surface and clouds tops here are a little higher, presumably due to including the OLR in 12–13 μm.
- The methane temperature is from the tropical Pacific Ocean Nimbus clear sky emission spectra 7.5–8.0 μm (Fig. 2).
The energy budget diagram in KT97 (their Fig. 7) labels 40 W m−2 of OLR as “Atmospheric Window”, and shows another 30 W m−2 of OLR coming from clouds (in contrast to 165 W m−2 of the OLR from clear air). Their 40 W m−2 is all-sky OLR from 8 to 12 μm from the surface; here it is 45 W m−2 because it is for 8 to 13 μm. Their 30 W m−2 is total clear-sky OLR minus all-sky (KT97 p. 201); here it is 34 W m−2 because we updated the total all-sky OLR from 235 to 239 W m−2 in line with Trenberth, Fasullo, and Kiehl 2009 [4].
Figure 2: The Nimbus emission spectrum over the tropical Pacific Ocean, partitioned approximately into emissions from various layers, ignoring overlaps. Dashed curves represent blackbody radiances at the indicated temperatures in Kelvin. From Petty 2006 [6] Fig. 6.6, via Kaempfer 2011 [7] and Glickstein 2011 [1].
REFERENCES
[1^] Glickstein, I. (2011, March 10). Visualizing the “Greenhouse Effect” – Emission Spectra. Retrieved Aug 28, 2014, from Watts Up With That?: http://wattsupwiththat.com/2011/03/10/visualizing-the-greenhouse-effect-emission-spectra/
[2^] Davies, R., & Molloy, M. (2012). Global cloud height fluctuations measured by MISR on Terra from 2000 to 2010. Geophysical Research Letters, L03701.
[3^] Kiehl, J. T., & Trenberth, K. E. (1997). Earth’s Annual Global Mean Energy Budget. Bulletin of the American Meteorological Society, 198 – 208.
[4^] Trenberth, K. E., Fasullo, J. T., & Kiehl, J. (2009). Earth’s Global Energy Budget. Bulletin of the American Meteorological Society, March, p. 311.
[5^] Costa, S. M., & Shine, K. P. (2012). Outgoing Longwave Radiation due to Directly Transmitted Surface Emission. American Meteorological Society.
[6^] Petty, G. W. (2006). A First Course in Atmospheric Radiation, 2nd Edition. Sundog Publishing.
[7^] Kaempfer, N. (2011, May 24). Atmospheric Physics Remote Sensing. Retrieved October 15, 2014, from IAP Microwave Physics, University of Bern: http://www.iapmw.unibe.ch/teaching/vorlesungen/atmosphaerenphysik/FS_2011/AT_FS11_Remote_sensing_1_handout.pdf
Thanks, Now I see why you chose the analogy of “pipes” for portals of CO2, H20 vapour, Methane, Ozone and Surface etc.
The Radiance x Wavelength view draws its own design.
Another nail in the coffin for…
db..
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Glad to see that you confirmed the 66 W/m2 for the surface “window” rather than 40 W/m2 (my post https://cementafriend.wordpress.com/2015/09/25/radiation-window/)
However, you said you did not take into consideration radiation absorption/emission overlap. This makes the so called CO2 and CH4 pipes too large and the water vapor pipe too small. Another thing is the cloud top radiation from water drops and ice particles. The emissivity water is around 0.95 and it radiates at all wavelengths including that around 15 micron for CO2 and that around 7.5-8.0 micron for CH4 (ie temperatures from about 230K to 380K. Ice has an emissivity around 0.7 (over all wavelengths from 200K to 273K) ie the water drops and ice particles in clouds further reduce the “pipe” size of CO2 and CH4. I suggest that you need for completeness to halve the latter.
411
cementafriend, ignoring overlaps made it far simpler. To do this exercise really precisely would be difficult. Where there is an overlap, the physically-higher emissions layer is the relevant one, because emissions from lower than that tend to be absorbed without making it to space. At most wavelengths, the CO2 emissions layer overlies the others (except ozone).
60
Ah, my old friend stratospheric ozone again.
https://climategrog.files.wordpress.com/2014/04/uah_tls_365d.png
https://climategrog.wordpress.com/?attachment_id=902
The real cause of the late 20th c. warming IMO.
Please don’t try to draw a straight line “trend” through ozone variations and blame it on CFCs.
40
Greg, ozone seems to me to be a lot more likely involved with recent global warming than CO2. This will be developed later in the series.
Also, http://joannenova.com.au/2015/01/is-the-sun-driving-ozone-and-changing-the-climate/
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Greg, you might find this of interest:
http://www.newclimatemodel.com/must-read-co2-or-sun-which-one-really-controls-earths-surface-temperatures/
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Well I’m glad that agree the straight line trend does not well represent the evolution of TLS over the record but the following comment is quite presumptuous and wrong.
Stating something is the ” only reasonable conclusion ” is usually a lazy way of saying you have not spent long looking but you’re sure you are right anyway.
Also for your fig8 you should note ( as I pointed out in David’s last installment ) that you can not add temperatures, so your TTS has no physical meaning.
I beg to differ on that. In terms of TLS they clearly do. After the initial blip, that mainstream recognises, there is a clear 0.5K drop in TLS after each of the two major events.
At least we are agreed that there is no CO2 signal there as AGW says there should be. Like the missing tropical tropospheric hot-spot, it is evidence that the “efficacy” of CO2 radiative forcing is negligible.
08
That argument is legitimate for determining the emission temperature but I don’t think you can ignore it when talking about pipes.
