Archive for the ‘Solar physics’ Category

Level and length of cyclic solar activity during the Maunder minimum as deduced from the active-day statistics
J. M. Vaquero, G. A. Kovaltsov, I. G. Usoskin, V. M. S. Carrasco and M. C. Gallego
A&A, 577 (2015) A71
Published online: 06 May 2015
DOI: http://dx.doi.org/10.1051/0004-6361/201525962
(open access with registration)

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ABSTRACT
Aims. The Maunder minimum (MM) of greatly reduced solar activity took place in 1645–1715, but the exact level of sunspot activity is uncertain because it is based, to a large extent, on historical generic statements of the absence of spots on the Sun. Using a conservative approach, we aim to assess the level and length of solar cycle during the MM on the basis of direct historical records by astronomers of that time.

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This paper published 10th March tries to identify major episodic solar activity by using both 14C and 10BeImage

(note to reader, above x-axis has advancing time running right to left)

Grand solar minima and maxima deduced from 10Be and 14C: magnetic dynamo configuration and polarity reversal
F. Inceoglu, R. Simoniello, M. F. Knudsen, C. Karoff, J. Olsen, S. Turck-Chiéze, B. H. Jacobsen
A&A 577 A20 (2015)
DOI: 10.1051/0004-6361/201424212

Abstract

Aims. This study aims to improve our understanding of the occurrence and origin of grand solar maxima and minima.
Methods. We first investigate the statistics of peaks and dips simultaneously occurring in the solar modulation potentials reconstructed using the Greenland Ice Core Project (GRIP) 10 Be and IntCal13 14 C records for the overlapping time period spanning between ~1650 AD to 6600 BC.

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I’ve included this on the front page because I think the bimodality of solar data is an important matter where this work adds weight to the effect being real.

http://www.aanda.org/articles/aa/abs/2015/04/aa21064-13/aa21064-13.html
Open access with registration

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A solar 'prominence' [credit: NASA]

A solar ‘prominence’ [credit: NASA]


Not being an expert in such matters I turn to NASA for a brief explanation of terms:

‘The primary source of energy to the Earth is radiant energy from the Sun. This radiant energy is measured and reported as the solar irradiance. When all of the radiation is measured it is called the Total Solar Irradiance (TSI); when measured as a function of wavelength it is the spectral irradiance.’
NASA – Solar Irradiance

The abstract of a new paper suggests there’s a need to take a lot more notice of ‘SSI’ compared to ‘TSI’.
Note in particular its last sentence
:
‘Therefore, it appears that SSI rather than TSI is a good indicator of the chromospheric activity, and its cycle length dependent variation would be more relevant to the possible role of the Sun in the cyclic variation of the Earth’s atmosphere.’

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This failed work is presented as a cautionary tale but nevertheless there might be good parts.

Earlier oldbrew published an article on a theory by Nelson on forecasting the armada of radio propagation conditions. There were not many comments, possibly from the lack of solid further material.
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From this paper, we can see why the technique fell at the hurdle. Nevertheless looking at what people were thinking and doing is important.

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A resent post by Roger and comments thereon led to my  realising there are misunderstandings on the intepretation of the polar field relationships.

Wilcox Observatory[1] measure and publish a time series of the solar polar magnetic field, a difficult measurement. Started 31st May 1976, data point every 10 days.

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Figure 1, straight plot of f10.7 radio noise[3] as a proxy for solar activity and mean solar polar magnetic field[1].

Firstly here are some clarification notes.

The polar field is not the interplanetary field[6] indirectly associated with terrestrial cosmic ray flux. This field at earth roughly follows the F10.7 / sunspot shape, is very noisy.

Neither is it the Livingstone & Penn[2] finding about the change in sunspot magnetic field possibly reducing with time.

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Back in 2011. Tim Channon used his cycles analysis software to predict the evolution of the solar polar fields. The basis of the curve he produced is the motion of the gas giant planets, Jupiter, Saturn, Uranus and Neptune. As they orbit the Sun, they force the Sun to move relative to the centre of mass of the entire solar system. We see this motion when astronomers look out into the near cosmos and observe other stars ‘wobbling’. By measuring the wobble with respect to time, they are able to deduce the mass and distance of planets orbiting those stars, even though they are too small and dim to see directly.

