Solar Science

A blog of solar physics

Archive for July 2009

What comes around

with 5 comments

Following on from my previous post noting the rotating back into view of the region formerly known as Sunspot 1024, we now have a clearer picture:

Sunspot 1024 is over, man

Sunspot 1024 is over, man

Its just a plage, the end game of a sunspot.

The Sun remains quiet.

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Written by John A

July 27, 2009 at 2:14 pm

Posted in Solar Cycle

Tagged with ,

Is the Earth's magnetic field a cosmic ray funnel?

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Portrait of Henrik Svensmark

Portrait of Henrik Svensmark

In this world of rampant climate alarmism, its to be expected that theories and hypotheses which do not support the AGW theory will get the full treatment of bad analysis and character assassination. After all,  where’s the funding going to go if there’s an alternative theory that bombs the bridge in front of the gravy train?

One such is Dr Henrik Svensmark‘s hypothesis on the modulating effect of the solar magnetic field on the Earth’s climate. In the recent article in the New York Times on the solar cycle that I recently mentioned, we have this:

The idea that solar cycles are related to climate is hard to fit with the actual change in energy output from the sun. From solar maximum to solar minimum, the Sun’s energy output drops a minuscule 0.1 percent.

But the overlap of the Maunder Minimum with the Little Ice Age, when Europe experienced unusually cold weather, suggests that the solar cycle could have more subtle influences on climate.

One possibility proposed a decade ago by Henrik Svensmark and other scientists at the Danish National Space Center in Copenhagen looks to high-energy interstellar particles known as cosmic rays. When cosmic rays slam into the atmosphere, they break apart air molecules into ions and electrons, which causes water and sulfuric acid in the air to stick together in tiny droplets. These droplets are seeds that can grow into clouds, and clouds reflect sunlight, potentially lowering temperatures.

The Sun, the Danish scientists say, influences how many cosmic rays impinge on the atmosphere and thus the number of clouds. When the Sun is frenetic, the solar wind of charged particles it spews out increases. That expands the cocoon of magnetic fields around the solar system, deflecting some of the cosmic rays.

But, according to the hypothesis, when the sunspots and solar winds die down, the magnetic cocoon contracts, more cosmic rays reach Earth, more clouds form, less sunlight reaches the ground, and temperatures cool.

“I think it’s an important effect,” Dr. Svensmark said, although he agrees that carbon dioxide is a greenhouse gas that has certainly contributed to recent warming.

Dr. Svensmark and his colleagues found a correlation between the rate of incoming cosmic rays and the coverage of low-level clouds between 1984 and 2002. They have also found that cosmic ray levels, reflected in concentrations of various isotopes, correlate well with climate extending back thousands of years.

All well and good. But then there’s always someone who produces a sophisticated argument why you shouldn’t believe your own lying eyes.

But other scientists found no such pattern with higher clouds, and some other observations seem inconsistent with the hypothesis.

Terry Sloan, a cosmic ray expert at the University of Lancaster in England, said if the idea were true, one would expect the cloud-generation effect to be greatest in the polar regions where the Earth’s magnetic field tends to funnel cosmic rays.

“You’d expect clouds to be modulated in the same way,” Dr. Sloan said. “We can’t find any such behavior.”

Still, “I would think there could well be some effect,” he said, but he thought the effect was probably small. Dr. Sloan’s findings indicate that the cosmic rays could at most account for 20 percent of the warming of recent years.

Would the Earth’s magnetic field “funnel cosmic rays”? This was taken up by Stephen Ashworth in an email to Benny Peiser’s CCNet mailing list:

Dear Benny,

Kenneth Chang in the New York Times reports that some observations seem inconsistent with the solar magnetic field–cosmic ray–cloud formation hypothesis.  He wrote (CCNet 113/2009 — 21 July 2009, item 3):

Terry Sloan, a cosmic ray expert at the University of Lancaster in England, said if the idea were true, one would expect the cloud-generation effect to be greatest in the polar regions where the Earth’s magnetic field tends to funnel cosmic rays.

“You’d expect clouds to be modulated in the same way,” Dr. Sloan said. “We can’t find any such behavior.” Still, “I would think there could well be some effect,” he said, but he thought the effect was probably small. Dr. Sloan’s findings indicate that the cosmic rays could at most account for 20 percent of the warming of recent years. [sic — he clearly means the *reduction* in cosmic ray influx to the Earth in recent decades of the more active Sun — SA]

I am skeptical about Dr Sloan’s claim.  The reason is as follows.

