Guest Post by Willis Eschenbach
I got to wandering through the three main datasets that make up the overall CERES data, and I noticed an odd thing. The three main datasets are the all-sky downwelling solar, upwelling reflected solar, and upwelling longwave radiation, measured in watts per square metre (W/m2). Here are those three datasets:
Figure 1 the three main datasets that make up the CERES all-sky data. Note that as you’d expect, total input (solar ~340 W/m2) equals total output (100 W/m2 reflected plus 240 W/m2 radiation).
What I’d never noticed before is that the three datasets are all running on different clocks. One peaks in December, one peaks in January, and one peaks in July. Not only that, they all have different cycles of rising and falling … go figure.
A word of foreshadowing. I have no particular point to make in this post. Instead, it is a meander, an appreciative inquiry into the components of the shortwave (solar) and longwave (thermal infrared) top-of-atmosphere radiation. And at the end of the day, I suspect you’ll find it contains more questions and wonderment and curiosities than it has answers and insights. So hop on board, the boat’s leaving the dock, there’s a forecast of increasing uncertainty with a chance of scattered befuddlement … what’s not to like?
First, the solar input. Although a lot of folks talk about the “solar constant”, over the course of the year the sun is anything but constant. Because the Earth’s orbit is not circular, annually the Earth moves closer and further from the sun. This gives an annual change of about 22 W/m2, with a high point in early January and a low point exactly six months later in early July. So that’s one clock—peaks in January, bottoms out in July, six months rise, six months fall.
Figure 2. Downwelling solar. Top panel shows actual data. Middle panel shows the regular seasonal variation. The bottom panel shows the residual, calculated as the data minus the seasonal component. Horizontal gold dashed lines show ± one standard deviation of the residual data. This range encompasses about 2/3 of the data. Vertical dashed and dotted lines show January (dashed) and July (dotted).
The sun, of course, is very stable, so the actual variation looks just like the seasonal variation. Note that the standard deviation of the residuals is only about plus or minus a tenth of a watt, which is a variation of about 0.03%, three hundredths of one percent of the size of the signal. In passing, the cyclical variation of about ± 0.03% you see highlighted by the blue line in the bottom panel is the TSI (total solar irradiation) variation associated with the sunspot cycle … but I digress, if one can do that while aimlessly meandering …
The next dataset, reflected solar, is on a slightly different clock. While reflected solar naturally varies with the strength of the sun, it actually peaks in December rather than January.
Figure 3. Reflected (upwelling) solar. Top panel shows actual data. Middle panel shows the regular seasonal variation. The bottom panel shows the residual, calculated as the data minus the seasonal component. Horizontal gold dashed lines show ± one standard deviation of the residual data. This range encompasses about 2/3 of the data. Vertical dashed and dotted lines show January (dashed) and July (dotted).
To me, this is a very curious signal. To start with, it is at a minimum in August, and a maximum in December. So it rises quickly for four months, then falls for eight months, and repeats. Odd.
In addition, it’s curious because it is so stable. Of the three datasets (downwelling solar, reflected solar, and longwave), the reflected solar is the only one that is unconstrained. The downwelling solar is basically fixed. And the upwelling longwave is physically constrained—in the long run (although not the short run) what goes out is limited by what goes in.
But the variations in reflected solar, both geographical and temporal, are not fixed. Given the varying annual snow, ice, and cloud cover in the polar regions, plus the varying tropical cloud cover, plus the differences in clouds over the extra-tropical areas, there’s nothing obvious that constrains reflected sunlight to be the same, year after year … and yet, as Figure 3 shows, the standard deviation of the residuals is only half a watt per square metre, that’s plus or minus half a percent. And that means that 95% of the months are within one watt of the seasonal average to me. To me, that’s a wonder.
Finally, here is the longwave. Upwelling longwave is basically a function of temperature, so it peaks in the northern hemisphere summer. Of the three datasets, longwave varies the least over the course of the year.
Figure 4. Upwelling longwave radiation. Top panel shows actual data. Middle panel shows the regular seasonal variation. The bottom panel shows the residual, calculated as the data minus the seasonal component. Horizontal gold dashed lines show ± one standard deviation of the residual data. This range encompasses about 2/3 of the data. Vertical dashed and dotted lines show January (dashed) and July (dotted).
