Where to find data for current polarity on the northern hemisphere of the sun?

[oemSpace]

Since Magnetic field reverses polarity throughout the solar cycle, how to know the current polarity on the northern hemisphere of the sun?

Any suggestions?

Thanks in advance for any suggestions :)

[Philalethes]

3 hours ago, oemSpace said:

Since Magnetic field reverses polarity throughout the solar cycle, how to know the current polarity on the northern hemisphere of the sun?

Any suggestions?

WSO has measured the polar fields for almost 50 years, you can find the measurements here. In later times we also have measurements made by SDO's HMI, which you can find a summary of here (as well as instructions on how to retrieve related data yourself).

Note however that at lower latitudes the field is much more chaotic, and during the active part of the cycle there's rarely a single polarity which dominates, although pairs of sunspots typically still organize themselves according to Hale's law. During the more quiet parts of the cycle the field is more dipolar; for example, during the transition between SC24 and SC25, we see from both the WSO and HMI data that the north pole had positive polarity and the south pole had negative polarity. Now it's in the process of flipping, and in the transition from SC25 to SC26 it will be the other way around.

[oemSpace]

54 minutes ago, Philalethes said:

WSO has measured the polar fields for almost 50 years, you can find the measurements here. In later times we also have measurements made by SDO's HMI, which you can find a summary of here (as well as instructions on how to retrieve related data yourself).

Note however that at lower latitudes the field is much more chaotic, and during the active part of the cycle there's rarely a single polarity which dominates, although pairs of sunspots typically still organize themselves according to Hale's law. During the more quiet parts of the cycle the field is more dipolar; for example, during the transition between SC24 and SC25, we see from both the WSO and HMI data that the north pole had positive polarity and the south pole had negative polarity. Now it's in the process of flipping, and in the transition from SC25 to SC26 it will be the other way around.

Based on following data, how to confirm polarity on the northern hemisphere of the sun?

How to tell polarity is North or South on the northern hemisphere of the sun?

Any suggestions?

Thank you very much for any suggestions

 

2023:10:12_21h:07m:13s     8N   14S   -3Avg   20nhz filt:   -0Nf    3Sf   -2Avgf
2023:10:22_21h:07m:13s     9N    9S    0Avg   20nhz filt:   -0Nf    3Sf   -2Avgf
2023:11:01_21h:07m:13s    14N    7S    4Avg   20nhz filt:    0Nf    4Sf   -2Avgf
2023:11:11_21h:07m:13s     4N   12S   -4Avg   20nhz filt:    1Nf    5Sf   -2Avgf
2023:11:21_21h:07m:13s     4N   14S   -5Avg   20nhz filt:    1Nf    6Sf   -2Avgf
2023:12:01_21h:07m:13s    -2N   23S  -13Avg   20nhz filt:    1Nf    6Sf   -3Avgf
2023:12:11_21h:07m:13s     6N   16S   -5Avg   20nhz filt:    2Nf    7Sf   -3Avgf
2023:12:21_21h:07m:13s    -5N   15S  -10Avg   20nhz filt:    2Nf    8Sf   -3Avgf
2023:12:31_21h:07m:13s   -23N    5S  -14Avg   20nhz filt:    2Nf    9Sf   -3Avgf
2024:01:10_21h:07m:13s   -23N    7S  -15Avg   20nhz filt:    3Nf    9Sf   -3Avgf
2024:01:20_21h:07m:13s   -11N    9S  -10Avg   20nhz filt:    3Nf   10Sf   -4Avgf
2024:01:30_21h:07m:13s   XXXN  XXXS  XXXAvg   20nhz filt:  XXXNf  XXXSf  XXXAvgf
2024:02:09_21h:07m:13s   XXXN  XXXS  XXXAvg   20nhz filt:  XXXNf  XXXSf  XXXAvgf
2024:02:19_21h:07m:13s   XXXN  XXXS  XXXAvg   20nhz filt:  XXXNf  XXXSf  XXXAvgf
2024:02:29_21h:07m:13s   XXXN  XXXS  XXXAvg   20nhz filt:  XXXNf  XXXSf  XXXAvgf
2024:03:10_21h:07m:13s    -5N  -12S    4Avg   20nhz filt:    4Nf   15Sf   -6Avgf

[Philalethes]

17 minutes ago, oemSpace said:

Based on following data, how to confirm polarity on the northern hemisphere of the sun?