Tim found that our Sun’s wobble due to the gas giant planets matched the observational data of the evolution of the Solar polar magnetic fields mentioned in the post put up by Stuart ‘Oldbrew‘ yesterday.

Here’s the plot Tim put up in 2011

Evolution of combined solar polar fields (red) vs motion of Sun relative to barycentre caused by planetary motion

At the time, it looked like the data was going to diverge from the prediction, but read on below the break to see the outcome.

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The Sun from NASA's SDO spacecraft

The Sun from NASA’s SDO spacecraft


According to new research entitled: “The crucial role of surface magnetic fields for the solar dynamo”, a prediction method for solar cycles, first proposed decades ago, has been validated:
‘As the dipole field [of the Sun] is the source of the toroidal field of the next cycle, its strength should be a measure of the activity of the next cycle.’

Phys.org reports:
Sunspots, bursts of radiation and violent eruptions are signs that our sun is permanently active. Researchers have long known that this activity varies in a cycle of around eleven years’ duration. Even if many questions are still unresolved, one thing is certain: magnetic fields which emerge on the surface of our sun from within its depths are the cause of the manifold activities.

Robert Cameron and Manfred Schüssler from the Max Planck Institute for Solar System Research in Göttingen have now proved that it is possible to deduce what the internal mechanism is simply by observing the magnetic processes on the surface. This even allows predictions to be made about the strength of a forthcoming activity cycle.

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Back in 1987, Robert M Wilson of NASA’s Space Science Laboratory in Huntsville published this paper in the Journal of Geophysical Research. It’s important to our solar-planetary theory because it shows that the Sun is bi-modal in terms of its solar cycle lengths. They cluster around  periods of a little over ten and a little under twelve years. These periods correlate to the periods of Jupiter-Earth-Venus syzygy cycles and Jupiter’s orbital period respectively. Leif Svalgaard vehemently denied this correlation when I pointed it out to him a few years ago.

rob-wilson-bimodal-sun

The same correlation was noted by independent researcher Timo Niroma in 1989, who conducted his own survey and analysis of solar cycle lengths. He produced this simple ascii-art graphic to present his results.

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Solar cycle 4b, support from 10BE proxy

Posted: February 28, 2015 by tchannon in Solar physics

One of the unsolved solar mysteries is the peculiar behaviour around year 1800. The data we have is poor leading to ambiguity on whether a solar sunspot cycle is missing from the record.

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Figures from paper. For a legible copy you will need to register and download the PDF.

The lost sunspot cycle: New support from 10Be measurements
C. Karoff, F. Inceoglu, M. F. Knudsen, J. Olsen, A. Fogtmann-Schulz
A&A 575 A77 (2015)
DOI: http://dx.doi.org/10.1051/0004-6361/201424927
(early preview with registration)

ABSTRACT

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Solar cycle 24 enigma: TSI on the rise again

Posted: February 25, 2015 by tallbloke in Solar physics
Tags: ,

The latest results from the TIM/SORCE TSI instrument show that solar cycle 24 hit a peak on Feb 6th at around 1362.3W/m^2. Does anyone think it’ll go any higher?

tim_level3_tsi_24hour_3month_640x480

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In Astronomy & Astrophysics this week is an article of interest to some Talkshop readers. The authors are looking at the little understood variation is solar rotation in the context of peculiar change in recent years. Article has been amended with a new figure kindly provided by  L. Zhang showing more detail.

Figure caption: Yearly values of the N-S asymmetry (N-S)/(N+S) of the solar rotation at latitude 17 deg in 1978-2013 for X-ray flares (blue open circles) and for sunspots (red open circles). The blue (red) filled circles denote 11 year running mean values for flares (sunspots).

Figure caption: Yearly values of the N-S asymmetry (N-S)/(N+S) of the solar rotation at latitude 17 deg in 1978-2013 for X-ray flares (blue open circles) and for sunspots (red open circles).
The blue (red) filled circles denote 11 year running mean values for flares (sunspots).