If you have a narrow section of ‘pipe’ before a large one, it will still affect the overall flow rate as much as if it came later.
It does not matter in which order you connect resistors !
02
Greg, in the analogy (as I’ve been using it!) pipes only go to space, so they cannot be in series.
30
Dr D. Evans:
I was commenting on you reply to clement. If there is spectral overlap with one layer above the other as you suggest they are in series, regardless of where they go.
If you want hopepipe analogies, it makes no difference if the water goes into a big hole in the ground afterwards.
00
Greg,
David’s description does not require emissions heights to be rigidly stratified one above another.
My view is that the locations of radiative emissions to space, from all available heights, and in three dimensions, constantly form and dissipate all the time as they follow the density variations caused by ever changing convective adjustments.
All radiative materials from surface to top of atmosphere operate in parallel and density variations are always being adjusted by convection to allow out exactly as much as comes in subject to inevitable variations about the mean during the time required for the convective adjustments to take effect.
Those variations about the mean manifest themselves as turbulence at the tropopause rather than a rise in surface temperature as I expect you will understand when Jo gets around to fitting my relevant article into her busy publication schedule.
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I look forward to reading what you present.
For the moment I’m trying to point out any flaws that I see in David’s developing model so that he can address them and hopefully avoid getting shot down for inconsistencies in his model.
If he wants to suggest that it is the higher altitude molecule that dominate because they absorb and re-emit what comes from lower down the processes ( pipes, resistors ) are in series.
20
I am sure David welcomes constructive comments and will amend his thesis if necessary.
I think he is suggesting that it is the higher molecules that dominate within each pipe and not that higher molecules dominate from pipe to pipe. That much seems clear from the fact that each pipe has a different emissions height and in any event the pipes are a broad brush concept to aid understanding of the basic concept.
Therefore, the pipes are in parallel and not in series.
50
I agree with the separate pipes being in parallel and this seems to be basic model. If the pipes are spectraly independent there is no problem with that.
The distinction here is that he and clement were discussing spectral overlap. In which case there is both spectral and spacial overlap and the pipes cannot simply be regarded as indpendent.
David specificall said that the higher one is the one which matters since it will absorb and re-radiate anything happending below.
Clearly that is not two parallel, independent processes. One feeds the other: ie in series.
30
Stephen Wilde October 22, 2015 at 9:12 am
‘I am sure David welcomes constructive comments and will amend his thesis if necessary. Therefore, the pipes are in parallel and not in series.’
Within the CO2 pipe only the 14.5-15.5 micron exitance is from CO2 at 210K 12kPa altitude.
The wing exitance is from combination Co2,and H2O (vapor and condensate) from a higher pressure altitude. Most of the exitance in the CO2 pipe is still from H20.
Barrett-Bellamy website Charts are intentionally misleading. At 10kPa CO2 has only three significant narrow lines at 15 microns, 661.1,662.8,664.2; wave-numbers. and another 9 minor ones all between 660 and 665 wave-numbers. All CO2 effects become non-relevent to temperature above 200 ppmv.
15
David: I suspect your results are biased slightly because you are looking at data from the tropics, where the surface is warmer, humidity higher and 100% relative humidity. So the KT value of 40 W/m2 through the atmospheric window ma be correct globally and you may be correct “tropically”.
I was a little surprised to see the water vapor emission level higher than CO2. If I use the “look down” feature of online MODTRAN and gradually raise the look down from altitude, the intensity of OLR stops changing at wavelengths emitted by water vapor about 10 km, but OLR emitted by CO2 continue to change well above 10 km. In both cases, the behavior of the strongest lines is most visible. The behavior of the average emission could be somewhat different, but the central region of the CO2 band (14-16 um) clearly comes from higher than any water vapor emission. And the strongest CO2 line has a brightness temperature of about 245 degK or about 35 km. This is similar to Gai’s info from Happer (47 km or 270 degK), but MODTRAN doesn’t show anything above 245 degK – possibly due to insufficient resolution.
So far, I’m not aware of any reason why any of these details should make a big difference. I’m not sure how one would obtain the best possible answer. The details changes at different latitudes, seasons and even at different wavelengths of one transition (the center and shoulders).
20
Frank: I used the tropical ocean and Niger valley Nimbus spectra for estimating some emissions temperatures, and the former for ratio-ing areas under the spectrum. Yes, that will lead to a tropical bias. Otherwise most of the figures are global, where possible. Also ignoring NOx etc. might skew things slightly.
As pointed out in the caption to Fig. 1 and in note 1, the “height” of the CO2 is a kludge that has no bearing on the analysis beyond pictorial. It is just the tropospheric height corresponding to the “average” temperature, averaging from 13 to 18 microns of actual CO2 emissions — but CO2 blockage is mainly from the stratosphere, which has little impact on the average temperature. Portraying the average CO2EL height at 7 km does have the benefit of happening to be be about where the most significant spectral changes are occurring (see the Barrett-Bellamy figure — last diagram here), so it has some merit, but please do not read too much into it.
“the intensity of OLR stops changing at wavelengths emitted by water vapor about 10 km”. Thanks, that’s good to know. Given the up and down random motion of the water vapor, and the range of heights at any instant from which wv is emitting OLR, that supports the notion of an average WVEL height around 8 km.
“but OLR emitted by CO2 continue to change well above 10 km”. I believe the OLR from the central line at 15 microns comes from about 40 – 50 km. It is so high that the stratosphere there is significantly warmer than at the tropopause — see the spike up in the Nimbus spectrum right at 15 microns, which suggests a temperature of about 232 K. Ozone has one too.
