Solar Cycle 24 Main Discussion IX

[lsvalgaard]

Dec 19, 2010 16:29:37 GMT af4ex said:

Bob k6tr
> It' s not
> It 's measured

I know that SFI starts off with a series of measurements of 10.7cm radiation from a Dic-ke radiometer, or such.
[edit: Had to insert a hyphen. Proboard won't allow any appearance of salty language and replaces it with "thingy"]

But aren't those measurements smoothed a bit to produce the final SFI report?

No.

[lsvalgaard]

Dec 19, 2010 19:13:46 GMT af4ex said:

jimcripwell
> How unusual is it to have a spotless sun at this stage of SC24?

I recall that Leif posted some links recently with statistics on that issue.

Here's another one that I found awhile ago that addresses the spotless statistics over history.
users.telenet.be/j.janssens/Spotless/Spotless.html

I'm no expert, having just started studying solar activity myself this year. My answer to your question would be to look at the current Sunspot Number, which divided by 15 gives the approximate number of spots visible. It's been hovering between 10 and 25 all year and is supposed to be around 45 now according to the NOAA projection (below).

So it's about half the expected value, which I guess you could call 'unusual'.
:-|

I've said many times that the NOAA prediction of 90 is too high. It should be more like 70. So subtract some 20 from the 'official' curve.

[af4ex]

@leif
> So subtract some 20 from the 'official' curve.

Now everything seems to be 'on track'.

So, going back to Jim's original question, how 'unusual' is this current spotless sun with respect to this curve?

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[lsvalgaard]

Dec 20, 2010 12:10:51 GMT af4ex said:

@leif
> So subtract some 20 from the 'official' curve.

Now everything seems to be 'on track'.

So, going back to Jim's original question, how 'unusual' is this current spotless sun with respect to this curve?

Cycle 14 started sometime in 1901, spotless days occurred in Sept. and Dec. 1903, Jan. 1904, Jan., May, Jul., 1905, and even Oct. 1906 [5 years into the cycle].

[tsh]

Shouldn't be too hard to make an estimate of mean and standard deviation of SSN, extrapolate to the daily spot number variance, and check for a cut-off at 11. Doesn't seem unusual at all to me, or at least no more unusual than a day with 6 spots.

[af4ex]

tsh
> ... no more unusual than a day with 6 spots.

That would correspond with an SSN of 90, which we're not likely to see this cycle, according to Leif's revised curve. So would be very unusual indeed.

[tsh]

Dec 20, 2010 14:34:33 GMT af4ex said:

tsh
> ... no more unusual than a day with 6 spots.

That would correspond with an SSN of 90, which we're not likely to see this cycle, according to Leif's revised curve. So would be very unusual indeed.

You are maybe confusing the single day with the 13 month smooth. We've not seen 6 yet, but here are two which come close (since they both have ex-spots which have just faded):
www.solen.info/solar/old_reports/2010/october/20101026.html
www.solen.info/solar/old_reports/2010/november/20101114.html

[af4ex]

tsh
> You are maybe confusing the single day with the 13 month smooth.

Yes, I was thinking of the smoothed count. I agree, the instantaneous count would be more likely.

[af4ex]

af4ex
>> But aren't those [SFI] measurements smoothed a bit
>> to produce the final SFI report?

@leif
> No.

So that means the observed SFI up and down ramps were not artifacts of observation, caused by filtering, as I presumed. Then perhaps they were artifacts of some solar process, unknown to me, related to microwave generation.


Maybe microwaves generated by gyrating electrons or other charged particles spiraling through some magnetic loops nearby? (Since AR1131 was rotated out of Earth view.)

At the other end of the EMR spectrum I note that the Xray background is ramping down, slowly and smoothly (see below). Recall that I commented when the background ramped up a few weeks ago, when the glow of some very bright Xray regions on the far side became visible in the GOES imagery.

To this uninformed observer it seems as if smooth global forces (inside the Sun) are at play, retarding solar activity.

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[twawki]

So it is quite unusual because it is not the norm and we have to go back 10 cycles to see it happening sporadically throughout the cycle

Dec 20, 2010 12:53:02 GMT lsvalgaard said:

Dec 20, 2010 12:10:51 GMT af4ex said:

@leif
> So subtract some 20 from the 'official' curve.

Now everything seems to be 'on track'.

So, going back to Jim's original question, how 'unusual' is this current spotless sun with respect to this curve?

Cycle 14 started sometime in 1901, spotless days occurred in Sept. and Dec. 1903, Jan. 1904, Jan., May, Jul., 1905, and even Oct. 1906 [5 years into the cycle].

[randwick]

.Early next year we should reach the inflection point of the curve .
maybe later if it's a low max , as seems to be the case

[twawki]

Dec 21, 2010 7:04:55 GMT randwick said:

.Early next year we should reach the inflection point of the curve .
maybe later if it's a low max , as seems to be the case

Well more and more are sayng 2013-2015 is when solar maximum will occur

[lku]

One ot two spotless days at this point in the cycle is nothing abnormal.

But we`re at 4 days now, and 5 looks a certainty. Will start to get intersting if we get a few more spotless days and flux drops to low 70s

[af4ex]

Old AR1131, the powerhouse with the monster sunspot and constantly bright 17Ghz microwave beacon, is approaching the STEREO blindspot on the far side. Still over a week away from rotating into view again, if it can hang on that long.

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[twawki]

Well the low spotless number, the low flux and the zero spotless days isnt the norm for recent history but may have been the norm for the maunder and dalton minimums!

Dec 21, 2010 12:24:45 GMT lku said:

One ot two spotless days at this point in the cycle is nothing abnormal.

But we`re at 4 days now, and 5 looks a certainty. Will start to get interesting if we get a few more spotless days and flux drops to low 70s