How to tell polarity is North or South on the northern hemisphere of the sun?

Any suggestions?

Thank you very much for any suggestions

 

2023:10:12_21h:07m:13s     8N   14S   -3Avg   20nhz filt:   -0Nf    3Sf   -2Avgf
2023:10:22_21h:07m:13s     9N    9S    0Avg   20nhz filt:   -0Nf    3Sf   -2Avgf
2023:11:01_21h:07m:13s    14N    7S    4Avg   20nhz filt:    0Nf    4Sf   -2Avgf
2023:11:11_21h:07m:13s     4N   12S   -4Avg   20nhz filt:    1Nf    5Sf   -2Avgf
2023:11:21_21h:07m:13s     4N   14S   -5Avg   20nhz filt:    1Nf    6Sf   -2Avgf
2023:12:01_21h:07m:13s    -2N   23S  -13Avg   20nhz filt:    1Nf    6Sf   -3Avgf
2023:12:11_21h:07m:13s     6N   16S   -5Avg   20nhz filt:    2Nf    7Sf   -3Avgf
2023:12:21_21h:07m:13s    -5N   15S  -10Avg   20nhz filt:    2Nf    8Sf   -3Avgf
2023:12:31_21h:07m:13s   -23N    5S  -14Avg   20nhz filt:    2Nf    9Sf   -3Avgf
2024:01:10_21h:07m:13s   -23N    7S  -15Avg   20nhz filt:    3Nf    9Sf   -3Avgf
2024:01:20_21h:07m:13s   -11N    9S  -10Avg   20nhz filt:    3Nf   10Sf   -4Avgf
2024:01:30_21h:07m:13s   XXXN  XXXS  XXXAvg   20nhz filt:  XXXNf  XXXSf  XXXAvgf
2024:02:09_21h:07m:13s   XXXN  XXXS  XXXAvg   20nhz filt:  XXXNf  XXXSf  XXXAvgf
2024:02:19_21h:07m:13s   XXXN  XXXS  XXXAvg   20nhz filt:  XXXNf  XXXSf  XXXAvgf
2024:02:29_21h:07m:13s   XXXN  XXXS  XXXAvg   20nhz filt:  XXXNf  XXXSf  XXXAvgf
2024:03:10_21h:07m:13s    -5N  -12S    4Avg   20nhz filt:    4Nf   15Sf   -6Avgf

Again, note that this for the polar field, i.e. at high latitudes, not for the entire hemisphere; closer to the Solar equator, which is where most sunspots appear, there tends to be a relatively equal mix of both positive and negative polarities.

But in that data the two leftmost values are the northern and southern hemispheres respectively, and the third value is their average; to the right there are three more values, two for the northern and southern hemispheres after having been filtered, and the last one for the average of those.

[3gMike]

40 minutes ago, oemSpace said:

Based on following data, how to confirm polarity on the northern hemisphere of the sun?

How to tell polarity is North or South on the northern hemisphere of the sun?

Any suggestions?

Thank you very much for any suggestions

 

