The Beauty of a Near Spotless Sun

tallbloke says:
June 27, 2010 at 6:14 pm
The ability to miss the point or desire to deliberately obscure it. Which is it I wonder.
How about the point being dubious to begin with?

Geoff Sharp says:
June 27, 2010 at 7:03 pm
The new region has now evolved into to a reversed polarity group for SC24 and is noted for is large size amongst previous reversed regions.
Regions rotate and for that reason if they live long enough might end up ‘reversed’. this is normal and is not a sign of SC24 ending, SC25 or SC27 or any such making an appearance. [I know you don’t make such claims, but others do]
Question: What effect do these reversed regions have on the migrating reversing poleward flux.
Not much as only 1/1000th of the flux makes it to the poles, so an occasional reversed spot won’t have much impact.
If there is a diminishing effect they could be responsible for the south not reversing polarity this maximum?
Hardly, as we can easily miss 30 out of a 1000 spots not making it to the poles.
Now, if more than 50% of spots were reversed, that would be significant. But such is not the case.
This along with Hathaway’s observation of the very slow conveyor belt (base) in the south make this hemisphere most interesting to watch.
‘very slow’ is relative. It normally takes about 1000,000,000[m]/15[m/s] ~ 2 years to reach the pole. should that be 4 years instead, just means that the cycle will be bit longer, which we expect anyway.
rbateman’s sunspot area graphs telling the true picture for SC24.
The true picture is given by the F10.7 flux.

David44 says:
June 27, 2010 at 7:28 pm
Leif Svalgaard says @ur momisugly June 27, 2010 at 6:05 pm
“…there is little, if any influence by the sun on the climate…”
To a novice such as my self, that sounds crazy. Do you mean it literally, or something more like: “the very small variations in solar output that we measure have little or no influence on variations in climate” ?
Clearly the latter.

Nasif Nahle says:
June 27, 2010 at 8:04 pm
The question is: Which one of the three is the most accurate, non biased reconstruction?
The latest one. And there is no bias here anymore. It was once thought that there was a long-term varying background approximately controlled by the 11-year running mean of the sunspot number. This ‘bias’ was partly motivated by the desire to account for the LIA [otherwise the variation in TSI would clearly be too small]. Lean’s and others [including yours truly] later research have undermined that idea, and nobody [except die-hard solar enthusiasts] believes anymore that there is such a background. Hence the almost flat curve.

Teh JC says:
June 27, 2010 at 8:58 pm
if the sun is asleep, so-to-speak, what is making it sleep?
It goes to sleep every eleven years.
Contrary to old school belief, the sun does not have a hydrogen core; it is high dense iron.
No, the old school is still correct. The iron core is plain nonsense.
James F. Evans says:
June 27, 2010 at 8:59 pm
Another cold northern hemisphere winter and those with the “sun doesn’t matter” position will be harder pressed to maintain that same position.
You mean when we approach solar maximum? And “harder pressed” by whom?
I seem to recall that the last several months of very low solar activity all had record-high temperatures. Perhaps caused by the recent tiny uptick in solar activity?

mikelorrey says:
June 27, 2010 at 9:12 pm
I find the past several months data on both sunspot and 10.7 to have remained significantly below (50% or more) predicted levels.
Remember that the ‘predicted’ levels were too high to begin with [a max around 70 seems more reasonable].
At this point in time we should be seeing monthly escalating levels of both as SC24 explodes in activity.
‘explodes’ is perhaps a bit too much to hope for. Also, as you know I think the sunspot number is too low by about a factor of two [Livingston&Penn – http://www.leif.org/research/Solar-Microwaves-at-23-24-Minimum.pdf ]. The flux is on its way up, albeit in fists and starts: http://www.leif.org/research/F107%20at%20Minima%201954%20and%202008.png
Note that the blue curve touched the red [coming out of the 1954 minimum into one of the biggest cycles ever], so give it a bit a time.

David44 says:
June 27, 2010 at 11:50 pm
Is it your understanding then, Dr. Svalgaard, that because of the ACRIM controversy, Lean and colleagues have or would today today recant their 1997 JGR paper
Not at all. The ACRIM controversy has nothing to do with this. First, it is very small [fractions of a Watt/m2, second]; second, her statement “the observed rise in solar irradiance of approximately 2.0 W m-2 at the top of the atmosphere” is not correct and conclusions based on that are therefore suspect.
