Solar Science

A blog of solar physics

Posts Tagged ‘Solar Cycle 24

David Hathaway: Mea Culpa

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I’m not going to add much more than to say that its enjoyable and refreshing to see a senior scientist admit that they were wholly wrong in their predictions.

How Long Will Our Sun Remain Quiet and Cosmic Rays Increase?

What Happened to 2006 Predictions of Huge Solar Cycle 24?

ISN’T IT ESPECIALLY STRANGE FOR YOU BECAUSE THREE YEARS AGO, ALL THE PHYSICS OF THE SUN THAT YOU AND NASA AND EVERYBODY ELSE WAS USING WERE ANTICIPATING THAT THIS COULD BE THE BIGGEST SOLAR MAXIMUM ON RECORD?

There were indications back then. I am writing a paper – it’s on my computer as we speak (laughs) – basically saying that I made a big mistake – myself and Bob Wilson – when we wrote a paper in 2006, suggesting Solar Cycle 24 was going to be a huge cycle based on conditions at that time. The problem we had with our prediction was that it was based on a method that assumes that we’re near sunspot cycle minimum.

We had just previously gone through three or four sunspot cycles that had been only ten years long each, so for the one in 1996 to 2006, it seemed like a reasonable assumption. But as we now know, we were off by at least two years. And if we take conditions on the sun now, it’s a completely different story. The conditions now – using even that same technique from 2006 – says that the next sunspot cycle is going to be half what we thought it was back in 2006.

Another big prediction in 2006 was based on a dynamo model – a model for how the sun produces magnetic fields – and it suggested a huge cycle.

But there also were people back at that time saying otherwise. A group of colleagues led by Leif Svalgaard, Ph.D., were looking at the sun’s polar fields and saying even at that point, the sun’s polar fields were significantly weaker than they had been before and those scientists back then predicted it was going to be a small cycle.

How Small Will Solar Cycle 24 Be?

…I’ve come around to that view now. I think there is little doubt in my mind now that we’re in for a small cycle. The big question now is how small? I think most of us are predicting small cycles. I think even the techniques I’m using now are suggesting HALF the size of the last three or four solar cycles, but my fear is that even that might be too big just from the fact that it’s taken so long for this Solar Cycle 24 to really get off the ground and start producing sunspots.

I have no doubt at this point that it’s going to be a little cycle. My current prediction is that it’s going to be about half of what we’ve seen in the last four solar cycles or so. But in my gut, I feel it’s going to be smaller than that! (laughs) It’s just so slow in taking off and the indicators that we see – both the polar fields and the geomagnetic indicators are lower than anything we’ve seen before.

So kudos to David Hathaway for writing a paper talking about how wrong his previous papers have been. Absolutely no sarcasm intended or implied.

Written by John A

October 31, 2009 at 2:58 am

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

Another SC24 spot – the start of something?

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Solar Cycle 24 spot - the start of something?

Solar Cycle 24 spot - the start of something?

At least, it could be SC24 but the last magnetogram is from nearly 3 days ago.

I think the true test is if this spot lasts more than 48 hours. The others haven’t lasted that long.

Written by John A

May 31, 2009 at 10:17 pm

Posted in Solar Cycle 24

Tagged with , ,

Hathaway announces the bleeding obvious

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NASA’s David Hathaway has announced, again, that Solar Cycle 24 may have begun:

After more than two years of very low sunspot activity and hardly any flares, the sun is ramping up activity now.

The sun’s activity ebbs and flows on a roughly 11-year cycle. It can range from very quiet to violent space storms that knock out power grids on Earth and disrupt radio and satellite communications. The last peak was in 2000, and scientists have in recent months figured the low point was occurring. Fresh sunspots during October suggest the corner has been turned.

“I think solar minimum is behind us,” said David Hathaway of NASA’s Marshall Space Flight Center in Huntsville, Ala. “Last month we counted five sunspot groups.” he says.

Sunspots are cool areas on the solar surface where magnetic energy is bottled up. While five groups is not extraordinary, it is significant in comparison to the months of virtually no spots.

“This represents a real increase in solar activity,” Hathaway said in a statement today.

Your tax money at work. At least he won’t have to keep stretching out the start of SC24 every few months.

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Written by John A

November 13, 2008 at 11:16 am

Posted in Solar Cycle 24

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The Sun is in a deep minimum

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Yesterday I pulled this magnetogram picture from the SOHO website

20081006_0141_mdimag_512.jpg

Ignoring the phage in the Southern Hemisphere (which is SC23 polarized, natch) there is no magnetic activity at all to speak of.