2023:10:12_21h:07m:13s     8N   14S   -3Avg   20nhz filt:   -0Nf    3Sf   -2Avgf
2023:10:22_21h:07m:13s     9N    9S    0Avg   20nhz filt:   -0Nf    3Sf   -2Avgf
2023:11:01_21h:07m:13s    14N    7S    4Avg   20nhz filt:    0Nf    4Sf   -2Avgf
2023:11:11_21h:07m:13s     4N   12S   -4Avg   20nhz filt:    1Nf    5Sf   -2Avgf
2023:11:21_21h:07m:13s     4N   14S   -5Avg   20nhz filt:    1Nf    6Sf   -2Avgf
2023:12:01_21h:07m:13s    -2N   23S  -13Avg   20nhz filt:    1Nf    6Sf   -3Avgf
2023:12:11_21h:07m:13s     6N   16S   -5Avg   20nhz filt:    2Nf    7Sf   -3Avgf
2023:12:21_21h:07m:13s    -5N   15S  -10Avg   20nhz filt:    2Nf    8Sf   -3Avgf
2023:12:31_21h:07m:13s   -23N    5S  -14Avg   20nhz filt:    2Nf    9Sf   -3Avgf
2024:01:10_21h:07m:13s   -23N    7S  -15Avg   20nhz filt:    3Nf    9Sf   -3Avgf
2024:01:20_21h:07m:13s   -11N    9S  -10Avg   20nhz filt:    3Nf   10Sf   -4Avgf
2024:01:30_21h:07m:13s   XXXN  XXXS  XXXAvg   20nhz filt:  XXXNf  XXXSf  XXXAvgf
2024:02:09_21h:07m:13s   XXXN  XXXS  XXXAvg   20nhz filt:  XXXNf  XXXSf  XXXAvgf
2024:02:19_21h:07m:13s   XXXN  XXXS  XXXAvg   20nhz filt:  XXXNf  XXXSf  XXXAvgf
2024:02:29_21h:07m:13s   XXXN  XXXS  XXXAvg   20nhz filt:  XXXNf  XXXSf  XXXAvgf
2024:03:10_21h:07m:13s    -5N  -12S    4Avg   20nhz filt:    4Nf   15Sf   -6Avgf

Perhaps it will help to see the data for Cycle 25 plotted graphically

                                                       

Alternatively, if you want to see magnetograms for the whole hemisphere you could use this link     http://wso.stanford.edu/#Magnetograms

[hamateur 1953]

16 minutes ago, Philalethes said:

Again, note that this for the polar field, i.e. at high latitudes, not for the entire hemisphere; closer to the Solar equator, which is where most sunspots appear, there tends to be a relatively equal mix of both positive and negative polarities.

But in that data the two leftmost values are the northern and southern hemispheres respectively, and the third value is their average; to the right there are three more values, two for the northern and southern hemispheres after having been filtered, and the last one for the average of those.

Hey @Philalethes  I recall Jan indicated not long ago that we are either at or currently very near reversal.  Do you have an idea where we might be at present?  I think he also mentioned around May unless I am mistaken.  Tnx Mike.   Hey  @3gMike  simultaneous posting. Ya beat me. Haha good to see ya back! 

Edited April 7 by hamateur 1953

[Philalethes]

9 minutes ago, hamateur 1953 said:

Hey @Philalethes  I recall Jan indicated not long ago that we are either at or currently very near reversal.  Do you have an idea where we might be at present?  I think he also mentioned around May unless I am mistaken.

Well, it depends on exactly what you consider reversal. Measurements at the lower polar latitudes indicate that the average field there flipped quite a while ago; for example, the 50-60° band as measured by HMI flipped as early as roughly halfway through 2022. If we're talking about the WSO average field, then the flip of the filtered average field happened in July of last year (2023). I marked this in the plot I posted not long ago in the "Growth of Cycle 25" thread if you want to see a visual.

So not entirely sure exactly what metric Jan is referring to here. The 60-70° band has also flipped, as have the 50°+ and 60°+ caps; the only thing left is the 70°+ cap, which I've discussed in some of my updates in that thread too, but I suspect that's not what Jan is talking about. Maybe you know exactly what he might be referring to?

[hamateur 1953]

1 minute ago, Philalethes said:

Well, it depends on exactly what you consider reversal. Measurements at the lower polar latitudes indicate that the average field there flipped quite a while ago; for example, the 50-60° band as measured by HMI flipped as early as roughly halfway through 2022. If we're talking about the WSO average field, then the flip of the filtered average field happened in July of last year (2023). I marked this in the plot I posted not long ago in the "Growth of Cycle 25" thread if you want to see a visual.

