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Post by lsvalgaard on Nov 6, 2010 18:12:09 GMT
Hello Dr. lsvalgaard, Pardon me is this question could require some archive searching, but I would be interested in knowing the amount of solar activity during the days preceding and following Sept. 11, 2001, and specifically, their influence on Earth (and the geomagnetic field, of course). Thanks in advance for the answer.  Here is a good source: hirweb.nict.go.jp/sedoss/solact3/do?d=2001,9,11 But don't think for a moment that any of this has any bearing on the terror attacks. |
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Post by austinq on Nov 6, 2010 18:33:49 GMT
Thanks for the prompt response ^^ and I will be careful on making assumptions, thanks for the advice |
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Post by semimadscientist on Nov 7, 2010 14:05:01 GMT
Dr Svalgaard
As solar cycle 14 seems the only cycle comparable to the current one, I ran a count, based on the Greenwich data of the first 22 months of cycle 14 and of our current cycle, and it seems that if, and this an assumption ( and one which doesn’t take into account the L+P effect), the cycles are comparable in length and “ ramp up ” time, the ISSN at peak for this cycle would be around 37. The L+P effect may well have been kicking in during cycle 14 of course, so could this be a fair comparison? In addition, both cycles seem to be displaying the rather wild yet regular SSN swings, with peaks every 7 months in the case of this cycle, and perhaps every 8 months in cycle 14.
I know that your own predictions are for a considerably higher peak sunspot number, so I was wondering what extra factors you take into account to arrive at you figures. I know that weak cycles tend be be longer, and the ramp-up times longer, too, but would this not be compensated by their tendency to be “ flattened ”? Perhaps also the time at which the L+P effect kicks in makes the difference(?). And in your assessment, did cycle 14 really start in February 1902 ( i.e. am I using the right data )? Thank you in advance.
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Post by lsvalgaard on Nov 7, 2010 15:39:58 GMT
Dr Svalgaard As solar cycle 14 seems the only cycle comparable to the current one, I ran a count, based on the Greenwich data of the first 22 months of cycle 14 and of our current cycle, and it seems that if, and this an assumption ( and one which doesn’t take into account the L+P effect), the cycles are comparable in length and “ ramp up ” time, the ISSN at peak for this cycle would be around 37. The L+P effect may well have been kicking in during cycle 14 of course, so could this be a fair comparison? In addition, both cycles seem to be displaying the rather wild yet regular SSN swings, with peaks every 7 months in the case of this cycle, and perhaps every 8 months in cycle 14. I know that your own predictions are for a considerably higher peak sunspot number, so I was wondering what extra factors you take into account to arrive at you figures. I know that weak cycles tend be be longer, and the ramp-up times longer, too, but would this not be compensated by their tendency to be “ flattened ”? Perhaps also the time at which the L+P effect kicks in makes the difference(?). And in your assessment, did cycle 14 really start in February 1902 ( i.e. am I using the right data )? Thank you in advance. my current view on that is here: www.leif.org/research/Predicting%20the%20Solar%20Cycle%20(SORCE%202010).pdfMy old prediction is for SSN = 72. This corresponds to a F10.7 flux of 120 and a number of active regions [groups] of 72/12 = 6. The 120 and 6 should be less influenced by L&P, so those predictions should still be good. What the L&P modified SSN will be is anybody's guess. |
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Post by semimadscientist on Nov 7, 2010 22:32:35 GMT
my current view on that is here: www.leif.org/research/Predicting%20the%20Solar%20Cycle%20(SORCE%202010).pdfMy old prediction is for SSN = 72. This corresponds to a F10.7 flux of 120 and a number of active regions [groups] of 72/12 = 6. The 120 and 6 should be less influenced by L&P, so those predictions should still be good. What the L&P modified SSN will be is anybody's guess. Thanks for the link, Dr Svalgaard. I understand now that you didn’t factor in the L+P effect when you came up with 70 for maximum SSN, which is fair enough, of course, as it’s not yet a certainty. Aa and other values are similar between cycles 14 and 24 so far, so I’m guessing that it is indeed the L+P effect, i.e. fading contrast, which is what is making the difference this time, with regard to sunspot numbers. If we are indeed at the beginning of something like the Maunder minimum, is there anything in theory which suggests how long this will last? Thanks. |
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Post by lsvalgaard on Nov 7, 2010 22:41:32 GMT
my current view on that is here: www.leif.org/research/Predicting%20the%20Solar%20Cycle%20(SORCE%202010).pdfMy old prediction is for SSN = 72. This corresponds to a F10.7 flux of 120 and a number of active regions [groups] of 72/12 = 6. The 120 and 6 should be less influenced by L&P, so those predictions should still be good. What the L&P modified SSN will be is anybody's guess. Thanks for the link, Dr Svalgaard. I understand now that you didn’t factor in the L+P effect when you came up with 70 for maximum SSN, which is fair enough, of course, as it’s not yet a certainty. Aa and other values are similar between cycles 14 and 24 so far, so I’m guessing that it is indeed the L+P effect, i.e. fading contrast, which is what is making the difference this time, with regard to sunspot numbers. If we are indeed at the beginning of something like the Maunder minimum, is there anything in theory which suggests how long this will last? Thanks. we have no good theory for this, but since we have knowledge of some 23 Grand Minima in the past 10,000 years we can use statistics and come up with about 50 years for an average. |
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Post by semimadscientist on Nov 7, 2010 22:42:04 GMT
Sorry, I meant 72 for your previous prediction.