“And the strongest CO2 line has a brightness temperature of about 245 degK or about 35 km.” Ok, your MODTRAN simulation has higher frequency resolution than the Nimbus spectrum, so presumably if Nimbus had better resolution the spike at 15 microns would extend up to 245 K or more.
I was surprised this data didn’t already exist in tabular form; I searched all the obvious places I could think of on the Web. No readers here have suggested a source for the figures. I presume that if the method that follows proves of interest, these results can be refined. Presumably this means no one has systematically gone after emission layer properties before, in an averaged sense, suitable for a basic model?
Yes, none of these details are going to matter hugely for what follows, because their uncertainty is going to get swamped by something else.
00
David: If it isn’t clear, the results I am discussing come from the free online MODTRAN calculator. It CALCULATES the radiation intensity and brightness temperature you would observe looking down (or up) from any altitude. The default altitude is 70 km – the TOA. It takes only a few minutes look down from 1, 2, 3, … km and discover at what altitude an particular wavelength is effectively transparent. You also get the brightness temperature and a graph of altitude vs temperature. In the “about this model”, the have an overlay of calculated and Nimbus data and you can see that the calculation has higher wavelength resolution than the detector on Nimbus.
http://climatemodels.uchicago.edu/modtran/
More sophisticated tools exist at Spectralcalc, but many of them require a subscription.
http://www.spectralcalc.com/info/about.php
30
This chart seem to indicate that CO2 doesn’t start emitting until something like 12-15km.
http://postimg.org/image/t0kc6y71r/
210
Dr Happer found that experimental data shows CO2 emitting barely any radiation at 11 KM and that radiating is mainly in the stratosphere ~ 47 KM above the surface.
The other take away from Dr Happer’s 2014 UNC lecture was the CO2 ‘modeling’ is a mish-mash of theoretical equations and experimentally derived data. Where the Climate alarmists missed the boat is in using equations for ‘line broadening’ aka the ‘wings’ where the additional CO2 absorption ( at 400 ppm) is supposedly taking place. These equations produce results that do not match up to the experimental data. The lines are not as broad as theory would have it.
http://www2.sunysuffolk.edu/mandias/global_warming/images/stratospheric_cooling.jpg
The legend with the illustration:
The slides and Audio from the UNC Physics lecture plus a video geared towards a lay audience
http://www.sealevel.info/Happer_UNC_2014-09-08/
Slides 16, 22, 42, 43 and 44 are the critical slides.
30
Gai, it certainly would be interesting if the CO2 data used by the establishment is seriously inaccurate.
For this series we are going with the establishment story on CO2, principally that each doubling of CO2 reduces OLR from CO2 molecules by about 3.7 W/m2.The figures I presented above in the post are all from establishment sources, btw.
20
Dr Evans if you wish to contact Dr Happer I can possible get you in touch with him via David Burton who put up an audio video and slides (and dragged me to the lecture). David has his e-mail address.
00
Thanks Gai, we’ve emailed before (different matter).
Challenging the CO2 figures is a different project from re-architecting, so there is no use for better CO2 figures right here and now. However it would be hilarious if the CO2 numbers were quite wrong too.
40
AndyG55 October 21, 2015 at 5:04 pm
Your chart is very misleading there is stratospheric CO2 with the temperature of the stratosphere. Horizontal path lengths there are 400km, enough for an optical depth for the tiny b1t of CO2 still at 400ppmv of 3kPa. This is not enough mass to much effect exitance in the 30 km upward stratosphere direction. Most all 15 micron CO2 exitance comes from the 12-20 kPa pressure altitudes, (very high in the tropics). There is also some 620 and 720 Ghz CO2 exitance from these altitudes.
All the best! -will-
03
The difference 135W/m-2 shows the importance of cloud cover in the whole climate discussion.
CO2 forcing of just over 2 W/m-2 is about 2% of this figure. We certainly do not have measurements of global cloud “amount” accurate to anything like that.
As Roy Spencer pointed out some years ago, it only takes a change of 2% in cloud cover to produce a change equivalent to that calculated for the basic ( real per “basic physics” ) CO2 forcing.
Until evaporation, cloud formation and precipitation are understood to that level of accuracy the rest the AGW debate is a load of hot air. ( no pun intended ).
127
Steve Goddard put up picture from the NOAA that pretty much shows how much OLR comes from condensing water. No link so I haven’t read any details about which IR region was scanned.
The hottest parts are tropical cyclones but notice the jet stream and emission from above the Arctic. Imagine what happens when there is meridonal movement of that jet stream (moving North from above warm ocean to cool Arctic). How could this be ignored. Greater humidity means not only more cloud cover but also more out the water pipe.
90
Great image RB. Stephen Wilde and others have been elaborating on the effect of jet-stream movements (maybe involving ozone) for a while now.
90
Off topic: India decides solar is useless.
http://www.scientificamerican.com/article/coal-trumps-solar-in-india/
30
Increasing the concentration of CO2 is clearly going increase the rate of atmospheric cooling by increasing the size of the CO2 pipe while at the same time decreasing the surface pipe through absorption of CO2 through the non saturated portion of spectrum.
This is basic chemistry. The CO2 acts as catalyst, taking sensible heat energy and converting it to radiant energy. The concentration of catalyst determines the rate, as long as the atmosphere contains sufficient energy (temp) for the excited quantum state to form. Based on the fact the atmosphere does not instantly cool to the temp of the surrounding space the moment the sun goes down indicates it is rate limited by lack of cooling catalyst. (aka greenhouse gasses)
As for watts determining temp, and vice versa, just compare a fluro light globe vs an incandescent or different powered lasers with the same colour light. The force (watts) is determined by the energy of the photon times the number of photons. The energy of the photon emitted by CO2 is fixed by is physical chemistry. The warming and cooling effects of CO2 are independent of each other and must be modelled with separate functions.
