Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Solar Cycle & Explanation for Recent Changes?

  1. Mar 25, 2007 #1
    Is the Sun heading towards a Maunder Minimum?

    http://science.nasa.gov/headlines/y2006/10may_longrange.htm

    The following is an excerpt from the above link:

    The sun's "Great Conveyor Belt"
    And from the next link, it appears there was a failed solar magnetic field reversal.

    http://science.nasa.gov/headlines/y2006/15aug_backwards.htm

    Incidentally, Solar Activity in the 20th century was the highest in 8,000 years:

    http://cc.oulu.fi/~usoskin/personal/nature02995.pdf

    There was a Doubling of the Sun’s Coronal Magnetic Field in the last 100 years.

    http://www.nature.com/nature/journal.../399437a0.html
    And based on proxy data, the sun appears to vary cyclically.
    http://www.essc.psu.edu/essc_web/seminars/spring2006/Mar1/Bond et al 2001.pdf

    Has anyone reviewed the results from the Wilson H-K study, where astronomers examined 70 solar like stars, to determine if stars varied cyclically?
     
  2. jcsd
  3. Mar 25, 2007 #2

    Astronuc

    User Avatar

    Staff: Mentor

    Based on history, there could be another minimum coming up during the next 100-200 years, but it would not necessarily be as low as the Maunder minimum, although it could be. Don't forget the other recent minimums, Dalton, Spörer, Wolf, Oort, and perhaps hundreds before that.

    Apparently we are at some maximum at the moment.
    http://en.wikipedia.org/wiki/Maunder_minimum#Other_observations

    http://en.wikipedia.org/wiki/Sporer_Minimum

    http://en.wikipedia.org/wiki/Dalton_Minimum

    http://en.wikipedia.org/wiki/Cosmogenic#Natural
    (Always verify Wikipedia information with alternative and authenticated sources)

    A recent solar maximum occured in 2000, so we should be headed into a local minimum. We might have to wait 3-5 or more decades to know if the intensity of mixima are still increasing or starting to decrease.

    http://www.windows.ucar.edu/tour/link=/sun/solar_activity.html&edu=high

    http://www.windows.ucar.edu/tour/link=/sun/activity/solar_cycle.html&edu=high

    http://www.windows.ucar.edu/tour/link=/sun/images/butterfly_jpg_image.html&edu=high

    The good news is that there is a reduction in GCR in our neighborhood.

    http://hesperia.gsfc.nasa.gov/sspvse/oral/Ken_McCracken/wintergreen1.pdf

    I guess we just wait a see where things are going.

    http://sohowww.nascom.nasa.gov/pickoftheweek/ - March 25, 2007

    http://sohowww.nascom.nasa.gov/gallery/images.html
     
    Last edited: Mar 25, 2007
  4. Mar 25, 2007 #3
    Solar Tripping Point Vs Cycle Slow Down?

    Hi Astonuc,

    Why would the next solar Maunder like minimum be in 100 to 200 years, as opposed to the next cycle? Is there evidence of a tripping point change in the solar cycle, as opposed to a slowing down in the solar cycle? (i.e. A change from one type of solar cycle to another?)

    Solar cycle 23 appears to be phased shifted as compared to cycle 21 and 22. See the attached link to a daily solar observation site that also provides a record of solar activity.

    http://www.dxlc.com/solar/cyclcomp.html

    Also recent solar observations have noted an asymmetry between the solar hemispheres. If this was simply a slowing down in solar activity, would we expect the change would be the same for both hemispheres?

    http://sait.oat.ts.astro.it/MSAIt760405/PDF/2005MmSAI..76.1072Z.pdf

    From the above referenced paper:


    GCR Levels
    The reduction of galactic cosmic rays in the vicinity of the earth is due to the doubling of the solar large scale magnetic field. If the solar activity slows down and the length of solar cycles increases, the solar large scale magnetic field will decrease and GCR intensity will increase. GCR is also reduced by the geomagnetic field.
     
