Livingston and Penn paper: "Sunspots may vanish by 2015".

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:

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”.