Data from NASA’s Solar Dynamics Observatory offer clues about sun’s coronal irradiance

Posted: July 18, 2017 by oldbrew in Astrophysics, Measurement, research, Solar physics, solar system dynamics
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Credit: NASA

Extreme ultraviolet radiation (EUV) is perhaps an aspect of solar activity that gets less attention than it should. The authors make the interesting point in their introduction to the research article that ‘Although the total solar irradiance at Earth varies very little, the relative variance in the EUV is as large as the mean irradiance. This EUV light interacts with Earth’s thermosphere and stratosphere and may affect climate in a “top-down” process in regions such as northern Europe’.

A pair of researchers with Aberystwyth University in the U.K. has used data from NASA’s Solar Dynamics Observatory to learn more about how the sun’s corona behaves over differing stages of its 11-year cycle, reports Bob Yirka at

In their paper published on the open access site Science Advances, Huw Morgan and Youra Taroyan describe attributes of the sun they observed over time and what they discovered about the “quiet corona” and its possible impact on us back here on Earth.

As the researchers note, most research to date regarding the sun’s corona has covered relatively small datasets, which provides only a limited view of what happens with the sun over longer periods of time—specifically, over the course of an entire coronal cycle.

But now, thanks to NASA’s Solar Dynamics Observatory, the pair were able to look at data that covered the time between 2010 and 2017, which covers a large portion of one cycle.

Scientists have known for some time that the corona experiences solar cycles of approximately 11 years—solar flare activity grows and ebbs over the course of a single cycle. But until now, there has been no way to measure what happens over the course of a single cycle to explain the changes that occur.

Continued here.
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Research article: Global conditions in the solar corona from 2010 to 2017
Authors: Huw Morgan and Youra Taroyan
Science Advances 14 Jul 2017

  1. Jim says:

    Interesting. But, they miss one thing. The chrono holes are not polar. Or rather, just polar. And they finally recognize that the star is a variable star, variable output star! And like a fire, it varies in temperature of output, now, why?

  2. oldbrew says:

    Jim – see Fig. 7 in their paper but note what they say: ‘The short-band EVE measurements unfortunately end in May 2014’.

    Obviously the full reason(s) for any solar variability are still up for study and discussion, but saying that ‘the relative variance in the EUV is as large as the mean irradiance’ is quite telling IMO.

  3. richard verney says:

    I have been pointing this out for years.

    It is not only in the atmosphere. Absorption of solar irradiance by the oceans (ie., the depth at which irradiance is absorbed) is wavelength dependent. And of course, on this water world of ours, the oceans are the key storers of energy, and the key drivers of energy redistribution.

    In a 3D system, a watt is not necessarily just a watt. Not all watts are necessarily equal. Precisely where a watt is absorbed could be material, especially given the varying speeds at which the 3D components of the atmosphere and the 3D components are mixed and/or distributed.

  4. oldbrew says:

    NASA’s Van Allen Probes mission analyzing eerie whistling sounds coming from space

    [includes 30 second sound sample]