Again, we see only a small variation in the residuals, only ± half a watt per square metre, or about ± 0.2%, two tenths of a percent of the size of the signal. And again the signal is not symmetrical, with the peak in July and the minimum five months later in December. So globally, longwave rises for seven months, then drops for five months.
Having looked at that, I got curious about the strange shape of the seasonal variations in the reflected solar. So I decided to take a look at the latitudinal variations in the solar, reflected solar, longwave, and albedo.
Figure 5. Top of atmosphere (TOA) radiation by latitude. Area weighted. Note the units are terawatts (10^12 watts) per degree of latitude. Area-weighting is done using the official CERES latitude areas, which are for an oblate spheroid rather than a sphere. It makes no visible or numerical difference at this scale, but Gavin Schmidt busted me for not using it, and he’s right, so why not use the recommended data? The radiation in W/m2 is averaged for each degree of latitude. That average value is multiplied by the surface area of the degree of latitude (in square metres / ° latitude). The square metres cancel out, and we are left with watts per degree of latitude.
You can see the increased reflection from 0-10°N of the Equator. This is the sunlight reflecting from the massed cumulonimbus of the Inter-Tropical Convergence Zone (ITCZ). These tropical thunderstorms of the ITCZ provide the power driving the global equator-to-pole circulation of the atmosphere and the ocean. The increased reflection from 0-10°N is important because of the strength of the incoming sunshine. Half of the incoming TOA solar energy strikes the planet between 25°N and 25°S.
It’s also clear that the albedo in the southern polar regions is much higher than that of the northern polar regions. To investigate the effects of that difference on the radiation datasets, I decided to re-do Figure 5, the radiation by latitude, and look at the differences between June and December. Figure 6 shows June (darker of each pair of lines) and December (lighter lines) for the TOA solar, reflected, and longwave radiation.
Figure 6. As in Figure 5 (without albedo), but for June and December. For each pair of lines, the darker of the pair is the June data, and the lighter is the December data. The dotted blue line is the reverse (north/south) of the light blue line, and is shown in order to highlight the difference in reflected solar near the poles.
OK, so here we finally can see why the shape of the reflected solar data is so wonky. In December, there is much more solar reflection from the Antarctic region, with its very high albedo. December reflections at 70°S are about 500 TW/°. On the other hand, in June at 70°N the reflections are much smaller, only about 350 TW/°. As a result, when these regions swing into and out of view of the sun, we get large differences in reflected sunlight.
But the real surprise for me in Figure 6 was the upwelling longwave. The downwelling and reflected solar profiles are quite different from June to December … but to my shock, the upwelling longwave hardly changes at all. Say what? Heck, in the extra-tropical southern hemisphere there’s almost no difference at all in longwave radiation over the year … why so little change in either hemisphere?
And that, to me is the joy of science—not knowing which bush hides the rabbit … or the tiger.
Finally, Figure 7 shows the TOA net radiation imbalance. This is the downwelling solar energy, less what is reflected, less what is radiated.
Figure 7. Net top-of-atmosphere (TOA) radiation imbalance. Note that this is an anomaly, because there is a known error of about a 5 W/m2 difference in the incoming and outgoing CERES radiation data. So while we can use it for trends and standard deviations, it cannot tell us if there is an overall persistent imbalance in the TOA radiation. Positive values show the system gaining energy, and negative values show it losing energy. Panels as in previous figures, showing the data (top panel) along with the seasonal and residual components of the signal.
I see that this has the reverse of the four-month rise, eight-month fall pattern of the reflected data. The TOA imbalance falls for four months, and then rises for eight months.
Once again, however, the most surprising aspect of this net imbalance data is the amazing stability. There is no trend in the data, and the standard deviation of the residuals is only a bit above about half a watt per square metre.
Remember that this is a system that is moving huge, unimaginable amounts of energy, with average downwelling total surface radiation of half a kilowatt, and peak surface solar insolation of about a kilowatt. More importantly, it is a system with the significant albedo variables being nothing more solid than the ephemeral, seasonal, mutable phenomena of clouds, wind, snow, ice, and vegetation.
In such a system, it is something eminently worthy of study that over the thirteen years of the CERES dataset, for reflected solar and upwelling longwave, 95% of the months are within one watt/m2 of the seasonal average. Within one lousy watt! We assuredly do not know all the reasons why that might be so …
Anyhow, thanks for coming along. Looks like the weather forecast for the voyage was about right.
