Guest Post by Willis Eschenbach
To continue my investigations utilizing the CERES satellite dataset of top of atmosphere radiation, here is a set of curious graphs. The first one is the outgoing (upwelling) longwave radiation at the top of the atmosphere (TOA) versus the sea surface temperature, for the northern hemisphere, at the times of the solstices and equinoxes.
Figure 1. Northern Hemisphere TOA outgoing longwave, versus sea surface temperature. Colors represent latitudes, as follows: dark blue, 10°; red 30°; yellow 50°; sky blue 70°. Vertical dashed line is at 30.75°C. Horizontal dashed line is at 300 W/m2. Black solid line shows the surface upwelling longwave radiation (calculated at emissivity = 0.95). Click to enlarge.
I find this graph both interesting and puzzling.
The first puzzle to me is, why is outgoing radiation in July about 230-250 W/m2 from the pole to the Equator? I mean, the upwelling radiation from the surface (solid black line) increases by 50% from the coldest to the warmest areas … but the upwelling longwave is all about the same regardless of the sea surface temperature. How bizarre!
The second puzzle is that there seems to be a fairly hard limit of about 300 W/m2 of TOA upwelling LW. Not only that, but it doesn’t vary much month to month.
The third puzzle is that even up in the Arctic regions, there’s little seasonal change in the upwelling LW. It only swings about 30 W/m2 at the most variable point, and less as you move away from the poles.
Now, what I think is happening at the warmest temperatures is the same thing that the TOA reflected solar showed in my last post—a significant increase in clouds. Let me explain why more clouds means less upwelling longwave radiation. Remember that this is upwelling longwave radiation. Suppose we have some amount X of upwelling radiation coming from the ground. If we interpose a layer of cloud between the surface and the TOA, the cloud will absorb that upwelling LW radiation, and then re-radiate it, half upwards and half downwards. This reduces the amount of upwelling longwave at the TOA, as we see happening at the warm end of the scale above.
Here is the same analysis, but this time for the southern hemisphere.
Figure 2. Southern Hemisphere TOA outgoing longwave, versus sea surface temperature. Colors represent latitudes, as follows: dark blue, 10°; red 30°; yellow 50°; sky blue 70°. Vertical dashed line is at 30.75°C. Horizontal dashed line is at 300 W/m2. Black solid line shows the surface upwelling longwave radiation (calculated at emissivity = 0.95). Click to enlarge.
Want to know what is surprising to me about the southern hemisphere?
I’m surprised at how little the TOA upwelling longwave changes from season to season. The sun comes and goes … but the southern hemisphere upwelling LW is largely unaffected. Every season of the year it’s about the same, 200 W/m2 around the icy antarctic, rising to 300 W/m2 at about 28°C, and then dropping from there. What’s up with that?
My goodness, the amount there is to learn about this incredibly complex system has no end, I can only shake my head in awe …
w.
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Flaming hockey sticks!
Willis,
I am an engineer who analyzes buildings, and your thought process is remarkably similar to mine…. It is a very large complex puzzle, yet to be solved. Keep digging, I know yow will find the answer.
While I don’t doubt your professionalism and integrity, why has no one looked it this in the past 20+ years?
Is it because those who figured it out couldn’t make a dollar off it???? Follow the money and you will typically find the answer.
Interesting graphs. Well done. I am looking forward to the comments.
Upwelling and downwelling isn’t a 50/50 ratio. Most of the atmosphere is above the horizon so even some “downwelling” radiation is still aimed at the stars. Thanks to our cleaning up the air we breath our air is more transparent (fewer aerosols, smoke, tire particles, soot, etc) so it is possible to graze the horizon with light and have it leave earth forever. The bandwidth of our atmosphere is much improved over my lifetime and our angle of radiation of light is wider than it was when coal was king. I wonder if the satellites deal with this. Sorry I can’t find the link to the study just now of the impact of changing atmospheric transparency.
My goodness, the amount there is to learn about this incredibly complex system has no end, I can only shake my head in awe …
w.
======================
awe Willis, I know you are smiling. Me too.
Well lo and behold Willis finally “discovers” what I was trying to point out to him across many prior articles, let’s see, before December 14, 2012 since that is the date Roger at TalkShop took serious what I was saying and published a small and simple correction to TFK’s new and “improved and balanced” energy budget. See the 264 W/m² outgoing averaged global upwelling LWIR that is what you see in the CERES data.
Model: http://i46.tinypic.com/21931xt.png (the blue cells are the only given parameters)
Article: http://tallbloke.wordpress.com/2012/12/14/emissivity-puzzle-energy-exchange-in-non-vacuums/
Yes, it does seem our planet does have an effective emissivity of right at 0.67, globally averaged, or that is what I gather from your plots Willis.
The atmosphere lower part block most of IR upwelling from earth surface.