  5. Mar 25, 2007 #4

    Astronuc

    User Avatar

    Staff: Mentor

    We have only been doing a detailed study of the sun's energy generation system for about 50 years or so - there were no modern day plasma physicsist around in the 1600's - 1800's, so we don't really know the preceeding conditions leading to these minima. We certainly can see when they start happening, but that takes decades of observing the decreasing number of sunspots.

    The peak-to-peak period is about 200 years between maxima based on radiocarbon. So the sun could start a drop toward a new minimum, but we won't know for a while if it is a shallow (Oort or Dalton min) or deep (Maunder or Spörer). If the next minimum occurs on the same schedule as the previous, then perhaps we will know in 100 year how significant it will be - but we won't be around for it - but out grandchildren or great grandchildren will be.

    Then again, looking at the current solar maximum, it is greater than the one 1000 years ago, so perhaps the maximum could continue for the next cycle or so.

    I plan to contact some colleagues at NASA who model solar activity and GCR with respect to the conditions associated with decreasing solar activity, and I want to follow up on some of the other questions and links.
     
  6. Mar 26, 2007 #5
    how do spots or the lack of sun spots relate to energy out put and earth temps
    as I understand it, spots are cooler but avg total sun surface temps go up making for more heat
    or do we get our heat from the outer bits of the solar atmosphere or the surface
     
  7. Mar 26, 2007 #6

    Astronuc

    User Avatar

    Staff: Mentor

    That's what a lot of people would like to know. Looking at the spots - they represent a small fraction, ~ <1% of the projected area.

    In addition to the photoelectric spectrum, there is the interaction of the 'solar wind' and GCR which may (or may not) have a significant impact on the weather.

    Perhaps an answer would be found in correlating auroral activity (in addition to sunspots) with cold/hot cycles of the earth.

    I want to look into the "results from the Wilson H-K study, where astronomers examined 70 solar like stars, to determine if stars varied cyclically", which William mentioned. Ostensibly stars do vary cyclically like the sun, but perhaps with different fequencies and intensities. However, how would one observe starts where sunspots are not 'discernable'. I am wondering spectroscopically - which begs me to ask if the solar cycle has been correlated with changes in emission/absorption line intensities.
     
  8. Mar 27, 2007 #7
    Solar Cycle & Solar Variability

    The following is from a solar review article write by a solar research team. The article summarizes at a high level current solar research findings and understanding. It includes a list of basic questions that this solar research project hopes to answer.


    http://sdo.gsfc.nasa.gov/sdo_sdt_report.doc

    From page 4-5

    From page 21
     
  9. Mar 27, 2007 #8
    Recent Solar Variability and Planetary Temperature

    There is significant data and supporting analysis that has been published in the last five years to support the hypothesis that solar variability and geomagnetic field changes are the principal cause of past large scale climate changes. As this paper notes, however, the mechanism is more complicated than a simple linear relationship to number of sunspots. See figure 6 in the attached paper that shows there is close correlation between observed global temperature anomalies and the solar index "ak".

    I found this article also interesting as it notes the 20th century solar changes are very unusual.

    Paper by Georgieva, Bianchi, & Kirov “Once again about global warming and solar activity”

    http://sait.oat.ts.astro.it/MSAIt760405/PDF/2005MmSAI..76..969G.pdf

    From above linked paper

     
  10. Mar 30, 2007 #9
    Hypothesis, Doubling of Sun's Large Magnetic Field

    Attached below is a paper that provides a hypothesis for why the solar large scale magnetic field has more than doubled in the 20 th century.

