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Post by Bob k6tr on Dec 23, 2010 1:15:39 GMT
What do the red circles on the lower graph mean ?
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Post by lsvalgaard on Dec 23, 2010 8:17:34 GMT
What do the red circles on the lower graph mean ? The blue and pink dots are yearly medians, but the blue and red circles show yearly means
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Post by Bob k6tr on Dec 23, 2010 8:38:42 GMT
What do the red circles on the lower graph mean ? The blue and pink dots are yearly medians, but the blue and red circles show yearly means Thanks Leif It appears there seems to be a larger and larger cluster of Spots at the 1500 Gauss Level or lower.
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Post by lsvalgaard on Dec 23, 2010 9:23:25 GMT
The blue and pink dots are yearly medians, but the blue and red circles show yearly means Thanks Leif It appears there seems to be a larger and larger cluster of Spots at the 1500 Gauss Level or lower. That is the L&P effect. Eventually most of the spots will move down there [and below to become invisible], provided L&P holds up.
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Post by af4ex on Dec 23, 2010 16:07:19 GMT
Bob k6tr>> It appears there seems to be a larger and larger cluster of >> Spots at the 1500 Gauss Level or lower. @leif > That is the L&P effect. I understand that B > 1500 Gauss is a necessary condition for sunspots to be visible. Is it also a sufficient condition for visibility? Or are there other structural considerations that must hold for sunspots to appear in a highly magnetic region? For example, is there any way to prove that AR1131, now on the far side, is still a 'visible' sunspot? We can see that it's still active in EUV light. Can STEREO measure any of the Zeeman splitting wavelengths, e.g. Fe I or Ni I, from which magnetic field strength can be deduced? So, if we measure B > 1500 inside the AR1131 area, would that be sufficient to 'prove' that it's still visible as a sunspot?
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Post by lsvalgaard on Dec 23, 2010 19:27:11 GMT
Bob k6tr>> It appears there seems to be a larger and larger cluster of >> Spots at the 1500 Gauss Level or lower. @leif > That is the L&P effect. I understand that B > 1500 Gauss is a necessary condition for sunspots to be visible. Is it also a sufficient condition for visibility? Or are there other structural considerations that must hold for sunspots to appear in a highly magnetic region? For example, is there any way to prove that AR1131, now on the far side, is still a 'visible' sunspot? We can see that it's still active in EUV light. Can STEREO measure any of the Zeeman splitting wavelengths, e.g. Fe I or Ni I, from which magnetic field strength can be deduced? So, if we measure B > 1500 inside the AR1131 area, would that be sufficient to 'prove' that it's still visible as a sunspot? Unfortunately STEREO does not measure Zeeman splittings [or even just an image in visible light], so no magnetic measurements. As long as the magnetic field is there, there will be EUV light. I think the 1500 G limit is also a sufficient conditions as the magnetic field simply acts as a refrigerator and cools the material making it darker. There is one caveat: the field has to be 1500 G over a large enough area to live long enough to be called a 'spot'.
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Post by toughluck on Dec 27, 2010 15:10:02 GMT
L&P do not quite make that statement, although it is implicit in their finding. I may have been the one guilty of the speculation that Grand Minima are like that. The reason we think there were invisible spot during the Maunder Minimum is that the cosmic rays were still modulated by an 11-year cycle even during the Maunder and Spoerer Minima. Mr. Svalgaard: 1) How do you know the cosmic rays were modulated during that time period? 2) Even if they were 'modulated' did the mean cosmic rays falling on the earth during that time period increased (compared to other time periods) or remain more or less constant? 3) I think I read you mention that the L&P charts are fitted with a quadratic. Is there a particular reason for it? My understanding is that L&P is just an observation with no underlying physics that would help guide the type of equation to be fitted... is that correct? Given the scatter in the data I would assume that a quadratic would need more parameters for fitting and a fit with less parameters would be more adequate.. The thing the really bother me about your quote is that about the only mechanism that makes sense (to me) about sun output modulating earth climate is the increase in cloud formation with increased cosmic rays (since TSI changes are too small), in that case it would indicate the Maunder minimum was not only a sunspot minimum but also a cosmic ray maximum and a sun magnetic field minimum. Could you elaborate on your thoughts on the quantity of cosmic rays (or sun magnetic field) during the Maunder minimum?
