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Growth of Cycle 25


3gMike

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Since we are now 2 years into Cycle 25, and we seem to be seeing a growth of activity in the Southern hemisphere with ARs 2906 to 2908 all lining up closely one behind the other, I thought it might be interesting to analyse how the number of active regions in each hemisphere has developed on a month by month basis.

It seems that the Northern hemisphere (Blue) is lagging slightly behind the Southern (Red) at the moment. Perhaps there is a slight suggestion of a peak in activity in certain months?

 

1783316932_GrowthofCycle25.thumb.png.a5e06d1344a05d47c881ba6f8305d76a.png

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Another hypothesis to test is whether the mean distance between ARs is shorter in the southern versus northern hemisphere.  ARs do seem to cluster more closely together or line up back-to-back more often in the southern hemisphere.  I don't think that's an impression biased by current observations, but it could be.

There are differences in the AR distribution between the hemispheres, as is evident in this 10 year composite SDO image (2010-2020):

https://ibb.co/fkS8NZV

Credit: NASA's Goddard Space Flight Center/SDO

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2 hours ago, Drax Spacex said:

Another hypothesis to test is whether the mean distance between ARs is shorter in the southern versus northern hemisphere.  ARs do seem to cluster more closely together or line up back-to-back more often in the southern hemisphere.  I don't think that's an impression biased by current observations, but it could be.

There are differences in the AR distribution between the hemispheres, as is evident in this 10 year composite SDO image (2010-2020):

https://ibb.co/fkS8NZV

Credit: NASA's Goddard Space Flight Center/SDO

My gut feeling is that mean distances will be shorter in the southern hemisphere. This would be supported by my observation that we have seen 87 ARs in the southern hemisphere compared with only 68 in the Northern hemisphere so far in this cycle. I have now completed some analysis which shows:

Mean days between ARs- Year 1     64.3 days North and 36.2 days South

Mean days between ARs - Year 2     7.58 days North and 5.57 days South

The SDO image is interesting - the Northern hemisphere appears to be much less organised in the higher latitudes over the 10 year period.

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1 hour ago, Joe.Ludwig said:

The question that arises about this diagram is the following: Since when does the number of events allow conclusions about their intensity? It is negligent to evaluate such complex systems monocausally.

Welcome to the forum !

There was no intention to investigate the intensity of events in this thread. It was stimulated by an observation that the southern hemisphere seems to be more active, supported by a string of three ARs appearing on very similar latitudes, and close together longitudinally. 

Feel free to add any data that you may have concerning intensity.

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Another factor that may be of interest is "what is happening on the far side?" Obviously that is difficult to tell with any certainty, but an examination of the AR data allows us to determine what proportion of spots first appear on the eastern limb. Given that the sun rotates approximately 13 degrees / day, as observed from earth, and that I can find no record of ARs appearing beyond -79 degrees I have assumed that any AR first recorded between -60 and -79 degrees probably originated on the far side.

On that basis we find that 47 arise on the far side, with 20 being in the North and 27 in the South. For those appearing on the earth-facing side we find 49 in the North and 61 in the South.

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2 hours ago, Orneno said:

Related to the progression of Solar Cycle 25, we now have 7 different named ARs on the sun at once.
As far as I know, this hasn't happened since the last cycle! (We've hit 6 once or twice in the last year, but not 7)

Yes, it is definitely getting interesting. 10.7cm flux exceeding 100 today. A nice line of ARs in the southern hemisphere suggesting that the magnetic field is getting organised and now a fairly active spot on the East limb of the northern hemisphere as well. Let's hope there are more to follow.

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  • 4 months later...

Since there are now suggestions that SC25 may be growing faster than predicted I thought it might be interesting to compare this cycle with the two previous cycles. Using the very useful Historical cycles feature on this website we can easily produce two comparative images.

solar-cycle-comparison.thumb.jpeg.8a5157ab18f2d9d12247651b6cb92b6c.jpeg1246576979_solar-cycle-comparison(1).thumb.jpeg.d56335497c75a5d7bfe16090272a0992.jpeg

 

It is interesting to note that the current latest raw values are very similar for all three cycles, but in terms of the smoothed curves it has to be said that SC25 currently looks more similar to SC24 than to SC23. As always it seems that we have to wait to see how it develops in the next few months.

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2 hours ago, Catchmenova said:

Just looking at the data in different ways, time between lows...

You might find this link interesting https://link.springer.com/article/10.1007/s11207-020-01723-y#Fig4

Rather than using time between minimums they use time between terminators, where terminators are defined as the point where equatorial fields cancel out and, according to the theory, allow an acceleration of activity in the new cycle. Using this theory they are predicting a relatively strong cycle.