Letter to the Editor

Solar surface rotation: N-S asymmetry and recent speed-up
L. Zhang, K. Mursula and I. Usoskin
A&A 575 L2 (2015)
DOI: http://dx.doi.org/10.1051/0004-6361/201425169
(open access)

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As regular readers know, I’m interested in small devices for generating trickle charging solutions for batteries out in the cloudy mountains where the sun rarely shines. We’ve looked at potentially useful stirling engine designs before, but I just found this interesting video on Youtube which differs fundamentally from the stirling design, while retaining some of its thermodynamic features.

 

This type of very simple engine is known by various names such as laminar flow, thermo-acoustic, thermal lag etc, but no-on seems to have a fully developed thermodynamic theory of exactly how it works. Unlike classic stirling engines, there is no ‘displacer’ to shunt the working gas from the hot to the cold end in order to drive a cycle of expansion/contraction which then sucks and pushes a power piston which drives a flywheel (or a linear electric motor). It’s more reminiscent in a way of a pulse-jet engine, but with a closed cycle, rather than an open system generating thrust directly from the explosive expansion of combustible gases.

But besides thinking about the way this engine operates as a collection of glass and aluminium parts heated at one end, it put me in mind of the way the Sun ‘pulses’ every eleven years or so. So this is today’s brainstormer. If objects can be set into oscillation by the application of heat (and let’s not forget thermodynamic theory here, whereby atoms and molecules ‘vibrate’ more vigorously as heat is applied to them), then what if the heavy dense metallic hydrogen core of the Sun is set into oscillation by the heat generated in the fusion process? It wouldn’t oscillate so easily in the X-Y plane, because the Sun is rotating, but it is freer to move in the Z axis.
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Solar contiguous activity cycle 23/24

Posted: December 20, 2014 by tchannon in Astrophysics, Solar physics

At first sight this Brazilan paper in Astronomy & Astrophysics is relatively uninteresting if you are familar with sunspot activity, appears to be another general look using waveletts.

Two features strike me as worthy of highlighting

  • a double burst of activity during cycle 23, not obvious from sunspot data alone
  • continuing activity right through the 23/24 transition

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Extract from paper Fig. 5, my highlight of strong X activity post the cycle 23 sunspot peak.

Wavelet analysis of CME, X-ray flare, and sunspot series

M. R. G. Guedes, E. S. Pereira and J. R. Cecatto

A&A 573 A64 (2015)

DOI: http://dx.doi.org/10.1051/0004-6361/201323080

(access with registration, large PDF 17.7MB)

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Repost from Roger Pielke Sr’s weblog. Important this isn’t lost, because it shows a fatal error in Schmidt and Benestad’s paper. A paper still relied on by the IPCC in AR5 to dismiss solar forcing as an important climate variable, five years after Nicola demolished it. Benestad and Schmidt claim they successfully rebutted Scafetta’s exposure of their fatal error, something Scafetta vigorously disproved. We’ll take a look at that part of the controversy later.

Roger Pielke Sr’s original intro:
On July 22 2009 I posted on the new paper on solar forcing by Lean and Rind 2009. In that post, I also referred to the Benestad and Schmidt 2009 paper on solar forcing which has a conclusion at variance to that in the Lean and Rind paper.

After the publication of my post, Nicola Scafetta asked if he could present a comment (as a guest weblog) on the Benestad and Schmidt paper on my website, since it will take several months for his comment to make it through the review process. In the interests of presenting the perspectives on the issue of solar climate forcing, Nicola’s post appears below. I also invite Benestad and Schmidt to write responses to the Scaftta contribution which I would be glad to post on my website.
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Earth proton events as a solar activity measure

Posted: December 4, 2014 by tchannon in Solar physics

A recent Talkshop comment led me to look at a data directory where something tripped a thought

There is an earth affecting proton event dataset running from 1976, named SPE (Solar Proton Event). These are rare and erratic in time.

A very difficult maths problem is pulse density integration, one of the reasons why producing a statistical distribution shape is very hard where the data is sparse and spasmodic.

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I’ve faked up  innovated something visual, some kind of meaningful plot. Far from ideal so don’t be misled.

SSN is from SIDC

Taking the natural log of the energy value produces something sane looking, intuitively would be something like that. Added in some missing points for years with no events. Event data is provided to the second via NOAA.

