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(Thanks TO ‘OLDBREW’)
for finding this information . If there is a connection with Earths climate it warrants a post of its own.
As get more info’ I will do a few time series correlations
Heliospheric current sheet
Sleepy sun thickens the slow solar wind
17:14 10 January 2014 by Stuart Clark
Even the sun needs a break. A slowdown in solar activity has given us the first real clue about a period of dramatic solar behaviour 350 years ago.
In 2008, the sun entered a deep lull in magnetic activity. Spacecraft measurements show that this caused a belt of sluggish particles, known as the slow solar wind, to thicken. Produced near the sun’s equator, the belt is normally narrow and ruched like a ballerina’s tutu. The particles there flow at about 336 kilometres a second, as opposed to 550 kilometres a second in the fast solar wind produced closer to the sun’s poles.
Because Earth orbits at a 14 degree tilt relative to the sun’s equator, it passes in and out of these ruches during the year. As solar activity dwindles, the belt thickens, and we spend more time passing through it. The speed of the slow solar wind affects the temperature of Earth’s upper atmosphere, and impacts climate.
To find out how severe such slowdowns might be, Mike Lockwood and Matt Owens at the University of Reading, UK, used the 2008 measurements to model the belt’s thickness during the most extreme solar minimum on record: the Maunder Minimum. This lasted from 1645 to 1715 and corresponded to a minor ice age.
Not so windy
The model showed that the solar wind speed probably dropped to just 250 to 275 kilometres a second during this period. Earth spent six months of the 2008 minimum in the slow solar wind, but it probably spent all 70 years of the Maunder Minimum there.
Lockwood says the current weak cycle could herald the sun dipping into another extended period of inactivity. The temperature of Earth’s upper atmosphere affects the speed at which satellite orbits decay, so a prolonged drop in the solar wind speed would cool and shrink the atmosphere and diminish the drag on satellites. This would exacerbate the space junkMovie Camera problem because debris would be slower to re-enter Earth’s atmosphere, where it burns up harmlessly.
But don’t expect another mini ice age, says Lockwood. The Maunder Minimum was also characterised by an almost total lack of sunspots, which record how the solar dynamo, which creates the sun’s magnetic field, is churning. We still do not understand that well enough to predict when another Maunder Minimum might occur.
“Until we know why the sun occasionally drops into these grand minima, we won’t really understand the solar dynamo,” says Lockwood.
LOCKWOOD and OWENS
Journal reference: Astrophysical Journal Letters, DOI: 10.1088/2041-8205/781/1/L7
Implications of the Recent Low Solar Minimum for the Solar Wind during the Maunder Minimum
M. Lockwood and M. J. Owens
M. Lockwood and M. J. Owens 2014 ApJ 781 L7. doi:10.1088/2041-8205/781/1/L7
Received 18 November 2013, accepted for publication 5 December 2013. Published 23 December 2013.
? 2014. The American Astronomical Society. All rights reserved.
The behavior of the Sun and near-Earth space during grand solar minima is not understood; however, the recent long and low minimum of the decadal-scale solar cycle gives some important clues, with implications for understanding the solar dynamo and predicting space weather conditions. The speed of the near-Earth solar wind and the strength of the interplanetary magnetic field (IMF) embedded within it can be reliably reconstructed for before the advent of spacecraft monitoring using observations of geomagnetic activity that extend back to the mid-19th century.
We show that during the solar cycle minima around 1879 and 1901 the average solar wind speed was exceptionally low, implying the Earth remained within the streamer belt of slow solar wind flow for extended periods. This is consistent with a broader streamer belt, which was also a feature of the recent low minimum (2009), and yields a prediction that the low near-Earth IMF during the Maunder minimum (1640-1700), as derived from models and deduced from cosmogenic isotopes, was accompanied by a persistent and relatively constant solar wind of speed roughly half the average for the modern era.