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On 4/27/2022 at 9:19 AM, 3gMike said:

Since there are now suggestions that SC25 may be growing faster than predicted I thought it might be interesting to compare this cycle with the two previous cycles. Using the very useful Historical cycles feature on this website we can easily produce two comparative images.

solar-cycle-comparison.thumb.jpeg.8a5157ab18f2d9d12247651b6cb92b6c.jpeg1246576979_solar-cycle-comparison(1).thumb.jpeg.d56335497c75a5d7bfe16090272a0992.jpeg

 

It is interesting to note that the current latest raw values are very similar for all three cycles, but in terms of the smoothed curves it has to be said that SC25 currently looks more similar to SC24 than to SC23. As always it seems that we have to wait to see how it develops in the next few months.

Would be good to see cycle comparisons for 10.7cm radio flux as well when sufficient data timeseries become available. I find the sunspot number too subjective, especially given the inconsistencies in numbering and classifying sunspots by SWPC. 10.7cm flux is set to increase for the 5th consecutive month, and it does seem like solar activity is increasing rapidly and consistently at the moment. A maximum somewhere between that of SC24 and SC23 looks pretty likely at the moment, but I am still hoping for a nice surprise.

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47 minutes ago, Tristan said:

I find the sunspot number too subjective, especially given the inconsistencies in numbering and classifying sunspots by SWPC.

I understand your concern . I have noticed recently some confusion over numbering, with the same number being assigned to spots in different locations. Also a few tiny spots being assigned a number, then rapidly decaying to a plage. Of course that could skew my data in respect of the original plot of number of sunspots / hemisphere. However, the recent plot comparing the current cycle with cycles 23 and 24 is using verified data held on this website, and sourced from WDC-SILSO

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  • 1 year later...
5 hours ago, Philalethes said:

Provisional monthly average for June is 163.4 at the moment of posting this, making it the highest of the cycle so far, and the first month to break 150. It also seems to be further confirmation of SC25 being more active than SC24 given that this monthly average is higher than the peak of the latter, but I guess there are other factors at play too and that judgment can still be suspended for a few months to see where things are headed.

I agree, but the smoothed sunspot number still has a way to go before it matches the peak of Cycle 24. On a more positive note, Jan Alvestad reports solar flux data for June 30th as follows 

"Solar flux density measured at 20h UT on 2.8 GHz was 158.6 - decreasing 6.3 over the previous solar rotation. (Centered 1 year average SF at 1 AU - 183 days ago: 145.51. In comparison SC24 peaked on June 28, 2014 at 145.50)."

On that basis it seems very likely that the maximum solar flux will comfortably exceed that of Cycle 24.

For reference, the flux has grown steadily from 130.83 at January 31st

Interesting times !

 

 

 

Edited by 3gMike
Added info re January measurement and corrected Cycle 23 to 24
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1 hour ago, 3gMike said:

I agree, but the smoothed sunspot number still has a way to go before it matches the peak of Cycle 24.

Yeah, I was just referring to the individual monthly average peak (February of 2014 for SC24, at 146.1). That being said, we're not necessarily that far off from beating even the peak SSN if it continues like this; if the two next months have a monthly average of just 135 or more we'd end up with an SSN for February of more than the 116.4 of April of 2014.

Of course it remains to be seen, it's definitely not unheard of for a quick drop in the SN to occur. I'm looking particularly at SC20, which I've mentioned a few times seems similar to SC25 in some ways, and there it reached quite similar values to the ones we see now before dropping down for a few months; but then again, that one did keep climbing in general and the SSN continued to rise to 156.6 in November of 1968.

Interestingly, that reminds me of the geomagnetic activity that @hamateur 1953 mentioned at some point (or maybe it was someone else, but I remember discussing it with them) where sea mines were triggered and exploded, which was in 1972, on the descent of SC20; if SC25 ends up being similar to it I guess we could see similar activity if we're lucky (minus the exploding mines, hopefully).

In any case, I agree that we're not quite there yet, but still seems promising!

Nice to see the flux continuing to rise as well, I'm sure there are a lot of happy ham radio enthusiasts out there hoping for that trend to continue.

Edited by Philalethes
typo
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47 minutes ago, Philalethes said:

Nice to see the flux continuing to rise as well, I'm sure there are a lot of happy ham radio enthusiasts out there hoping for that trend to continue.

You're right. More flux, please. The upper bands are just starting to open up. Just enough to be maddeningly tantalizing.  And everyone is being reminded that solar max is a double-edged sword: better propagation and more blackouts. Haha. The sun giveth and the sun taketh away.