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Gerry Pease has sent us a solar cycle 24 update:

It’s all downhill now for solar cycle 24. Cycle 24 Max (smoothed sunspot number 81.9) appears to have occurred in April, 2014:

Cycle 24 progress (last update December 1, 2014

Cycle 23 Solar Max (smoothed sunspot number 120) was in early 2000:

Solar cycles 23-24 (last update December 1, 2014)

Note the progression from cycle 21 to 24:

Graphical comparison of cycles 21, 22, 23 and 24 (last update December 1, 2014)

Similar cycles 12, 14, and 16 had lower peaks than cycle 24, and similar cycles 10, 12, 13, 14, and 16 all had earlier peaks:

Graphical comparison of cycles 10, 12, 13, 14, 16 and 24 (last update December 1, 2014)

Smoothed solar activity since April is projected to be successively lower each month.

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By Kelly Dickerson for Yahoo News:

ESA-Magnetospheres_600_MThe sun may be partly responsible for lightning strikes on Earth, and scientists think fluctuations in the sun’s magnetic field could be used to predict lightning storms weeks in advance.

The sun’s magnetic field can bend Earth’s own magnetic field, and this twisting and turning may be allowing an influx of high-energy particles into the planet’s atmosphere. These particles can cause a buildup of electric charge that can trigger lightning strikes.

From 2001 to 2006, during a period when the sun’s magnetic field was severely skewing the Earth’s magnetic field, the United Kingdom saw 50 percent more lightning strikes than normal, according to the new study. This severe skewing happens regularly as the sun’s magnetic field shifts. Scientists say this suggests the sun’s magnetic field could be used to predict the occurrence of lightning.

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A new facility here for creating clear air insolation data, without the more involved absorption effects or cloud, etc. needed some testing and so…

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This plot appeared during July 2012[1] after Dr. Hans Jelbring made available hourly data from the Koorin Expedition to Daly Waters, Australia during the astral winter of 1974[2]. A new plot trace has been added, computed by a new dynamic language[3] library, a wrapper around an unaltered version of NREL SOLPOS[4]. This produces an output value for one point in time, the plots here were created by a program feeding in different parameters, producing a time series, all very simple.

This result is similar to a result with data from Chilbolton Observatory, England from a Kip & Zonnen CNR4 net pyranometer / pyrgeometer[5]. Around 22% of inward solar radiation is absorbed by the atmosphere in excess of that computed by SOLPOS.

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Nicola Scafetta has emailed me to let us know he has a new paper in press which adresses critiques of our solar-planetary theory. I can’t do justice to presenting this work by illustrating this post with figures from the paper using my cellphone, but this a seriously impressive piece of work which Nicola generously shares with Talkshop readers via a link below the break. Nicola writes:

I just would like to share my latest paper
 
Nicola Scafetta, 2014. Discussion on the spectral coherence between planetary, solar and climate  oscillations: a reply to some critiques.

Astrophysics and Space Science in press.

http://link.springer.com/article/10.1007%2Fs10509-014-2111-8

For those who followed this research, the paper strongly rebuts some interesting critiques of the planetary theory of solar and climate variation made by Holm andCauquoin et al. that emerged in the literature during the first months of the 2014. (It also rebuts the very improper and unprofessional criticism made by Anthony Watts)

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Fig.14. 361-day moving average of the integrated flux in the reconstruction and in UARS and SORCE SSI between a) 120 and 180 nm, b) 180 and 250 nm, c) 250 and 300 nm, and d) 300 and 410 nm. The UARS and SORCE time series are normalized to the reconstruction at the 1996 and 2008 solar cycle minima, respectively. The dashed lines indicate the uncertainty range of the reconstruction.

 

Reconstruction of total and spectral solar irradiance from 1974 to 2013 based on KPVT, SoHO/MDI, and SDO/HMI observations
K. L. Yeo, N. A. Krivova, S. K. Solanki, and K. H. Glassmeier

18 page PDF available on registration with Astronomy & Astrophysics
http://dx.doi.org/10.1051/0004-6361/201423628

ABSTRACT

  • Context. Total and spectral solar irradiance are key parameters in the assessment of solar influence on changes in the Earth’s climate.
  • Aims. We present a reconstruction of daily solar irradiance obtained using the SATIRE-S model spanning 1974 to 2013 based on full-disc observations from the KPVT, SoHO/MDI, and SDO/HMI.

 

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