The sun sure is quiet in the high energy spectrum

[Michael Mozina]

I've been studying high energy solar satellite imagery since the Yohkoh satellite program over twenty five years ago. In all that time, I can't recall the sun ever being so quiet in the higher energy wavelengths over such an extended period of time.

I realize that we're not at the peak of the solar cycle yet, but we're also not at the bottom of that cycle either. Typically there would be a lot more activity in the x-ray and gamma ray spectrum, with several active areas in both the northern and southern hemisphere, but that's just not happening in recent years. It seems to me like there's been a steady decline in higher energy wavelength activity over the past few decades. The lack of sunspots is directly related to the lack of higher energy active regions.

https://wattsupwiththat.com/2013/12/13/ ... eak-cycle/


This decrease in higher energy output from the sun is verified by changes that we observe in sunspot activity over the past several decades as well. It looks as though the sun's higher energy activity peaked in the 1960's and it's been steadily declining since then. Sunspot activity still shows variability in energy output that is consistent with the sun's solar cycles as we would expect, but the last few solar peaks have produced significantly fewer sunspots and fewer corresponding active regions. Based on recorded sunspot activity the sun is more quiet than it's been in the past 150 years.

That observation would suggest that the sun's overall energy output is much more variable over time than most mainstream models suggest. it also tends to lend credence to the notion that at least some of the sun's energy is externally driven rather than internally driven.

[GaryN]

I have been looking for figures for solar UV/EUV output levels measured from orbit, preferably geostationary, but have been unable to find such data. UV levels at the surface have increased considerably over the last 30 years, attributed to ozone layer depletion. If there has been an increase of incoming solar UV/EUV radiation though then the proffered global warming due to carbon emissions might be explained by increase in incoming UV/EUV resulting in increased infrared generation in the atmosphere by the UV/EUV interacting with certain atmospheric molecules, some of which emit in the IR for up to 5 minutes when struck by a single UV photon. Just a thought.

[seasmith]

1 nanometr-10 angstoms
Since solar radiations are normally measured by sampling ion groups which emit certain wave bands of the spectrum that they are looking for, when heated. The temps for producing UV and EUV you are looking for seems to be primarily from coronal flare and ejection type events.
Maybe x-ray and g-ray have more effect on earth climate, but we don't have the satellites to detect and quantify that high up-spectrum ?

SDO scientists, for example, chose 10 different wavelengths to observe for its Atmospheric Imaging Assembly (AIA) instrument. Each wavelength is largely based on a single, or perhaps two types of ions — though slightly longer and shorter wavelengths produced by other ions are also invariably part of the picture. Each wavelength was chosen to highlight a particular part of the sun's atmosphere.

From the sun's surface on out, the wavelengths SDO observes, measured in angstroms, are:

4500: Showing the sun's surface or photosphere.
1700: Shows surface of the sun, as well as a layer of the sun's atmosphere called the chromosphere, which lies just above the photosphere and is where the temperature begins rising.
1600: Shows a mixture between the upper photosphere and what's called the transition region, a region between the chromosphere and the upper most layer of the sun's atmosphere called the corona. The transition region is where the temperature rapidly rises.
304: This light is emitted from the chromosphere and transition region.
171: This wavelength shows the sun's atmosphere, or corona, when it's quiet. It also shows giant magnetic arcs known as coronal loops.
193: Shows a slightly hotter region of the corona, and also the much hotter material of a solar flare.
211: This wavelength shows hotter, magnetically active regions in the sun's corona.
335: This wavelength also shows hotter, magnetically active regions in the corona.
94: This highlights regions of the corona during a solar flare.
131: The hottest material in a flare.

https://svs.gsfc.nasa.gov/cgi-bin/details.cgi?aid=11071

[Michael Mozina]

https://sdo.gsfc.nasa.gov/assets/img/la ... 4_0131.mp4

There isn't even a single large active region that is visible on our side of the sun at this point, and this is the new "normal", it's not even unusual anymore. This cycle seems very different from every solar cycle that I've seen during my lifetime. The sun's outer atmosphere is just not nearly as active as it's been in the past.

[seasmith]

GaryN » Thu Jan 17, 2019 2:32 pm
I have been looking for figures for solar UV/EUV output levels measured from orbit, preferably geostationary, ...

GOES sat EUV, XUV, X-ray data 1986-2004, but following links for more recent data sets was met with message that NOAA has capered off to Party in Puerto Rico for the 20% govt. 'shut-down".


http://www.spacewx.com/pdf/SET_TR2006_002.pdf
https://www.goes-r.gov/conferences/AMS% ... S_2017.pdf

[GaryN]

Thanks seasmith. I have some issues with the GOES series of satellites, which orbit within the outer Van Allen belt, and how they measure and interpret the UV measurements. I won't go into that in this thread. It seems from the value of UV at the GOES altitude that any variations in levels would have very little effect on the total solar irradiance measured at the ground, but one thing I would like to see as far as total solar irradiance in concerned is the use from those high orbits of the same instrument that has been used from lower elevations. I don't think such an experiment has ever been performed.

Accurate solar “constant” determination by cavity pyrheliometers
https://www.researchgate.net/publicatio ... eliometers

[neilwilkes]

https://sdo.gsfc.nasa.gov/assets/img/la ... 4_0131.mp4

There isn't even a single large active region that is visible on our side of the sun at this point, and this is the new "normal", it's not even unusual anymore. This cycle seems very different from every solar cycle that I've seen during my lifetime. The sun's outer atmosphere is just not nearly as active as it's been in the past.

And the next cycle is set to be even less active as we march on towards a Grand Minimum.
By 2040 things are going to be very bad.