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Every notice for all the predictions, they don't seem to get right.  Makes me think of all the old saying,"best laid plans of mice and men". We are missing the bigger rhythm to this. Scientist have forgotten how to listen to nature.   Nature moves in patterns, and long ago we knew how to understand those patterns. You aren't looking at a pattern on the sun.   Notice it quiets as it turns into earth facing till day after directly facing earth, then something is triggered and it sparks off.  Start watching patterns on the sun, then look at numbers. Scientist haven't gotten too much right in last two cycles, otherwise we would be in grand minimum.

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18 minutes ago, MichiganAuroraHunter said:

Every notice for all the predictions, they don't seem to get right.  Makes me think of all the old saying,"best laid plans of mice and men". We are missing the bigger rhythm to this. Scientist have forgotten how to listen to nature.   Nature moves in patterns, and long ago we knew how to understand those patterns. You aren't looking at a pattern on the sun.   Notice it quiets as it turns into earth facing till day after directly facing earth, then something is triggered and it sparks off.  Start watching patterns on the sun, then look at numbers. Scientist haven't gotten too much right in last two cycles, otherwise we would be in grand minimum.

"Predicting" space weather is still a bit of a guessing game, and confirmation bias makes us remember the times they get it wrong, but not remember all the times the predictions work well!
There are many patterns on the sun, but "Earth-facing quiet" is not one of them.  Many people have speculated on that, as it can often feel like that to us, but if you do the math and look at data it doesn't show up.  There are really only 30 degrees of the sun that I would say are truly Earth-facing, but the sun is 360 degrees around, so something like 8% of all activity should be facing Earth! We just have to get lucky!
Some people predicted a grand solar minimum, but their predictions for SC25 of a very weak cycle have already been pretty conclusively refuted, as indicated by this thread's original topic.

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3 hours ago, MichiganAuroraHunter said:

Every notice for all the predictions, they don't seem to get right.

Plenty of predictions are actually gotten right all the time. While a lot of Solar physics is still a big mystery, we do know sufficiently about it to make certain statements about the general behavior of Solar cycles that are backed up by sufficient evidence to be predictive in nature (e.g. something as general as the Solar cycle itself).

3 hours ago, MichiganAuroraHunter said:

We are missing the bigger rhythm to this.

If you think there's a rhythm we're missing, feel free to provide your own unproven theories about such over in the appropriate thread for it.

3 hours ago, MichiganAuroraHunter said:

Scientist have forgotten how to listen to nature.

Listening to nature is exactly what scientists, particularly physicists, do. The very word "physics" itself is derived from the Greek (and further back the language tree too) word for nature, "phusis".

3 hours ago, MichiganAuroraHunter said:

Nature moves in patterns, and long ago we knew how to understand those patterns.

The idea that ancient people had a better understanding of nature and physics in general than we do is extremely speculative and unsupported by good evidence. Based on all we know, we have a better understanding of the patterns of nature than any organism has ever had on this planet, and by a wide margin too.

3 hours ago, MichiganAuroraHunter said:

You aren't looking at a pattern on the sun.

That's exactly what we're doing; and again, if there's a pattern you think we're missing, feel free to provide it in the appropriate thread.

3 hours ago, MichiganAuroraHunter said:

Notice it quiets as it turns into earth facing till day after directly facing earth, then something is triggered and it sparks off.

The other day I had someone claim this too, and I've also had someone claim the exact opposite, that flares and CMEs were mostly coming from the other limb. Turns out that over long periods of time, flares are actually very evenly distributed, and that what you're doing here is falling prey to some sort of selection or confirmation bias; in fact, I went through and checked every single X-flare so far this cycle, and turns out 7 of them were from the limb you're mentioning here, the western limb, while 9 were from the other limb, the eastern limb.

Very typical to get something like this wrong when you're not thinking scientifically enough to actually check the data. I'd recommend doing that in the future before making unsupported statements that don't check out with the observed facts.

4 hours ago, MichiganAuroraHunter said:

Start watching patterns on the sun, then look at numbers.

We're already doing that; but we don't skip the "looking at numbers" part, something it seems like you're doing when you make statements like the above one.

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Indeed @Philalethes  Good memory. 

And unless I am mistaken Tamitha Skov is looking into SC 20 as well. Although I know little more than the fact that she mentioned this a few months prior.  

22 hours ago, Philalethes said:

Yeah, I was just referring to the individual monthly average peak (February of 2014 for SC24, at 146.1). That being said, we're not necessarily that far off from beating even the peak SSN if it continues like this; if the two next months have a monthly average of just 135 or more we'd end up with an SSN for February of more than the 116.4 of April of 2014.

