Livingston and Penn paper: “Sunspots may vanish by 2015″.

2 06 2008

From the “I hope to God they are flat wrong department”, here is the abstract of a short paper on recent solar trends by William Livingston and Matthew Penn of the National Solar Observatory in Tucson. It was sent to me by reader Mike Ward.

I previously highlighted a news story on this paper on May 21st, but didn’t have the actual paper until now. If anyone has an update to this paper, which uses data up to 2005, please use the comment form to advise.

Here is the complete paper, and below are some excerpts:

Abstract: We have observed spectroscopic changes in temperature sensitive molecular lines, in the magnetic splitting of an Fe I line, and in the continuum brightness of over 1000 sunspot umbrae from 1990-2005. All three measurements show consistent trends in which the darkest parts of the sunspot umbra have become warmer (45K per year) and their magnetic field strengths have decreased (77 Gauss per year), independently of the normal 11-year sunspot cycle. A linear extrapolation of these trends suggests that few sunspots will be visible after 2015.

Figure – 1. Sample sunspot spectra from the data set. The dashed line is from a sunspot observed in June 1991, and the solid line was observed in January 2002. These provide examples of the trends seen in the data, where the OH molecular lines decrease in strength over time, and the magnetic splitting of the Fe line decreases over time. A magnetic splitting pattern for the January 2002 Fe line of 2466 Gauss is shown, while the June 1991 spectrum shows splitting from a 3183 Gauss field

Figure 2. – The line depth of OH 1565.3 nm for individual spots. The upper trace is the smoothed sunspot number showing the past and current sunspot cycles; the OH line depth change seems to smoothly decrease independently of the sunspot cycle.

Figure 3. – A linear fit to observed magnetic fields extrapolated to the minimum value observed for umbral magnetic fields; below a field strength of 1500G as measured with the Fe I 1564.8nm line no photospheric darkening is observed.

Figure 4 – A linear fit to the observed umbral contrast values, extrapolated to show that by 2014 the average umbrae would have the same brightness as the quiet Sun.

They write: Sunspot umbral magnetic fields also show systematic temporal changes during the observing period as demonstrated by the sample spectra in Figure 1. The infrared Fe 1564.8 nm is a favorable field diagnostic since the line strength changes less than a factor of two between the photosphere and spot umbra and the magnetic Zeeman splitting is fully resolved for all sunspot umbrae. In a histogram plot of the distribution of the umbral magnetic fields that we observe, 1500 Gauss is the smallest value measured. Below this value photospheric magnetic fields do not produce perceptible darkening. Figure 3 presents the magnetic fields smoothed by a 12 point running mean from 1998 to 2005. The ordinate is chosen so that 1500 G is the minimum. A linear fit to the changing magnetic field produces a slope of 77 Gauss per year, and intercepts the abscissa at 2015. If the present trend continues, this date is when sunspots will disappear from the solar surface.

Let us all hope that they are wrong, for a solar epoch period like the Maunder Minimum inducing a Little Ice Age will be a worldwide catastrophe economically, socially, environmentally, and morally.

I’m still very much concerned about the apparent step change in 2005 to a lower plateau of the Geomagnetic Average Planetary (Ap) index, that I’ve plotted below. This is something that does not appear in the previous cycle:

solar-geomagnetic-Ap Index
click for a larger image

What is most interesting about the Geomagnetic Average Planetary Index graph above is what happened around October 2005. Notice the sharp drop in the magnetic index and the continuance at low levels, almost as if something “switched off”.


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Categories : Science, climate_change

Solar Cycle 24 Could Be 13 Years Long – Cooler Times Ahead?

2 06 2008

On Climate Audit’s unthreaded comment forum, David Archibald noted some interesting facts about the solar cycle lengths and upcoming Solar Cycle 24, and provided the graph above.

Solar Cycle 20 was slightly longer than average at 11.6 years. The average solar cycle length from 1643 to 1996 is 11.4 years. Now that Dr Svalgaard has mentioned it, let’s talk about Solar Cycle 21. It was short at 10.3 years and hot (it started at the same time as the PDO shift in 1976) and was followed by a solar cycle 22 which was shorter again at 9.6 years and hotter. According to Friis-Christensen and Lassen theory, Solar Cycle 23 should have been hotter than Solar Cycle 22, and it was, even thought it is going to be a long one at about 13 years. There is plenty of correlation, all in our lifetimes. As for the physics, Hathaway found a correlation between Solar Cycle Length and the amplitude of the following cycle.

As for Solar Cycle 23 being almost done with, those are comforting words but the observational data suggests otherwise. Jan Janssens does it best – a recent plot is above. That suggests that we have a year to go and that Solar Cycle 23 is likely to be 13 years long. This is 3.4 years longer than Solar Cycle 22 and thus with mid-latitude temperatures responding at the rate of 0.7 degrees C per year of solar cycle length, Solar Cycle 24 will be 2.4 degrees cooler than the one we are still in.

The Financial Post has a story (Our Quiet Sun) that is echoing much of what Archibald is saying, but is quoting from other sources:

The sun, of late, is remarkably free of eruptions: It has lost its spots. By this point in the solar cycle, sunspots would ordinarily have been present in goodly numbers. Today’s spotlessness — what alarms Dr. Chapman and others — may be an anomaly of some kind, and the sun may soon revert to form. But if it doesn’t – and with each passing day, the speculation in the scientific community grows that it will not – we could be entering a new epoch that few would welcome.

Joe D’Aleo did an essay on IntelliCast on the possible consequences of a Solar Cycle 23 running out to 13 years, using some of the same things Archibald is saying:

Looking back at the full record of sunspot cycles, we can see this general behavior of short active cycles and longer, quiet ones. Successive 11 year cycles are different in their magnetic fields and the 22 year Hale cycle has in the past been related to some phenomena such as drought. Longer term cycles are apparent when you carefully examine the data. Very obvious from the long term plot of the 11 year cycles is the approximate 100 (106) year cycle. There is also a 213 year cycle. The last 213 minimum was in the early 1800s. The turn of each of the last 3 centuries has started with quiet long cycles with mid-century shorter, higher amplitude cycles. The quietest period was in the early 1800s (the Dalton Minimum). The 100 and 200 year minima are due the next decade suggesting a quieter sun ahead.

I’ll take Global Warming any day of the week and twice on Sundays over a Little Ice Age.


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