Were We There Yet ? Solar Minimum

[VK2ZRH]

By now, anyone with even a modest interest in progress of the solar cycle knows that the current period of solar minimum is the "lowest and longest" since 1913.

The run of monthly sunspot numbers for the past year (indeed, 2.5 years) has led the solar science world on slow waltz to Armageddon (or so it seems), not to mention DXers, solar bloggers, climate change skeptics and other interested parties.

Taking the monthly smoothed sunspot numbers from January 2007 to December 2008, you can see where they took a dip, rose again after the dip - only to plunge relentlessly downward . . . no less than three times ! See Graph 1 below.

Graph 1: Smoothed monthly sunspot numbers, Jan 2007 through December 2008. (Source: IPS)

Projections for the date (month) of the solar cycle minimum, from the various space weather agencies, have been pushed out time after time since 2007. The latest - from our own IPS Radio and Space Services - now has it as April 2010

See: http://www.ips.gov.au/Solar/1/6

Having prepared and given a series of presentations on the current solar cycle over the past 12 months, I decided to check the "3-monthly running mean" (a smoothing technique - no 'magic' to it) of sunspot numbers for the past year to see how things were going. The running mean is a way of showing trends in variable data.

The "gold standard" for sunspot number data is the Solar Influences Data Analysis Center (SIDC) in Belgium (http://www.sidc.be). SIDC issues a series of "relative sunspot numbers" (R), derived from data sent to them by 60-or-so observatories across the world. The numbers given by Tad Cook K7RA in his week ARRL Propagation Bulletin are generally from the US's Space Weather Prediction Center (SWPC) - one of the contributors to the SIDC data set. Our own IPS Radio and Space Services also issues monthly sunspot numbers, which closely track those issued by SIDC.

So I've graphed the 3-monthly running means for the period June 2008 through June 2009, for these three sources of sunspot numbers - and the results are intriguing, indeed. From the figure below, it appears we have two successive minima, six or seven months apart - one in August last year, the second either in February (SIDC and IPS figures) or March (SWPC figures).

Graph 2. 3-month running means for sunspot numbers, June 2008 through June 2009. (Sources: SIDC, IPS, SWPC)

The one marked RI is the SIDC data; IPS is the IPS (Aust) data; and SWO is the SWPC (USA) data. The 3-month running means are marked with blue spots. Looking at the months around the "dips" in the blue spots, I've place a red bar, which is the mean of the three months across the dips. The vertical scale on each is the smoothed sunspot number running mean.

The SIDC graph (RI) shows the February minima to be lowest (1.1 compared to 1.3 for August 2008).

The IPS graph (IPS) shows the two minima to be the same, although the February figure has been round up (from 1.17 to 1.2), because we can only work to one decimal place.

The SWPC graph (SWO) shows the August 2008 minima to be lowest (1.6 compared with 1.8 for March 2009).

Were we there, yet

Maybe. Remember, it looked like we were there several times before

Perhaps we'll know - for sure - sometime in the last quarter of 2009. Or not.

Posted in the interests of intrigue.

73, Roger Harrison VK2ZRH

[VK4CP]

Roger, very interesting.

To be absolutely correct, isn't a complete "solar cycle" actually 22 years (nominal)?
Where the sun's magnetic poles flip every 11 years, and to get back to where it was, it would involve two of what is commonly referred to as a "cycle".

If this is the case, and given the fact that we saw a double-peak last time, would it be reasonable enough to consider this double-dip as an inverted mirror image to what transpired in the first half of this 22-year cycle?

[VK2ZRH]

Hi Adam,

To be absolutely correct, isn't a complete "solar cycle" actually 22 years (nominal)?

By common scientific agreement since the 19th century, the solar cycle is defined by the rise and fall of sunspot activity. A new cycle begins at solar minimum, proceeds through the maximum and ends at the succeeding minimum. This is the convention adopted by solar scientists in the 19th century, and retained ever since.

The month of the solar minima is determined from the 12-month smoothed sunspot numbers, which only falls out of the calculations about 6 months after the 'fact' (because of the smoothing method).

The solar magnetic cycle, wherein the Sun's polar field reverses polarity every approx. 22 years, is a related but only a relatively recently detected phenomenon. The reversal happens around the time of solar cycle maximum (but not quite "in sync").