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Post by semimadscientist on Nov 7, 2010 22:54:23 GMT
we have no good theory for this, but since we have knowledge of some 23 Grand Minima in the past 10,000 years we can use statistics and come up with about 50 years for an average. Thanks. From what I can gather of the data we have for the past 10,000 years or so based on radioisotope data, grand minima as deep and prolonged as the Maunder are very rare. I wish I could find the source of the graph I got this info from, ( seems I didn't save it), but it seemed to suggest that the Maunder was THE deepest ). Is this true? It'll be really interesting to get two really big minima within 400 years of each other. Thanks. |
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Post by lsvalgaard on Nov 8, 2010 1:49:25 GMT
we have no good theory for this, but since we have knowledge of some 23 Grand Minima in the past 10,000 years we can use statistics and come up with about 50 years for an average. Thanks. From what I can gather of the data we have for the past 10,000 years or so based on radioisotope data, grand minima as deep and prolonged as the Maunder are very rare. I wish I could find the source of the graph I got this info from, ( seems I didn't save it), but it seemed to suggest that the Maunder was THE deepest ). Is this true? It'll be really interesting to get two really big minima within 400 years of each other. Thanks. The Spoerer was deeper, but the Maunder lasted longer. But we are not really sure about the true depths of any of these [and others] because there are extrapolations involved that we have little hard evidence for. |
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Post by semimadscientist on Nov 8, 2010 13:10:44 GMT
[quote author=lsvalgaard board=general thread=622 post=59195 time=1289180965
The Spoerer was deeper, but the Maunder lasted longer. But we are not really sure about the true depths of any of these [and others] because there are extrapolations involved that we have little hard evidence for.
[/quote]
Interesting, thanks. For the sake of curiosity, I'm kind of hoping that we ARE on the brink of another one!
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Post by lsvalgaard on Nov 10, 2010 21:34:07 GMT
Going through some of the old files came across this: Longitudinal (angular) distribution of number of days with negative field (marked with X) For a short stretch of years this might work, but since the Longitude has a period of 27.2753 days and the sector structure is either 27 days or 28.5 days, they will soon drift out of phase. Maunder 100 years ago pointed out that certain longitudes are more active than others. Since then people have noticed that the Carrington Longitude [and rotation period] is not a 'physical' thing and that the recurrence period varies with phase of the sunspot cycle and that there are more than one period [cf. the 27 and the 28.5 days referred to above], so plotting in Longitudes is not a very reasonable thing to do [so reasonable people don't do that anymore]. Now, it is possible that you don't really mean 'Longitudinal' in the sense of Carrington Longitude [where time runs from right to left] and you simply mean days in a 27-day scheme. It is important to be precise and use accepted terminology [and label the Figure in 'days' if 'days' is what is meant]. |
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Post by france on Nov 28, 2010 13:59:20 GMT
a great work you made Dr Svalgaard. So it's better way to take days than longitudes as Vukcevik and Landeicht successors explain ? Do you know this study Dr Svalgaard based on Korean records ? It looks like a good reference with ancient aurorae observations www.springerlink.com/content/v2210576x5lw665n/fulltext.pdf |
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Post by lsvalgaard on Nov 28, 2010 15:42:29 GMT
a great work you made Dr Svalgaard. So it's better way to take days than longitudes as Vukcevik and Landeicht successors explain ? Do you know this study Dr Svalgaard based on Korean records ? It looks like a good reference with ancient aurorae observations www.springerlink.com/content/v2210576x5lw665n/fulltext.pdf27 days diagrams is by far the best. |
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ve1dx
New Member
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Post by ve1dx on Nov 29, 2010 0:11:50 GMT
Dr Svalgaard,
If L& P are correct, and as some seem to opine, the sunspots will not be as visible as "normal", butthey will still exist (if I understand the theory correctly.) In your view, will the strong correlation between SSN and average solar flux still hold if the L&P phenomena unfolds? Can we expect the same average level of atmospheric ionization with invisible sunspots as with visible? I'm wondering if there is a metric to judge what the ionization level was in previous Grand Minima. To a layman like myself, the best measure of solar flux is SW propagation, which we only have been able to measure for 100 years at best.
Paul VE1DX
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Post by lsvalgaard on Nov 29, 2010 3:26:47 GMT
Dr Svalgaard, If L& P are correct, and as some seem to opine, the sunspots will not be as visible as "normal", butthey will still exist (if I understand the theory correctly.) In your view, will the strong correlation between SSN and average solar flux still hold if the L&P phenomena unfolds? Can we expect the same average level of atmospheric ionization with invisible sunspots as with visible? I'm wondering if there is a metric to judge what the ionization level was in previous Grand Minima. To a layman like myself, the best measure of solar flux is SW propagation, which we only have been able to measure for 100 years at best. Paul VE1DX The strong correlation between SSN and solar flux has changed the last 15 year: www.leif.org/research/Solar%20Radio%20Flux.pdfand www.leif.org/research/Solar-Microwaves-at-23-24-Minimum.pdfand www.leif.org/research/SHINE-2010-Microwave-Flux.pdf |
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