NASA: Deciphering the Mysterious Math of the Solar Wind

Posted: February 22, 2013 by Rog Tallbloke in Astrophysics, cosmic rays, Geomagnetism, Solar physics, solar system dynamics, Tides
Tags: ,

From Science Daily:

A constant stream of particles and electromagnetic waves streams from the sun toward Earth, which is surrounded by a protective bubble called the magnetosphere. A scientist at NASA Goddard has recently devised, for the first time, a set of equations that can help describe waves in the solar wind known as Alfven waves. (Credit: European Space Agency)

A constant stream of particles and electromagnetic waves streams from the sun toward Earth, which is surrounded by a protective bubble called the magnetosphere. A scientist at NASA Goddard has recently devised, for the first time, a set of equations that can help describe waves in the solar wind known as Alfven waves. (Credit: European Space Agency)

Feb. 21, 2013 — Many areas of scientific research — Earth’s weather, ocean currents, the outpouring of magnetic energy from the sun — require mapping out the large scale features of a complex system and its intricate details simultaneously.

Describing such systems accurately, relies on numerous kinds of input, beginning with observations of the system, incorporating mathematical equations to approximate those observations, running computer simulations to attempt to replicate observations, and cycling back through all the steps to refine and improve the models until they jibe with what’s seen. Ultimately, the models successfully help scientists describe, and even predict, how the system works.

Understanding the sun and how the material and energy it sends out affects the solar system is crucial, since it creates a dynamic space weather system that can disrupt human technology in space such as communications and global positioning system (GPS) satellites.

However, the sun and its prodigious stream of solar particles, called the solar wind, can be particularly tricky to model since as the material streams to the outer reaches of the solar system it carries along its own magnetic fields. The magnetic forces add an extra set of laws to incorporate when trying to determine what’s governing the movement. Indeed, until now, equations for certain aspects of the solar wind have never been successfully devised to correlate to the observations seen by instruments in space. Now, for the first time, a scientist at NASA’s Goddard Space Flight Center in Greenbelt, Md., has created a set of the necessary equations, published in Physical Review Letters on Dec. 4, 2012.

“Since the 1970s, scientists have known that movement in the solar wind often has the characteristics of a kind of wave called an Alfvén wave,” says Aaron Roberts, a space scientist at Goddard. “Imagine you have a jump rope and you wiggle one end so that it sends waves down the rope. Alfvén waves are similar, but the moving rope is a magnetic field line itself.”

Read the rest here.

h/t to oldbrew on Suggestions 3

Comments
  1. oldbrew says:

    More info about solar wind etc. here…

    http://helios.gsfc.nasa.gov/sw.html

    How does the solar wind affect Earth?

    http://www.sciencedaily.com/releases/2009/09/090910091337.htm

    “It’s like something else is heating the atmosphere besides the sun. This discovery is like finding it got hotter when the sun went down”

  2. Greg Goodman says:

    TB, you seem to forgotten how to spell maths ;)

  3. Paul Vaughan says:

    From oldbrew’s 2nd link:

    “”Heejeong separated the data into when the solar wind was fluctuating a lot and when it was fluctuating a little [...]“”

    Refreshing.

    Search terms for gathering related background:
    conditional variance
    cyclic heteroskedasticity
    volatility clustering
    burst bunching

    Careful sorting empowers us to break free of the paralyzing grip of statistical paradox, which is caused by blind pooling across important but ignored gradients & categories. With careful sorting, central limit theorem empowers us to see the shifting attractor of extremes, even in noisy & nonlinear contexts.

  4. Gerry says:

    Rog,
    Science Daily didn’t even provide the name of the author or the title of the paper! Here’s what I found:

    http://prl.aps.org/abstract/PRL/v109/i23/e231102

    Construction of Solar-Wind-Like Magnetic Fields

    Download: PDF (248 kB) Buy this article Export: BibTeX or EndNote (RIS)

    D. Aaron Roberts
    NASA Goddard Space Flight Center, Code 672, Greenbelt, Maryland 20771, USA

    Received 5 July 2012; published 4 December 2012

    Fluctuations in the solar wind fields tend to not only have velocities and magnetic fields correlated in the sense consistent with Alfvén waves traveling from the Sun, but they also have the magnitude of the magnetic field remarkably constant despite their being broadband. This Letter provides, for the first time, a method for constructing fields with nearly constant magnetic field, zero divergence, and with any specified power spectrum for the fluctuations of the components of the field. Every wave vector, k, is associated with two polarizations; the relative phases of these can be chosen to minimize the variance of the field magnitude while retaining the “random” character of the fields. The method is applied to a case with one spatial coordinate that demonstrates good agreement with observed time series and power spectra of the magnetic field in the solar wind, as well as with the distribution of the angles of rapid changes (“discontinuities”), thus showing a deep connection between two seemingly unrelated issues. It is suggested that using this construction will lead to more realistic simulations of solar wind turbulence and of the propagation of energetic particles.

    Published by the American Physical Society

    URL:http://link.aps.org/doi/10.1103/PhysRevLett.109.231102
    DOI:10.1103/PhysRevLett.109.231102
    PACS:96.50.Ci, 96.50.Bh, 96.50.Ry, 96.50.Tf
    ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
    Unfortunately, the PDF seems to be behind a paywall. !!!!????!!!!
    This research was funded by U.S. taxpayers, who are expected to pay again just to be able to see the equations online. Perhaps they don’t want AGW skeptics to see this.

  5. tallbloke says:

    Hi Gerry,
    They did link it at the foot of the page. But the paywall is annoying. I’ll grab a copy at work on Monday.

  6. Gerry says:

    Thanks, Rog. A sentence that stands out: “This Letter provides, for the first time, a method for constructing fields with nearly constant magnetic field, zero divergence, and with any specified power spectrum for the fluctuations of the components of the field.”

    Note – not constant, but “nearly constant.” I’m convinced that the long-term deviations from constancy of the interplanetary magnetic field (IMF B) are caused by the mysterious solar Livingston & Penn Effect. Both the IMF B and the L&P effect appear to be correlated with long-period solar cycle activity. Currently the smoothed value of the IMF seems to be in a state of decline, as it may have also previously been in the late 19th century (and the late 17th century!). See slide 10, Conclusions chart 1 of

    http://leif.org/research/Coupling-Function-AMS93.pdf

    Much as you and others may dislike cranky old Leif, I give him a lot of credit for promptly putting the results of his research in the public domain. His coupling function paper seems to provide strong evidence for a firm link between the IMF and the L&P Effect, though Leif himself has not yet suggested this (probably because he has not been successful in evaluating the coupling function as far back in time as the Maunder Minimum).:) Just want to be on record as being the first to come right out and suggest the connection. I’m still working on a hopefully near-future post on this for you.

    -Gerry Pease

  7. tallbloke says:

    Gerry, I’ve exchanged around a hundred email with ‘cranky old Leif’ today, and at least three of the responses were scientifically useful to me. ;)

    Look forward to your post.

  8. Paul Vaughan says:

    “[...] as well as with the distribution of the angles of rapid changes (“discontinuities”), thus showing a deep connection between two seemingly unrelated issues.”

    It’s concerning that their intuition suggested “unrelated”. This clarifies right out in the open that they don’t have a solid conceptual handle on aggregation fundamentals, but at least they’re working on awakening.