Relationships between 10.7 Solar Flux and Sunspot characteristics

[hamateur 1953]

For at least some sixty years we have been monitoring 10.7 solar flux and counting sunspots.  Counting sunspots began long before my time, and we have very good records therefore using several different methods and resolutions.  For many years I observed and noted the tendency in general for SFI to ride 10-30 percent above the ISN. ( International Sunspot Number).   Only in this cycle have I noticed several marked disparities:  Twice at least we have had SFI numbers at least double the simultaneous SN. I doubt this is a single occurrence.   Last November 2023 we had close to 190 SFI with under 100 sunspots.  @Patrick P.A. Geryl noted this also and at the time neither of us could really make much sense of it.   I feel so incredibly blind now, it’s embarrassing because the answer is in front of us every day:  Each sunspot or plage area  is unique in character in its production of energy imparted, it was that simple.  Funny about that!!   Mike/Hagrid. 

Edited January 21 by hamateur 1953

[Patrick P.A. Geryl]

1 uur geleden, hamateur 1953 zei:

For at least some sixty years we have been monitoring 10.7 solar flux and counting sunspots.  Counting sunspots began long before my time, and we have very good records therefore using several different methods and resolutions.  For many years I observed and noted the tendency in general for SFI to ride 10-30 percent above the ISN. ( International Sunspot Number).   Only in this cycle have I noticed several marked disparities:  Twice at least we have had SFI numbers at least double the simultaneous SN. I doubt this is a single occurrence.   Last November 2023 we had close to 190 SFI with under 100 sunspots.  @Patrick P.A. Geryl noted this also and at the time neither of us could really make much sense of it.   I feel so incredibly blind now, it’s embarrassing because the answer is in front of us every day:  Each sunspot or plage area  is unique in character in its production of energy imparted, it was that simple.  Funny about that!!   Mike/Hagrid. 

2023:11:01_21h:07m:13s    14N    7S    4Avg   20nhz filt:    3Nf    4Sf   -1Avgf
2023:11:11_21h:07m:13s     4N   12S   -4Avg   20nhz filt:    4Nf    5Sf   -1Avgf
2023:11:21_21h:07m:13s     4N   14S   -5Avg   20nhz filt:    4Nf    6Sf   -1Avgf
2023:12:01_21h:07m:13s    -2N   23S  -13Avg   20nhz filt:    5Nf    7Sf   -1Avgf
2023:12:11_21h:07m:13s     6N   16S   -5Avg   20nhz filt:    6Nf    8Sf   -1Avgf
2023:12:21_21h:07m:13s    -5N   15S  -10Avg   20nhz filt:    6Nf    9Sf   -1Avgf

The average polar field went negative for good in November…

Related?🤔😉

[Philalethes]

1 hour ago, hamateur 1953 said:

For at least some sixty years we have been monitoring 10.7 solar flux and counting sunspots.  Counting sunspots began long before my time, and we have very good records therefore using several different methods and resolutions.  For many years I observed and noted the tendency in general for SFI to ride 10-30 percent above the ISN. ( International Sunspot Number).   Only in this cycle have I noticed several marked disparities:  Twice at least we have had SFI numbers at least double the simultaneous SN. I doubt this is a single occurrence.   Last November 2023 we had close to 190 SFI with under 100 sunspots.  @Patrick P.A. Geryl noted this also and at the time neither of us could really make much sense of it.   I feel so incredibly blind now, it’s embarrassing because the answer is in front of us every day:  Each sunspot or plage area  is unique in character in its production of energy imparted, it was that simple.  Funny about that!!   Mike/Hagrid. 

It's definitely true that the F10.7 to SN ratio has been higher lately than it's typically been before; I detailed some findings about that here (might need some adjustments to the data processing if I recall correctly, but the overall finding still stands). I don't know what the reason for that is; it could e.g. be natural variation in sunspot sizes (larger sunspots would raise the F10.7 without requiring a corresponding increase in SN), or it could be an increase in sunspots that are too small to be counted properly, contributing to higher F10.7 without increasing the SN (I believe this is the explanation Patrick favors, although I'm not sure), or maybe it could even be changes to the counting procedure itself, given how this is an element which inherently has a lot of room for humans to make some choices in counting that can be arbitrary to a certain extent.