A few years ago I read a suggestion that an interstellar space probe might be able to do a flyby of the star Sirius, and use its gravity to redirect itself to a subsequent flyby of Procyon, in the same way that Pioneer, Voyager and other probes have used the gravity of Jupiter to redirect themselves to Saturn and beyond.  I have a formula for the change in direction caused by a flyby of a massive body, so I was able to check this idea numerically.

It turned out that if the interstellar probe was travelling at a speed that was a significant fraction of the speed of light, say 0.1c — which it would have to if it was to reach Sirius in only a few decades flight time — then the deflection of its trajectory even on a flyby which grazed the star’s atmosphere was only in the region of one degree, totally insufficient to redirect it to Procyon.

The lesson was that the gravitational fields of planets and even stars (Sirius is more massive than our Sun) are almost imperceptible to a vehicle if it is travelling at such a high speed.

Cosmic ray particles come into the Solar System at a significant fraction of the speed of light.  I would therefore expect them to be largely immune to our local gravitational and magnetic fields.  I would not expect Earth’s magnetic field to funnel them towards the poles, as it does with the lower-energy solar particle flux.  (Presumably someone has already checked this numerically?)

It would seem that Svensmark’s cosmic ray–cloud formation hypothesis depends on the difference in strength between the Sun’s and the Earth’s magnetic fields: the Sun being strong enough to modulate the cosmic ray flux in the inner Solar System over its longer-term cycles of activity, while the Earth is too weak to redistribute incoming particles geographically during their last second or so of flight before hitting the atmosphere.

Best wishes,

Stephen Ashworth
23 July 2009

Stephen Ashworth, Oxford, U.K.
http://www.astronist.demon.co.uk/

Quite so. Cosmic rays travel at significant percentages of the speed of light and wouldn’t be deflected significantly by the Earth’s weak magnetic field.

I wonder if Terry Sloan would care to answer? Someone should ask him.

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Written by John A

July 25, 2009 at 4:08 pm

Posted in Uncategorized

What goes around…

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It looks as though the active region formerly known as Sunspot 1024 is still active and will be rotating back into view in the next few days.

Here’s the region as pictured by the Stereo satellites which give a view of some of the solar farside. The active region is the bright area at about 7.30 on this image:

behind_euvi_195_260709

and here is the SOHO view which is close to what is almost the terrestrial view of the Sun. The active region is the bright area on the lower left edge of the photosphere.

eit_284_260709

Apart from this one region, there’s nothing else to report. I’m going to be checking the solar flux to see whether there is any change, but I’m not optimistic.

Meanwhile Dr David Hathaway has popped up in the New York Times saying that contrary to his previous forecasts, a Dalton Minimum-like weak sunspot cycle (ramping up to only 50-70)

For example, in 2006, Dr. Hathaway looked at disturbances in the Earth’s magnetic field that are caused by the Sun, and they were strong. During past cycles, strong disturbances at minimum indicated strong fields all over the Sun at maximum and a bounty of sunspots. Because the previous cycles had been shorter than average, Dr. Hathaway thought the next one would be shorter and thus solar minimum was imminent. He predicted the new solar cycle would be a ferocious one, consistent with a short cycle.

Instead, the new cycle did not arrive as quickly as Dr. Hathaway anticipated, and the disturbances weakened. His revised prediction is for a smaller-than-average maximum. Last November, it looked like the new cycle was finally getting started, with the new cycle sunspots in the middle latitudes outnumbering the old sunspots of the dying cycle that are closer to the equator.

After a minimum, solar activity usually takes off quickly, but instead the Sun returned to slumber. “There was a long lull of several months of virtually no activity, which had me worried,” Dr. Hathaway said.

Worried? Why? Because your previous forecasts were flat out wrong?

Nobody’s perfect.

Not even me.

