Solar Science

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Archive for the ‘Solar Cycle’ Category

Solar Climate Linkages

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Just a couple of interesting articles that I think deserve wider readership.

Henrik Svensmark on the coming global cooling: “enjoy global warming while it lasts” (this is a Google translation from Danish, so the English is a little crazy)

While the sun sleeps

HENRIK SVENSMARK, Professor, DTU, Copenhagen

Indeed, global warming stopped and a cooling is beginning. No climate model has predicted a cooling of the Earth, on the contrary. This means that projections of future climate is unpredictable, writes Henrik Svensmark.

The star which keeps us alive, has over the last few years almost no sunspots, which are the usual signs of the sun’s magnetic activity.

Last week, reported the scientific team behind Sohosatellitten (Solar and Heliospheric Observatory) that the number of sunspot-free days suggest that solar activity is heading towards its lowest level in about 100 years’. Everything indicates that the Sun is moving into a hibernation-like state, and the obvious question is whether it has any significance for us on Earth.

If you ask the International Panel on Climate Change IPCC, representing the current consensus on climate change, so the answer is a reassuring ‘nothing’. But history and recent research suggests that it is probably completely wrong. Let us take a closer look at why.

Solar activity has always varied. Around the year 1000, we had a period of very high solar activity, which coincided with the medieval warmth. It was a period when frosts in May was an almost unknown phenomenon and of great importance for a good harvest. Vikings settled in Greenland and explored the coast of North America. For example, China’s population doubled over this period. But after about 1300, the earth began to get colder and it was the beginning of the period we now call the Little Ice Age. In this cold period all the Viking settlements in Greenland disappeared. Swedes [were surprised to see Denmark to freeze over in ice], and the Thames in London froze repeatedly. But more serious was the long periods of crop failure, which resulted in a poorly nourished population, because of disease and hunger [population was reduced] by about 30 per cent in Europe.

Read on here

New linkage between solar cycle and Earth’s atmosphere discovered

Scientists discover surprise in Earth’s upper atmosphere

By Stuart Wolpert

Heejeong Kim and Larry Lyons

Heejeong Kim and Larry Lyons

UCLA atmospheric scientists have discovered a previously unknown basic mode of energy transfer from the solar wind to the Earth’s magnetosphere. The research, federally funded by the National Science Foundation, could improve the safety and reliability of spacecraft that operate in the upper atmosphere.

“It’s like something else is heating the atmosphere besides the sun. This discovery is like finding it got hotter when the sun went down,” said Larry Lyons, UCLA professor of atmospheric and oceanic sciences and a co-author of the research, which is in press in two companion papers in the Journal of Geophysical Research.

The sun, in addition to emitting radiation, emits a stream of ionized particles called the solar wind that affects the Earth and other planets in the solar system. The solar wind, which carries the particles from the sun’s magnetic field, known as the interplanetary magnetic field, takes about three or four days to reach the Earth. When the charged electrical particles approach the Earth, they carve out a highly magnetized region — the magnetosphere — which surrounds and protects the Earth.

Charged particles carry currents, which cause significant modifications in the Earth’s magnetosphere. This region is where communications spacecraft operate and where the energy releases in space known as substorms wreak havoc on satellites, power grids and communications systems.

The rate at which the solar wind transfers energy to the magnetosphere can vary widely, but what determines the rate of energy transfer is unclear.

“We thought it was known, but we came up with a major surprise,” said Lyons, who conducted the research with Heejeong Kim, an assistant researcher in the UCLA Department of Atmospheric and Oceanic Sciences, and other colleagues.

Read on here

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Written by John A

September 11, 2009 at 12:13 pm

What comes around

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Following on from my previous post noting the rotating back into view of the region formerly known as Sunspot 1024, we now have a clearer picture:

Sunspot 1024 is over, man

Sunspot 1024 is over, man

Its just a plage, the end game of a sunspot.

The Sun remains quiet.

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Written by John A

July 27, 2009 at 2:14 pm

Posted in Solar Cycle

Tagged with ,

Popular Mechanics on the Solar Minimum

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Joe Pappalardo at Popular Mechanics has a fascinating article on the possible (probable?) result of an extended solar minimum such as that which we are experiencing: global cooling:

Every day, scientists hoping to see an increase in solar activity train their instruments at the sun as it crosses the sky. This is no idle academic pursuit: A lull in solar action could potentially drive the planet’s temperature down, or even prompt a mini Ice Age.

Woah! I wonder if Joe has heard about the overwhelming scientific consensus that denies such a result? Maybe I should sic James Hansen on him…

For millennia, thermonuclear forces inside the star have followed a regular rhythm, causing its magnetic field to peak and ebb, on average, every 11 years. Space weathermen are watching for telltale increases in sunspots, which would signal the start of a new cycle, predicted to have started last March and expected to peak in 2012. “When the sun’s active, it’s a little bit brighter,” explains Ken Tapping, a solar researcher and project director for Canada’s National Research Council.

So far, Tapping reports no change in the magnetic field strength, as measured by radio telescopes. On the more positive side, last month NASA reported a small, earth-sized sunspot with a magnetic field pointing in the opposite direction from those in the previous cycle; qualities that designate the spot as a signal of a new upturn in activity. At the solar maximum, scientists expect to see between 75 and 150 such sunspots per day.

Tapping oversees the operation of a 60-year-old radio telescope that he calls a “stethoscope for the sun.” Recent magnetic field readings are as low as he’s ever seen, he says, and he’s worked with the instrument for more than 25 years. If the sun remains this quiet for another a year or two, it may indicate the star has entered a downturn that, if history is any precedent, could trigger a planetary cold spell that could bring massive snowfall and severe weather to the Northern Hemisphere.