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Post by lsvalgaard on Dec 27, 2010 17:50:05 GMT
L&P do not quite make that statement, although it is implicit in their finding. I may have been the one guilty of the speculation that Grand Minima are like that. The reason we think there were invisible spot during the Maunder Minimum is that the cosmic rays were still modulated by an 11-year cycle even during the Maunder and Spoerer Minima. Mr. Svalgaard: 1) How do you know the cosmic rays were modulated during that time period? 2) Even if they were 'modulated' did the mean cosmic rays falling on the earth during that time period increased (compared to other time periods) or remain more or less constant? 3) I think I read you mention that the L&P charts are fitted with a quadratic. Is there a particular reason for it? My understanding is that L&P is just an observation with no underlying physics that would help guide the type of equation to be fitted... is that correct? Given the scatter in the data I would assume that a quadratic would need more parameters for fitting and a fit with less parameters would be more adequate.. The thing the really bother me about your quote is that about the only mechanism that makes sense (to me) about sun output modulating earth climate is the increase in cloud formation with increased cosmic rays (since TSI changes are too small), in that case it would indicate the Maunder minimum was not only a sunspot minimum but also a cosmic ray maximum and a sun magnetic field minimum. Could you elaborate on your thoughts on the quantity of cosmic rays (or sun magnetic field) during the Maunder minimum? 1) From: www.leif.org/EOS/muscheler05nat_nature04045.pdf : "Sunspot numbers fell to zero during the Maunder Minimum (AD 1650–1700), whereas 14C production and solar modulation continued to vary. " 2) The mean level also depends on the Earth's magnetic field and the amount in tree rings and ice cores even depends on the climate itself. 3) The quadratic fit has no physical significance, it just quantifies in a crude way [but slightly better than just at straight line] the change. You only need five data points for a quadratic fit and L&P have more than a thousand. 4) the Sun's magnetic field was probably a bit smaller than it has been during the 20th century, but not by an order of magnitude as is often assumed. Figure 9 of www.leif.org/research/Determination%20IMF,%20SW,%20EUV,%201890-2003.pdf summarizes my thoughts on this.
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Post by toughluck on Dec 27, 2010 20:05:36 GMT
4) the Sun's magnetic field was probably a bit smaller than it has been during the 20th century, but not by an order of magnitude as is often assumed. Figure 9 of www.leif.org/research/Determination%20IMF,%20SW,%20EUV,%201890-2003.pdf summarizes my thoughts on this. Dr. Svaalgard: Very educational, thank you. I am a lay person and don't know the terminology, but it seems what I am looking for is the 'Solar wind magnetic field strength (B)' which in the same paper is also called the 'interplanetary magnetic field (IMF)'. It is shown to correlate well (R^2=0.7) with the sunspot number: B = 4.54 + 0.268 R1/2 nT Which then the paper uses to reconstruct B all the way back to the Maunder minimum using sunspot numbers. Unfortunately it is clear from that graph that the bottom of B is clipped where the sunspots are zero, and to me at least indicates that B went lower than 4.5 nT during that time period. The curve of B vs. sunspots really decreases and its slope becomes greater as you approach sunspots=0. Eyeballing the graphs, B probably goes to 3.5-4 around 1675. This is supported by the other paper you link to, in which the C14 production rate dips even though the sunspot number is clipped in Figure 2 (and which also goes further back in time). I don't understand why this is being dismissed as not being a 'order of magnitude decrease'. Why would it need to be? It seems to me that the range of variation of B (4-7 nT) is more than enough to account for changes in the GCR and earth albedo to reflect itself in the observed earth temperatures. But I don't want to go too much further on the climate change subject here... Given that the sunspot number as a proxy for B (or GCR's) only goes back in time to ~1600 and is clipped below B=4.5nT, have there been other proxies made such as correlating the C14 production rate data from Muscheler to B ?.
