Posted on 11/28/2017 9:30:15 PM PST by Ernest_at_the_Beach
Solar minimum surprisingly constant
More than half a century of observation yields new discovery
NATIONAL INSTITUTES OF NATURAL SCIENCES
Using more than half a century of observations, Japanese astronomers have discovered that the microwaves coming from the Sun at the minimums of the past five solar cycles have been the same each time, despite large differences in the maximums of the cycles.
Solar microwave observation telescopes in 1957 (top left) and today (bottom left). Fluctuations observed during 60 years of solar microwave monitoring (top right) and the solar microwave spectrum at each solar minimum (bottom right). The background is full solar disk images taken by the X-ray telescope aboard the Hinode satellite. CREDIT NAOJ/Nagoya University/JAXA
In Japan, continuous four-frequency solar microwave observations (1, 2, 3.75 and 9.4 GHz) began in 1957 at the Toyokawa Branch of the Research Institute of Atmospherics, Nagoya University. In 1994 the telescopes were relocated to NAOJ Nobeyama Campus, where they have continued observations up to the present.
A research group led by Masumi Shimojo (Assistant Professor at NAOJ Chile Observatory), including members from Nagoya University, Kyoto University, and Ibaraki University, analyzed the more than 60 years of solar microwave data from these telescopes. They found that microwave intensities and spectra at the minimums of the latest five cycles were the same every time. In contrast, during the periods of maximum solar activity, both the intensity and spectrum varied from cycle to cycle.
Masumi Shimojo explains that,
“Other than sunspot observations, uniform long-term observations are rare in solar astronomy. It is very meaningful to discover a trend extending beyond a single solar cycle. This is an important step in understanding the creation and amplification of solar magnetic fields, which generate sunspots and other solar activity.”
The Sun goes through a cycle of active and quiet periods approximately once every 11 years. This “solar cycle” is often associated with the number of sunspots, but there are other types of solar activity as well. So simply counting the number of sunspots is insufficient to understand the solar activity conditions.
Microwaves are another indicator of solar activity. Microwaves have the advantage that, unlike sunspots, they can be observed on cloudy days. Also, monitoring multiple frequencies of microwaves makes it possible to calculate the relative strength at each frequency (this is called the spectrum).
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The paper: Variation of the Solar Microwave Spectrum in the Last Half Century
http://iopscience.iop.org/article/10.3847/1538-4357/aa8c75/meta
Abstract:
The total solar fluxes at 1, 2, 3.75, and 9.4 GHz were observed continuously from 1957 to 1994 at Toyokawa, Japan, and from 1994 until now at Nobeyama, Japan, with the current Nobeyama Radio Polarimeters. We examined the multi-frequency and long-term data sets, and found that not only the microwave solar flux but also its monthly standard deviation indicate the long-term variation of solar activity. Furthermore, we found that the microwave spectra at the solar minima of Cycles 20–24 agree with each other. These results show that the average atmospheric structure above the upper chromosphere in the quiet-Sun has not varied for half a century, and suggest that the energy input for atmospheric heating from the sub-photosphere to the corona have not changed in the quiet-Sun despite significantly differing strengths of magnetic activity in the last five solar cycles.
Interesting
Interesting discussion as to whether this is a “NEW” fact in the comments.
Wow. The universe is self-regulating. Astounding.
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Paul Penrose says:
The article did not claim the Japanese results were “new” or “surprising”. Neither did I. So that part of your argument is a straw man. All I said is that this data is useful and worth reporting, even if it only adds to all the other data we have. Stop projecting your own biases onto me.
OK, I just noticed the article subheading which claimed the results are new. I didn’t read that before (I usually ignore the subheadings). From what I know, this is not really new, but I didn’t read the entire paper to see if there really was anything new in it.
How does this relate to other data showing that the Sun's magnetic field is in decline:
OK...cancel that question...seems the Suns magnetic field has perked up:
The current solar cycle 24 reached its probable peak in 2014, with a yearly averaged sunspot number of 79, compared with maximum numbers ranging from 106 to 190 for the previous five cycles of the space age.1 The low amplitude of the current cycle, and the unusually quiet nature of the sunspot minimum of 2008–2009, have led to speculation that the Sun may be entering a prolonged period of extremely low activity resembling the Maunder Minimum of 1645–1715, when sunspots almost disappeared (Eddy 1976; Barnard et al. 2011; Lockwood et al. 2011). Thus, it was surprising when the Sun's large-scale magnetic field underwent a sudden rejuvenation toward the end of 2014.
http://iopscience.iop.org/article/10.1088/0004-637X/809/2/113
THE RECENT REJUVENATION OF THE SUN'S LARGE-SCALE MAGNETIC FIELD: A CLUE FOR UNDERSTANDING PAST AND FUTURE SUNSPOT CYCLES
N. R. Sheeley Jr. and Y.-M. Wang
Published 2015 August 14 • © 2015. The American Astronomical Society. All rights reserved. The Astrophysical Journal, Volume 809, Number 2
If this is the solar minimum where is the cooler weather? I’m not a globull warming acolyte but I do wonder what happened to the colder and wetter fall and winter weather of my younger years some 40 years or more ago? We used to have consistent wet and cool falls. What Dad called tree planting weather. Days on end of overcast skies with steady drizzle and temperatures never over the 50s in the daytime.
Last fall and this one it has been blue bird days, warm and NO rain. We had almost no rain at all for the entire winter last year and only one brief period of cold weather in December and January.
When I was a kid we sledded often in winter. We bundled up for foot ball games in late September. Not now and not for many years.
What area of the country are you living in. I have noticed similar trends over 60 years in the mid-Atlantic area, especially regarding temperature.
Arkansas river valley near fort smith
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