So not entirely sure exactly what metric Jan is referring to here. The 60-70° band has also flipped, as have the 50°+ and 60°+ caps; the only thing left is the 70°+ cap, which I've discussed in some of my updates in that thread too, but I suspect that's not what Jan is talking about. Maybe you know exactly what he might be referring to?

I don’t because he really wasn’t that explicit. I suppose it really matters little at this point.  I do recall now your earlier mention of the 70 degree cap.   Perhaps that is what he was really thinking of when he mentioned May of this year, but that is only speculation on my part.  Tnx for quick reply.  Mike 

[oemSpace]

36 minutes ago, Philalethes said:

Again, note that this for the polar field, i.e. at high latitudes, not for the entire hemisphere; closer to the Solar equator, which is where most sunspots appear, there tends to be a relatively equal mix of both positive and negative polarities.

But in that data the two leftmost values are the northern and southern hemispheres respectively, and the third value is their average; to the right there are three more values, two for the northern and southern hemispheres after having been filtered, and the last one for the average of those.

Which value is typically used as the primary indicator of the polarity direction on the northern hemisphere of the sun?

Furthermore, for -5N, how to interpret the polarity direction on the northern hemisphere of the sun?

Any suggestions?

Thanks everyone for any suggestions

26 minutes ago, 3gMike said:

Perhaps it will help to see the data for Cycle 25 plotted graphically

                                                       

Alternatively, if you want to see magnetograms for the whole hemisphere you could use this link     http://wso.stanford.edu/#Magnetograms

I cannot find this image from given link, could you please post the direct link for related information?

Thanks

[Philalethes]

2 minutes ago, oemSpace said:

Which value is typically used as the primary indicator of the polarity direction on the northern hemisphere of the sun?

The fourth of the values would be the best general indicator of the northern hemisphere polar field in the WSO data. For the latest measurement listed, that's the one that says "4Nf". The "N" refers to that it's the northern hemisphere, and the positive value means the average northern polar field is positive. 4 is a very small value, close to 0, which indicates that the polar field is currently very weak and in the process of undergoing reversal, which happens around the time of Solar maximum.

That being said, that's just one aspect of it. If you e.g. were to consider the 60°+ polar field as measured by HMI instead, you'd see that it's already negative, and likely headed towards the stronger negative values we'll see around minimum.

And once again, keep in mind that these are polar fields, and not necessarily indicative of the field at lower latitudes where sunspots occur, which is more mixed.

[3gMike]

16 minutes ago, oemSpace said:

I cannot find this image from given link, could you please post the direct link for related information?

I produced the graph by entering the WSO polar data into a spreadsheet.

The link I posted referred to magnetograms, which look like this....

                                                        

Blue areas are positive fields and red are negative. The contour lines indicate local field strength, with the innermost lines representing the highest field strength.

[oemSpace]

1 hour ago, Philalethes said:

The fourth of the values would be the best general indicator of the northern hemisphere polar field in the WSO data. For the latest measurement listed, that's the one that says "4Nf". The "N" refers to that it's the northern hemisphere, and the positive value means the average northern polar field is positive. 4 is a very small value, close to 0, which indicates that the polar field is currently very weak and in the process of undergoing reversal, which happens around the time of Solar maximum.

That being said, that's just one aspect of it. If you e.g. were to consider the 60°+ polar field as measured by HMI instead, you'd see that it's already negative, and likely headed towards the stronger negative values we'll see around minimum.

And once again, keep in mind that these are polar fields, and not necessarily indicative of the field at lower latitudes where sunspots occur, which is more mixed.

Does 4Nf is for the polar field at high latitudes? not for the entire hemisphere; closer to the Solar equator,
At high latitudes, it is highly chance to become solar winds, correct?

Do you refer to the fifth of the values 4Nf, instead of forth of the value 20nhz?

2024:03:10_21h:07m:13s    -5N  -12S    4Avg   20nhz filt:    4Nf   15Sf   -6Avgf
1st : -5N
2nd : -12S
3rd : 4Avg
4th : 20nhz
5th : 4Nf
6th : 15Sf
7th : -6Avgf

For 4Nf,
N = North hemisphere of the Sun
+4 = average northern polar field is positive
-3 = what does negative value mean in term of -3Nf? Magnetic field polarity consider reversal?

