Sun and Solar

Sun and Solar

2009-05-13
Nature: Quiet Sun enters new sunspot cycle Nature 459, 152 (2009) | doi:10.1038/459152f

After a prolonged lull in activity, sunspots, and their associated solar storms, are on the rise again.

According to a panel of scientists led by the US Space Weather Prediction Center, part of the National Oceanic and Atmospheric Administration, a minimum in sunspot activity was passed in December 2008. In a consensus forecast on 8 May, the researchers said a new cycle of solar storms would peak in May 2013. But judging by the historical record, the recent persistence of a quiet Sun suggests that sunspot activity at this peak will be the weakest since the solar maximum of 1928.

NASA’s STEREO mission spotted large regions of magnetic activity (white spots on image) on the Sun this month.


SunFig1a

Sun Fig. 1a Sunspots 1750 - present


Sun Fig. 1b Sunspots

Sun Fig. 1b Sunspots


Sun Fig. 2 Sunspot rate of change (5 and 11 year slopes) 1900 - present

Sun Fig. 2 Sunspot rate of change (5 and 11 year slopes) 1900 - present


Sun Fig. 3 Cosmic Rays, Sunspots and Temperatures 1953 - 2006

Sun Fig. 3 Cosmic Rays, Sunspots and Temperatures 1953 - 2006


Ecologist – 2009-02-06: New studies disprove cosmic ray and solar influence theories of global warming

Get into an argument with a climate change sceptic, and sooner or later they’ll trot out the old arguments about it being all due to cosmic rays, or the sun.

Now, two new studies will help you set them straight. An international group of scientists writing in the journal Atmospheric Chemistry and Physics investigated the hypothesis that a reduction in the amount of cosmic radiation hitting the earth reduces the size and number of cloud droplets, which leads to more sunlight reaching the earth’s surface and consequent temperature rise.

Using satellite data, the researchers looked at what happened to cloud droplet size, water content, and depth during so-called ‘Forbush decrease’ events – periods in which the intensity of rays hitting the earth decreases by up to 30 per cent. They could find no statistically significant association between the Forbush events and any of the cloud factors they studied.

See also Kristjánsson, J. E., Stjern, C. W., Stordal, F., Fjæraa, A. M., Myhre, G., and Jónasson, K.:
Cosmic rays, cloud condensation nuclei and clouds – a reassessment using MODIS data , Atmos. Chem. Phys., 8, 7373-7387, 2008.
… Averaging the results from the 22 Forbush decrease events that were considered, no statistically significant correlations were found between any of the four cloud parameters and GCR, when autocorrelations were taken into account.


Carnegie Mellon, Pittsburgh – 2009-05-11: No link has been found between cloud cover, cosmic rays and global warming

With the U.S. Congress beginning to consider regulations on greenhouse gases, a troubling hypothesis about how the sun may impact global warming is finally laid to rest.

Carnegie Mellon University‘s Peter Adams along with Jeff Pierce from Dalhousie University in Halifax, Canada, have developed a model to test a controversial hypothesis that says changes in the sun are causing global warming.

The hypothesis they tested was that increased solar activity reduces cloudiness by changing cosmic rays. So, when clouds decrease, more sunlight is let in, causing the earth to warm. Some climate change skeptics have tried to use this hypothesis to suggest that greenhouse gases may not be the global warming culprits that most scientists agree they are.

In research published in Geophysical Research Letters, and highlighted in the May 1 edition of Science Magazine, Adams and Pierce report the first atmospheric simulations of changes in atmospheric ions and particle formation resulting from variations in the sun and cosmic rays. They find that changes in the concentration of particles that affect clouds are 100 times too small to affect the climate.

“Until now, proponents of this hypothesis could assert that the sun may be causing global warming because no one had a computer model to really test the claims,” said Adams, a professor of civil and environmental engineering at Carnegie Mellon.

“The basic problem with the hypothesis is that solar variations probably change new particle formation rates by less than 30 percent in the atmosphere. Also, these particles are extremely small and need to grow before they can affect clouds. Most do not survive to do so,” Adams said.

Despite remaining questions, Adams and Pierce feel confident that this hypothesis should be laid to rest. “No computer simulation of something as complex as the atmosphere will ever be perfect,” Adams said. “Proponents of the cosmic ray hypothesis will probably try to question these results, but the effect is so weak in our model that it is hard for us to see this basic result changing.”