We have all learned something the past 13 years, and one thing we have learned is that there has very likely not been such a large increase. Lean today would agree with this.

Hockey Schtick says:
June 27, 2010 at 11:38 pm
It’s apparently ok with Dr. Svalgaard if the IPCC chooses one solar physicist to feature her own paper as an implied balanced consensus – without mentioning alternative views or any controversies regarding the way her data was adjusted – ok got it.
Your bias shows in the way you uncritically parrot the JudithGate nonsense without actually knowing what IPCC said in their AR4.
Here is a sample:
2.7.1 Solar Variability
“The estimates of long-term solar irradiance changes used in the TAR (e.g., Hoyt and Schatten, 1993; Lean et al., 1995) have been revised downwards, based on new studies indicating that bright solar faculae likely contributed a smaller irradiance increase since the Maunder Minimum than was originally suggested by the range of brightness in Sun-like stars (Hall and Lockwood, 2004; M. Wang et al., 2005). However, empirical results since the TAR have strengthened the evidence for solar forcing of climate change by identifying detectable tropospheric changes associated with solar variability, including during the solar cycle (Section 9.2; van Loon and Shea, 2000; Douglass and Clader, 2002; Gleisner and Thejll, 2003; Haigh, 2003; Stott et al., 2003; White et al., 2003; Coughlin and Tung, 2004; Labitzke, 2004; Crooks and Gray, 2005). The most likely mechanism is considered to be some combination of direct forcing by changes in total solar irradiance, and indirect effects of ultraviolet (UV) radiation on the stratosphere. Least certain, and under ongoing debate as discussed in the TAR, are indirect effects induced by galactic cosmic rays (e.g., Marsh and Svensmark, 2000a,b; Kristjánsson et al., 2002; Sun and Bradley, 2002).
2.7.1.1.1 Satellite measurements of total solar irradiance
Four independent space-based instruments directly measure total solar irradiance at present, contributing to a database extant since November 1978 (Fröhlich and Lean, 2004). The Variability of Irradiance and Gravity Oscillations (VIRGO) experiment on the Solar Heliospheric Observatory (SOHO) has been operating since 1996, the ACRIM III on the Active Cavity Radiometer Irradiance Monitor Satellite (ACRIMSAT) since 1999 and the Earth Radiation Budget Satellite (ERBS) (intermittently) since 1984. Most recent are the measurements made by the Total Solar Irradiance Monitor (TIM) on the Solar Radiation and Climate Experiment (SORCE) since 2003 (Rottman, 2005).
2.7.1.1.2 Observed decadal trends and variability
Different composite records of total solar irradiance have been constructed from different combinations of the direct radiometric measurements. The Physikalisch-Meteorologisches Observatorium Davos (PMOD) composite (Fröhlich and Lean, 2004), shown in Figure 2.16, combines the observations by the ACRIM I on the Solar Maximum Mission (SMM), the Hickey-Friedan radiometer on Nimbus 7, ACRIM II on the Upper Atmosphere Research Satellite (UARS) and VIRGO on SOHO by analysing the sensitivity drifts in each radiometer prior to determining radiometric offsets. In contrast, the ACRIM composite (Willson and Mordvinov, 2003), also shown in Figure 2.16, utilises ACRIMSAT rather than VIRGO observations in recent times and cross calibrates the reported data assuming that radiometric sensitivity drifts have already been fully accounted for. A third composite, the Space Absolute Radiometric Reference (SARR) composite, uses individual absolute irradiance measurements from the shuttle to cross calibrate satellite records (Dewitte et al., 2005). The gross temporal features of the composite irradiance records are very similar, each showing day-to-week variations associated with the Sun’s rotation on its axis, and decadal fluctuations arising from the 11-year solar activity cycle. But the linear slopes differ among the three different composite records, as do levels at solar activity minima (1986 and 1996). These differences are the result of different cross calibrations and drift adjustments applied to individual radiometric sensitivities when constructing the composites (Fröhlich and Lean, 2004).