That latter point is also why we should probably turn more to more objective measurements as standards of Solar activity, like focusing more on F10.7 (or other wavelengths, like F30); as mentioned previously the main reason we're still primarily using sunspot numbers is likely due to having records dating quite far back, but one can't help but question just how valid those records really are given the differences in visibility and human factor, even though there's obviously been a ton of effort put into methods like cross-validation and using k-values for scaling and so on to ensure that it does have a fair amount of integrity. This paper really delves into it, and while I haven't read it in its entirety it does ultimately conclude that sunspot numbers can still be very useful and can be relied upon for at least a while back; the introduction highlights some of the problems, and the paper as a whole attempts to reconcile the discrepancies and anomalies.

 

[hamateur 1953]

The conclusion seemed so obvious to me, that I was pretty sure it had to be incorrect!!   But I can’t easily see any other factors  we might have missed, however inadvertently.  Thanks for weighing in @Philalethes Mike 

One last thought.  As I see it anyway, the only way this might have a chance of being verified is by measuring the 10.7 discretely for a small sunspot group, and the aperture of such a device would seem difficult at best to attain.  To say nothing of its ability to survive.  Haha! 

Edited January 21 by hamateur 1953

[Drax Spacex]

From

https://www.sws.bom.gov.au/Educational/2/2/5#:~:text=The following equations are useful for converting between,3 where F D %3D F - 67.0

"considerable scatter" is observed in the relationship between flux and sunspot number.

[hamateur 1953]

5 hours ago, Patrick P.A. Geryl said:

2023:11:01_21h:07m:13s    14N    7S    4Avg   20nhz filt:    3Nf    4Sf   -1Avgf
2023:11:11_21h:07m:13s     4N   12S   -4Avg   20nhz filt:    4Nf    5Sf   -1Avgf
2023:11:21_21h:07m:13s     4N   14S   -5Avg   20nhz filt:    4Nf    6Sf   -1Avgf
2023:12:01_21h:07m:13s    -2N   23S  -13Avg   20nhz filt:    5Nf    7Sf   -1Avgf
2023:12:11_21h:07m:13s     6N   16S   -5Avg   20nhz filt:    6Nf    8Sf   -1Avgf
2023:12:21_21h:07m:13s    -5N   15S  -10Avg   20nhz filt:    6Nf    9Sf   -1Avgf

The average polar field went negative for good in November…

Related?🤔😉

I tend to disbelieve that it won’t cross over yet again @Patrick P.A. Geryl as this cycle has quite a bit left to go…, all due respect.  Mike.   Edit. Although you may ultimately be proven correct, what I was really getting at was that despite a fairly close relationship between SFI and sunspots, the net energy produced by any active region could be highly variable and the differences would be “ washed out” when following 10.7 only without being able to assess the specific strength of a particular AR.  Mike. 

Edited January 21 by hamateur 1953
Clarity

[Drax Spacex]

The past few days provide good examples of the occasional outliers and potential for considerable scatter, especially in the short term, when comparing actual data to empirical curve fits of SFI versus sunspot number:

observed:
2024-02-20, SFI=153, SN=50
2024-02-21, SFI=170, SN=45
2024-02-22, SFI=173, SN=46

predicted, e.g.:
Using the formula from the Australian Spaceweather Forecasting Centre, for SN=45, predicted SFI=99

The sustained flux brightness of AR3590 dominates, with only 1 other weak active region currently on the solar disk.

[hamateur 1953]

On 2/22/2024 at 12:23 PM, Drax Spacex said:

The past few days provide good examples of the occasional outliers and potential for considerable scatter, especially in the short term, when comparing actual data to empirical curve fits of SFI versus sunspot number:

observed:
2024-02-20, SFI=153, SN=50
2024-02-21, SFI=170, SN=45
2024-02-22, SFI=173, SN=46

predicted, e.g.:
Using the formula from the Australian Spaceweather Forecasting Centre, for SN=45, predicted SFI=99

The sustained flux brightness of AR3590 dominates, with only 1 other weak active region currently on the solar disk.

This is particularly interesting, in view of the fact that I think SFI has remained above 150 for a good part of February, and isn’t likely to drop anywhere close to 100 for a few more years, even with a spotless sun I should imagine.