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.
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Mike the QE (21:58:24) :
The Ap index is an ordinal scale, not a ratio scale, no?
Yes. See section 3 of http://www.leif.org/research/suipr699.pdf
page 14 ff [on the pdf]
I just want to say I double checked Svensmark’s comments on clouds and I was wrong to say it’s medium height clouds that are correlated to cosmic rays. It’s low-level clouds. My apologies for the mistake.
James F. Evans (22:07:49) :
Show the hard data and the apparatus used to observe & measure Sun output data 100 years ago, or 150 years ago and so on.
Here is the apparatus: http://upload.wikimedia.org/wikipedia/commons/thumb/9/97/The_Earth_seen_from_Apollo_17.jpg/240px-The_Earth_seen_from_Apollo_17.jpg
It measures solar output today, 50 years ago, 100 years ago, 150 years ago, …
Here are some hard data from January 1883 (one per hour – average for the month from Wilhelmshaven, Germany):
582 578 576 579 576 568 577 579 572 562 548 543 535 538 548 558 562 559 580 587 593 594 584 584
You cannot generalize and the only assumption in the above example is the the universe worked the same back then as it does now.
Leif Svalgaard (21:03:30) :
[/nit pick on]
“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.”
You mean, approximately when you have a thin shell of uniform depth? Hmm… where have I heard that before?
[/nit pick off]
OK, here’s another completely off-the-wall suggestion. The bulge acts like a lens, focusing the light in such a way as to warm the troposphere and cool the stratosphere, and vice versa when the bulge diminishes. By focusing the sunlight inward, it takes a shorter path to the surface, so it doesn’t spend as much time taking the longer path “sideways” through the atmosphere. It might not be as crazy as it sounds. Generally speaking, objects on the horizon are refracted a full 1/2 degree or so through the atmosphere. The inward flux is so large that even a small change might have a significant effect.
I’m just throwing out ideas here so, no snark from anyone, please.
Jim Arndt (16:26:03) :
Here is a comparison using many different aspects of magnetism and comparing it to temperature variability.
http://www.appinsys.com/GlobalWarming/EarthMagneticField.htm
From that link:
“Most of the energy transfer to the Earth from the solar wind is accomplished electrically, and nearly the entire voltage associated with this process appears in the polar cap region, which extends typically less than 20° in latitude from the magnetic pole. The total voltage across the polar cap can be as large as 100,000 volts, rivaling that of thunderstorm electrification of the planet in magnitude. This polar cap electric field is the major source of largescale horizontal voltage differences in the atmosphere. Moreover, the dynamic polar region accounts for a large fraction of the variability inherent in our upper atmosphere, variability due to chaotic changes in the solar wind magnetic field that produces large-scale restructuring of the cavity enclosing the Earth’s magnetic field. This restructuring visibly manifests itself most clearly in the production of ionized plasmas and the associated distribution of aurora high over the north and south polar regions. In turn, the Earth’s lower atmosphere (that part responsible for weather phenomena) undergoes variations in composition and dynamics influenced by these coupling effects through a complex and as yet not fully understood feedback system. [http://www.arcus.org/logistics/svalbard/Svalbard.pdf]
“It can be seen from this plot that there have been a number of changes in the general trend of secular variation in the past, in particular at about 1925, 1969, 1978 and 1992. These sudden changes are known as jerks or impulses and, at the present time, are not well understood and are certainly not predictable. Some researchers have found evidence for a correlation with length-of-day changes.” [http://www.geomag.bgs.ac.uk/earthmag.html]
It’s also correlated with another entirely predictable phenomenon. I won’t discuss it here in deference to Anthony’s wishes, but I have a blog post up if you click on my name. I’d welcome comments and discussion.
One small spot for the Sun, one giant storm for the nation’s heartland.
Kind of ironic. and that pic of the Sun at the top made me do it.
Onar Åm (19:30:43) “If that is the case then this strongly suggests that the ENSO and the sun are fairly independent factors that control cloud cover.”
I would describe the multivariate phase-contrasts as being at least intermittently non-random (so cross-wavelet methods will be more fruitful than cross-correlation, at least until the conditioning is worked out). I would encourage you to reconsider the nature of what you are calling “the sun”. Also, we need to keep in mind that SOI is just one index of pressure patterns. The work that needs to be done on this file is going to require a clear agenda for an indefinite amount of time, but I can see no higher priority in climate research at this stage. I’ve shelved my work on this file, knowing that I will have to be funded to the teeth, with no competing obligations, to arrange the operations necessary to advance on this front. Hopefully others are better-positioned to launch an offensive.
Why do so many people speculate inaccurately about what they imagine Henrik Svensmark thinks, when all but his very latest work was set out in plain language by him and me, in our book The Chilling Stars, published in 2007 and updated in 2008?
The geomagnetic field has very little influence on the Svensmark effect. Here’s what we wrote on pp. 59-60 of The Chilling Stars (both editions).