If anything the whole concept of emission hight seems back to front.
Greenhouse gasses would appear create an energy well at the temp corresponding to their quantum emissions. Maybe we should be modelling the energy flow as a series of springs and drains.
21
Rob JM: The IPCC and the climate establishment has always maintained that an increasing atmospheric concentration of CO2 decreases the amount of OLR emitted by CO2 molecules, by about 3.7 W/m2 per doubling of CO2 (post 2). Thus, as CO2 increases the CO2 pipe carries less OLR (“is smaller”). We are going with that theory in this blog series — see, for example, post 6.
Since ASR = OLR, increasing CO2 means the other pipes must (collectively) carry more OLR. Because the surface pipe presumably carries slightly more, the atmosphere emits slightly less OLR — which suggests the rate of atmospheric cooling to space is actually reduced by increasing CO2. However more CO2 might also mean the CO2 is creating more back radiation, so perhaps total atmospheric cooling (to the ground and space combined) in increased.
50
“Because the surface pipe presumably carries slightly more, the atmosphere emits slightly less OLR — which suggests the rate of atmospheric cooling to space is actually reduced by increasing CO2. However more CO2 might also mean the CO2 is creating more back radiation, so perhaps total atmospheric cooling (to the ground and space combined) in increased.”
One also needs to take account of the cooling effect of convective uplift converting heat (kinetic energy)to potential energy which is not heat and the reverse (warming effect) in descending air.
It is that constantly varying exchange between KE and PE within convective columns that provides the necessary buffering effect to prevent average net surface warming whilst convective adjustments eliminate radiative imbalances by moving emissions between pipes.
That buffering effect provides a failsafe mechanism to prevent system warming during the time required for the convective adjustments to take effect. The visible sign of the buffering process in action is variations in the amount of turbulence at the top boundary of the layer of air being considered. Turbulence at the tropopause is the best example for current purposes but it could equally be at the boundary with space in the absence of discrete layering within the atmosphere.
I have a more detailed description of the process in preparation.
1013
Except that sattelite measurements show increased emission with CO2.
David, assuming we allow that CO2 can exchange excited quantum states with KE (heat) then the emission you see in the Nimbus plot may be the saturated emission of CO2 and atmosphere with no contribution from the ground. That is all the outgoing energy from CO2 might be sourced from convection. If this is the case then increased CO2 concentration increases emission providing that the convection is not rate limiting the emission (that convection can move sufficient energy to supply the radiant emission). CO2 would then overall be a cooling influence, the radiance converted to heat in the lower atmosphere being irrelevant to emission.
The data showing that emission increases with Co2 concentration would seem to support that hypothesis.
Another point here, I am nervous about these emission layers. The accepted mechanism for frequency smearing is the doppler effect. That is emission from molecules moving away from the satellite show a redshift and the molecules moving toward the satellite at the fastest rate show a blue shift. The magnitude of the shift being related to the speed of the molecule. The Speed being related to the temperature. The reason the wings are emitted from the surface is because the CO2 needs to be hot in order to be red/blue shifted by that much. The emission pattern we see is due to the statistics of the distribution of molecular velocity in the sample of CO2 being monitored. The Layers actual temperature is an average of the velocities, above a certain height it becomes increasing less probable that a kinetic collision will impart enough energy to change the vibration of the molecule and therefore less IR out.
Colder CO2 cannot move fast enough to match the red/blue shift of this radiation and therefore the wings go further without intersecting with a molecule having the right relative velocity to absorb the doppler shifted photon. If this is the mechanism then the shape of the wings wont be changed by concentration, the whole characteristic will just be moved up and down ( until the trough clips at some minimum value (where all the IR emitted is sourced from convection), once the surface IR in the stop band is fully absorbed. It seems to me this is exactly what we see here.
56
bobl. Yes, the OLR at the CO2 wavelengths of the Nimbus spectrum is almost entirely from CO2 high in the atmosphere, supplied with energy largely by convection. Increased CO2 lifts the CO2 emission layer higher, to a colder place in the troposphere, at the wavelengths in the wings where it changes the spectrum. (See this page of the Barrett-Bellamy website, last diagram.) Because the emission layer is colder, it emits less OLR. Yes, CO2 is a cooling influence, but oddly enough more of it reduces the amount of OLR from CO2. Establishment climate science is pretty certain that OLR from CO2 molecules decreases as the CO2 concentration rises, by about 3.7 W/m2 per doubling of concentration — total emissions may increase, but emissions to space decrease.
Yes, the layer concept is a big average. But as the Nimbus spectrum shows, the OLR at a wavelength comes from a fairly narrow range of temperatures, from which we are able to deduce the height of the layer.
As the diagram on the Barrett-Bellamy website website shows, apparently it is the wings of the CO2 spectrum that are most affected by changing concentration from current levels.
60
But David is it a “Layer” at a height or is it just the emission at an average temperature (average kinetic energy sourcing the emission) from the whole atmosphere. I don’t see how you can replace that diffuse temperature based emission with an equivalent layer of air. To me it seems non-physical. The only way I see this working is if you say the average energy has increased by height, and working back through the lapse rate (assuming it’s unchanged by the extra radiative gasses) conclude that the surface must be hotter. Surely this ignores the fact that the extra radiative gasses lower the lapse rate and that this lower lapse rate (increased energy flow) may be the cause of the increased average temperature of the emission layer.
