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theartist

Breaking! 'aa Index' holds a huge clue in Solar Cycle Forecasting

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The following two tweets are from someone whose name is showing up in some of the scientific literature I've been reviewing;  he has been at this for several years.

1928923328_ScreenShot2019-09-09at7_49_48PM.thumb.png.23791d1481a91ddeb0924b611d699dad.png1131865678_ScreenShot2019-09-09at7_41_10PM.thumb.png.eed7503d64cc940f53f495c23bb175d0.png

Really?  It is that simple?!  LOL...(I) may want to look at the data discussed in this thread more closely now.

Edited by theartist

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7 hours ago, The Atmosphere Guy said:

the weakest for 200 years

Yes, you may recall that is covered in the thread titled, Solar Cycle 25 Predictions/Forecasts by 1. 'The Panel' & 2. NASA; (but this is an opportunity to bring new viewers 'up-to-speed'.😊)

It was only after mentioning it over in the 'climate' thread, and going back and 'fact checking' the sunspot count that it occurred to me the current SC24 is already at 'Dalton Minimum' levels.  That was a period of "lower-than-average global temperatures", as was (been hypothesized) the time of the Spörer Minimum, but those views on the latter have been challenged in the scientific literature (per this Wikipedia article).

Edited by theartist

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Even if one knew that the Solar Minimum (nadir) has passed (as I was hypothesizing with the 'Bremen Metric', although that is far from certain at the moment), I think it still is early to make a forward prognostication on the next cycle sunspot magnitude based strictly on magnitudes of a cycle's geomagnetic behavior during its prior solar minimum period.  The reason for this is that the 'aa Index' can change significantly between the time of the Solar Minimum (nadir) and before the next cycle 'onset'; witness particularly the SC23/SC24 transition in the following graph:1339034227_ISNaaIndex.thumb.jpg.4634a35dbc076916405dfa8a115cbd46.jpg

(Source of ISN data.)  (Source of 'aa Index" data.)

Edited by theartist

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"It is shown that in the declining phase the occurrence frequencies of Kp = 4±5 (consecutively over 4 intervals) can be used as a precursor for the maximum sunspot number to be expected in the next cycle." 

https://hal.archives-ouvertes.fr/hal-00316331/document

Bartels first looked at systematic temporal changes in the geomagnetic indices in correlation with solar activity before the satellite era.  This should probably have received more attention since then.  I would caution the researchers wishing to pursue further the evaluation of a correlation based on historical data, that we now may be in a new phase of solar activity (as discussed on other threads here), observed with the dramatic drop in Ap activity starting in SC23, which continued in SC24; we now may be embarking upon what possibly might be the weakest solar cycle in 200 years. 

Edited by theartist

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5 hours ago, theartist said:

we now may be embarking upon what possibly might be the weakest solar cycle in 200 years

We may be in a different 'phasing' of the solar system; maybe we've entered a new Gleissberg Cycle (as discussed in the thread titled, Ap & aa Indices and Solar Minimum), and so any historical correlation drawn in the previous Gleissberg Cycle, between the geomagnetic indices in solar minimum and the following cycle, may need to be modified, somewhat, for this new era.

Edited by theartist

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