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Post by lsvalgaard on Dec 27, 2010 21:50:00 GMT
4) the Sun's magnetic field was probably a bit smaller than it has been during the 20th century, but not by an order of magnitude as is often assumed. Figure 9 of www.leif.org/research/Determination%20IMF,%20SW,%20EUV,%201890-2003.pdf summarizes my thoughts on this. Dr. Svaalgard: Very educational, thank you. I am a lay person and don't know the terminology, but it seems what I am looking for is the 'Solar wind magnetic field strength (B)' which in the same paper is also called the 'interplanetary magnetic field (IMF)'. It is shown to correlate well (R^2=0.7) with the sunspot number: B = 4.54 + 0.268 R1/2 nT Which then the paper uses to reconstruct B all the way back to the Maunder minimum using sunspot numbers. Unfortunately it is clear from that graph that the bottom of B is clipped where the sunspots are zero, and to me at least indicates that B went lower than 4.5 nT during that time period. The curve of B vs. sunspots really decreases and its slope becomes greater as you approach sunspots=0. Eyeballing the graphs, B probably goes to 3.5-4 around 1675. This is supported by the other paper you link to, in which the C14 production rate dips even though the sunspot number is clipped in Figure 2 (and which also goes further back in time). I don't understand why this is being dismissed as not being a 'order of magnitude decrease'. Why would it need to be? It seems to me that the range of variation of B (4-7 nT) is more than enough to account for changes in the GCR and earth albedo to reflect itself in the observed earth temperatures. But I don't want to go too much further on the climate change subject here... Given that the sunspot number as a proxy for B (or GCR's) only goes back in time to ~1600 and is clipped below B=4.5nT, have there been other proxies made such as correlating the C14 production rate data from Muscheler to B ?. The lower limit of B [called the 'floor'] is an extrapolation and as such is a bit uncertain. could be anywhere between 3.5 and 4.5. In recent papers we have settled on 4 as a happy medium. There are many papers that purport to reconstruct the 14C and 10Be production rates with B. Some of them we referred to in www.leif.org/research/2009JA015069.pdf and some we disagree with. Science progresses when there is well-reasoned disagreement.
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Post by maundalt on Dec 27, 2010 22:14:35 GMT
3) The quadratic fit has no physical significance, it just quantifies in a crude way [but slightly better than just at straight line] the change. You only need five data points for a quadratic fit and L&P have more than a thousand. Technically you only need three points for a quadratic fit. You need five for a quartic (4th-power).
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Post by lsvalgaard on Dec 28, 2010 4:36:21 GMT
3) The quadratic fit has no physical significance, it just quantifies in a crude way [but slightly better than just at straight line] the change. You only need five data points for a quadratic fit and L&P have more than a thousand. Technically you only need three points for a quadratic fit. You need five for a quartic (4th-power). You are correct, on a plane [2D]. I was thinking in 3D, where five is needed.
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Post by jcarels on Jan 1, 2011 14:00:31 GMT
Dr. Svalgaard:
Today most sunspots have an average magnetic field strength of 2000 Gauss. In the early 80's most sunspots had a strength of 3000 Gauss (The Secret Sun). Do you know if there are even older measurements? Do L&P have any idea when this effect started?
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Post by lsvalgaard on Jan 1, 2011 15:36:59 GMT
Dr. Svalgaard: Today most sunspots have an average magnetic field strength of 2000 Gauss. In the early 80's most sunspots had a strength of 3000 Gauss (The Secret Sun). Do you know if there are even older measurements? Do L&P have any idea when this effect started? From and [calculating SSN from F10.7] one would say some time in the 1990s
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Post by jcarels on Jan 2, 2011 12:50:43 GMT
Thanks Leif
Seems like things are speeding up.
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