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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philincalifornia (12:29:37) :
This may be OT but, then again, it may not be. Whatever, it’s super interesting. Weather patterns (literally) on Saturn:
http://www.sphere.com/science/article/cassini-spacecraft-images-show-mysterious-hexagon-on-saturn/19273284
It’s not just Saturn that shows interesting harmonic patterns in it’s weather.
http://ray.tomes.biz/b2/index.php/a?s=jupiter+storms&sentence=AND&submit=Search
My belief is that as new and hopefully more accurate hypothesises are tested that more people will jump from the AGW bandwagon.
People, and scientists in particular, want to be on the cutting edge of innovation – not stuck defending defunct and inelegant ideas.
Thanks Roy. So we can say that on the face of it Solar Geomagnetic Ap is not associated with cloud formation. What is the certainty that Ap is associated with GCR? It sounds like sound reasoning (Solar Ap) might be an indicator. But I would think that Terrestrial magnetic fields are the key and first we might whether Solar Geomagnetic Ap has a straight or lagged R2 to Terrestrial fields? Might that be a missing link or did I read it wrong on which field was used?
David L. Hagen (12:31:15) : Cosmic rays, 90% proton, are not those simple mix of particles and lines we inmediately imagine, they are hydrogen nucleii, which if react with ozone make water as a result.
OK, one thing is, my familiarity with the bulge is a good bit higher than the stratosphere. But, the higher the clouds, as I understand it, the more they induce net warming.
Exactly – (with exceptions noted below) …
“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.”
Hint: SOI, IOD, NAM, …
My sense is that we’re just looking for things that affect pressure & circulation patterns and hence redistribution. I don’t imagine any “magic” forces at work – just basic stuff Barkin talks about that affects insolation (not irradiance) – Earth’s shells shaking relative to each other – maybe a multi-layered rattle (tangled with seasonal effects) is a good analogy.
Cautionary notes:
1) Low r^2 (even very low r^2) sometimes comes with low p-value; this could indicate complex conditioning (see Roy’s above note – i.e. it’s not always simple bivariate linear – it can be multivariate nonlinear — also, there are summer/winter contrasts – filtering them out can substantially change the r^2 and hint at why sometimes NAM & sometimes SOI, etc. seem to follow regional (local mountains or whatever are important) precipitation & temperature range (loose proxy for cloud cover) more closely…).
2) Confounding! I encourage people to keep an open mind about what (lurking, unmeasured) factors are partially confounded with GCR/aa/R.
Relationships I find between aa index, LOD, temperature range, lunar nodal cycle, & Earth orientation parameters are happening at the Earth end so far as I can tell. Here are a few glimpses:
http://www.sfu.ca/~plv/-LOD_aa_Pr._r.._LNC.png
However politically incorrect it may be in our times, this is no trivial result to scoff at. (note: ~1990s anomaly is known to relate to nutation obliquity – so no problem there – just more work to include another variable…)
http://www.sfu.ca/~plv/CCaa1mo&11aT1mo.PNG
(A challenge “screwing up” this analysis is serious issues with temperature homogenization procedures — it will be serious business sorting it out — FUNDING NEEDED!!)
http://www.sfu.ca/~plv/sqrtaayoy.sq22.png
(Note that averaging over hale cycles loosely means we’re looking at something on the Earth end here.)
Although most of the shared signals appear to be at the Earth end, I need to look into solar wind speed (haven’t yet), because there is something “weird” going on there that seems related to regional precipitation patterns. Anyone know where I can find monthly (&/or daily) summaries (&/or reconstructed estimates) of solar wind speed going back as far as possible in time (on a plain-text webpage)?
Confounding!
Conditioning!
We’ll never get anywhere without relentlessly unyielding awareness of these. The alarmists might love it if the complexity causes us to give up on pursuit of the complex-but-clearly-nonrandom.
Dr. Spencer: Since cosmic radiation reaching earth is a function of several things–solar magnetic activity, fluctuations in the earth’s magnetic field strength, fluctuations in cosmic ray flux entering the heliosphere–wouldn’t it be better to look directly at the cosmic ray flux reaching earth, rather than using a proxy that only addresses one of the factors?
I tried to find a plot of neutron counts over the last 9 years without luck, but the raw data is available from the University of Delaware:
http://neutronm.bartol.udel.edu/
I have seen so many blue skies spoiled by high-flying aircraft — their jetstreams broaden out till the whole sky is covered by high cloud — that I think that is more operative than cosmic whatevers.
The break in the time series is because there are 2 months of missing data from the CERES instrument.
Leif Svalgaard :
“The ‘breathing’ of the ionosphere has been known by decades and has nothing to do with the climate.”
Reply:
If it increases the rate of energy loss to space during a period of more turbulent solar activity then it would have an effect on climate.