It’s all very circular
25
bobl,
That is a good point and leads to the slight difference between David’s opinion and mine.
David is of the view that the surface may warm a little but not as much as the AGW proponents claim.
I am of the view that the surface warms a little below rising columns of air but cools by an equal and opposite amount below falling columns of air.
I think both of us are of the view that lapse rates change as a result of the presence of radiative material.
If I have misundersood David’s position then maybe he will comment.
411
I think you have characterised it well. There is no need for the surface to warm to warm the EL when a simple lowering of the lapse rate will do that – we KNOW (in caps) that radiative gasses, water in this case lowers the lapse rate, CO2 and it’s water feedback must have the same effect. If this is the case then the warming at height represents MORE energy being transmitted from surface to space as CO2 increases. That’s by definition Cooling!
06
bobl. Either interpretation is fine with me, so long as you recognize that there is a distribution of heights from which OLR originates and that the distribution is often pretty narrowly clustered around a height. In the analysis that follows, incremental moves in height just change the average of the distribution.
Recall that at 15 microns photons can only move a few meters at sea level before being absorbed. While these distances get larger as the pressure drops or the wavelength moves out to the wings, there is a distinct layering phenomenon.
We’ll cover lapse rates and links to surface temperature next; it’s not circular.
40
David, you say:
But why? This means that your series will not really get us anywhere. The warmists will simply ignore your model objections and focus solely on your admitting their basic premise as being correct. And so the train will just keep rolling …
21
Because Kristian, even with their understanding of how CO2 and the greenhouse effect works (which I believe is about correct, AFAIK), we can show that they have applied the basic physics incorrectly to the climate, and that when it is applied properly it shows that Co2 is only about a fifth or a tenth as potent a warming agent as they say. This will have an impact because most climate establishment figures believe in the theory because of the basic model, not because of opaque computer models.
The warmists will ignore us as long as possible anyway. But if we show they made a huge logical error and kick up a big fuss then they will come around eventually. On top of that, it will likely cool in the next few years — but if it cooled and they still believed in the basic model, they would just ignore the cooling like they ignore all the other contrary evidence, because they know the “basic physics” proves CO2 is dangerous.
10
David, you say:
Well, I certainly don’t. There most definitely is an ‘atmospheric insulation effect’ on the solar-heated surface. However, this effect is fundamentally a ‘massive’ one, not a ‘radiative’ one.
Here’s my take on this issue:
https://okulaer.wordpress.com/2015/05/13/to-heat-a-planetary-surface-for-dummies-part-5b/
https://okulaer.wordpress.com/2015/06/20/why-atmospheric-mass-not-radiation-p1/
https://okulaer.wordpress.com/2015/06/20/why-atmospheric-mass-not-radiation-p2/
02
Nice, coming together well, even for non mathematicians.
60
The pipe diagram is an interesting visualisation. It would be great to see a visualisation of how the pipe sizes change with varying altitude. Maybe a rate of change with altitude. Obviously the CO2 pipe gets smaller as it gets higher, but if the amount of water vapour increases in the atmosphere, does it necessarily get higher? Its not “well mixed” like CO2 is thought to be… Does the pipe size increase?
10
Tim, the pipes are for OLR, carrying heat to space from each type of emitting molecule. Not sure they vary with height.
20
Well the CO2 one does, afterall its the basis for AGW.
More CO2 means higher average effective radiating altitude meaning lower energy radiated due to the lower temperature.
10
Ok, yes, the height of the emission layer certainly changes. I suppose the pipe might be thought of as starting there.
00
And where do you get that data? How has more CO2 done anything about energy radiated? Where are the measurements?
Does some pipe size determine flux? Why? What gives you the impression that anyone knows how the atmosphere works? For you my good friend Very good price on set of knives that never get dull! 😉
04
I believe the MODTRAN database has that data although I’ve never looked it up myself. If it weren’t true from there, I expect someone would have noticed by now 😉
Having said that, I expect it could only have been calculated through line by line radiation calculation models as I doubt we have accurate enough measurements to definitively confirm it, nevertheless its about the only relatively undisputed part of the AGW physics that exists.
All feedbacks that surround that effect are up for grabs as far as I’m concerned.
Incidentally the sizes of the pipes David has shown are a measure of that flux.
20
“In terms of “pipes” David has managed to estimate the comparative sizes of different pipes, with a table I haven’t seen elsewhere — which I’ve graphed here. (Though we expect the IPCC crew would have done this ).”
The graphic is similar to the one in Goody and Yung, Atmospheric Radiation, 1989 page 4
https://books.google.com.my/books?id=Ji0vfj4MMH0C&printsec=frontcover&dq=goody&ei=S1wnVqTAGIyHjAOq07GgAw&cd=2#v=onepage&q=goody&f=true
A more detailed graph specific to CO2 is in Murry Salby’s text, Physics of the Atmosphere and Climate (2012) page 221, adapted from McClatchey and Selby, Atmospheric Transmittance of CO2 laser radiation, Env. Res. Paper 419. AFCRL-72-0611.
40
Frederick – Have you got a link to either?
The Goody and Yung link goes to their book, but page 4 does not have a table or the numbers?
30
Physics of the Atmosphere and Climate (2012): <a href="http://www.atmosfera.unam.mx/jzavala/OceanoAtmosfera/Physics%20of%20the%20Atmosphere%20and%20Climate%20-%20Murry%20Salby.pdf“>
20
Thank you Ted. Nice resource!
