Geomagnetic Forcing of Earth’s Cloud Cover During 2000-2008?
Guest post by Roy W. Spencer, Ph. D.
I’ll admit to being a skeptic when it comes to other skeptics’ opinions on the potential effects of sunspot activity on climate. Oh, it’s all very possible I suppose, but I’ve always said I’ll start believing it when someone shows a quantitative connection between variations in global cloud cover (not temperature) and geomagnetic activity.
Maybe my skepticism is because I never took astronomy in college. Or, maybe it’s because I can’t see or feel cosmic rays. They sound kind of New Age to me. After all, I can see sunlight, and I can feel infrared radiation…but cosmic rays? Some might say, “Well, Roy, you work with satellite microwave data, and you can see or feel those either!” True, but I DO have a microwave oven in my kitchen…where’s your cosmic ray oven?
Now…where was I? Oh, yeah. So, since I’ve been working with 9 years of global reflected sunlight data from the CERES instrument flying on NASA’s Terra satellite, last night I decided to take a look at some data for myself.
The results, I will admit, are at least a little intriguing.
The following plots show detrended time series of monthly running 5-month averages of (top) CERES reflected shortwave deviations from the average seasonal cycle, and (bottom) monthly running geomagnetic Ap index values from the NOAA Space Weather Prediction Center. As I understand it, the Ap index is believed to be related to the level of cosmic ray activity reaching the Earth. (I will address the reason for detrending below).
Note that there is some similarity between the two plots. If we do a scatterplot of the data (below), we get an average linear relationship of about 0.05 W per sq. meter increase in reflected sunlight per 1 unit decrease in Ap index. This is at least qualitatively consistent with a decrease in solar activity corresponding to an increase in cloud cover.
(I’ve also shown a 2nd order polynomial fit (curved line) in the above plot for those who think they see a nonlinear relationship there.)
But just how big is this linear relationship seen in the above scatterplot? From looking at a 70-year plot of Ap data (originally from David Archibald), we see that the 11-year sunspot cycle modulates the Ap index by at least 10 units. Also, there are fairly routine variations on monthly and seasonal time scales of about 10 Ap units, too (click on image to see full-size):
When the 10 Ap unit variations are multiplied by the 0.05 scale factor, it suggests about a 0.5 W per sq. meter modulation of global reflected sunlight during the 11 year solar cycle (as well as in monthly and yearly variations of geomagnetic activity). I calculate that this is a factor of 10 greater than the change in reflected sunlight that results from the 0.1% modulation of the total solar irradiance during the solar cycle.
At face value, that would mean the geomagnetic modulation of cloudiness has about 10 times the effect on the amount of sunlight absorbed by the Earth as does the solar cycle’s direct modulation of the sun’s output. It also rivals the level of forcing due to anthropogenic greenhouse gas emissions, but with way more variability from year to year and decade to decade. (Can anyone say, “natural climate variability”?)
Now, returning to the detrending of the data. The trend relationship between CERES reflected sunlight and the Ap index is of the opposite sign to that seen above. This suggests that the trend in geomagnetic activity during 2000-2008 can not explain the trend in global reflected sunlight over the same period of time. However, the ratio of the trends is very small: +0.004 Watts per sq. meter per unit Ap index, rather than -0.045. So, one can always claim that some other natural change in cloud cover is overpowering the geomagnetic modulation of cloudiness. With all kinds of climate forcings all mingled in together, it would be reasonable to expect a certain signal to emerge more clearly during some periods, and less clearly during other periods.
I also did lag correlation plots of the data (not shown), and there is no obvious lag in the correlation relationship.
All of this, of course, assumes that the observed relationship during 2000-2008 is not just by chance. There is considerable autocorrelation in the reflected sunlight and geomagnetic data, which I have made even worse by computing monthly running 5-month averages (the correlation strengths increased with averaging time). So, there are relatively few degrees of freedom in the data collected during 2000-2008, which increases the probability of getting a spurious relationship just by chance.
All of the above was done in a few hours, so it is far from definitive. But it IS enough for me to keep an open mind on the subject of solar activity affecting climate variations. As usual, I’m just poking around in the data and trying to learn something…while also stirring up some discussion (to be enjoyed on other blogs) along the way.
UPDATE (12:30 p.m. 10 December 2009)
There is a question on how other solar indices compare to the CERES reflected sunlight measurements. The following lag correlation chart shows a few of them. I’m open to suggestions on what any of it might mean.
Fitzy – you suspect that the earth is tethered electromagnetically to the sun?
http://www.nasa.gov/mission_pages/themis/news/magnetic_tremors.html
http://www.spacedaily.com/reports/Giant_Electrical_Tornadoes_In_Space_Drive_The_Northern_Lights_999.html
http://www.thunderbolts.info/tpod/2009/arch09/090429stir.htm
This video won’t play:
http://cdsweb.cern.ch/record/1181073/
No idea idea why – and no interest in software techno-babble.
Anyone know of an alternate that simply works when one hits “play”?
