Questions for Dr. L Svalgaard ---- II

[timb]

Sept 13, 2012 1:45:47 GMT lsvalgaard said:

Sept 12, 2012 22:49:24 GMT timb said:

Is it just me or does the magnetogram look like Joy's law angle has decreased very quickly? They all look pretty flat. In fact some even look like they have the proper SC24 polarity but the leading polarity isn't lower in latitude than the trailing. Joy's law is usually stated in terms of latitude but latitude and reversals are also related. Is it possible that Joys law breaks down near flips?

No, but Joy's law is most visible early in the cycle when the spots are at high latitude. When the spots migrate closer to the equator, the tilt of the bipolar axis diminishes.

I was talking more over the last month or so. I understand it's more visible early in the cycle. My question is more cause/effect. As I understand it, latitude and Joy's law angle correlate but is the cause of both the angle and the latitude due to the magnetic field.

Is there a dataset of measurements of Joy's law angle that could be used to correlate to magnetic field strength (i.e. plot the angle vs. L&P or other magnetic indicator rather than just latitude)? It would be interesting to pick a latitude and compare average sunspot angle to magnetic strength and solar activity. It would also be interesting to measure the distance between N/S breach points and compare to L&P (are the N/S spot centers getting closer as the magetic field declines)?

When the toroidal plasa "ropes" breach the surface is it purely a larger rotation difference at high latitude that causes the angle or can the magnetic field affect it?

[lsvalgaard]

Sept 13, 2012 16:30:38 GMT timb said:

Sept 13, 2012 1:45:47 GMT lsvalgaard said:

No, but Joy's law is most visible early in the cycle when the spots are at high latitude. When the spots migrate closer to the equator, the tilt of the bipolar axis diminishes.

I was talking more over the last month or so. I understand it's more visible early in the cycle. My question is more cause/effect. As I understand it, latitude and Joy's law angle correlate but is the cause of both the angle and the latitude due to the magnetic field.

Is there a dataset of measurements of Joy's law angle that could be used to correlate to magnetic field strength (i.e. plot the angle vs. L&P or other magnetic indicator rather than just latitude)? It would be interesting to pick a latitude and compare average sunspot angle to magnetic strength and solar activity. It would also be interesting to measure the distance between N/S breach points and compare to L&P (are the N/S spot centers getting closer as the magetic field declines)?

When the toroidal plasa "ropes" breach the surface is it purely a larger rotation difference at high latitude that causes the angle or can the magnetic field affect it?

Joy's law has been investigated many times and there are several claimed explanations for it. The easiest would be simply to google "Joy's law sunspot" to get a sampling of what is out there, e.g. arxiv.org/pdf/1005.1774v1.pdf

[justsomeguy]

Does this paper show the Grand Maximum of the late 20th Century was real?

wattsupwiththat.com/2012/09/13/paper-demonstrates-solar-activity-was-at-a-grand-maxima-in-the-late-20th-century/#more-71007

[lsvalgaard]

Sept 14, 2012 12:12:53 GMT justsomeguy said:

Does this paper show the Grand Maximum of the late 20th Century was real?

wattsupwiththat.com/2012/09/13/paper-demonstrates-solar-activity-was-at-a-grand-maxima-in-the-late-20th-century/#more-71007

no, progress has happened since 2010. Here is the current status of things www.leif.org/research/Reconstruction%20of%20Sunspot%20Number.pdf

[justsomeguy]

Well, we are very near polar reversal and thus the middle of the cycle: www.leif.org/research/WSO-Polar-Fields-since-2003.png

I said earlier that we would flip near the time we should and closer to the original estimate than the current one (which they have late next year). Am I wrong?

wattsupwiththat.files.wordpress.com/2009/05/swpc_sunspot_combined_080509.png

[lsvalgaard]

Sept 20, 2012 7:30:26 GMT justsomeguy said:

Well, we are very near polar reversal and thus the middle of the cycle: www.leif.org/research/WSO-Polar-Fields-since-2003.png

I said earlier that we would flip near the time we should and closer to the original estimate than the current one (which they have late next year). Am I wrong?

wattsupwiththat.files.wordpress.com/2009/05/swpc_sunspot_combined_080509.png

The north and south pole reverse at different times and it is hard to pick a time as 'the global reversal', but we are certainly in the maximum phase now.

[justsomeguy]

Certainly possible but if trend continue does this mean that the change is happening when the red and blue lines pass 0? Am I just wrong about that?

[lsvalgaard]

Sept 20, 2012 12:25:30 GMT justsomeguy said:

Certainly possible but if trend continue does this mean that the change is happening when the red and blue lines pass 0? Am I just wrong about that?

The red line will go down below the zero mark and the blue line will move up above. This on average happens a year or so after maximum, so we are well on our way.

[Bob k6tr]

Sept 20, 2012 14:31:42 GMT lsvalgaard said:

The red line will go down below the zero mark and the blue line will move up above. This on average happens a year or so after maximum, so we are well on our way.

One year after ?

Is there any explanation for that ?

One would intuitively think the highest production of spots would occur right at reversal as the magnetic flows would encompass the maximum "sweet area" between +/- 35 degrees lattitude where most spots form on the Sun. And the fields have not begun their migration back to the poles.

[lsvalgaard]

Sept 20, 2012 23:40:03 GMT Bob k6tr said:

Sept 20, 2012 14:31:42 GMT lsvalgaard said:

The red line will go down below the zero mark and the blue line will move up above. This on average happens a year or so after maximum, so we are well on our way.

One year after ?

Is there any explanation for that ?

One would intuitively think the highest production of spots would occur right at reversal as the magnetic flows would encompass the maximum "sweet area" between +/- 35 degrees lattitude where most spots form on the Sun. And the fields have not begun their migration back to the poles.

Check out slide 21 of www.leif.org/research/Asymmetric-Solar-Polar-Field-Reversals-talk.pdf

[Bob k6tr]

Sept 21, 2012 1:05:52 GMT lsvalgaard said:

Sept 20, 2012 23:40:03 GMT Bob k6tr said:

One year after ?

Is there any explanation for that ?

One would intuitively think the highest production of spots would occur right at reversal as the magnetic flows would encompass the maximum "sweet area" between +/- 35 degrees lattitude where most spots form on the Sun. And the fields have not begun their migration back to the poles.

Check out slide 21 of www.leif.org/research/Asymmetric-Solar-Polar-Field-Reversals-talk.pdf

So what I take away from the slide is not so much an attempt to explain the dynamics but to say this is what we measured and this is what we found.

Am I reading that right ?

[ncfcadam]

Those WSO charts are terrific: very clear. What is the reason for the annual variation in the Tesla magnitude? It's very regular.

[lsvalgaard]

Sept 21, 2012 4:27:02 GMT Bob k6tr said:

Sept 21, 2012 1:05:52 GMT lsvalgaard said:

Check out slide 21 of www.leif.org/research/Asymmetric-Solar-Polar-Field-Reversals-talk.pdf

So what I take away from the slide is not so much an attempt to explain the dynamics but to say this is what we measured and this is what we found.

Am I reading that right ?

yes

[lsvalgaard]

Sept 21, 2012 8:07:44 GMT ncfcadam said:

Those WSO charts are terrific: very clear. What is the reason for the annual variation in the Tesla magnitude? It's very regular.

www.leif.org/research/The%20Strength%20of%20the%20Sun's%20Polar%20Fields.pdf

[chickenlittle]

Dr. Svalgaard,

When the poles get near reversing isn't there an increasing swarm of sunspots with reversed leading/trailing magnetic poles? Have those indications begun to appear in large numbers yet?
Thanks.