All the best to each of you,
w.
Standard Proclaimer: If you disagree with something that I or anyone has said, please QUOTE THE EXACT WORDS that you disagree with. Only then can we understand what it is you object to.
[UPDATE]:
DATA AND CODE: The code is in a zipped folder here. Unzip it and put the individual files into the workspace. You’ll also need the CERES TOA data in the same workspace (WARNNG: 230 Mbytes). The main file is called “Three Clocks.R”, I think it’s all turnkey.
Discover more from Watts Up With That?
Subscribe to get the latest posts sent to your email.
Willis, to me clearly looks like a case of a Negative feedback system. The mutable phenomena of clouds, wind, snow, ice, and vegetation would seem to act in a way that preserves an equilibrium balance. Who would’a thunk-it? Makes you wanna bet that the feedbacks to CO2 induced warming are also net negative.
Standard Proclaimer: If you disagree with something that I or anyone has said, please QUOTE THE EXACT WORDS that you disagree with. Only then can we understand what it is you object to.
The phrase I disagree with is…
Net top of the atmosphere.
Awesome post! Sure to get a variety of good responses, just what a true scientist should be asking his students. Instead of what we currently have, with professors TELLING everyone what to believe. It is not settled….
Then there’s the Kelvin temperature variation….. assuming that the Earth is at 288K, or 288.7K now….that’s 0.7/288.7 or roughly a quarter of a percent change that everyone has everyone all in a huppabout.
charles nelson says:
March 8, 2014 at 10:02 pm
Ummm … the satellite is flying around above the top of the atmosphere, measuring the radiation going down and coming up … if you don’t like “net TOA radiation”, what would you call the net of the radiation entering and leaving the system as measured by satellite?
w.
The system Willis describes has run through at least 1.53 Trillion diurnal cycles (365.25 x 4.2 Billion) since the earth’s basic atmosphere and water surface formed more than 4.2 Billion years ago (actually, probably more since the earth’s rotation has been slowed by tidal interactions since then).
1.5×10^12 cycles is a long, long time for natural bio-geo-chemical dampening-feedback systems to evolve to an equilibrium. It allows us to breath that wonderful combination of 78% N2, 21% O2, 0.93% Ar, and 0.04% CO2 and some variable amount of H2O vapor (“vapour” for our AUS, NZ, and UK friends). So, I doubt 0.06% to 0.08% CO2 will give this system little if any trouble adjusting since it’s been much higher in many times in past and terrestrial and aquatic life obviously flourished. ANd it’s that stubborn ECS and inertia that the modelers just can’t seem to grasp. My guess is if they keep training their computer models they will figure it out in about 4.2×10^9 years, too.
“So hop on board, the boat’s leaving the dock, there’s a forecast of increasing uncertainty with a chance of scattered befuddlement … what’s not to like?”
====
That was a most interesting voyage. Seemingly without a destination yet very interesting and insightful. Never lost nor trapped in ice.
As always Skipper, great work! There is quite a bit to consider from your results. Maybe much more than meets the eye at first glance.
“Several features of the last interglacial/glacial transition resemble the recent temperature and precipitation trends They are:
“I) Preferential warming of the low latitudes.
2) Increasing meridional temperature gradient.
3) Increasing precipitation in cold season in the high northern latitudes (which supposedly also accompanied the ice build-up in MIS 5d).
4) Cooling of the northern North Atlantic with simultaneous warming of the equatorial one.
“While some of the above features may be due to the increase of man-made greenhouse gases, they may also indicate that the natural redistribution of shortwave radiation is already affecting the ongoing climate change (Kukla et al., 1992). However no increase of ice volume, nor a decrease of mean sea level have yet been observed. So even if not completely counter balanced by future impact of man-made greenhouse gases, the natural shift toward cooler climates in the middle latitudes of the Northern Hemisphere would be still many millennia ahead. Another point to consider is that the orbitally caused seasonal insolation changes, although qualitatively similar, are less expressed than in the last interglacial. Their amplitude is closer to the exceptionally long Holsteinian interglacial (MIS 11).”
http://geolines.gli.cas.cz/fileadmin/volumes/volume11/G11-009.pdf
Perhaps a 4th clock?
The upwelling longwave in your Figure 6 is interesting.