20
Sorry Frederick, I misread and was looking for a table. Yes, those graphs are interesting. It’s hideously complex in fine detail. (Ted posted a link to Slaby’s book in Comment 11.1.)
20
Joanne,
Please, please, please, reconsider your chart presentation.
In your first graph the gray is the spectral radiance W/(m^2 x sr x cm)for a blackbody at less than 200 kelvin, 18 micron peak. But you give nothing about what: W,m,sr,or;cm may possibly mean!!! This is a nonsense curve and your explanation of ‘Turn things upside down in your mind’, I understand; with the caveat of I believe I will have another beer. 😉
If you put solar irradiance at those frequencies; the top of your chart would be way beyond the distance to the Moon. The actual maximum spectral radiance curves for different temperatures never intersect at any frequency.
How to present such for learning I have not a clue!
For your comprehension flip the chart to that (cm) on the top.
This represent specular radiance from left to right as a function of wavelength interval rather than frequency interval (the negative complex conjugate), whatever that is! 😉
The Sun’s radiance how peaks on the left rather than on the right. The top/bottom logarithmic/linear also flip but the two different curves look the same as they have the exact same information about blackbody spectral radiance.
There are no black-bodies or isothermal bodies anywhere! All a deliberate scam!!
514
In my addled brain, with “pipes” come faucets. I instantly pictured a hose tree with many outlets, each with its own control. I probably pictured this because I was looking at it, upside down, in my yard, from the hammock, trying to recover from the news that out prosperous resource dependent neighbor to the north decided to give up its prosperity and join the progressive party.
Anyway — the faucets differ — the one controlling clouds is being tweaked continually, while the one for CO2 is being turned slowly. This leads to speculation that a daily measurement, during which some faucets are turned and others not, wouldn’t make much sense. Months perhaps, except our earthly hemispheres differ so much in water coverage that equal seasonal response in unlikely. Years, then: once around and take a tally. Don’t see how a more granular measure than years can be very useful with this model.
rri
10
Far off the left of those wavelength charts things still happen. There are many lower frequency longer wavelenth 100% absorbtion bands.
https://en.wikipedia.org/wiki/File:Atmospheric_Microwave_Transmittance_at_Mauna_Kea_(simulated).svg
Assuming that nothing happens at the frequency you heat things in the microwave with may lead to stuff like this below being ignored. I think the energy in is less than the energy out but does the sun cause the oceans to send large volumes of warm hydrogen quickly up to the TOA?
https://www.youtube.com/watch?v=VQMXzpTaIh4
00
While these guys measure that these 1420.4058 MHz signals are only strong enough for amateurs to see the distant parts of the galaxy AT NIGHT with, it would be intesting to see what they get at sunset from a still warm sky.
“…Moon noise (around 0.25dB over cold sky)” ….”can be seen in the last bulge before diagram goes sky high because of ground noise.”
http://lea.hamradio.si/~s53rm/Radio%20Astronomy.htm
00
Microwave absorbtion link did not work.
Click here
“Beginning at about 40 GHz, the atmosphere becomes less transparent to microwaves, at lower frequencies to absorption from water vapor and at higher frequencies from oxygen. A spectral band structure causes absorption peaks at specific frequencies (see graph at right). Above 100 GHz, the absorption of electromagnetic radiation by Earth’s atmosphere is so great that it is in effect opaque, until the atmosphere becomes transparent again in the so-called infrared and optical window frequency ranges.”
Text from Associated page.
Click here
00
Another problem.
“I think the energy in is less than the energy out”
For the inventor it would be the other way around. I bet he is putting more RF energy in than the flame gives off.
From the sun far more energy would come in than the energy available for re-combustion but the enhancement of convection may be significant.
00
Sliggy,
There are lots of systems that “Appear” to create an output of more than you put in. For example you can put 900 Watts into an air conditioner and get 3kW of cooling on one side and 3.9kW of warming on the other 6.9 kW out of just 900Watts input. This shows that Work is not conserved just energy. The Equation is actually 3.9kW-3kW=0.9Kw, so when you take into account the sign of the effect everything meets conservation of energy. Any system which emits more energy that it used is pumping the additional energy from some other source against entropy.
That is not to say there aren’t energy sources unknown to science to draw on
20
Bobl I think you missed the point I was tying to make. It is NOT about the free energy scam at all!
It is about solar radiation at the frequency he is using liberating hydrogen over 70% of the earths surface (salt water)! Hydrogen will rise ALL THE WAY to the top of the atmosphere in just three to five minutes. Hydrogen in that form is itself a huge amount of energy that is going up. If it carries heat that is even more. If it reacts up there , cools then falls down again that is more and more. So forget the free energy scam and focus on how this could be yet another pipe with a very real and strong solarcycle spectoral shift response if UV also plays a part.
00
Are you trying to say to say that UV insolation energy density is sufficient to disassociate H2O molecules near the oceans surface?
that would be an interesting theory! 🙂
10
Actually there is something in this. There are photons energetic enough to dissociate weak bonds, this is for example how methane is broken down, maybe not in water but certainly H2 from methane could carry of a fair amount of energy, it’s yet another loss.
10
Will
“Are you trying to say to say that UV insolation energy density is sufficient to disassociate H2O molecules near the oceans surface?”
Not for the main source. He is operating in the Ghz range. UV would only suppliment and play an increasing part with altitude and this would vary over the solar cycle. Thus UV may modulate a threshold set by the GHz component.
00
Why is the Nimbus graph of OLR presented with the x-axis reversed? Usually radiation spectra are presented with the high energies ( short wavelengths) to the left side.