The last such solar funk corresponded with a period of bitter cold that began around 1650 and lasted, with intermittent spikes of warming, until 1715. While there were competing causes for the climatic shift—including the Black Death’s depopulation of tree-cutting Europeans and, more substantially, increased volcanic activity spewing ash into the atmosphere—the sun’s lethargy likely had something to do with it.

Of course, no mention of greenhouse gases.

Just how much influence the sun has on global temperatures has been the subject of sometimes acrimonious debate. While an upswing in solar activity may cause a warming trend, it was discounted in the mid-1990s as the sole driver of current climate change. And for anyone hoping that a solar downswing might bail us out of our current dilemma: Solar influence on climate is slight compared to the impact of man-made greenhouse gases, a National Academy of Sciences report concluded in 1995.

Ah, there it is! So what we have is a contest between global warming due to greenhouse gases, and global cooling due to solar dimming.

Its a dilemma as to what to wish for. Global cooling such as the Little Ice Age would have been a technological challenge to modern 21st Century agriculture, technology and energy resources. What’s there to worry about with global warming? Deserts like the Sahara shrinking is a bad thing to be avoided…like the Plague?

Written by John A

February 7, 2008 at 12:32 pm

What shall we call the next minimum?

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Still absolutely no sign of Solar Cycle 24.

sunspotsthru30sept2007.gif

I wonder what we should call the next minimum in solar activity? The Hansen Minimum?

Written by John A

October 17, 2007 at 7:14 am

Still no sign of Solar Cycle 24

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Here’s the latest trend chart from NASA. Apparently the Sun knows nothing of the predictions of NASA solar scientists regarding solar cycle 24.

Today’s pictures of the Sun show an absolutely featureless disk:

featurelesssolardisk.gif

and the magnetogram shows absolutely no sign of any magnetic activity

feratureless-magnetogram.gif

I’ve no idea what this portends for the Earth’s climate so we’ll just have to see what happens next.

Written by John A

September 9, 2007 at 9:11 pm

Posted in Solar Cycle

Solar Influence in the last 400 years

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A paper from N. Scafetta and B. West submitted to Geophysical Research Letters:

We study the solar impact on 400 years of a global
surface temperature record since 1600. This period includes
the pre-industrial era (roughly 1600–1800 or 1600–1900),
when negligible amount of anthropogenic-added climate
forcing was present and the sun realistically was the
only climate force affecting climate on a secular scale, and
the industrial era (roughly since 1800–1900), when
anthropogenic-added climate forcing has been present
in some degree. We use a recent secular Northern
Hemisphere temperature reconstruction (Moberg et al.,
2005), three alternative total solar irradiance (TSI) proxy
reconstructions (Lean et al., 1995; Lean, 2000; Wang et al.,
2005) and a scale-by-scale transfer climate sensitivity model
to solar changes (Scafetta and West, 2005, 2006). The
phenomenological approach we propose is an alternative to
the more traditional computer-based climate model approach,
and yields results proven to be almost independent on the
secular TSI proxy reconstruction used. We find good
correspondence between global temperature and solar
induced temperature curves during the pre-industrial period
such as the cooling periods occurring during the Maunder
Minimum (1645–1715) and the Dalton Minimum (1795–
1825). The sun might have contributed approximately 50%
of the observed global warming since 1900 (Scafetta and
West, 2006). We briefly discuss the global cooling that
occurred from the medieval maximum (1000–1100 AD)
to the 17th century minimum.

So they used the Moberg reconstruction. At least it wasn’t the Hockey Stick.

Written by John A

March 22, 2007 at 10:00 pm

Posted in Solar Cycle

Previous predictions of solar cycle 24

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From NASA website:

Solar cycle 24, due to peak in 2010 or 2011 “looks like its going to be one of the most intense cycles since record-keeping began almost 400 years ago,” says solar physicist David Hathaway of the Marshall Space Flight Center. He and colleague Robert Wilson presented this conclusion last week at the American Geophysical Union meeting in San Francisco.

Their forecast is based on historical records of geomagnetic storms.

Hathaway explains: “When a gust of solar wind hits Earth’s magnetic field, the impact causes the magnetic field to shake. If it shakes hard enough, we call it a geomagnetic storm.” In the extreme, these storms cause power outages and make compass needles swing in the wrong direction. Auroras are a beautiful side-effect.

Hathaway and Wilson looked at records of geomagnetic activity stretching back almost 150 years and noticed something useful:. “The amount of geomagnetic activity now tells us what the solar cycle is going to be like 6 to 8 years in the future,” says Hathaway. A picture is worth a thousand words:

Hathaway's comparison of solar and geomagnetic fields

Hathaway's comparison of solar and geomagnetic fields

Above: Peaks in geomagnetic activity (red) foretell solar maxima (black) more than six years in advance. [More]

In the plot, above, black curves are solar cycles; the amplitude is the sunspot number. Red curves are geomagnetic indices, specifically the Inter-hour Variability Index or IHV. “These indices are derived from magnetometer data recorded at two points on opposite sides of Earth: one in England and another in Australia. IHV data have been taken every day since 1868,” says Hathaway.

Cross correlating sunspot number vs. IHV, they found that the IHV predicts the amplitude of the solar cycle 6-plus years in advance with a 94% correlation coefficient.

“We don’t know why this works,” says Hathaway. The underlying physics is a mystery. “But it does work.”

And here’s the prediction for Solar Cycle 24 based on this “mystery”:

Hathaway's 2006 prediction of SC24

Hathaway's 2006 prediction of SC24

Never mind that this thing looks a lot like numerology – if its from NASA and has a nice graph it must be worth something

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Written by John A

March 21, 2007 at 9:50 pm