Probably the most interesting – and important – curve is that of the residuals in Fig 7. The mean is exactly centred on 0 watts/sq m. So on that basis over that period the earth never lost or gained energy. Desirable would be Fig 8, showing (a) a linear regression of the residuals, and (b) the results of a F….. harmonic separation of components making up the residuals (just like separating the various tidal elements). Sorry – forgot the word but it starts with ‘F’.
Very strong supportive evidence for your emergent phenomena theory of climate I would think. The Earth dumps as much heat as it absorbs.
Dudley Horscroft says:
March 8, 2014 at 10:51 pm
Thanks, Dudley. Actually, not so. Figure 7 shows an anomaly, because there is a known difference of 5 W/m2 between the totals of the incoming and outgoing radiation … so the CERES data can’t help us determine if the earth is gaining or losing energy. I’ll clarify that in the head post.
Regards,
w.
Sorry – forgot the word but it starts with ‘F’.
===========================
Fourier, as in Fourier transform: to transform a time series domain data set into a frequency series domain data set (frequencies, phases).
The first post “Alcheson” makes the point – negative feedback. The variable is Earth’s temperature which adjusts itself to maintain balance between incoming and outgoing radiation. However the further point to make is that the time constant of this feedback is clearly very short – at very most a year or two (because the excursions of the residual from zero are of short duration). That means all these claims of stored up warming, ‘even if we stop emitting tomorrow the earth will keep warming for hundreds of years’ is not supported by the experimental data. That means that even if all the warming since 1950 was due to CO2 (with none due to other causes or biased adjusting of the record) the total impact of the half doubling to date is at most 0.7C. Thus the further rise in temperature by 2070 (when CO2 is predicted to be 560ppm) would be a further 0.7C. Thats a little short of the 3C predicted and clearly not in the catastrophic catagory. Of course the probability that all the warming since 1950 is due to CO2 is pretty small given that even warmists now admit to a significant “natural” component plus of course the lack of warming for the last 17 or so years while CO2 has continued to rise.
Willis,
I’m looking at a map of the earth in one open tab and your Figure 6 in another. Trying to understand the upwelling longwave 20S to 20N July and Dec. Primarily focused around 5N to 10N. Something has my attention but I’m not sure what it is.
Maybe Bob Tisdale can take a look and tell me if I’m seeing signal of ocean surface temps or Sahara desert.
At what height is the TOA?
Or is it defined by pressure?
Does the height of the TOA vary between poles and equator?
Does the height of the TOA vary with different atmospheric conditions.
Is the up/down welling radiation measurement the same above a massive cloud bank as it is above a cloudless desert? Or above an ice sheet as compared to the Amazon? Or above a hurricane as compared to an ocean high?
Is the ‘upwelling’ radiation the same over the Sahara Desert in July as it is over Antarctica?
How many Ceres satellites are there?
How long does it take it/them to observe the entire planet?
What is its resolution?
Thank you Willis it was a very interesting trip and I and others have found out much and understand there is so much more to learn.
That is one of the things with wanting to know things you find that the more you learn the more you find you don’t know unless you;re a “claimit” scientist when everything is settled and known.
James Bull
Very good post.
Figure 5 and 6 have the latitude at y-axis. If You change that to an area scaled latitude y-axis will the figures show even more how important the tropics are compared with high latitudes for the energy balance of the earth.
Willis,
I note you have not responded to charles nelson. You used the words “TOA radiation imbalance.” As the TOA seems to be incapable of rigorous definition, any attempt to use it in calculations seems a bit silly. The TOA looks like a Warmist fabrication to ensnare the gullible. I may be wrong, of course, but the prospect of something that by definition would appear to have almost zero mass either absorbing or radiating significant amounts of energy appears dubious at best.
So what definition of TOA have you used?
Live well and prosper,
Mike Flynn.
Willis Eschenbach says:
March 8, 2014 at 10:19 pm
“”charles nelson says:
March 8, 2014 at 10:02 pm
“The phrase I disagree with is…Net top of the atmosphere.”
Ummm … the satellite is flying around above the top of the atmosphere, measuring the radiation going down and coming up … if you don’t like “net TOA radiation”, what would you call the net of the radiation entering and leaving the system as measured by satellite?””
—————————————-
I’m not a scientist but I also have some concerns about the validity of TSI data.
There are some issues with the satellites being in low Earth orbit about 90,000 km below the geocorona.