“The calculations focused on the cosmic-ray activity in the lowest 2,000 metres of the atmosphere, which contributes to the formation of the climatically important low clouds. Remarkably, as many as 60 per cent of the all-important muons are products of cosmic rays coming in from the Galaxy with so much energy that the Sun’s magnetic defences offer no protection against them. They are not involved in the climatic variations over the centuries due to changes in the Sun’s behaviour. Over millions of years, the input of these energetic cosmic rays changes as the Earth travels with the Sun through changing scenery in the Galaxy. Later in the book we’ll see how big the consequences were for the Earth’s climate.
“The remaining 40 per cent of cosmic rays that influence events in the lower air are subject to control by the Sun’s magnetic field. That’s plenty to account for the swings between warm and cold periods already described. But the Earth’s magnetic field has a much weaker effect. The outcome of the calculations is that only 3 per cent of the cloud-making muons that penetrate to low altitudes originate from incoming particles of such relatively feeble energy that changes in the Earth’s magnetism can affect them.”
Why cant we just point a particle accelerator at a clear sky, fire it up, and see if we cant start a cloud off?
I’ve already said why there won’t be much of a corelation between total cloud cover and magnetic index \ cosmic ray count.
cloud formabilty increases with increasing cosmic ray counts.
But also,
Precipitation-abilty ( cloud destruction ) also increases with increasing cosmic ray counts.
The net amount of cloud does not change much.
Clouds form easier, but also precipate easier.
You can’t have your cloud and eat it.
Average cloud lifetime decreases with increasing cosmic rays.
The main effect of increase in cosmic rays on climate is the variation in location of cloud cover, which shifts to the oceans. This warms the oceans slightly, while the land becomes colder and more arid.
I’d like to see a wattsupwiththat article on this effect. But we’ve got 150 ideas in the comments on how GCR cause Earth temperture to go down. So the idea is somewhat lost in the blizzard. I’m glad you posted Roy Spencer’s take on the increase GCR = increase cloud cover because it shows it to be poor at best and likely false. Now we’ve got that theory out the way ( again ), can we please move onto the truth?
Maybe the answer is more simple that we think.
Maybe the low magnetic solar induces changes in the rotarion of the Earth. First, the core the Earth, later the mantle and later the crust.
In the crust, first the solids change the velocity. Later the liquids. In plain words, first the change in velocity afects the continents and later the oceans. Because the cinetic energy of the waters the behaviour is different .
But if that changes in velocity afects in different ways and time the solids and the liquids in the crust, maybe afects diferently the gases. So, when the velocity of the earth changes, the global air circulation changes too. And the temperatures.
So, nothing of this is new as we thougth. The answer maybe is more “simple” than we think.
We can read more about that explanation here:
http://www.natsci.colostate.edu/jurs/example/index.htm
http://sait.oat.ts.astro.it/MSAIt760405/PDF/2005MmSAI..76..957D.pdf
And following the others…
Perhaps we should open the eyes to others works and be less pretensious. Who knows?
Leif Svalgaard (17:05:59)
“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.”
I don’t see that that matters. You are still fixated on energy content rather than the degree of turbulence in the flow of energy through space to the Earth from the sun.
The observed ‘breathing’ of the upper atmosphere, which you confirm has been known about for decades suggests that the rate of energy loss from atmosphere to space does vary with the turbulence or unevenness of the flow of solar energy through space to the Earth.
A deductive leap needs to be made so as to realise that if such an effect occurs on a small scale with individual solar flares then that effect is going to be present on a very much larger scale as the level of solar turbulence changes over centuries from say Maunder Minimum to Modern Maximum and back again.
The fact that the absolute power of the sun varies hardly at all seems to be irrelevant. What seems to happen is that the more uneven, irregular, turbulent (or whatever) the flow of energy from the sun is then the faster energy is lost from the upper layers of Earth’s atmosphere to space.
The more stable it is the less quickly energy is lost from the upper layers to space.
The SABER observation is evidence of that.
The observation referred to by Tenuc is evidence of that.
The observation that the cooling of the stratosphere correlates with an active sun and a warming stratosphere correlates with a less active sun is evidence of that.
All the earlier knowledge about the ‘breathing’ effect is evidence of that.
Once one reverses the sign of the temperature effect of a more active sun then a great deal falls into place as I have pointed out.
Reversing the sign allows an obvious balancing act to emerge whereby the temperature of the troposphere is dictated by interplay between oceans and sun. Sometimes offsetting one another and sometimes reinforcing one nother.
The evidence that a reversal of the sign is correct is that one can then postulate a reason why interglacials are relatively stable ( ocean effects are offset by solar effects and vice versa) and why glacial epochs are so unstable (ocean and solar effects compound one another resulting in much larger temperature swings).