Double-humped peaks are not new. Cycle 18 (1947-50) was a double-humper, as were all the cycles from number 20 (1969-70) onwards. Take a look at the long-run record of solar cycles here: http://www.sidc.be/news/113/welcome.html

. . . would it be reasonable enough to consider this double-dip as an inverted mirror image to what transpired in the first half of this 22-year cycle?

No. Slice and dice the chicken entrails however you like, they're still . . . chicken entrails.

"Double-dip" mimina, as it turns out, aren't rare, either. Take a look at the minima which began Cycle 19 (with a smoothed peak SSN of 201.3, the largest on record) - which the Sun prepared earlier. I've plotted it in Graph 3 below.

Graph 3. The minima that sparked Cycle 19 (3-month running means of monthly sunspot numbers). Source: SIDC.

3-Month Running Means Graphed 1953-54.gif (9.13 KiB) Viewed 1171 times

This graph is best compared with the top one in Graph 2 above.

Features of Graph 3 to note include: (a) the much wider range in monthly SN values compared with the current minima; (b) the pair of minima (red bars) only four months apart (compared with 6-7 months); (c) the red bullseye marking the 12-month smoothed sunspot minima: April 1954 (smoothed SN of 3.4).

Posted in the interests of maintaining interest in the solar cycle.

73, Roger Harrison VK2ZRH

[VK4CP]

By common scientific agreement since the 19th century, the solar cycle is defined by the rise and fall of sunspot activity. A new cycle begins at solar minimum, proceeds through the maximum and ends at the succeeding minimum.

Well, ok, but in AC theory I still reckon that would only be half a cycle.
Scientists can't be all that bad though... they made De Loreans, flux capacitors, and time travel popular.

[VK2GOM]

...but the 1.21 gigawatts (of course pron. 'Jig-a-watts') power requirement for the flux capacitor is sadly beyond capabilities of a panel on the govt's solar rebate scheme...

And I'm going to go into Dick Smith one day and ask for a Flux Capacitor, possibly on April 1st, just for fun. If I can get them to at least look for it on their sales computer

And on a more serious note again, great data Roger, and interesting reading. Patiently waiting for the solar condx to perk up...

73 - Rob VK2GOM

[VK2DAG]

I like to torment 419 email scammers. And I always asked for a "flux capacitor". And they always seem able to supply one for a price of course - just send your Western Union money order to .....

Join us at http://www.419eater.com/ and go into the forum. You WILL laugh yourself sick, no I am serious like painful laughing. Every time I see someone with a loaf of bread on his head I just ROFL. ENJOY

[VK2GOM]

Yes, that site is great... lots of entertainment. I found it a while back - and loved the Professor of Stock Car Economics, the herd of goats, and 'Tom Jones' with his 'Whats new pussycat' letter sign-offs

The best though would have to be the guy who was on his way to the Western Union place to mail the money and faked his own death in a pedestrian accident on his mobile phone!

Plenty of fun there until the solar conditions pick up HI.

73 - Rob VK2GOM

[VK2ZRH]

It seems, maybe, we weren't there, yet

The latest ARRL Propagation Bulletin from Tad Cook K7RA tells us that, to 21 August, we had 42 spotless days in a row.
See viewtopic.php?f=43&t=8687

That puts this period in the top 10 of spotless periods since 1849.

Mind you, over September-October 1996 (pre-Cycle 23), we had a run of 37 days. See http://www.ips.gov.au/Educational/2/2/7

So far, during this trough between solar cycles, we've seen a collection of spotless days in the 20s and 30s, all studiously recorded here: http://users.telenet.be/j.janssens/Spot ... tless.html

So, this run of 42 spotless days (which may grow . . .) will pull down the smoothed sunspot number for July and August. Even so, a rise in the number of spots over the next 6 weeks will pull it up again.

All the while, the total of spotless days accumulate relentlessly. Owen VK1OD will have to update his "Spotless days around solar cycle transition" web page. [http://www.vk1od.net/propagation/solar/spotless.htm]

That's the trouble with examining chicken entrails, when you think you're come to the end, you find there's yet another length there.

Posted in the interests of maintaining interest.

73, Roger Harrison VK2ZRH

[vk6zry]

Spotless days since 2004 was 696 days, and 485 days is a normal period.
Coronal holes send out protons in a stream, with luck towards Earth, they haven't disappeared as yet.
The solar wind has waxed and waned buffeting the planet causing Auroras and providing good HF paths.

