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What makes AR3684 magnetically distinct from AR3685?


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I am curious what the criteria for making larger but closer sunspot regions distinct versus a more spread out region like 3674, or the 3670/3671 pair. I assume it comes more from the HMIBC data than the HMIIF data?

Any insights would be welcome!

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Posted (edited)

It seems as those if region develops on our side of the disk it will be give a single number. If larger regions come back around broken up, they may be given several numbers. Overall, given the position and polarities of the sunspots.

Region 3684 was fairly separated from the other regions, though not much of it is left at this point. Region 3685 is a new region to its area from the previous rotation. Region 3686 already existed as a sunspot in the same location in the previous rotation.

Region 3670 was a region that came over the limb, then in magnetogram and intensitygram imagery you can see region 3671 develop. It does get somewhat confusing as to if 3670 or 3671 is developing more spots at one point, but I guess the SWPC can do what they want.

For SC25, you will typically see negative polarity spots of a region leading in the southern hemisphere of the Sun, while positive polarity spots lead in the north. Then the polarities will reverse per solar cycle.

Edited by Jesterface23
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Posted (edited)

Yeah, I feel a bit dumb, I was only going off the position of the numbers on the map. With everything being out on the limb (no pun intended), it made it a bit difficult to distinguish what was where. I had mistakenly thought 3684 was where 3686 actually is, once things became more visible, it was much easier to see the spotless plague that is actually 3684.

I imagine the work the folks do over at the SWPC is just as much art as it is science, but they've also been at it for quite some time now. No idea if they have any lurkers here or not, or if the enthusiasts much more knowledgeable than me would be to clarify, as well.

(Also, I made a thing earlier this week and forgot to share, heh)

8q8yp9.jpg

Edited by Adam Young
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D

2 hours ago, Adam Young said:

Yeah, I feel a bit dumb, I was only going off the position of the numbers on the map. With everything being out on the limb (no pun intended), it made it a bit difficult to distinguish what was where. I had mistakenly thought 3684 was where 3686 actually is, once things became more visible, it was much easier to see the spotless plague that is actually 3684.

I imagine the work the folks do over at the SWPC is just as much art as it is science, but they've also been at it for quite some time now. No idea if they have any lurkers here or not, or if the enthusiasts much more knowledgeable than me would be to clarify, as well.

(Also, I made a thing earlier this week and forgot to share, heh)

8q8yp9.jpg

Hey @Adam Young we actually have a spaceweather memes section. Trust me you should enjoy it!  Welcome dude 

Mike

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On 5/17/2024 at 3:10 AM, Adam Young said:

I am curious what the criteria for making larger but closer sunspot regions distinct versus a more spread out region like 3674, or the 3670/3671 pair. I assume it comes more from the HMIBC data than the HMIIF data?

Any insights would be welcome!

On 5/18/2024 at 2:02 AM, Barfolomew said:

Adam- I hope someone responds to your question as I have the exact same question regarding 3685/3686. 

Generally it's more of an art than a science at this point how NOAA regions are identified and numbered, heh. In this case of 3684 it's evidently quite separate from 3685; 3686 is a better question, and as Jesterface says it can have something to do with having been previously identified, and there's also a matter of looking at how intertwined the magnetic fields are, where in this case you can see that there's a relatively clear separation between them with nothing of interest magnetically (mostly grey in the colored magnetogram). A better question is when two previously separate regions grow and complexify and turn into what would likely have been classified as a single region if it had emerged on its own, in which case they might remain two regions or end up being absorbed into one of them depending on circumstances (like we saw with e.g. 3664 and 3668 if you move forward day by day in the archive here). 3674 doesn't look very spread out, but perhaps you meant 3679 instead, in which case you could certainly make a case for two separate regions, but there there is less separation between sunspot pairs, so it's understandable that it's made a single region.

As you can tell there's a definite element of human judgment involved in that process, in contrast to e.g. the SHARPs from the HMI data, which are detected entirely automatically through an algorithm, but which don't fully correspond to NOAA's ARs at all (here you can see the latest SHARPs with the NOAA ARs marked with the blue pluses and the arrows pointing to them).

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