Figure 2.16. Percentage change in monthly values of the total solar irradiance composites of Willson and Mordvinov (2003; WM2003, violet symbols and line) and Fröhlich and Lean (2004; FL2004, green solid line). 
Solar irradiance levels are comparable in the two most recent cycle minima when absolute uncertainties and sensitivity drifts in the measurements are assessed (Fröhlich and Lean, 2004 and references therein). The increase in excess of 0.04% over the 27-year period of the ACRIM irradiance composite (Willson and Mordvinov, 2003), although incompletely understood, is thought to be more of instrumental rather than solar origin (Fröhlich and Lean, 2004). The irradiance increase in the ACRIM composite is indicative of an episodic increase between 1989 and 1992 that is present in the Nimbus 7 data (Lee et al., 1995; Chapman et al., 1996). Independent, overlapping ERBS observations do not show this increase; nor do they suggest a significant secular trend (Lee et al., 1995). Such a trend is not present in the PMOD composite, in which total irradiance between successive solar minima is nearly constant, to better than 0.01% (Fröhlich and Lean, 2004). Although a long-term trend of order 0.01% is present in the SARR composite between successive solar activity minima (in 1986 and 1996), it is not statistically significant because the estimated uncertainty is ±0.026% (Dewitte et al., 2005).
Current understanding of solar activity and the known sources of irradiance variability suggests comparable irradiance levels during the past two solar minima. The primary known cause of contemporary irradiance variability is the presence on the Sun’s disk of sunspots (compact, dark features where radiation is locally depleted) and faculae (extended bright features where radiation is locally enhanced). Models that combine records of the global sunspot darkening calculated directly from white light images and the magnesium (Mg) irradiance index as a proxy for the facular signal do not exhibit a significant secular trend during activity minima (Fröhlich and Lean, 2004; Preminger and Walton, 2005). Nor do the modern instrumental measurements of galactic cosmic rays, 10.7 cm flux and the aa geomagnetic index since the 1950s (Benestad, 2005) indicate this feature. While changes in surface emissivity by magnetic sunspot and facular regions are, from a theoretical view, the most effective in altering irradiance (Spruit, 2000), other mechanisms have also been proposed that may cause additional, possibly secular, irradiance changes. Of these, changes in solar diameter have been considered a likely candidate (e.g., Sofia and Li, 2001). But recent analysis of solar imagery, primarily from the Michelson Doppler Imager (MDI) instrument on SOHO, indicates that solar diameter changes are no more than a few kilometres per year during the solar cycle (Dziembowski et al., 2001), for which associated irradiance changes are 0.001%, two orders of magnitude less than the measured solar irradiance cycle.
2.7.1.2.1 Reconstructions of past variations in solar irradiance
Long-term solar irradiance changes over the past 400 years may be less by a factor of two to four than in the reconstructions employed by the TAR for climate change simulations. Irradiance reconstructions such as those of Hoyt and Schatten (1993), Lean et al. (1995), Lean (2000), Lockwood and Stamper (1999) and Solanki and Fligge (1999), used in the TAR, assumed the existence of a long-term variability component in addition to the known 11-year cycle, in which the 17th-century Maunder Minimum total irradiance was reduced in the range of 0.15% to 0.3% below contemporary solar minima. The temporal structure of this long-term component, typically associated with facular evolution, was assumed to track either the smoothed amplitude of the solar activity cycle or the cycle length. The motivation for adopting a long-term irradiance component was three-fold. Firstly, the range of variability in Sun-like stars (Baliunas and Jastrow, 1990), secondly, the long-term trend in geomagnetic activity, and thirdly, solar modulation of cosmogenic isotopes, all suggested that the Sun is capable of a broader range of activity than witnessed during recent solar cycles (i.e., the observational record in Figure 2.16). Various estimates of the increase in total solar irradiance from the 17th-century Maunder Minimum to the current activity minima from these irradiance reconstructions are compared with recent results in Table 2.10.