Bart (16:26:00) :
I am only interested in the upper atmosphere from here on out.
Bart (16:27:10) :
And, I am suggesting that lower pressure in the upper atmosphere should lead to cloud formation there.
Upper atmosphere is from 100 km on up. Not many clouds up there [NC excepted].
Stephen Wilde (16:33:26) :
The energy loss described in my link:
“Sunspots unleash solar flares that create a ripple effect well beyond Earth. But when that energy flow does reach Earth, the atmosphere reciprocates by ejecting radiation as a cooling effect.”
that statement borders on nonsense [probably caused by the PR people]. Again: what energy flow?
Even the largest solar flares produce only 1/4,000 extra energy from what we get from TSI and that only for a few minutes. In fact, only one case has been observed: http://sprg.ssl.berkeley.edu/~tohban/wiki/index.php/Chree_Analysis_for_Flares
Roy
On lags, see Charles Perry finding a 34 year lag as most significant with R2 ~ 0.35. See Fig. 6 in:
Evidence for a physical linkage between galactic cosmic rays and regional climate time series Charles A. Perry, Advances in Space Research 40 (2007) 353–364
You just had to do it, didn’t you! And with a nice stretch of spot free days, too.
But now you post on sunspots, and: Daily Sun: 10 Dec. 09
Emerging sunspot 1034 is a member of new Solar Cycle 24. Credit: SOHO/MDI
http://spaceweather.com/
It’s not a very impressive one, though.
http://spaceweather.com/images2009/10dec09/midi512_blank.gif?PHPSESSID=kbk87q8jm8b4f2bavjfspqmg16
(it’s at about 10:00, just coming over the rim)
“Proxy” reconstructions are problematic.
Science can now observe & measure the sun’s output in high resolution.
Before the space age much of the Sun’s observation was limited to sunspot counts and apparent magnitude.
Conclusions about present solar activity based on assumptions, “proxy” reconstructions, of past solar activity is subject to the same weaknesses as other “proxy” paleo-reconstructions.
To eliminate the Sun’s output as a cause of temperature change when hard data is unavailable and paleo-reconstructions is all Science has for comparison/analysis is unwarranted.
While rare, a solar “superstorm” can, and and even has, occurred.
http://science.nasa.gov/headlines/y2003/23oct_superstorm.htm
But when that happens again, cloud cover or the lack of it will be the least of our worries.
James F. Evans (17:36:42) :
Conclusions about present solar activity based on assumptions, “proxy” reconstructions, of past solar activity is subject to the same weaknesses as other “proxy” paleo-reconstructions.
No, they are not. And many paleo-reconstructions are actually measurements, just using the Earth as the instrument. You can’t generalize here.
Leif Svalgaard (17:05:59) :
“Upper atmosphere is from 100 km on up. Not many clouds up there.”
The bulge can extend from about 100 km to maybe 500 km. The atmosphere in it is not very comparatively dense, but the volume grows with R^3, so I would imagine that could be sucking a large number of air molecules from the higher altitudes (~8-23 km I am guessing) which do have clouds.
At the risk of sending you on another tangent, the difference between stormy and fair weather at the surface is less than 10% of total pressure, so in an analogous situation, it might not take too much mass exchange at high cloud forming altitudes to make a big difference.
3/4 of earths (exposed) land mass is in the northern hemishere, 7/10 of the earth is covered by water.
i.e. land temperatures didn’t cause the ice ages,wonder what did? combination of many cyclic forces that happen to coinside every 100k years or so? with smaller coinsidences around the main event every 20k years or so? looks like thats whats been happening lately. somebody figure it out and let me know, i’m curious.
Crosspatch:
The question was posted with respect to the posting of the global editorial on Realclimate.org.
RC.O posted a preamble to the editorial with the disclaimer that the mods of RC took no position on the editorial.
This prompted two very relevant questions:
1. Why won’t you take a position on the editorial?
2. Were you instrumental in its authorship?
If they participated in its authorship, then they are being dishonest about not taking a position about it…it’s their own workproduct.
In the end, the issue is transparency.
Re:
ShrNfr (11:26:47) : “Actually, you can “see” cosmic rays (or rather their byproducts) when you are the ISS. When a muon goes through the right area of your skull it causes a flash of light in you visible field.”
“OT, but as a word of caution, those flashes could also indicate a torn or about to be torn retina. Been there, done that. If they persist have it checked.”
OR, these flashes could mean onset of the “Al Gore Syndrome”; a psychiatric disorder causing the patient to see things that plainly are not there.
CH
Bart (18:05:34) :
The bulge can extend from about 100 km to maybe 500 km. The atmosphere in it is not very comparatively dense, but the volume grows with R^3, so I would imagine that could be sucking a large number of air molecules from the higher altitudes (~8-23 km I am guessing) which do have clouds.
The density decreases by a factor of 1000 for each 50 km you ascend, so at 100 km it is a million times smaller than at the surface, at 150 km, a billion times smaller, etc. Not much air to exchange.