10
To a radio guy it is the right way round. Low frequency goes on the left.
The brightest electromagnetic events known to occur in the universe go on the right.
” releases as much energy in a few seconds as the Sun will in its entire 10-billion-year lifetime”
https://en.wikipedia.org/wiki/Gamma-ray_burst
00
Peter, it’s the old frequency vs wavelength thing. One can think in either, but like Siliggy says, it’s traditional for frequency to increase from left to right. When discussing absorption, most people seem to use wavelength rather than frequency. Most of those who prefer to talk about absorption spectra in terms of frequency instead use an unusual frequency measure called “wavenumber”, for reasons that escape me but maybe they are simply more convenient than the appropriate numbers in Hertz (cycles per second).
10
Save number is proportional to energy, and is hence very useful, especially in spectroscopy.
21
Rrrr, autocorrect can be a pain. “Wavenumber” is proportional to energy.
11
Turn it off…
00
There are some serious issues with the second figure in the opening post – the altitudes are incorrect.
* Water vapor emissions follow a black body curve of about 270 K, demonstrating as per the lapse rate rate an average tropospheric altitude of roughly 3-4km.
* CO2 emissions range from blackbody temperatures of 220 K (the average temperature at the tropopause, 11km). There is a spike at the bottom of the CO2 trough at a wavenumber of ~660, the CO2 absorption peak, and that is the only CO2 stratospheric emission contribution – emissions from the lower stratosphere, which warms from the tropopause. If you are averaging over the entire absorption bands perhaps 250 K, roughly 6km.
Note that the CO2 effective emission altitude is well above that of water vapor.
The dot plot lists effective emission altitudes of 8km for water vapor and 7km for CO2. Neither is correct.
74
Well, KR, David has previously placed the CO2 emissions height in the stratosphere which is above clouds and water vapour emissions. I see the Fig 2 as being an attempt to indicate the relative sizes of the pipes rather than their precise heights.
Makes no difference to the basic thesis of interchangeable routes for radiation to space mediated by changes in lapse rate slopes and thus convection thereby minimising (as per David)or eliminating (as per my opinion) any need for a change in average global surface temperature.
511
KR, for water vapor see note 3, and for CO2 see note 1 and the caption to figure 1.
10
An admirable attempt to gather the observational data for effective radiating height based on temp inferred from wavelength. A note of caution. This is pretty sketchy data, with substantial error bands. One example is Dessler’s attempt to infer positive cloud feedback from clear sky/ all sky differences. r^2 of 0.02— statistical junk indistinguishable from random noise.
If I find the time, will dig into the uncertainties behind Dr. Evans tabular summary of others data, as it is a point of potential vulnerability for his laudable enterprise as a whole.
20
So, I assume the uncertainties could be carried though the calculations – and they need to be! Otherwise, how do we know how significant the final number(s) are? Any other sources of uncertainties should also be carried though. That way, we can see if Dr. Evans’ range of sensitivity overlaps the IPCC one or just how they compare.
00
Jim, there are bigger uncertainties ahead that swamp these ones.
10
Rud, if you spot a similar table on your travels I would be very interested. I couldn’t find one, and it took weeks to put this together after reading on the net. I’ve run it past a spectroscopicist friend of mine who cautiously reckons it is probably about right, as far as he can see.
11
” indistinguishable from random noise.” Just out of curiosity what are the sources of the random noise power?
00
When you first mentioned “pipes” I was surprised there was no oxygen pipe? Perhaps this is context.
You are showing selective plots similar to the practice of many others. What is hidden from view? (bandwidth ought to be larger)
As a point, these radiance plots should usually be log-log, get a straight line.
All probably unimportant in relation to what you are trying to do.
00
Tim! AFAIK oxygen doesn’t emit significant OLR, so I omitted a pipe for it.
There is some OLR from oxygen, however. The satellite temperature measurements work by microwave sounding near 60 GHz (5000 microns), where the OLR is “proportional to the thermal state of emission of oxygen molecules”. This was the technique pioneered by Roy Spencer and John Christy, deployed from late 1978.
Sorry, the Nimbus plots only ever seem to cover this bandwidth. I accounted for the range 25 to 67 microns in note 3.
The Nimbus spectra are from the 1970s; it seems odd to me that there aren’t more up-to-date, higher-resolution measured emission spectra available now. Anybody know why?
20
The same (incorrect) altitude numbers are in the ‘Parameters’ table as well.
It’s not a trivial difference – the effective emission altitude is set by the highest GHG that emits at a particular wavelength, and the higher CO2 levels explain why water vapor does _not_ preclude CO2 forcing.
The CO2 effective emission altitude is roughly twice that of water vapor.
62
KR, please see Comment 16.2.
10
While researching magnet pole shift I discovered this web site.
http://oregonstate.edu/ua/ncs/archives/2005/dec/movement-earths-north-magnetic-pole-accelerating-rapidly
It appears to me that the magnetic poles have shifted into a location that could be affecting global temperature. Is anyone looking at this effect? With the information about cosmic particles changing cloud cover wouldn’t the movement of the poles have some effect? Also isn’t the location of the ozone hole affected by the location of the magnetic poles?
30
Does David Evans plan on providing a more easily readable file of this series when completed?
00
Rich, yes I do, but not sure how. Hopefully much of it will come out as a pair of scientific papers. Maybe a book if there is sufficient interest, which would be easier to read for most people.
20
Very nice post, I like the way each depends on the previous post and explains more and more.
Thanks for the the huge amount of work to analyze the theory and data and then to summarize it so well.