Each of the above three assumptions for the existence of a significant long-term irradiance component is now questionable. A reassessment of the stellar data was unable to recover the original bimodal separation of lower calcium (Ca) emission in non-cycling stars (assumed to be in Maunder-Minimum type states) compared with higher emission in cycling stars (Hall and Lockwood, 2004), which underpins the Lean et al. (1995) and Lean (2000) irradiance reconstructions. Rather, the current Sun is thought to have ‘typical’ (rather than high) activity relative to other stars. Plausible lowest brightness levels inferred from stellar observations are higher than the peak of the lower mode of the initial distribution of Baliunas and Jastrow (1990). Other studies raise the possibility of long-term instrumental drifts in historical indices of geomagnetic activity (Svalgaard et al., 2004), which would reduce somewhat the long-term trend in the Lockwood and Stamper (1999) irradiance reconstruction. Furthermore, the relationship between solar irradiance and geomagnetic and cosmogenic indices is complex, and not necessarily linear. Simulations of the transport of magnetic flux on the Sun and propagation of open flux into the heliosphere indicate that ‘open’ magnetic flux (which modulates geomagnetic activity and cosmogenic isotopes) can accumulate on inter-cycle time scales even when closed flux (such as in sunspots and faculae) does not (Lean et al., 2002; Y. Wang et al., 2005).
A new reconstruction of solar irradiance based on a model of solar magnetic flux variations (Y. Wang et al., 2005), which does not invoke geomagnetic, cosmogenic or stellar proxies, suggests that the amplitude of the background component is significantly less than previously assumed, specifically 0.27 times that of Lean (2000). This estimate results from simulations of the eruption, transport and accumulation of magnetic flux during the past 300 years using a flux transport model with variable meridional flow. Variations in both the total flux and in just the flux that extends into the heliosphere (the open flux) are estimated, arising from the deposition of bipolar magnetic regions (active regions) and smaller-scale bright features (ephemeral regions) on the Sun’s surface in strengths and numbers proportional to the sunspot number. The open flux compares reasonably well with the cosmogenic isotopes for which variations arise, in part, from heliospheric modulation. This gives confidence that the approach is plausible. A small accumulation of total flux (and possibly ephemeral regions) produces a net increase in facular brightness, which, in combination with sunspot blocking, permits the reconstruction of total solar irradiance shown in Figure 2.17. There is a 0.04% increase from the Maunder Minimum to present-day cycle minima.
Prior to direct telescopic measurements of sunspots, which commenced around 1610, knowledge of solar activity is inferred indirectly from the 14C and 10Be cosmogenic isotope records in tree rings and ice cores, respectively, which exhibit solar-related cycles near 90, 200 and 2,300 years. Some studies of cosmogenic isotopes (Jirikowic and Damon, 1994) and spectral analysis of the sunspot record (Rigozo et al., 2001) suggest that solar activity during the 12th-century Medieval Solar Maximum was comparable to the present Modern Solar Maximum. Recent work attempts to account for the chain of physical processes in which solar magnetic fields modulate the heliosphere, in turn altering the penetration of the galactic cosmic rays, the flux of which produces the cosmogenic isotopes that are subsequently deposited in the terrestrial system following additional transport and chemical processes. An initial effort reported exceptionally high levels of solar activity in the past 70 years, relative to the preceding 8,000 years (Solanki et al., 2004). In contrast, when differences among isotopes records are taken into account and the 14C record corrected for fossil fuel burning, current levels of solar activity are found to be historically high, but not exceptionally so (Muscheler et al., 2007).