And the volume of a shell [an atmospheric layer] increases with R^2, not R^3, if R was supposed to mean distance from Earth’s center.
A polite discussion. Who needs peer review.
Roy,
If my memory serves me correctly there is a major correlation between cloud cover and various climatic oscillations, in particular the ENSO. it would be interesting to see the crosscorrelation between the Ap index, cloud cover and the ENSO. My guess is that the correlation between the cloud cover and ENSO is much higher than the correlation between the Ap index and the ENSO. If that is the case then this strongly suggests that the ENSO and the sun are fairly independent factors that control cloud cover. In that case it should be possible to filter out the ENSO-contribution to get a better correlation.
yonason (17:35:51) :
I projected it this morning, a shade darker than 60% black.
It should not last long as the diffusion rate of it’s underlying Active Region is proceeding unhindered.
Regarding increasing cloud cover. Given that many, but not all, met sites record sunshine hours, can this data be used as a proxy indicator for cloud cover (or tha lack of)? By this I mean, are we seeing any noticeable decreases in sushine hours around the world, and if so does this confirm an increase in cloudiness? Or is this just too simplistic?
“And the volume of a shell [an atmospheric layer] increases with R^2…”
Only approximately for a thin shell of uniform depth.
The volume of a spherical shell is (4/3)*pi*(R2^3-R1^3), where R2 is the upper radius, and R1 is the lower. Perhaps more usefully, I calculate the volume of a conic segment of a spherical shell as (4/3)*pi*(R2^3-R1^3)*sin(phi/2)^2, where phi is the half angle of the cone. If you fix R1, the volumes grow as R2^3. That is what I meant.
“The density decreases by a factor of 1000 for each 50 km you ascend, so at 100 km it is a million times smaller than at the surface, at 150 km, a billion times smaller, etc.”
But, that profile is precisely what the bulge changes. And, of course, we are looking for pressure, not density, variation, although I suppose they ought roughly to be proportional to one another…
I admit, prima facie, it does not look too promising, but it all depends on how sensitive the cloud bearing layer is to pressure variation, and whether perhaps I have simplified things too much by neglecting temperature variation.
Eh, it was worth a try anyway. /shrug
-35 F in Wyoming USA this morning
-58 F in Siberia Russia this morning
I don’t think -PDO explains that
I’m with UK(US) at 14:22… ITSS
Bart (19:57:38) :
Perhaps more usefully, I calculate the volume of a conic segment of a spherical shell as (4/3)*pi*(R2^3-R1^3)*sin(phi/2)^2, where phi is the half angle of the cone. If you fix R1, the volumes grow as R2^3. That is what I meant.
No, because R2 is almost the same as R1, say R2 = R1 + dR, then R2^3 = R1^3 + 3R1^2*dR, and (R2^3-R1^3) = 3 R1^2 dR, hence R^2 not R^3.
[/nit pick off]
…the potential effects of sunspot activity on climate.
I think it’s not about sunspots. I can’t remember Henrik Svensmark singling out sunspots.
Does Henrik Svensmark know he is being discussed here?
Onar Åm (19:30:43) :
Basically, that is where I was headed with my comment earlier. The problem is that if(<–) the sun warms the ocean, then when the AP index goes down and theoretically, cloud cover goes up, SSTs should also go down?
But then I got thinking about how land masses bleed their radiative energy faster than water and it only made sense that the land temps would drop before an El Nino and cooler air would settle over the Pacific which would then allow heat to escape and warm the continents, which would then bleed the energy off into space. Then I decided I was thinking way too deeply about it and sat down with my daughter to color.
Off the topic:
The notion that the earth revolved around the sun was heresy to the Church, since it took man away from the centre of the universe.
Actually, a) it was not declared a heresy and b) the earth was at the bottom of the universe, the most ignoble spot, farthest from heaven. The science was against Galileo. The lack of parallax falsified the theory, and the Church was not prepared to abandon any literal readings [not in the face of Protestant accusations that they were soft on the Bible] just on Galileo’s say-so. Bellarmine invited him to submit empirical evidence, but he never did so. The Proof of the Tides was bogus, and people at the time knew it. Now, the lack of parallax was because the stars were much farther away than astronomers had supposed, but you can’t prove one unproven hypothesis by making a second unproven hypothesis.
On the topic:
The Ap index is an ordinal scale, not a ratio scale, no?
I have seen many a correlation as a QE where at one process level of X there was no correlation with Y and at another level no correlation — but the difference in level of X clearly matched a difference in the level of Y.
Show the hard data and the apparatus used to observe & measure Sun output data 100 years ago, or 150 years ago and so on.
Without hard data, “proxy” paleo-reconstructions are problematic.
Reconstructions are not primary evidence, rather reconstructions are a series of assumptions.
Any and all assumptions must be viewed with scepticism, especially any that can’t be directly verified.
Essentially, AGW relies on assumptions for its viability as a science.
Too many assumptions.