    The following is an excerpt from the paper: "Evolution of the Sun's large-scale magnetic field since the Maunder minimum"

    http://www.nature.com/nature/journal/v408/n6811/abs/408445a0.html

     
  11. Apr 9, 2007 #10
    Sun is spotless. Implications?

    As can be seen in the attached link to a daily solar observatory, the sun is currently spotless. That link provides daily and monthly solar data. As can be seen in the table “Monthly Solar Data”, the solar magnetic cycle appears to be currently unstable, based on the monthly changes in the number of sun spots. (The number of sunspots is an indication of how the solar magnetic cycle is progressing.)

    Link to Daily and Monthly Solar Terrestrial Activity Data:

    http://www.dxlc.com/solar/

    The solar monthly sunspot number dropped to 4.9 in February 2006, which was a minimum for solar cycle 23. The monthly sunspot number then increased from the February, 2006 cycle 23 minimum of 4.9 to 30 in April 2006. It appears solar cycle 24 failed to start as the number of monthly sun spots dropped from 30 in April 2006, to 12 in July, 2006 and then increased to 21 November, 2006. The number of monthly sunspots dropped from 21 in November 2006 and was 4.8 for the month of March, 2007.
     
  12. Apr 20, 2007 #11
    What Causes the Solar Cycle?

    I am interested in what event precipitates a change in the solar cycle from normal cycle to Maunder like minimum. The following is what I have found concerning "What Causes the Solar Cycle?"

    From Jack Zirker's book "Journey from the Center of the Sun" Princeton Science Library. Zirker's book is a summary of recent solar observations and theories. There is a significant number of fundamental solar processes that are not understood.

    The sun is a magnetic star. The sun spots have very strong magnetic fields associated with them (around 3000 gauss, the earth's magnetic field is around 0.5 gauss.). The strong magnetic fields move to the sun's surface and are then removed as part of the solar cycle. As there is not sufficient time during the 11 year long solar cycle, to generate such strong magnetic fields, in the solar convection zone, the sun spot magnetic fields cannot be generated in the solar convection zone. The following is Zirker's description of the problem and the current theory as to where the strong solar magnetic field is generated.

    Based on this mechanism, a Maunder minimum could be triggered by the larger planets moving the solar core and radiative zone, separating it from the convection zone. The magnetic field then would build up in the radiative zone but not rise to the surface of the sun.

    Interesting super solar flares (X flares) have been observed during recent solar minimums. Very, very high stellar flares has been observed for other solar like stars (as part of the Wilson H-K and other similar studies where the objective is to study other stars to see how the stellar cycle varies.) when the star in question was during a minimum.

    I am also interested in the magnitude and periodicity of super solar flares as there is geological evidence of residual that could be cause by a super solar flare. The residual appears to coincide with geomagnetic field minimums and reversals
     
  13. Apr 29, 2007 #12

    Astronuc

    User Avatar

    Staff: Mentor

    NOAA ANNOUNCES NEXT SOLAR STORM CYCLE WILL LIKELY START NEXT MARCH
    http://www.noaanews.noaa.gov/stories2007/s2847.htm
     
  14. May 17, 2007 #13
    Maunder Minimum?

    A Maunder Minimum has predicted in the following paper based on solar observations in 2003, by the authers who used a physical solar model. (See link for details.)

    Comment:
    The sun is currently not following the expected solar cycle behaviour. The NASA solar cycle prediction group are planning to meet every 3 months to re-evaluate the cycle 24 prediction based on new data.

    http://adsabs.harvard.edu/abs/2003SPD....34.0603S

     
  15. May 20, 2007 #14
    More analysis supporting a Solar Cycle Change

    The following is a 2004 paper that predicts the sun is heading towards a Maunder Minimum based on an analysis of the paleo record of solar activity.

    http://adsabs.harvard.edu/abs/2004ApJ...605L..81B

     
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook

Have something to add?



Similar Discussions: Solar Cycle & Explanation for Recent Changes?
  1. Solar Cycle 24 (Replies: 3)

  2. Recent solar tornado (Replies: 3)

  3. Current Solar Cycle (Replies: 5)

Loading...