* Astronomy

Title: Modelling atmospheric effects of the September 1859 solar flare
Authors: Brian Thomas (Washburn Univ.), Charles Jackman (NASA GSFC), Adrian Melott (Univ. of Kansas)
(revised v2)

We have modelled atmospheric effects, especially ozone depletion, due to a solar proton event which probably accompanied the extreme magnetic storm of 1-2 September 1859. We use an inferred proton fluence for this event as estimated from nitrate levels in Greenland ice cores. We present results showing production of odd nitrogen compounds and their impact on ozone. We also compute rainout of nitrate in our model and compare to values from ice core data.
Comment: Revised version including improved figures; Accepted for publication in Geophys. Res. Lett, chosen to be highlighted by AGU

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Newly uncovered scientific data of recorded history's most massive space storm is helping a NASA scientist investigate its intensity and the probability that what occurred on Earth and in the heavens almost a century-and-a-half ago could happen again.
In scientific circles where solar flares, magnetic storms and other unique solar events are discussed, the occurrences of September 1-2, 1859, are the star stuff of legend. Even 144 years ago, many of Earth's inhabitants realized something momentous had just occurred. Within hours, telegraph wires in both the United States and Europe spontaneously shorted out, causing numerous fires, while the Northern Lights, solar-induced phenomena more closely associated with regions near Earth's North Pole, were documented as far south as Rome, Havana and Hawaii, with similar effects at the South Pole.

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While most weather forecasters focus on the six or seven miles of earth's atmosphere where clouds drift and storms form, Jonathan Makela's sights are set much higher.
Makela, a University of Illinois electrical- and computer-engineering professor, is working on a way to forecast the weather in the ionosphere, the region of Earth's atmosphere found about 45 to 600 miles above the planet.
What happens in the ionosphere — so named because it is heavily ionised by the sun's radiation — can have dramatic effects on satellite communications, air travel and power grids.

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On July 31st, 2006, a tiny sunspot was born. It popped up from the sun's interior, floated around a bit, and vanished again in a few hours. On the sun this sort of thing happens all the time and, ordinarily, it wouldn't be worth mentioning. But this sunspot was special: It was backward.

"We've been waiting for this. A backward sunspot is a sign that the next solar cycle is beginning" - David Hathaway, a solar physicist at the Marshall Space Flight in Huntsville, Alabama.

"Backward" means magnetically backward.

Sunspots are planet-sized magnets created by the sun's inner magnetic dynamo. Like all magnets in the Universe, sunspots have north (N) and south (S) magnetic poles. The sunspot of July 31st popped up at solar longitude 65° W, latitude 13° S. Sunspots in that area are normally oriented N-S. The newcomer, however, was S-N, opposite the norm.



This tiny spot of backwardness matters because of what it might foretell: A really big solar cycle.
Solar activity rises and falls in 11-year cycles, swinging back and forth between times of quiet and storminess. Right now the sun is quiet.

"We're near the end of Solar Cycle 23, which peaked way back in 2001" David Hathaway.

The next cycle, Solar Cycle 24, should begin "any time now," returning the sun to a stormy state.

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The next sunspot cycle will be 30 to 50 percent stronger than the last one, and begin as much as a year late, according to a breakthrough forecast using a computer model of solar dynamics developed by scientists at the National Centre for Atmospheric Research (NCAR) in Boulder, Colorado, US. The research results, funded by the National Science Foundation (NSF) and NASA, were published on-line on March 3 in the American Geophysical Union journal Geophysical Research Letters.

Scientists now predict that the next cycle, known as Cycle 24, will produce sunspots across an area slightly larger than 2.5 percent of the visible surface of the Sun. The cycle is projected to reach its peak about 2012, one-year later than indicated by alternative forecasting methods that rely on statistics.
By analysing recent solar cycles, the scientists also hope to forecast sunspot activity two solar cycles, or 22 years, into the future. The team is planning in the next year to issue a forecast of Cycle 25, which will peak in the early 2020s.
The researchers expect that predicting the Sun's cycles years in advance will lead to more accurate plans for solar storms, which can slow satellite orbits, disrupt communications, and bring down power systems.
The team has verified the information by using the relatively new technique of helioseismology, based in part on observations from NASA instruments. This technique tracks sound waves reverberating inside the Sun to reveal details about the interior, much as a doctor might use ultrasound to see inside a patient.

"Forecasting the solar cycle will help society anticipate solar storms. Important discoveries are being made using helioseismology. Through this technique, we can image even the far side of the Sun" - Paul Bellaire, program director in NSF's division of atmospheric sciences, which funded the research.

The scientists gained additional confidence in the forecast by showing that the newly developed model could simulate the strength of the past eight solar cycles with more than 98 percent accuracy.

"The model has demonstrated the necessary skill to be used as a forecasting tool" - Mausumi Dikpati, NCAR scientist, the leader of the forecast team at NCAR's High Altitude Observatory. The team also includes NCAR scientists Peter Gilman and Guiliana de Toma.

"This is a significant breakthrough with important applications, especially for satellite-dependent societies" - Peter Gilman .

The Sun goes through approximately 11-year cycles, from peak storm activity to quiet, and back again. Solar scientists have tracked these cycles without being able to predict their relative intensity or timing.
Solar storms are linked to twisted magnetic fields that suddenly snap and release tremendous amounts of energy. They tend to occur near dark regions of concentrated magnetic fields, known as sunspots.
The NCAR computer model, known as the Predictive Flux-transport Dynamo Model, draws on research indicating that the evolution of sunspots is caused by a current of plasma, or electrified gas, that circulates between the Sun's equator and its poles over a period of 17 to 22 years.
The plasma acts as a conveyor belt, transporting the imprints of sunspots from the previous two solar cycles. As they return toward the equator, they become stretched and twisted by the internal rotation of the Sun, gradually becoming less stable than the surrounding plasma. This eventually causes coiled-up magnetic field lines to rise up, tear through the Sun's surface, and create new sunspots, beginning the cycle again.

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