50
As an upper bounds of the “warming” provided by all “greenhouse gases”, estimate the near-surface atmospheric (nitrogen-oxygen) temperature as though the other pipes didn’t exist. i.e. You only have surface radiation to get rid of the insolation.
11
I am presuming that you are familiar with Miskolczi. His early work, HART code paper demonstrating that the IR optical depth of the atmosphere had not changed. A drop in water vapor compensated for the increase in CO2. In any case, keep up the good work.
21
Al, we are going to come to a similar conclusion via different means in this series.
10
A little over 19 years ago I started working with a whole new software/hardware problem and had to very quickly get used to the idea of simplifying assumptions in order to turn an intractable or impractical to solve problem into one we could manage reasonably (different application domain but similar difficulty). So your average emission layers and the statement that small differences won’t matter, do not bother me. But I assume your model will substantiate or validate these simplifications as you continue. ***
I’m not attacking your work but I like to know the working assumptions are reasonably verified. And if I missed something along the way I won’t be bothered by being told I missed it.
10
Roy, it’s only a basic model, but it is going to indicate that establishment climate science has been playing in the wrong ballpark!
00
*** It would obviously become very messy if you couldn’t make them.
00
Just for my understanding, when blocking of radiation by CO2 only occurs at higher altitudes and not near the surface, would that imply CO2 only has an impact on temperature at this higher altitude? Raising the temperature with 1 C by doubling CO2 at a height of 7 km would probably results in a temperature increase near the surface of maximum 0.2 C? Or does CO2 also blocks IR radiation near the surface?
00
Marinus, a good analogy is picture of the dam at the top of post 11. The radiation out is equal to the radiation in, which does not change as CO2 increases (except via minor surface albedo changes). So increasing CO2 just causes the outward radiation to be redistributed between the various emitters (pipes). The big question is what the new distribution is.
Increasing CO2 reduces outward radiation (OLR) from CO2 molecules. Therefore OLR fromthe water vapor, surface, and cloud tops combined must increase. If it increases from surface, that means the surface warmed. Hence the warming at the surface.
The establishment view is that increasing CO2 that raised the radiating temperature by 1 deg would raise the surface temperature by 2 – 3 deg, because of water vapor amplification — they reckon the water vapor pipe would also be impeded, so less radiation is emitted to space from water vapor, requiring the surface to emit more than if the water vapor emissions did not fall.
CO2 blocks some radiation wavelengths (mainly around 15 microns) throughout the atmosphere, so it can only emit radiation to space from CO2 molecules near the top of the swathe of CO2 enveloping the planet.
00
David wrote: “The establishment view is that increasing CO2 that raised the radiating temperature by 1 deg would raise the surface temperature by 2 – 3 deg,”
That is a very clever and inspiring way to phrase the feedback issue. But, is it accurate?
Technically speaking, an instantaneous doubling CO2 deduces the brightness temperature of the planet by about 1 degK. The resulting radiation imbalance results in warming until balance has been restored.
GHGs in the atmosphere reduce OLR from 390 W/m2 at the surface to 240 W/m2 at the TOA. If I express that in terms of brightness temperature, that is the infamous 33 degK GHE (a description I dislike). About 2/3 of this (22 degK) can be attributed to water vapor (Modtran). Saturation vapor pressure for water vapor rises about 7% per degK. 7% of 22 degK is 1.5 degK of warming from enhanced water vapor feedback. Granted, it isn’t appropriate to assume linearity, but that is the best I can do without getting into radiative transfer calculations and a water vapor feedback of about 2 W/m2/K.
According to what I’ve read, more feedback may occur in the SWR channel than in the LWR. So we can’t just think in terms of “radiating temperature”. The radiating temperature of the earth would be 279 degK, not 255 degK, if the earth’s albedo were 0. So, roughly speaking, every 1% change in albedo is worth about 1 degK.
[Inspiration terminated.]
10
Frank: Thanks, yes what you quote me saying is quite inaccurate — I left out a vital bit, and said “radiating temperature” when I meant no-feedbacks surface temperature. I should have said: “The establishment view is that increasing CO2 that would lower the radiating temperature by 1 deg in the absence of any climate feedbacks (if only CO2 and surface temperature were allowed to change), eventually raises the surface temperature by 2 – 3 deg after those feedbacks occur (they restore the radiating temperature to its original level, by warming the surface).” The rest of the comment is ok.
00
If you have a vessel with 100% CO2 within and you beam a 15u light through its contents, the CO2 molecules have to begin to shake, rattle and roll and gain kinetic energy and 1/2 mv^2….and therefore get hotter…doesn’t it? Why does the CO2 15u band look cooler from the satellite? Alas, this is a fact, I guess, so that this must mean that the energy CO2 gains from the shaking must be shed to other neighboring molecules who then radiate into space. How else can this be interpreted? The total energy leaving the earth is not affected by its gases unless these change the albedo.
00
William: Yes. The CO2 insulates on its emission wavelengths because it radiates mostly (close to 15 microns) from the lower stratosphere, very cold (215k). So as you say, this must mean it transfers energy to to other molecules via thermal collisions, and they (principally water vapor) emit. And yes, adding more CO2 to the atmosphere merely causes the Earth’s emissions spectrum to rearrange itself – less radiation from CO2, more from other molecules, but the same OLR overall (excepting a small change due to albedo feedbacks to surface warming).
Our task in modeling this is to estimate the increase in OLR from the surface, as CO2 increases and the redistribution of OLR occurs. Knowing the change in OLR from the surface allows us to calculate the surface warming.
00