Solar Cycle 24 Main Discussion IX

[Bob k6tr]

The c 1.5 Flare came from region 1133 in the Northwest. The C 4.5 flare came from 1135 in the Northeast.

[af4ex]

> The C 4.5 flare came from 1135 in the Northeast.
NOAA is now reporting that flare as C5.3.
www.swpc.noaa.gov/ftpdir/indices/events/yesterday.txt

Nobeyama's last frame was at 0620Z, so just missed getting the microwaves from the blast. But it did catch a B5.0 xray event from the same area a few hours earlier (below).

There was another B7.0 event reported today, so a half dozen xray events for 1135 since it appeared. Seems to be very active for a region that is barely visible. Consistent with L&P effect, I believe (but not 'proof' of course).

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[af4ex]

I know that we are expecting (and hoping) that solar activity will start increasing as SC24 evolves. The SFI hovering just under 90 for the last 2 weeks might be an indication of that.

But I have a hunch that the SFI was primarily influenced by AR1131, which has now rotated over the western limb. 1131 was an unusually bright 17Ghz microwave radiator, as you may recall from the Nobeyama plots I have posted recently. It was constantly bright during the last 2 weeks. Most other active regions got that level of microwave brightness only briefly during Xray flare events.

I'm basing my hunch on the fact that the SFI is also based on microwave flux (2.8Ghz), so I'm assuming 1131 was radiating a lot at the frequency too. But I don't have any 3Ghz image plots to prove my point.

Nobeyama used to plot 3Ghz imagery. Why did they stop? Seems like it would localize and thus help further characterize the SFI activity (which in turn is strongly linked to sunspots).

In any case I predict the SFI will drop for awhile. (Still hoping it will hit 100 early next year).
:-\

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[af4ex]

Looks like the new region rotating into view, near the equator, is another microwave emitter.

Might mess up my prediction. That's good.

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[af4ex]

... another one of those no-spot regions. Looks bright in EUV and Xray.

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[colinaldridge]

and I thought we were heading for a spotless day today then 1135 splutters into a very modest sunspot

[ironghost]

Does anyone think this solar cycle is starting to look more and more like the one that was involved in the Carrington event?

[THEO BAKALEXIS]

Fair seeing today from athens but we have sun.

So CORONADO PST D.S SM 40mm in action.

The elements is:

1) One Big Polar filament at South.

2) Other two big Q.R.Filaments at NE.

3) One Fila/prom phainomenon

4) AR 1135 only with plages.

www.solar-007.eu/

[af4ex]

@theo
> Fair seeing today from athens but we have sun.

Thanks for contributing these images Theo.

I can understand that viewing conditions in a big city like Athens are not ideal, but your Coronado images (in Ha light) are excellent.

Inverting the image definitely improved the rendering of the filaprom (below).

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[af4ex]

af4ex
> In any case I predict the SFI will drop for awhile. ...

My prediction came true. Not surprising, I guess, due to vanishing sunspots.

But my claim was that the bulk of the 2.8Ghz SFI activity over the last two weeks or so was caused by AR1131, whose "rise" and "set" times seemed to coincide with a period of increased SFI activity.

This is all 'armchair science' on my part, so I have to be careful claiming 'cause and effect' from coincidental observations. But this 'finding' seems very compelling to me. Do the experts out there agree with my claim that AR1131 was principally responsible for this increased activity?

If my claim is true, then I also need to explain why there was no sudden ramp up and down associated with the appearance and disapperance of AR1131.

I think this can be explained by the way SFI is calulated. Appears to be a running average of some sort, which is equivalent to convolving a square "boxcar" filter over the signal, which typically produces this kind of ramp artifact, dependent on the window size.

Exactly how is the SFI computed?

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[Bob k6tr]

Dec 19, 2010 13:12:56 GMT af4ex said:

Exactly how is the SFI computed?

It' s not

It 's measured

www.spaceweather.gc.ca/sx-2-eng.php

[af4ex]

ironghost
> Does anyone think this solar cycle is starting to look
> more and more like the one that was involved in the
> Carrington event?

That would be SC10. Why do you think it's like SC24? What does the Carrington event have to do with it?

I think SC14 has been cited by Dr. S. as a closer prototype for SC24.

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[af4ex]

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?

[jimcripwell]

As someone who is new to looking at the details of how solar cycles develop, may I ask what could be a stupid question. How unusual is it to have a spotless sun at this stage of SC24?

[af4ex]

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'.
:-|

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