Any suggestions?
Thanks everyone very much for any suggestions

 

1 hour ago, 3gMike said:

I produced the graph by entering the WSO polar data into a spreadsheet.

The link I posted referred to magnetograms, which look like this....

                                                        

Blue areas are positive fields and red are negative. The contour lines indicate local field strength, with the innermost lines representing the highest field strength.

 

I prefer to get data into Excel instead of chart or image,

Where do you get data? would following link be correct link for 2024? there is a lot of empty data within table.

http://wso.stanford.edu/meanfld/mf.2024

Any suggestions?
Thanks everyone very much for any suggestions

[Philalethes]

19 minutes ago, oemSpace said:

Does 4Nf is for the polar field at high latitudes? not for the entire hemisphere; closer to the Solar equator,

Correct; the WSO data measures from ~55° of latitude and up to the poles, so not near the equator. But as 3gMike posted above, WSO also have data on the field elsewhere, but you can see that it's more mixed and chaotic near the equator.

22 minutes ago, oemSpace said:

At high latitudes, it is highly chance to become solar winds, correct?

Not entirely sure what you mean by this, since the English is a bit subpar. If there is some other language you speak better you could perhaps try using something like Google Translate from that language to make yourself better understood.

But to address what you might mean, higher latitudes do tend to have more fast Solar wind, since there are typically polar coronal holes there permanently; however, as the Solar cycle progresses these holes typically become smaller and smaller until the field reverses, and I believe they're at they're smallest around maximum.

26 minutes ago, oemSpace said:

Do you refer to the fifth of the values 4Nf, instead of forth of the value 20nhz?

The "20nhz filt." part isn't a value in the data, it's just an indication that the three values to the right of it have been filtered with a 20 nHz. The fourth value would be the "4Nf" part.

28 minutes ago, oemSpace said:

-3 = what does negative value mean in term of -3Nf?

"-3Nf" means "the filtered magnetic field strength of the northern polar field is -3"; the negative value means that the field there is negative, i.e. that the magnetic field is directed into the pole from outside the Solar surface.

30 minutes ago, oemSpace said:

Magnetic field polarity consider reversal?

A negative value by itself doesn't mean anything is reversing. The field is reversing when it goes from positive to negative or from negative to positive.

[oemSpace]

35 minutes ago, Philalethes said:

Correct; the WSO data measures from ~55° of latitude and up to the poles, so not near the equator. But as 3gMike posted above, WSO also have data on the field elsewhere, but you can see that it's more mixed and chaotic near the equator.

Not entirely sure what you mean by this, since the English is a bit subpar. If there is some other language you speak better you could perhaps try using something like Google Translate from that language to make yourself better understood.

But to address what you might mean, higher latitudes do tend to have more fast Solar wind, since there are typically polar coronal holes there permanently; however, as the Solar cycle progresses these holes typically become smaller and smaller until the field reverses, and I believe they're at they're smallest around maximum.

The "20nhz filt." part isn't a value in the data, it's just an indication that the three values to the right of it have been filtered with a 20 nHz. The fourth value would be the "4Nf" part.

"-3Nf" means "the filtered magnetic field strength of the northern polar field is -3"; the negative value means that the field there is negative, i.e. that the magnetic field is directed into the pole from outside the Solar surface.

A negative value by itself doesn't mean anything is reversing. The field is reversing when it goes from positive to negative or from negative to positive.

if -3 mean that magnetic field is directed into the pole from outside the solar surface, then what data to show on whether northern hemisphere is carrying north pole or south pole? please see attached images for details

Any suggestions?
Thanks everyone very much for any suggestions

 

[Philalethes]

34 minutes ago, oemSpace said:

if -3 mean that magnetic field is directed into the pole from outside the solar surface, then what data to show on whether northern hemisphere is carrying north pole or south pole?

When I wrote "pole" above I was referring to the heliographic north pole, i.e. the northern hemisphere.