As the energy loss to space increases from the stratosphere upwards it will also increase the rate of flow from troposphere to stratosphere and thus help to offset warming of the troposphere from other causes such as a greater rate of energy flow from oceans to air.
In the process the speed of the hydrological cycle within the troposphere would also increase with a consequent shift in the latitudinal positions of all the air circulation systems.
On that basis the speed of the hydrological cycle would be dictated by an ever changing balance between the rate of energy release from the oceans and the rate of energy loss from upper atmosphere to space.
Such solar induced acceleration and deceleration of energy loss to space as a result of increased or decreased turbulence in the flow of solar energy even in the absence of a substantial variation in solar power would also explain why the climate effect is disproportionate to the change in solar power output.
I know nothing about the sun’s effect on clouds but my practical experience in a now neglected technology may be helpful. Long before geostationary satellites made communication anytime, anywhere so easy, my introduction to the effect of the sun on day to day activities on earth started when, over fifty years ago, I joined the UK Army, and trained as a radio operator using morse code. We were given a course in radio theory, which included the constitution of the upper parts of the earth’s atmosphere used in radio transmissions, the ionosphere.
There are three layers of the ionosphere which control point to point radio. These are termed the D, E and F layers. The highest, the F layer, is about 200 miles above the earth. The sun’s radiation causes ionisation of the atmosphere which makes the layers electrically conductive. The D and E layers lie below the F layer and are less important, the F layer being the principal element in long distance communications. At night time, in the absence of the sun’s radiation, the D layer ceases to exist while the F layer becomes a single layer. During daylight hours, under the effects of exposure to the sun’s radiation, the D layer reappears and the F layer separates into two distinct layers called F1 and F2. This is settled science originated by Marconi in 1901, and fully developed in the first twenty five years of the last century. It is non-controversial, but today is largely forgotten as reliance on point to point radio communication has greatly reduced.
Maintaining communications required a transmitted signal to enter the F layer and be bent, or refracted, back down to earth. If the frequency of the transmitted signal was too low, it would be absorbed in the atmosphere. If the signal frequency was too high, the signal would pass through the atmosphere and be lost in space. Therefore, careful calculation of the route the signal had to take between sender and receiver, as well as the skip distance, i.e. point of return to earth, time of year and time of day was required.
At night the effect of the absence of sun’s radiation and the subsequent reduction in electrical conductivity of the ionosphere, is that a radio link using a transmitter at a frequency of 15 to 20 Megahertz during the day, would have to reduce its frequency to circa 3 to 5 Megahertz during the night. The absence of the sun’s radiation introduced a factor of over three in the choice of day/night frequency.
The most important overall element in frequency selection was the point in the average eleven year sunspot cycle at the time. If sunspot activity was at a peak, then much higher levels of ionisation of the atmosphere occurred, creating greater electrical conductivity enabling higher radio frequencies to be used. Conversely, if sunspot activity was at minima, electrical conductivity decreased and usable frequencies would be greatly reduced. In my experience, usable radio frequencies reduced by at least 15 – 20% during sunspot minima.
If sunspot activity has such demonstrably dramatic affects on the upper atmosphere, it is a racing certainty that it affects the twelve miles or so of the lower atmosphere that controls our weather.
Reaffirming my faith in humanity:
lowercasefred (12:33:51) “Anyone who expects a simple relationship just does not understand what is, or may be, going on.” / lowercasefred (12:50:08) “It is just not reasonable to expect a simple correlation.”
crosspatch (12:05:23)
Yes, the increased surface area has already been proposed by me as the reason for the increased rate of energy loss during a more turbulent solar energy flow.
However I likened it more to the wind causing waves so that the more turbulent flow of energy from the sun causes ripples in the boundary layers in the upper atmosphere causing a greater surface area for each and a faster flow of energy to space from the top of the stratosphere upwards.
Note that this is contrary to normal expectations.
What it means is that the cooler stratosphere during a period of more active sun (late 20th Century) is caused by the higher level of turbulence in the flow of energy from the sun and NOT by an increase in GHGs keeping back more energy in the troposphere.
In fact the consequent cooling of the upper atmosphere more than offsets the extra surface warming from the slightly more active sun and mitigates the heating effects from warmer ocean surfaces but only during the current interglacial whilst there is a coincidence between active solar cycles and warm ocean cycles.
Once that coincidence ceases the solar and oceanic cycles start to reinforce one another rather than offsetting one another leading to the wilder climate variations observed during ice ages.
Thanks Dr Spencer for yet another post to get me thinking.
The solar cycle affects the earth in many different ways during it’s course. As you mention, it is difficult to separate out how the different earth/sun interactions effect our climate against a background of natural climate ‘noise’.
For example, we know that TSI stays roughly the same, but other things like Ap index and amount of UV vary strongly (see quote).
