Dalton Minimum Returns

Relationship between Solar Cycle Length and Global Temperature Anomalies

Stephen Strum, Frontier Weather, Inc.

The most recent solar cycle, currently estimated to have reached a minimum in December 2008 based on a 12 month centered moving average of monthly sunspot numbers, was the longest solar cycle since 1798‐1810, measured trough to trough. The cycle lasted approximately 150 months or 12.5 years, two full years longer than the 20th century average of 10.5 years. The impact of a long solar cycle is twofold. First of all, there is a definite correlation between the length of one solar cycle and the peak sunspot number during the following cycle as the graph below shows.

Only two solar cycles since 1750 have lasted as long as or longer than the most recent cycle, and both were followed by the weakest solar maximums of the past 250 years, a period during the early 1800s known as the Dalton Minimum. Given the length of the previous cycle, the upcoming solar cycle could be among the weakest on record since 1750 if the relationship holds. Additionally, of the last five solar cycles that persisted twelve or more months longer than average, four were followed by another cycle lasting longer than average. In every instance, however, the next solar cycle was somewhat shorter in length than the previous cycle.

Since net solar radiation is slightly higher during periods of heightened sunspot activity (and lower during periods of little sunspot activity), the combination of long solar cycles and low sunspot numbers results in cumulatively more months on a decadal time scale with below average net solar radiation. The result is that weak and long solar cycles lead to cooling on a global basis while short and intense solar cycles tend to result in warming on a global basis. The following plot illustrates the relationship between the length of a given solar cycle and the average temperatures during the following solar cycle.

The Sun could be heading into period of extended calm

Physics World, by James Darcy

Researchers in the US may have discovered further evidence that the Sun is heading towards an extended period of quiet activity, the like of which has not been seen since the 17th century. 

The Article Continues:

Extended calm

We were expecting to reach the next solar maxima around 2011–2012. However, space weather experts have been surprised over the past few years to report very few signs that the number of sunspots has been picking up since the last solar minimum in 2006. This has prompted some space scientists to forecast that we are heading towards another prolonged spell of quiet sunspot activity, the last of which was observed between 1645 and 1715 in a period called the "Maunder Minimum".

In this latest research, Sarah Gibson at the National Center for Atmospheric Research (NCAR) in Colorado and her colleagues focused on another process by which the Sun discharges energy. They looked at the lower-energy streams of plasma that carry protons and electrons towards the Earth at a steadier rate than the storms associated with sunspots. Scientists had previously thought that these streams largely disappeared during periods of quiet sunspot activity.

The researchers found that the Sun's effect on the Van Allen radiation belt was three times greater in 2008 than the effect recorded in 1996 during the previous solar minimum. The result comes as a surprise given that the current solar minimum has fewer sunspots than any minimum of the past 75 years.

Strength a sign of weakness

Gibson told physicsworld.com that it could be the current "weakness of the Sun" that could account for the strengthened solar streams. This is because during solar maxima, when sunspots appear in abundance, the strong solar magnetic field acts to contain the solar streams. However, when sunspot activity is very quiet, this is a sign that the field is significantly weakened and this can allow stronger solar streams to escape through "coronal holes". "The solar wind can hit Earth like a fire hose even when there are virtually no sunspots," she said.

The particularly strong solar streams of 2008 could, according to Gibson, be another sign that the Sun is in an unusually weak state at the moment. The study also raises questions about how the streams may have affected Earth in the past when the Sun went through extended periods of low sunspot activity.

More than sunspots

Solar Cycle Driven by More than Sunspots; Sun Also Bombards Earth with High-Speed Streams of Wind.

From an NCAR press release September 17, 2009

BOULDER—Challenging conventional wisdom, new research finds that the number of sunspots provides an incomplete measure of changes in the Sun’s impact on Earth over the course of the 11-year solar cycle. The study, led by scientists at the High Altitude Observatory of the National Center for Atmospheric Research (NCAR) and the University of Michigan, finds that Earth was bombarded last year with high levels of solar energy at a time when the Sun was in an unusually quiet phase and sunspots had virtually disappeared.

“The Sun continues to surprise us,” says NCAR scientist Sarah Gibson, the lead author. “The solar wind can hit Earth like a fire hose even when there are virtually no sunspots.”

See the put down by Leif Svalgaard and the discussion of this latest PR Stunt by NCAR at WUWT.

Danish Scientist: World growing cooler

Russ Steele

Svensmark: “global warming stopped and a cooling is beginning” – “enjoy global warming while it lasts”

Details at Watts Up With That. Be sure and take a few minutes to read the debate in the comments, very interesting exchange of ideas. Yes, there are some fluff comments, but you can skip those.

The Ap Solar Magnetic Index remains low, going on 4 years

Anthony Watts has an interesting review of the Ap Index over the past four years at WUWT

SOLAR MINIMUM - VS - GLOBAL WARMING

This was originally posted at spaceweather.com

From 2002 to 2008, decreasing solar irradiance has countered much anthropogenic warming of Earth's surface. That's the conclusion of researchers Judith Lean (NRL) and David Rind (NASA/GISS), who have just published a new analysis of global temperatures in the Geophysical Research Letters. Lean and Rind considered four drivers of climate change: solar activity, volcanic eruptions, ENSO (El Nino), and the accumulation of greenhouse gases. The following plot shows how much each has contributed to the changing temperature of Earth's surface since 1980:



Volcanic aerosols are a source of cooling; ENSO and greenhouse gases cause heating; the solar cycle can go either way. When added together, these factors can account for 76% of the variance in Earth's surface temperature over the past ~30 years, according to the analysis of Lean and Rind.

Several aspects of their model attract attention: "The warmest year on record, 1998, coincides with the 'super-El Nino' of 1997-98," points out Lean. "The ESNO is capable of producing significant spikes in the temperature record." Solar minimum has the opposite effect: "A 0.1% decrease in the sun's irradiance has counteracted some of the warming action of greenhouse gases from 2002 - 2008," she notes. "This is the reason for the well-known 'flat' temperature trend of recent years."

What's next? Ultimately, the authors say, temperatures will begin rising again as greenhouse gases accumulate and solar activity resumes with the coming of the next solar cycle. Of course, the solar cycle could be out of whack; if solar minimum deepens and persists, no one is certain what will happen. Lean and Rind reveal their predictions for the future here.

Reference: Lean, J. L., and D. H. Rind (2009), How will Earth's surface temperature change in future decades?, Geophys. Res. Lett., 36, L15708

NASA: Are Sunspots Disappearing?

From NASA News: Are Sunspots Disappearing?

September 3, 2009: The sun is in the pits of the deepest solar minimum in nearly a century. Weeks and sometimes whole months go by without even a single tiny sunspot. The quiet has dragged out for more than two years, prompting some observers to wonder, are sunspots disappearing?

“Personally, I’m betting that sunspots are coming back,” says researcher Matt Penn of the National Solar Observatory (NSO) in Tucson, Arizona. But, he allows, “there is some evidence that they won’t.”

More details and discussion at Watts Up With That.

Two tiny spots breaks spotless streak

Two sun spots appeared, breaking a 52 day streak.   See this recap at The Examiner.



This solar minimum may be about to end a 52 day streak in which no sunspots were observed.  That period of time is the 4th longest since 1849!   On this chart which displays the top sunspotless days per year note that 2008 is #4 and 2007 is #19.  If 2009 ended today then this year is ALREADY #15! This year still has has 122 days in it.

According to spaceweather.com the spots appear to be fading.

My question is would spot this small be observed in the 1800s?