As for what orientation of a bar magnet that corresponds to, north on a bar magnet would be positive and south would be negative, so if e.g. the northern hemisphere had a negative magnetic field, it would be like in the second image.

Edited April 7 by Philalethes
clarity

[oemSpace]

Thanks everyone very much for suggestions

 

[oemSpace]

Thanks

Edited April 9 by oemSpace

[oemSpace]

Referring to following link, I would like to know on which kind of data is being used most often

1) Daily hemispheric sunspot number [1/1/1992 - now]
2) Monthly mean North-South sunspot numbers [1/1992 - now]
3) 13-month smoothed monthly hemispheric sunspot number [1/1992 - now]

https://www.sidc.be/SILSO/datafiles

Any suggestions?

Thanks everyone

[Philalethes]

1 hour ago, oemSpace said:

Referring to following link, I would like to know on which kind of data is being used most often

1) Daily hemispheric sunspot number [1/1/1992 - now]
2) Monthly mean North-South sunspot numbers [1/1992 - now]
3) 13-month smoothed monthly hemispheric sunspot number [1/1992 - now]

https://www.sidc.be/SILSO/datafiles

Any suggestions?

Thanks everyone

Like with the overall sunspot number, it's typically the 13-month smoothed number that's used in most contexts (at least that I've come across) to give a representation of cycles in terms of the relative hemispheric development. You can an example here, the section "Hemispheric sunspot activity" and the second plot there.

Edited April 10 by Philalethes
wrong plot

[oemSpace]

On 4/11/2024 at 12:50 AM, Philalethes said:

Like with the overall sunspot number, it's typically the 13-month smoothed number that's used in most contexts (at least that I've come across) to give a representation of cycles in terms of the relative hemispheric development. You can an example here, the section "Hemispheric sunspot activity" and the second plot there.

Cycle for sunspot numbers is about 11 years, could you please describe more about what representation of cycles in terms of the relative hemispheric development is for 13-month smoothed number?

Thanks everyone very much for suggestions :)

[3gMike]

16 hours ago, oemSpace said:

Cycle for sunspot numbers is about 11 years, could you please describe more about what representation of cycles in terms of the relative hemispheric development is for 13-month smoothed number?

Thanks everyone very much for suggestions

You mean something like this? https://www.sidc.be/SILSO/monthlyhemisphericplot

[oemSpace]

On 4/13/2024 at 12:20 AM, 3gMike said:

You mean something like this? https://www.sidc.be/SILSO/monthlyhemisphericplot

Yes, any suggestions?

Furthermore, based on following image,  would G1 is high likely hit Earth on 14 Apr?

Any suggestions?

Thanks everyone

[Philalethes]

54 minutes ago, oemSpace said:

Yes, any suggestions?

The image they posted is of the 13-month smoothed hemispheric sunspot number. It's generally those smoothed numbers that are used to represent the ~11-year Solar cycles. If that's not what you were looking for, try to see if you can formulate a bit more clearly what you're seeking.

56 minutes ago, oemSpace said:

Furthermore, based on following image,  would G1 is high likely hit Earth on 14 Apr?

Based on the image on the bottom, yes. There was a filament eruption yesterday which is estimated to arrive tomorrow, and which might cause some geomagnetic storming. There's a thread dedicated to it here.

The top left image is the WSO polar field data, it doesn't have anything to do with the CME.

The top right image is a live measure of the Bz, it's measured at L1 (Lagrange point 1), which is roughly 1.5 million km from Earth (roughly 1% of the Earth-Sol distance).

[oemSpace]

hemispheric sunspot number represent the ~11-year Solar cycles
What about cycles for following measurements?

• Excess North vs South
• Excess South vs North

Any suggestions?
Thanks in advance for any suggestions

[hamateur 1953]

https://www.stce.be/content/sc25-tracking  Yes.  STCE has those. Will post a link on an edit if they still do..Mike.  Scroll down, they have good data and plenty to keep you busy for a month of study on all Solar Cycles. Good luck.  You should be able to contact them directly for specific numbers.  Those charts are interesting  for phase studies as well. 

Edited April 14 by hamateur 1953
Added link to STCE 25 tracking