The outgoing IR measured at TOA are mostly from higher colder part of atmosphere. That IS the green house effect. Coldest part of atmosphere is by the way in the tropics.
wayne says:
October 8, 2013 at 10:55 pm
Wayne, I don’t have the slightest clue what you’re talking about. I’m banned from Tallbloke’s Talkshop, and I haven’t any idea what you were “trying to point out” to me, either there or elsewhere. Your tinypic is of no help either.
Nor am I impressed by your tone …
w.
Carnwennan says:
October 8, 2013 at 10:13 pm
Definitely, what’s not to like?
Best regards,
w.
Willis: “Wayne, I don’t have the slightest clue what you’re talking about.”
Thanks Willis, didn’t think you would. Maybe some others can see through it.
What band do they consider “LW”? I would expect that maybe the power doesn’t change, but the wavelength will. I would expect the wavelength to increase as the temperature cools. The amount of power radiated will probably remain unchanged until the surface temperature started to near equilibrium with space. For example, if the sun were to turn off right now, earth would continue radiating heat into space but the wavelength would get longer and longer as it cools. There would likely be a “burst” of heat as various gasses condense out of the atmosphere depending on their latent heat but overall the amount of power wouldn’t change much until we got below about -250F or so. What is the variation of outgoing LW from the moon at the equator across the dark side from terminus to terminus? My guess is it won’t vary much but the frequency of it will. It is probably radiating pretty close to the same amount when the surface first goes dark as it is just before dawn. It would keep radiating, too, if it could, all the way down to double-digit kelvins and then at that point portions of the colder parts of the surface start to come into equilibrium with space and the radiation begins to fall off.
In other words, if I have a radiator that can radiate 100W/m^2 and it is +200F in a room that is -350F it will continue radiating 100W/m^2 when it has cooled to +100F and when it is at 0F. When the power begins to fall off, that means it is no longer cooling. All this says is the efficiency of the radiator doesn’t change much by season. It doesn’t say much about temperature. Earth cools at about the same rate in winter as it does in summer. The winter hemisphere doesn’t receive as much energy as it did in the summer so the temperature falls. In summer, it receives more than it radiates and the temperature rises. But the radiation is, apparently, relatively constant. For some reason I don’t find that puzzling at all.
Something that l think is been overlooked is what impact does the increase in Noctilucent clouds have on the atmosphere. The brightest and extent of these clouds waxes during the summer months and wanes during the winter. Also these type’s of clouds rarely stray further then 50 degree’s from the poles. These clouds are also known to be highly reflective to radar and can only be seen when the sun is below the horizon.
Think of an inner tube with a leak in it. Imagine the leak is constant (doesn’t change with pressure) in CFM per minute. But now imagine I have a varying amount of air (energy) being pumped into it. Imagine that air (energy) varies in roughly a sine function. As the amount of air being pumped in increases to a rate greater than the leak, the inner tube swells (hemisphere heats) and as the amount of ingress declines below the amount of leakage the tube shrinks (hemisphere cools) but the rate of air coming out of the “leak” won’t change until the inside begins to reach equilibrium with the outside. The “global warming” argument is that CO2 reduces the size of the “leak” and reduces the amount of heat allowed to escape. And that would probably be true if we had some convective barrier that was a clear piece of solid CO2 like glass is in a greenhouse. The convective “lid” on our “greenhouse”, though, is the tropopause which allows that heat to be transported well above most of the atmospheric CO2. Even worse (for the warmanistas), if you think of the atmosphere from ground to tropopause as a balloon, when you heat it, it expands (troposphere rises). This increases the effective surface area of the balloon meaning that it can still radiate from the tropopause at the same watts/m^2 but it now has more m^2 from which it can radiate. So when you try to warm the troposphere, it just expands a little and the temperature stays the roughly the same. Well, it might increase a tiny bit, but not by much. The expanding tropopause results in the excess convective heat being radiated away over a larger surface area. It is like a radiator that expands to a greater surface area as you heat it.
some pretty colors in the graphs…might make some good art
In a greenhouse, the LW IR blocking entity is at the convective barrier and prevents the air from rising above it to dissipate its heat. In our atmosphere, the air CAN rise above the LW blocking entity. Imagine a conventional greenhouse but imagine air could permeate the glass roof. It wouldn’t be very effective, would it? That’s what happens on Earth. Most of the CO2 (most of the gas, period) is close to the ground. At 50,000 feet where water might be condensing/cooling from the top of a thunder head, very little of the total atmospheric CO2 lies between it and space. If I radiate 1 watt per m^2 at the surface and radiate 1 watt per m^2 at 50,000 feet, I think it’s a safe bet that the energy radiated at 50,000 feet has less chance of impacting a CO2 molecule and is more likely to pass right out into space. A conventional greenhouse is a bad model for an atmosphere. In fact, I would be willing to bet that if Earth had a pure CO2 atmosphere at the same atmospheric pressure it has today (1.0 bar), it would be cooler than it is now at the equator but warmer at the poles (assuming a perfectly dry atmosphere) because CO2 would be better at spreading the heat around.
Wayne; from your links:
LW resident in atmosphere? That is a very unusual way to explain ordinary heat transfer.