It also follows that ocean effects and solar effects are not always timed so as to offset one another as they do currently (on average). You have previously accepted that the current timing of weak sun with low temperatures (such as during the Maunder Minimum) might be coincidental. I now agree with that. It would seem that with current landmass distributions that timing has to be as it now is to allow an interglacial at all.
So, during say the Carboniferous one would regularly see low solar turbulence reducing energy loss to space and a build up of energy in the troposphere during periods of warm ocean surfaces that would not be fully offset by reductions of energy in the troposphere during periods of cool ocean surfaces thus a warm period overall.
During ice ages the ocean warm periods would be met with a less active sun thus both processes acting to accumulate energy in the troposphere at the same time whilst during ocean cool periods there would be a more active sun thus both processes acting to reduce energy in the tropsphere with the warmer spells failing to fully offset the cooling of the cooler periods leading to large climate swings and ice cap growth.
The logic seems sound and it fits rather a lot of real world observations.
Following Nigel Calder’s comment above. Maybe we need think about that idea that its only strong events like forbush events or a really stong AP index that can drive away GCR’s that form clouds. I think the grain cleaner analogy might just be correct. The only way to clean the light grain out well is to turn the fan up pretty high. A low Ap index does nothing.
Nigel :
.
Why do so many people speculate inaccurately about what they imagine Henrik Svensmark thinks, when all but his very latest work was set out in plain language by him and me, in our book The Chilling Stars, published in 2007 and updated in 2008?
.
I also wondered . I hope that it is now clearer for everybody after your comment .
I think that the arctic has been cooler for the last two winters because of low solar activity and volcanic activity ,if it was cold in the arctic last winter because of a la Nina it cannot be cold in the arctic this year because of an el nino we need another explanation.The great global warming scandal showed a graph which linked arctic temperatures and solar activity maybe if the graph was updated it would still show arctic temperature tracking solar activity.
meemoe_uk (02:25:30) :
As a former science teacher (I am resting on my lauels and reading this for entertainment) I have spent some fair amount of embarrassing moments in front of a class trying to get a cloud chamber to work. As you may know if the saturation of alcohol is not high enough there are no particle traces. My own partially educated guess is that Leif Svalgaard’s phenomenon is based on creating clouds in marginal conditions of water vapor saturation where no clouds would form in normal conditions, and cause denser clouds than normal conditions would form.
Admittedly there is also rain in marginal conditions as well. But as a Louisiana boy, born and breed, I can say I never saw a cloud dissapate after raining on me for as much as a week at a time. Though no rain falls out the bottom, the cloud still reflects off the top.
Nigel Calder (00:27:03) :
“But the Earth’s magnetic field has a much weaker effect.”
Thank you for the clarification.
The sun’s behavior is a major player behind the ENSO phases and we all know that the latter can have an effect upon global temperatures. So might I suggest when looking for possible relationships between solar and climate, or even weather, that you look into the prior forecasting record of those who have been using this type of methodology for over a decade now. (And not one miscue ever, ENSO phase wise. ) Just a helpful hint Roy.
[quote] Why do so many people speculate inaccurately about what they imagine Henrik Svensmark thinks, when all but his very latest work was set out in plain language by him and me, in our book The Chilling Stars, published in 2007 and updated in 2008? [/quote]
An excellent book too. I’m looking forward to future developments. 🙂
“To be more clear, I asked Gavin directly to identify the natural variability that was effecting temperature since 1998. He deleted my comment.”
May I suggest a special blog? The “RealClimateCensored blog” of deleted comments from that blog. It would be quite interesting.
http://travismonitor.blogspot.com/2009/12/realclimate-blog-part-of-climategate.html
Leif Svalgaard:
Pleased to see you posting!
One thing is for sure though. At the moment the sun is not doing much. According to Ace ( http://www.swpc.noaa.gov/ftpdir/lists/ace2/200912_ace_swepam_1h.txt ) the wind has dropped to 225.8 (2009 12 05 0400 55170 14400 0 0.2 225.8 -1.00e+05) and the Ap index has been at or below 1 for 4 days this last week ( http://www.swpc.noaa.gov/ftpdir/lists/geomag/7day_AK.txt ).
What was that theoretical minimum wind speed Lief?
MattB (07:49:56) :
What was that theoretical minimum wind speed Leif?
About 250 km/s. You can see it being reached here:
http://www.swpc.noaa.gov/ace/MAG_SWEPAM_24h.html
Note the scatter of the solar wind speeds. This is mostly thermal in nature. Doesn’t make sense to cherry pick the lowest point without considering the natural scatter. 250 km/s looks good for right now.
I’m confused about the number of sunspots. This article says 1 (image at top of article.
The widget has “#13 sunspots”. I sthat 13 or a reference to spot 13?
The image way down on the right of the blog has two discernable spots, but more on the grey image.
Can anyone help?
A CUSUM of the CERES data would possibly be interesting.