Marty Mlynczak, of NASA Langley Research Center:-
“…In the quiet solar year of 2008, for instance, the upper atmosphere’s ultraviolet radiation emissions have dipped to levels 10 times lower than when SABER’s observations began in 2002…”
It would seem that we have a difficult jigsaw to put together before we can work out what’s happening – we could well be missing some of the pieces too.
Can the current buildup of the record amount of ice in the Arctic and Antarctic be explained by the current solar minimum?
Congratulations and thanks to Roy Spencer for doing this. Very interesting.
A couple of comments :
Instead of using the Ap index as a proxy for GCRs, wouldn’t it be better to use actual GCR data.
ENSO possibly has quite a large effect on cloud cover, so would make any study over a short time period rather problematic.
If I understand the GCR/cloud theory correctly …
There could also be regional / seasonal / other factors affecting cloud formation by GCRs – ie, GCRs may form the aerosols, and clouds form on the aerosols, more effectively at some times than at other times.
Please keep the research going, but it could take a while!
I, like Dr. Spencer, am skeptical on AGW and on the cosmic ray hypotheses. Dr. Spencer, if you read this, is there any possibility that minute global cooling due to tiny percentage reductions in solar radiation intensity at a global scale might result in slightly higher cloud cover (due simply to the mean temperature being ever so slightly closer to the dew point because of lag effects of moisture compared to incident solar radiation), thereby accelerating the cooling and causing more cloud, with the reverse process occurring during periods of slightly higher solar radiation? In a sense, I am proposing two ‘vicious’ cycles, cooling and warming, as enhancement mechanisms for the proportionally tiny changes in solar radiation intensity with the solar cycles. Of course, I am sure that other natural processes (eg. oceanic circulation, change variations in snow cover and even perhaps AGW) could mask or compensate for such a hypothesis at different time-scales. I guess I am just interested to hear whether there is a reason that this rather elementary hypothesis of mine is wrong.
Tenuc (13:55:14)
“”Marty Mlynczak, of NASA Langley Research Center:-
“…In the quiet solar year of 2008, for instance, the upper atmosphere’s ultraviolet radiation emissions have dipped to levels 10 times lower than when SABER’s observations began in 2002…””
As I pointed out. A less turbulent solar energy flow reduces energy loss to space and the stratosphere upwards starts to warm. Stratospheric (and upwards) temperature changes are caused by changes in the turbulence of the solar energy flow and not by changing levels of GHGs. Tropospheric temperature changes are caused by the rate of ocean energy release and not by changing levels of GHGs (or at least not enough to measure).
It has to be an issue of turbulence and not temperature because, as Leif says, the size of the change in solar power is not enough to cause the observed temperature changes. That also deals with crosspatch’s ballon analogy because the extra solar energy is not enough to make the atmosphere expand enough to produce the observed effect.
Typo: In the previous message, I meant ‘chance’ variations, not ‘change variations;’
P Wilson (11:11:42) “It seems that official climatology today is at the same stage of the papacy in Galileo’s day.”
Yes – Hansen’s recent comments were interesting too – (church turning a blind eye for sinners who paid 100s of years ago).
—
Re: tallbloke (13:07:53) [S & J spatiotemporal harmonics]
Interesting – thanks.
Dave L (11:26:26)
I had problems earlier today playing the CERN Jasper Kirkby lecture until I found the video on the main document server which plays perfectly.
http://cdsweb.cern.ch/record/1181073
Definitely one of the most outstanding presentations and absolutely essential viewing, in my opinion.
Dr Spencer and Dr. Svalgaard–What do you think of the folks who espouse The Electric Universe rather than fusion based?
Thanks
REPLY: lets leave that question unanswered for two reasons: 1) it is way off topic, it has nothing to do with earth’s climate and GCR’s 2) previous discussions like this have hijacked threads and I won’t allow it hear anymore – Anthony
Bart (13:07:36) :
In my naive view, the bulge could decrease pressure in the upper stratosphere, and when I get low pressure on my barometer here on Earth, I am likely to see clouds.
Isn’t the pressure at the surface simply the weight of all the overlying molecules which wouldn’t change?
Stephen Wilde (13:37:54) :
If it increases the rate of energy loss to space during a period of more turbulent solar activity then it would have an effect on climate.
What energy loss?
Also, if the Earth’s warms, its energy loss to space will increase correspondingly.
re: climate variability
after reading almost all threads since climategate started.
MY new mantra is: ITSS
It’s The Sun Stupid!
Alarmists take note:
Tilo Reber (09:43:18) “When I think of all the times that I’ve seen Gavin refer to “natural climate variability”, and I knew full well that he didn’t know what “natural climate variability” he was talking about, this all comes back as extremely funny. To be more clear, I asked Gavin directly to identify the natural variability that was effecting temperature since 1998. He deleted my comment.”
Thanks for sharing these telling anecdotes.