2009-05-13
Can cosmic rays affect cloud condensation nuclei by altering new particle formation rates?
, Geophys. Res. Lett., 36, L09820, doi:10.1029/2009GL037946

Although controversial, many observations have suggested that low-level cloud cover correlates with the cosmic ray flux. Because galactic cosmic rays have likely decreased in intensity over the last century, this hypothesis, if true, could partly explain 20th century warming, thereby upsetting the consensus view that greenhouse-gas forcing has caused most of the warming. The “ion-aerosol clear-air” hypothesis suggests that increased cosmic rays cause increases in new-particle formation, cloud condensation nuclei concentrations (CCN), and cloud cover. In this paper, we present the first calculations of the magnitude of the ion-aerosol clear-air mechanism using a general circulation model with online aerosol microphysics. In our simulations, changes in CCN from changes in cosmic rays during a solar cycle are two orders of magnitude too small to account for the observed changes in cloud properties; consequently, we conclude that the hypothesized effect is too small to play a significant role in current climate change.


Sun Fig. 4a Recent sunspots from NOAA 1991 - Source SWO: NOAA, Space Weather Prediction Center Source RI: S.I.D.C. Brussels International Sunspot Number

Sun Fig. 4a Recent sunspots from NOAA 1991 - Source SWO: NOAA, Space Weather Prediction Center Source RI: S.I.D.C. Brussels International Sunspot Number


Physorg 2006-12-22: Scientists Predict Big Solar Cycle

Sun Fig. 4b Predicted sunspots from the NASA Solar Physics Marshall Space Flight Center "Solar Cycle Prediction"

Sun Fig. 4b Predicted sunspots from the NASA Solar Physics Marshall Space Flight Center "Solar Cycle Prediction"

Evidence is mounting: the next solar cycle is going to be a big one. Solar cycle 24, due to peak in 2010 or 2011 [now projected for 2013]“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 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:

SolarCyclesVsGeomagneticActivity

2 Responses to Sun and Solar

  1. Alan Burke says:

    Published 2011-01-21 in Atmospheric Chemistry and Physics

    The Smithsonian solar constant data revisited: no evidence for cosmic-ray induced aerosol formation in terrestrial insolation data

    Abstract

    Apparent evidence for a strong signature of solar activity in terrestrial insolation data was recently reported. In particular, a surprisingly strong increase of terrestrial insolation with sunspot number as well as a decline of the brightness of the solar aureole and the measured precipitable water content of the atmosphere with solar activity was presented. The latter effect was interpreted as evidence for cosmic-ray induced aerosol formation. Here I show that these spurious result are due to a failure to correct for seasonal variations and the effects of volcanic eruptions and local pollution in the data. After correcting for these biases, the atmospheric water content, the solar aureole brightness, and the terrestrial insolation show no significant trend with solar activity. Hence there is no evidence for the influence of solar activity on the climate being stronger than currently thought, or a cosmic-ray mechanism linking the two.

    Conclusion …

    Solar activity has an influence on Earth’s climate, but it is comparatively small. The 11-year solar activity cycle, for example, has been shown to result in global temperature changes of ’0.1 ◦C between solar maxima and minima (Lean and Rind, 2008). Grand minima of solar activity like the Maunder minimum (Eddy, 1976) in the 17th century lowered global temperatures by ’0.5 ◦C, which is less than the warming of ’0.7 ◦C observed over the 20th century. Even a future Maunder-like solar-activity minimum would diminish global temperatures by ’0.3 ◦C at most, about a factor of ten smaller than the expected warming due to anthropogenic greenhouse-gas emissions (Feulner and Rahmstorf, 2010). Furthermore, these changes can be explained with the variations of the total and spectral solar irradiance, without any need to invoke hypothetical mechanisms involving cosmic rays for which there continues to be little supporting evidence.

    Citation: Feulner, G.: The Smithsonian solar constant data revisited: no evidence for cosmic-ray induced aerosol formation in terrestrial insolation data, Atmos. Chem. Phys. Discuss., 11, 2297-2316, doi:10.5194/acpd-11-2297-2011, 2011.
    © Author(s) 2011. CC Attribution 3.0 License.

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