But what is the point? You, Willis and everyone else show that most of outgoing LW at TOA are from the atmosphere not direct from the surface.
And since the value is low and more or less constant is the average altitude for LW outgoing rather high, and therefore cold.
Use the middle of the atmosphere at 500 mb, or 5,500 meters (18.000 ft) as example.
Temperature is reduced 6 K/1000m and that is average 33K colder than on earth surface.
And the Green house effect is, tada 33K as well. Not a coincident.
http://en.wikipedia.org/wiki/Greenhouse_effect
The temperature on ground change if the average altitude of this outgoing LW change. And what can change at 5,500 meters (18.000 ft)? Cloud maybe?
Willis,
” This reduces the amount of upwelling longwave at the TOA, as we see happening at the warm end of the scale above.”
Realy?? For how many seconds?? Or is some of it simply frequency shifted when downwelling is absorbed by the surface and reemitted??
gopal panicker says:
October 8, 2013 at 11:46 pm
Thanks, gopal. I always strive to present my findings in a way that is lovely as well as informative … no reason science can’t be beautiful.
Regards,
w.
Willis, I take it you are using the CERES-LW band 8-12 microns. Do you have the actual radiometer data, or you using a NASA interpretation of that data? I am looking for the along track data from a single area so I can observe the change in radiance at angls from normal.
Since the CERES instument has a fixed detector solid angle thr measurements should not vary with angle if the earth has anything like a Lambertian surface. Thank You! -will-
willis says:
The sun comes and goes … but the southern hemisphere upwelling LW is largely unaffected. Every season of the year it’s about the same, 200 W/m2 around the icy antarctic, rising to 300 W/m2 at about 28°C, and then dropping from there. What’s up with that?
=========================================================
In a word: Antarctica.
First, the Southern Hemisphere is mostly ocean, there’s only a fraction of the
land of the NH. The Southern Ocean is huge.
Secondly: the Antarctic ice cap is very high at the centre. Cold, dense air pours
down off that cap and across the Southern ocean, 24/7. The Roaring Forties are
always stormy. The weather fronts created by the cold gale march in monotonous
line from West to East.
Antarctica is the `weather factory’ for the SH
It’s my guess those would be why it’s so constant. No much land to warm, and a
constant gale of frigid air from the south.
Hope these ideas help…
” In fact, I would be willing to bet that if Earth had a pure CO2 atmosphere at the same atmospheric pressure it has today (1.0 bar), it would be cooler than it is now at the equator but warmer at the poles (assuming a perfectly dry atmosphere) because CO2 would be better at spreading the heat around.”
I think if increase CO2 by 2500 times it would finally be enough measurably increase Earth average temperature 🙂
But if you cooled the tropics, you cool the world.
It’s geometry. More surface area near equator.
And don’t see how a CO2 atmosphere cools the tropics.
To cool the tropics you could lower night time temperature- so their is a bigger difference than there is now between night and day. Or significantly reduce daytime temperature. I don’t see how CO2 would do either.
The best way to warm the poles is to increase average ocean temperature- cooling the tropics wouldn’t do this.
Willis, are you aware that in global average ~90% of the TOA outgoing longwave is atmospheric radiation and only ~10% is surface radiation? Furthermore, most of the energy radiated by the atmosphere is gained non-radiatively from the surface. Just asking.
http://edro.files.wordpress.com/2007/11/earths-energy-budget.jpg
dp says
“The bandwidth of our atmosphere is much improved over my lifetime…”
To my simplistic thinking that explains everything. Having removed most of the atmospheric pollution we were responsible for to start with, the Earth’s average temperature has increased slightly. So we are responsible for the warming, such as it is.
I remember the smogs of the 40s and 50s, and I lived in the country.
a 28*C span is about 10% of the Kelvin temperature of 300K. Outgoing LW radiation goes as the 4th power of the Kelvin temperature, so it should vary by about 40%. A variation from 200 to 300 W/m2 is about right. Reduced values, may be the effect of opaque clouds upper in the atmosphere radiating at a lower temperature than the ground.
Pretty much all that the CERES satellite is sensing in outgoing LWIR is energy emited by radiative gases, predominantly water vapour, in rising, translating and descending air masses at the top of the Hadley, Ferrel and Polar tropospheric convection cells.
Most of the energy being radiated by these air masses was not acquired by outgoing surface IR but rather by surface conduction and the release of latent heat from condensing water vapour.
If these air masses did not contain radiative gases and were not strongly radiating LWIR to space, they would rise but not lose energy, buoyancy and subside. Without radiative gases there would be no strong vertical convective circulation below the tropopause.
Without strong vertical convective circulation, the atmosphere would trend to isothermal (no lapse rate) with its temperature set by surface Tmax. Poorly radiative gases such as O2 and N2 stagnated at altitude would then start to radiatively super heat, just as in the thermosphere. Without radiative cooling and strong vertical convective circulation, most of our atmosphere would superheat and boil off into space.
Apparently some idiots want to reduce the amount of radiative gases in our atmosphere…