The Sporadic E season in the northern hemisphere has been quite good with trans Atlantic paths so far, sadly no TEP for Hams.

So all in all it's been fair, sadly however the regular openings down-under during winter seem to have been absent.
My HF has been down a little in recent days, but I hope it will pick up, I still spot 17,800KM stations using 1 watt.

But I do miss 50MHZ, let us hope the R1 stations in Russia and China never disappear as our fav beacons.

Such a long period of little or no sunspots is really unusual, forget trying to set a date for a minima, it doesn't
mean anything to regular hams.

We just adapt and get on with life, counting the days is really fruitless. Change your mode, find some other way
to make contacts in radio, phone contacts are a relic of the past.

[vk4abw]

Spotless days since 2004 was 696 days, and 485 days is a normal period.
Coronal holes send out protons in a stream, with luck towards Earth, they haven't disappeared as yet.
The solar wind has waxed and waned buffeting the planet causing Auroras and providing good HF paths.

The Sporadic E season in the northern hemisphere has been quite good with trans Atlantic paths so far, sadly no TEP for Hams.

no TEP your kidding me.
The 49 tv has been weak for some time now but it is still there. The JA beacons have been spotted this year and a few openings to JA have occurred during the WSSP and SSSP's this year and last, all with a SFI around 65 - 68.
Just because the numbers are down doesn't mean the TEP stops.

[VK2ZRH]

The latest ARRL Propagation Bulletin No.35 (at: viewtopic.php?f=43&t=8700) records 48 spotless days up to 26 August.

From the Solar Influences Data Center, it seems we may be able to add another two days - so, totalling 50 spotless days in a row.

As the Pope asked of Michalengelo when painting the Sistine Chapel: "When will you make an end?"

There were 54 spotless days between 16 Feb and 18 April 1879, the third-longest period since 1849 (when reliable continuous records begin).

Is this the way Cycle 23 is to end - not with a bang, but a whimper ? [Apologies to T.S. Eliot]

73, Roger Harrison VK2ZRH

[VK2ZRH]

OK - make that 52 spotless days in a row, now.

The SIDC daily bulletin for 30 August gave that day's estimated sunspot number as 0, based on 10 stations' observations.

The same bulletin gave the estimated sunspot number for 29 August as 0, based on 21 stations' observations.

This reminds me of a quote from the Goon Shows:

Henry Crun:"Oh dear, Min."
Spotty Minny Banister: "What . . . what is it, Henry?"
Henry Crun: "The wick in the engine's gone out !"

Anyone prepared to take a punt on which day the next spot appears ? C'mon guys - this is a great Australian sport

Name a day. No squibbing by saying "it'll be between this date and that date".

73, Roger Harrison VK2ZRH

[VK3BJM]

Well, while we're coughing up quotes... From "the Fireball Of Milton Street", in which it is discovered that the sun is on fire, and Seagoon & Co build a wooden rocket in order to put the fire out. In the concluding moments, just prior to lift-off:

Seagoon: Press the sulphur and light the old wick there. 5, 4, 3, 2, 1 -

Grams: [Explosion]

Grytpype: Oh dear, oh dear. After all that work. It's sad, Mor-I-arty, it's sad. However, let's count the money. 10, 20, 30... [both giggle evilly]

Moriarty: Oh dear, those poor fools.

Grytpype: Yes.

Moriarty: A wooden rocket, a wooden rocket! I ask you! Trying to put out the fire on the sun!

Grytpype: Yes.

Moriarty: They deserved to die, didn't they?

Grytpype: Yes they did, Mor-I-arty.

Moriarty: Oh, 25, 26 million, 28...

Grytpype: Moriarty, hasn't it gone dark?

Seagoon has succeeded at last?

How about Friday 4/9/09? Bidding's got to start somewhere...

73,
Barry
VK3BJM

[vk4abw]

I've counted the chickens on the roof twice,
checked the weather gauge once,
and flipped a coin....
25th September 2009

[VK4EKA]

I guess by now you are talking about the spot after 1025 that turned up on 31st August.
Perhaps Barry is right with 4th Sept.
That would be a change because 1025 is likely to still be visible, two spots at the same time?