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Written by John A

July 25, 2009 at 3:39 pm

Posted in Solar Cycle 24

Tagged with ,

This Quiet Sun

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The Sun has gone back to blank after having had just one sunspot group that caused otherwise rational people to go off their heads…

Here’s the magnetogram of the Sun showing precisely nothing that presages any sunspot formation:

Magnetogram of the Sun 16/07/2009

Magnetogram of the Sun 16/07/2009

As a comparison, here is the sun image from the Extreme ultraviolet Imaging Telescope at 304 ångstroms for today and near solar maximum in 2000 by way of comparison

Sun at 17/07/2009 (left) and near solar maximum 31/05/2000

Sun at 17/07/2009 (left) and near solar maximum 31/05/2000 (right)

Now its easy to see how quiet the Sun really is at the moment. The prominences are weak, the coronal holes are very small, the corona (the solar atmosphere) shrunken.

All of this can be seen to be normal behaviour for the Sun, except that this hiatus between Solar Cycle 23 finally winding down and the next cycle is unprecedented in nearly a hundred years. (By the way, the overuse of “unprecedented” by climate alarmists has me wincing at using it as a cliché)

Eventually the solar cycle must return. The question is whether solar scientists gain insight into the behaviour of the Sun by understanding why their models failed (see below). The result can only be better science.

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Written by John A

July 17, 2009 at 5:21 pm

Ken Tapping: Still no sign of the next cycle

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Previously on this blog, I’d mentioned my skepticism that one decent sunspot marked the end of the hiatus in the solar cycle we’ve seen for nearly two years. It might be my nature, but everybody has been wrong before.

As part of my public duty to actually ask real scientists monitoring the Sun, I wrote to Dr Ken Tapping of Canada’s National Research Council at the Herzberg Institute of Astrophysics in British Columbia:

Dear Dr Tapping

For the first time in a very long time, the Sun has managed to produce a sunspot (1024) which has lasted more than a few hours.

Is there any sign of an upswing in radio emissions indicating an end to the hiatus?

Best regards

John

and Dr Tapping replied (with my emphasis):

Hi John,

Last weekend I saw a really nice sunspot group on the Sun, which could have been part of the new cycle. The solar radio flux went up a little while it was there. However now the flux has slumped back to low values again.

Some theorists have suggested the new cycle is currently under way, but that for some unknown reason we are not getting the spots to go with it. I’m not sure what that really means, so I am making no suggestion as to what is going on.

Being very conservative, according to the measurements being made under our Solar Radio Monitoring Programme, we have yet to see signs the next cycle is really under way.

Regards,

Ken

Now this is what I’d thought, that the nice sunspot (1024) we’d seen did not presage a change in the behavior of the Sun: the solar wind speed remained subdued, coronal holes remained very small, there were no prominences to speak of.

It also baffles me how “some theorists have suggested the new cycle is currently under way, but that for some unknown reason we are not getting the spots to go with it”. If there are very few sunspots and the radio flux remains extremely subdued, on what basis are these theorists making their statements?

It could be that this is the first “radio quiet” solar cycle … anyone believe that?

So for solar physicists, it remains “interesting times” and probably a time to clear out some old theories and start again.

My thanks to Dr Tapping for the correspondence.

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Written by John A

July 10, 2009 at 8:53 am

A single sunspot means the minimum is over?

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Fox News reports:

After one of the longest sunspot droughts in modern times, solar activity picked up quickly over the weekend.

A new group of sunspots developed, and while not dramatic by historic standards, the spots were the most significant in many months.

“This is the best sunspot I’ve seen in two years,” observer Michael Buxton of Ocean Beach, Calif., said on Spaceweather.com.

Solar activity goes in a roughly 11-year cycle. Sunspots are the visible signs of that activity, and they are the sites from which massive solar storms lift off.

The past two years have marked the lowest low in the cycle since 1913, and for a while scientists were wondering if activity would ever pick back up.

And here is the same sunspot previously reported:

Sunspot 1024 as at July 8 2009

Sunspot 1024 as at July 8 2009

Now while I might welcome the return of the sunspot cycle, I caution everyone to be patient, as we’ve had these false dawns many times before.

Here’s the animation, courtesy of Solarcycle24.com:

Sunspot 1024 animation

Sunspot 1024 animation

The question is: have the other indicators of sunspot activity similarly risen?

More in a moment…

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Written by John A

July 7, 2009 at 11:16 am

Posted in Solar Cycle 24

Tagged with ,

Another southern hemisphere spot

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It’s difficult to tell whether SC24 is finally waking up, or its just bumping along the bottom
The Sun

and the magnetogram shows the SC24 signature (reversed from the Northern Hemisphere)
magneto050709

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Written by John A

July 4, 2009 at 7:51 pm