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northwind-adventurer

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About northwind-adventurer

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    Melbourne, Australia
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    Photography, outdoors activities, aurora-chasing, and music.

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  1. Thank you for the updates all. It will be interesting to see how (and if) this 'puff' CME interacts with the upcoming coronal hole stream - there has been a few events like this in the past where they actually enhanced auroral conditions. For example in August last year there was a small filament eruption which interacted with a coronal hole stream to cause a G3 storm.
  2. Another predictive method worth looking into, and has been moderately successful over the years is the Geomagnetic Activity Prediction Method. Ahluwalia (1998) https://www.researchgate.net/publication/253586281_The_predicted_size_of_cycle_23_based_on_the_inferred_three-cycle_quasi-periodicity_of_the_planetary_index_Ap Basically, it uses an equation of geomagnetic activity smoothed 'AP index' at each solar minimum to predict the sunspot number at the next maximum roughly 4 years later. Using this method, one can predict the sunspot number for Solar Cycles 23, 24, and possibly even 25, for which the data wasn't available yet in 1998. SC had a prediction of 119. The smoothed sunspot number in early 2000 (SC23 max) was 124. Note that these sunspot numbers are the official Wolf (or international) sunspot numbers. There was a revision made in 2015 increasing the entire sunspot series by a factor of 1.6 - That's lead to some confusion as all the predictions and measurements before then used the original Wolf numbers (not the revised). Using this method, we can try to predict SC24: 16.2(AP) - 27. SC24 = 16.2(5) - 27 (SC sunspot minimum was in Dec 2008) = 54 (Actual number was 81) That's quite a bit off, but it's a bit closer if you only count the first peak of the 'double peaked' solar activity. All the cycles measured SC23 and before in the paper had the solar cycle maximum in the first 'activity peak' - roughly 4 years after the SC minimum. Maybe we can make a tentative conclusion that this method is more accurate in predicting solar activity roughly 4 years from minimum, as opposed to the absolute maximum For the Solar Cycle 25 prediction, we can just assume the sunspot minimum is where the most recent 'smoothed' AP value is - roughly 6.5. That yields a prediction of 78 ~ meaning in 4 years according to this method the cycle will be similar strength as the one just gone - in line with what the NOAA 'Panel' and the solar polar fields method predict. But the solar maximum might even be in 6 years, and it could follow the SC24 trend of having the second solar activity peak stronger than the first one.
  3. There is an official NOAA presentation which goes through the NOAA Panel prediction for the previous Solar Cycle 24. It's worth having a look at https://www.swpc.noaa.gov/sites/default/files/images/u33/(1120) Biesecker Solar Cycle Update.pdf . It also mentions an 'early' expectation for Solar Cycle 25 - this document was last edited around 2016. Even though it mentions the polar fields precursor method as one of the 'main precursors', there are several other methods used, including the 'Spectral' method, which in hindsight was slightly more accurate in predicting the SC24 sunspot number than the polar fields method. The difference was about 10 sunspots. But the spectral method does not seem to have predictions before the SC23 era. It might be worth using this method in hindsight to see if predictions stack up. Looking briefly at the F10.7 Radio Flux (one spectral measure) since 1950, the solar minimums from 1950-2000 had a very similar solar flux value (~70-75 average) though some cycles were weaker (SC20) when this method would suggest that SC20 should have been a bit stronger, possibly at least as strong as SC23. Then there was a significant dip in 2007-08 which led to a weaker SC24. The SORCE data could be useful also, but I can see that it only goes back to 2004... I think the key thing about 'accepted method' is that the solar polar fields precursor method has been around for longer than the spectral method, and gained acceptance earlier. It can predict the upcoming solar cycles within a broad range time after time. While it is reasonably accurate, there may be newer and more complex methods nowadays that are more accurate (though they haven't gained acceptance over a long period). So over a long period the SPF precursor method has arguably been the most successful - even though for individual solar cycles other methods may have been more accurate individually. Also, it's worth noting that several 'Dynamo' models combine the solar polar fields, physics models and spectral measures. Furthermore, Leif Svalgaard himself was on the NOAA SC24 prediction panel. This panel was split 6-5 on a larger-smaller cycle, with the smaller one eventuating, and Leif Svalgaard at least correctly predicting it would be a smaller cycle using solar polar fields. In addition, the solar polar fields have now increased to an average value of 67, whereas around SC minimum in 2008 the max value was 61. (Can be seen on link in previous post) Sello (2019) also provides a literature review of the current predictions and predictive methods for SC25 that can be seen here https://www.researchgate.net/publication/331110677_Solar_cycle_activity_an_early_prediction_for_cycle_25. He quotes "Among predictors class one of the most efficient and the first physical based precursor is the Solar Polar Field Precursor Method developed by Schatten, Scherrer, Svalgaard et al. [1978]" Based on this information, it seems the solar polar fields method was at least one significant factor in the NOAA 'Panel' forecast this year that has been made for Solar Cycle 25. In any case, it's hard to predict exactly which method, panel or forecast will be the most successful for Solar Cycle 25 this early - though we can form an educated guess. As Sander said in another thread, we'll see what the result is in 3-5 years, and then there may be an even more accurate theory/method than the current ones.
  4. Aurora in Toivakka, south-central Finland, that lasted for the best part of two nights. At times there was pulsations and very fast movement. Most intense phase was reached at 3:00 AM local time on Sunday morning 1st September.
  5. There is an accepted methodology called the solar cycle 'precursor method' scientists use when predicting solar cycles. Generally speaking, they are able to predict more accurately the size of the coming solar cycle once the solar minimum has passed, usually by 1-2 years. This method basically means that if the solar minimum phase was shorter (300-400 spotless days, or 1-2 years), then the following solar cycle will be more active than average. Likewise, if the solar minimum was longer (600-900 spotless days, 2-3 years) then the following solar cycle will be less active than average. This data and more is on the Belgian solar activity website spotless days page http://www.sidc.be/silso/spotless. The only drawback of this method is that it can only predict the solar cycle several years after the solar minimum. In terms of making earlier predictions (before the solar cycle minimum), the most successful theory so far has been developed by Stanford University solar physics professor Leif Svalgaard. This is the Solar Polar Fields method. At Stanford they have been monitoring the strength of the solar polar fields since 1976 and found that this can predict the coming solar cycle more accurately than other methods ahead of time. Basically, the stronger the solar polar fields are at solar minimum, the stronger the coming solar cycle will be, and vice versa. In this current solar minimum, the polar fields are a little stronger than at the previous solar minimum, but still weaker than other solar cycles. This has led Professor Svalgaard to predict that Solar Cycle 25 will be marginally stronger than the Solar Cycle 24 just passed. The solar polar fields method is also the one endorsed & used by NOAA for early predictions. The values of the solar polar fields can be monitored at the Stanford Wilcox Solar Observatory webpage http://wso.stanford.edu/Polar.html Below is a graph showing Svalgaard's prediction - and the related article is here https://tallbloke.wordpress.com/2018/06/09/leif-svalgaard-reveals-his-solar-cycle-25-prediction-at-last/ And here is a statement from Leif Svalgaard http://lasp.colorado.edu/media/projects/SORCE/meetings/2018/Oral_Presentations/6_c_Svalgaard_Contri.pdf
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