Orbiting in the exosphere, the altitude above the lower boundary of the thermopause can range from 200-450km, depending on solar activity.
It is my understanding that the exosphere exhibits emission gains and absorption losses.
Infrared is emitted along with a lot of visible light and high energy ultraviolet is absorbed.
The CERES data are presented in a rather deceptive format.
The incident and reflected solar flux terms reported by CERES are spherical area averages. These have little or no relationship to the energy transfer processes that determine the Earth’s climate. The sun only illuminates the local surface during the day and the clouds can only reflect incident sunlight. Only the LWIR flux is continuously emitted to space. There is no equilibrium average, just a dynamic flux balance. Most of the Earth’s surface is water and the sun heats the oceans below the surface. About half of the solar flux is absorbed within the first meter. Another 40% is absorbed from 1 to 10 m depth and the balance is absorbed within the first 100 m.
The oceans can only cool at the surface through a combination of moist convection and net LWIR emission. In good round numbers, the net LWIR emission is around 50 W.m^-2 and the rest of the cooling is by moist convection. The evaporation and LWIR flux exchange are limited to a very thin surface layer. The cooler water from the surface then sinks and cools the bulk ocean layers below. The evaporation depends on the humidity gradient and the wind speed.
Outside of the tropics, the oceans accumulate the solar heat in summer and fall and release it winter and spring. At mid latitudes, this can easily be the equivalent of 40 days of full summer sun stored and released. Within the equatorial ocean gyre currents, the solar heating exceeds the evaporative cooling until the water reaches the ocean warm pools. Here the wind driven evaporation balance plus net LWIR flux balances the tropical solar flux at an average wind speed near 5 m s^-1 and a surface temperature near 30 C. The diurnal fluctuation in the surface temperature also depends on the balance between the solar flux and the wind speed.
The moist air is the working fluid of the atmospheric heat engine that transports the heat up through the atmosphere where the water condenses. Most of the CERES LWIR emission is just the water band emission from the middle troposphere. As the surface temperatures change, the peak emission band moves up and down in altitude. The troposphere also stores and releases heat on a daily and seasonal time scale.
The CERES data is basically the energy balance measured for the cold reservoir of the atmospheric heat engine. The Earth’s climate is determined mainly by [angular] momentum transport (ocean and troposphere) through a gravitational field. Small changes in LWIR flux are fully coupled the heat capacity of the climate thermal reservoirs. They cannot be separated out. There is no climate ‘equlibrium’, just a lot of heating and cooling of large thermal reservoirs.
The next thing to do is to take a walk through the ocean evaporation data analyzed by Lisan Yu and coworkers at Woods Hole [http://oaflux.whoi.edu/publications.html] and have a good look at the effect of the wind speed. How does the ocean evaporation contribute to the CERES data? How does the LWIR flux from a 100 ppm increase in atmospheric CO2 concentration change anything? It certainly does not heat the oceans below the surface. It just disappears deep into the noise of the wind driven evaporation.
The Earth obviously has to have a natural thermostat mechanism, which usually functions very well. At least it has since the last ‘Snowball Earth’ ended about 650 million years ago.
Of course, there have been the occasional ice ages, whose existence we really cannot explain. We are currently in a relatively rare and short lived interglacial of the current ice age, which began around 2.65 million years ago. Obviously, something goes a little awry with the thermostat from time to time.
Without this thermostat, evolution of life on Earth would have been impossible. I think the Ceres data demonstrates how well the thermostat is working right now.
It also helps demonstrate how overstated alarmist theories are in regards to rising carbon dioxide levels. Our climate is much less sensitive to rising CO2 levels than the purveyors of Thermageddon would like us to believe, part of the reason for this is our natural thermostat.
Joel O’Bryan says:
March 8, 2014 at 10:23 pm My guess is if they keep training their computer models they will figure it out in about 4.2×10^9 years, too.
Did you use the numerals ’42’ deliberately, on purpose ?
If so, they will have fogotten the question and will, true to form, start devising models to rectify the omission.
Douglas Adams, a man before his time!
“Once again, however, the most surprising aspect of this net imbalance data is the amazing stability”
What I’ve been saying…our planet is wonderfully balanced. 🙂
How far back does the outgoing LWIR data go? Is there any evidence to support the theory that CO2 has trapped IR energy and reduced the amount being radiated into space?