Throw in the result announced by NASA in the last few days:

“The sun’s million mile-per-hour solar wind inflates a protective bubble, or heliosphere, around the solar system. It influences how things work here on Earth and even out at the boundary of our solar system where it meets the galaxy,” said Dave McComas, Ulysses’ solar wind instrument principal investigator and senior executive director at the Southwest Research Institute in San Antonio, Texas. “Ulysses data indicate the solar wind’s global pressure is the lowest we have seen since the beginning of the space age.”

and

In 2007, Ulysses made its third rapid scan of the solar wind and magnetic field from the sun’s south to north pole. When the results were compared with observations from the previous solar cycle, the strength of the solar wind pressure and the magnetic field embedded in the solar wind were found to have decreased by 20 percent. The field strength near the spacecraft has decreased by 36 percent.

“The sun cycles between periods of great activity and lesser activity,” Smith said. “Right now, we are in a period of minimal activity that has stretched on longer than anyone anticipated.”

Its clear that the Sun has entered a phase that we might never have seen before with anything like modern instrumentation.

The spots on the Sun have become so evanescent and small that we now have the ludicrous arguments over whether a darkened spot that lasts a few hours is counted as a spot or a speck. Anthony Watts refers to this as “Speckwatch” and furthermore even these specks have been SC23 not SC24 polarized.

What is clear is that these spots or specks are way below the range at which our scientific ancestors from the 18th and 19th Centuries could ever have detected.

Written by John A

October 6, 2008 at 1:54 pm

Posted in News and Views

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Predicting the Future ain’t what it used to be

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A quick update on David Hathaway’s predictions for Solar Cycle 24.

Dr Hathaway has changed his prediction once again WITHOUT changing the page that it occurs on (other than the date it was updated), nor with any explanation as to why his previous predictions have been so wrong. It would be nice if he would treat us all to an explanation for modifying his prediction without modifying his methodology.

Here is an animation done by Michael Romayne on how Hathaway’s prediction has changed over time.

Hathaway predictions to OCtober 2008

Its clear that something so flexible as Hathaway’s predictions cannot have a theory behind them – this is just making ad hoc adjustments. Note also that between March 2007 and March 2008, the expected size of SC24 was reduced – why?

h/t to Anthony Watts 

Written by John A

October 6, 2008 at 12:54 pm

Posted in Solar Cycle 24

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Ken Tapping: The Current Solar Minimum

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I received this via e-mail from K7RA. The original document comes from Dr Kenneth Tapping who was quoted not long ago regarding the solar cycle being “the quietest [he’d] ever seen in 25 years”. This was taken to mean that the current solar minimum was historically unusual, and here Dr Tapping explains that this is not so.

I reproduce here the entire document (other than stylistic changes from PDF to the blog, not a word or a graph has been altered from the original):

The Current Solar Minimum

Ken Tapping, 2008-04-17

This note summarizes my current feeling about the state of solar activity and the solar activity cycle. Any conclusions currently in circulation that have been drawn by extrapolating what you see in this note should not be regarded as reflecting my views. My conclusions are in this note. The information used here is freely available and readers are strongly encouraged to get the data, look at it and draw their own conclusions.

The current solar activity is not that unusual. At this point it is completely unjustified to see current solar behaviour as an indication of any departure from its what the Sun has been doing for at least the last 300 years.

Figure 1 shows a plot of solar activity as measured by the solar radio flux monitors operated by the National Research Council of Canada.

tapping-figure11

Figure 1: Monthly averaged 10.7 cm solar radio flux solar activity index since 1947 (monthly means).

The arrow under the 1964-1977 cycle indicates the length of that cycle, which was a little longer than the others. That same arrow has been copied and put under the last cycle. The length is unchanged. It can be seen that the current solar activity cycle (now ending) has not yet exceeded the length of the 1964-77 cycle. It is also clear that the longish cycle in 1964-77 was followed by further activity cycles – normal solar behaviour. To exceed the duration of the 1964-1977 cycle, the new cycle would have to delay its start at least well into 2009.

Figure 2 shows the 1964-77 and the 1997-? cycles overlaid on the same plot. Once again we can see the last cycle has yet to last longer than the 1964-77 cycle.

tapping-figure-21

Figure 2: The 1964-77 cycles compared. The current cycle (black trace) has yet to last longer than the 1964-77 cycle (red trace).

The 10.7 cm solar flux covers only about six solar activity cycles. Sunspot number data covers at least 300 years. The histogram Figure 3 shows how the durations of the cycles as seen in the sunspot data have varied since 1700. A 13-year activity cycle is not that unusual.

tapping-figure-3

Figure 3: Distribution of solar cycle durations over the last 300 years. The 1964-1977 cycle, having a
duration of 13 years is unusual, but not that unusual.

CONCLUSION: AT THE MOMENT IT IS UNJUSTIFIED TO ASSUME THE SUN IS UNDERGOING A SIGNIFICANT CHANGE IN BEHAVIOUR. ON THE BASIS OF SUNSPOT NUMBER DATA, WE CANNOT ASSUME ANYTHING ODD IS HAPPENING UNLESS THE NEXT CYCLE DELAYS ITS START INTO 2009 OR 2010.