Of course it remains to be seen, it's definitely not unheard of for a quick drop in the SN to occur. I'm looking particularly at SC20, which I've mentioned a few times seems similar to SC25 in some ways, and there it reached quite similar values to the ones we see now before dropping down for a few months; but then again, that one did keep climbing in general and the SSN continued to rise to 156.6 in November of 1968.

Interestingly, that reminds me of the geomagnetic activity that @hamateur 1953 mentioned at some point (or maybe it was someone else, but I remember discussing it with them) where sea mines were triggered and exploded, which was in 1972, on the descent of SC20; if SC25 ends up being similar to it I guess we could see similar activity if we're lucky (minus the exploding mines, hopefully).

In any case, I agree that we're not quite there yet, but still seems promising!

Nice to see the flux continuing to rise as well, I'm sure there are a lot of happy ham radio enthusiasts out there hoping for that trend to continue.

 

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On 7/1/2023 at 4:56 PM, Philalethes said:

but I guess there are other factors at play too and that judgment can still be suspended for a few months to see where things are headed.

Thinking about other factors I began to wonder why we define solar maximum as the time when we have the highest number of sunspots. I suppose that comes down to comparison with historical data. But actually, what we are really interested in is the effect on earth - be that generation of Aurora, the effect on radio propagation, or the increased drag on satellites. So I decided to have a look at the Thermosphere Climate Index, held on Spaceweather.com. That shows that the effect from Cycle 25 is already considerably stronger than that from Cycle 24. A bit more work is required to understand why that is so, but my initial thoughts would be that the number of solar flares in this cycle is high compared to the number of sunspots. Might we also have seen more coronal holes?

TCI_Daily_NO_Power_Percentiles.png.7f4160d132c01c4d0fcb615595ec28d6.png

 

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16 hours ago, 3gMike said:

Thinking about other factors I began to wonder why we define solar maximum as the time when we have the highest number of sunspots. I suppose that comes down to comparison with historical data. But actually, what we are really interested in is the effect on earth - be that generation of Aurora, the effect on radio propagation, or the increased drag on satellites. So I decided to have a look at the Thermosphere Climate Index, held on Spaceweather.com. That shows that the effect from Cycle 25 is already considerably stronger than that from Cycle 24. A bit more work is required to understand why that is so, but my initial thoughts would be that the number of solar flares in this cycle is high compared to the number of sunspots. Might we also have seen more coronal holes?

Yeah, there are a lot of different views on that for sure. And I agree, I also think sunspots are primarily used because they've been observed for so long and provide a seemingly reliable proxy of Solar activity.

As for what's really interesting I'd say it's both the actual effects on Earth as well as Solar activity itself. Given how there's a stochastic element involved in e.g. large events (huge eruptions missing us by a few days, and so on), I'd at least think there could be a difference there; but geomagnetic indices and other measurements of effects here on Earth are certainly going to provide good estimates on average in the long run. So what I mean is more that rather than sunspots themselves it could give a better picture to keep track of more dynamic activity, like flaring and eruptions and such, in addition to keeping track of the actual effects here on Earth. That way we could also get more insight into some of the things Patrick has been inquiring about, i.e. sizes and numbers of sunspots relative to the more dynamic activity.

I did look at the TCI myself not long ago and posted about it here when I found there was an earlier thread discussing it, and it's definitely very interesting how it's not just well past SC24, but seems to even have risen to levels matching SC20 already. I haven't looked into it enough to know much about what extent to which it's a good indicator of Solar activity, but it does clearly seem to match with the cyclic patterns. Another question is also whether the effects on the thermosphere are necessarily going to have much of an effect on anything more immediate to us here on the surface, although I remember reading that the increased temperature leads to more drag on satellites due to the increase in viscosity of the (admittedly quite rarefied) air there.

I haven't compared flaring data against previous cycles, but I think what you're saying checks out, as I believe I saw some stats about the number of X-flares so far being significantly higher than that equally long into SC24. I'd be interesting in knowing just how this increases the thermospheric temperature so much though, because to my knowledge the total Solar irradiance doesn't fluctuate that much during flares, nor from minimum to maximum (only 1-3 W/m^2 if I recall correctly, around a baseline of ~1361 W/m^2); I suppose factors involved are the aforementioned low density and also how the most energetic radiation from the flares will tend to be absorbed farther up.

Checking for a potential increase in coronal holes also seems like a good idea, although I guess it's not always that easy to keep track of which ones were there previously and which are more transient, but some sort of index that simply measures e.g. coronal hole area visible at any given point in time (perhaps combined with some measure of how dark they are) might be useful to have as a reference. Ideally it would be great to have a combined view from all sides of the Solar surface and keep track of all the measurable activity, but I guess it's always going to be an interplay between new ways of measuring and keeping track of the old measurements that have been made for much longer.

Edited by Philalethes
grammar
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