2.7.1.2.2 Implications for solar radiative forcing
In terms of plausible physical understanding, the most likely secular increase in total irradiance from the Maunder Minimum to current cycle minima is 0.04% (an irradiance increase of roughly 0.5 W m–2 in 1,365 W m–2), corresponding to an RF[11] of +0.1 W m–2. The larger RF estimates in Table 2.10, in the range of +0.38 to +0.68 W m–2, correspond to assumed changes in solar irradiance at cycle minima derived from brightness fluctuations in Sun-like stars that are no longer valid. Since the 11-year cycle amplitude has increased from the Maunder Minimum to the present, the total irradiance increase to the present-day cycle mean is 0.08%. From 1750 to the present there was a net 0.05% increase in total solar irradiance, according to the 11-year smoothed total solar irradiance time series of Y. Wang et al. (2005), shown in Figure 2.17. This corresponds to an RF of +0.12 W m–2, which is more than a factor of two less than the solar RF estimate in the TAR, also from 1750 to the present. Using the Lean (2000) reconstruction (the lower envelope in Figure 2.17) as an upper limit, there is a 0.12% irradiance increase since 1750, for which the RF is +0.3 W m–2. The lower limit of the irradiance increase from 1750 to the present is 0.026% due to the increase in the 11-year cycle only. The corresponding lower limit of the RF is +0.06 W m–2. As with solar cycle changes, long-term irradiance variations are expected to have significant spectral dependence. For example, the Y. Wang et al. (2005) flux transport estimates imply decreases during the Maunder Minimum relative to contemporary activity cycle minima of 0.43% at 200 to 300 nm, 0.1% at 315 to 400 nm, 0.05% at 400 to 700 nm, 0.03% at 700 to 1,000 nm and 0.02% at 1,000 to 1,600 nm (Lean et al., 2005), compared with 1.4%, 0.32%, 0.17%, 0.1% and 0.06%, respectively, in the earlier model of Lean (2000).
Table 2.10. Comparison of the estimates of the increase in RF from the 17th-century Maunder Minimum (MM) to contemporary solar minima, documenting new understanding since the TAR.
Reference Assumptions and Technique RF Increase from the Maunder Minimum to Contemporary Minima (W m–2)a Comment on Current Understanding
Schatten and Orosz (1990) Extrapolation of the 11-year irradiance cycle to the MM, using the sunspot record. ~ 0 Irradiance levels at cycle minima remain approximately constant.
Lean et al. (1992) No spots, plage or network in Ca images assumed during MM. 0.26 Maximum irradiance increase from a non-magnetic sun, due to changes in known bright features on contemporary solar disk.
Lean et al. (1992) No spots, plage or network and reduced basal emission in cell centres in Ca images to match reduced brightness in non-cycling stars, assumed to be MM analogues. 0.45 New assessment of stellar data (Hall and Lockwood, 2004) does not support original stellar brightness distribution, or the use of the brightness reduction in the Baliunas and Jastrow (1990) ‘non-cycling’ stars as MM analogues.
Hoyt and Schatten (1993)b Convective restructuring implied by changes in sunspot umbra/penumbra ratios from MM to present: amplitude of increase from MM to present based on brightness of non-cycling stars, from Lean et al. (1992). 0.65 As above
Lean et al. (1995) Reduced brightness of non-cycling stars, relative to those with active cycles, assumed typical of MM. 0.45 As above
Solanki and Fligge (1999)b Combinations of above. 0.68 As above
Lean (2000) Reduced brightness of non-cycling stars (revised solar-stellar calibration) assumed typical of MM. 0.38 As above
Foster (2004) Model Non-magnetic sun estimates by removing bright features from MDI images assumed for MM. 0.28 Similar approach to removal of spots, plage and network by Lean et al. (1992).
Y. Wang et al. (2005)b Flux transport simulations of total magnetic flux evolution from MM to present. 0.1 Solar model suggests that modest accumulation of magnetic flux from one solar cycle to the next produces a modest increase in irradiance levels at solar cycle minima.
Dziembowski et al. (2001) Helioseismic observations of solar interior oscillations suggest that the historical Sun could not have been any dimmer than current activity minima. ~ 0
Notes:
a The RF is the irradiance change divided by 4 (geometry) and multiplied by 0.7 (albedo). The solar activity cycle, which was negligible during the Maunder Minimum and is of order 1 W m–2 (minimum to maximum) during recent cycles, is superimposed on the irradiance changes at cycle minima. When smoothed over 20 years, this cycle increases the net RF in the table by an additional 0.09 W m–2.
b These reconstructions extend only to 1713, the end of the Maunder Minimum.
Figure 2.17. Reconstructions of the total solar irradiance time series starting as early as 1600. The upper envelope of the shaded regions shows irradiance variations arising from the 11-year activity cycle. The lower envelope is the total irradiance reconstructed by Lean (2000), in which the long-term trend was inferred from brightness changes in Sun-like stars. In comparison, the recent reconstruction of Y. Wang et al. (2005) is based on solar considerations alone, using a flux transport model to simulate the long-term evolution of the closed flux that generates bright faculae.
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And so on and on…