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Smoothed Mean Sunspot Number (Rsm) for May 2000: 123.5

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Sudden Ionospheric Disturbance Report

Sudden Ionospheric Disturbances (SID) Recorded During November 2000

The events listed above meet at least one of the following criteria

Reported in at least two observer reports Visually analyzed with definiteness rating = 5 Reported by overseas observers with high definiteness rating

Solar Events

Greetings ! November was a fairly active SID month. If not for the number of SID events then for the magnitude. Of the 168 flares recorded by the Goes-8 spacecraft, fourteen of them were M-Class flares and 5 of them were X-Class flares. Our observers detected 38 of those. The most active periods were on November 8, November 18 and November 24/25 . November 8th had 3 M-Class flares and resulted in a very large proton event that was accompanied by significant aurora. November 18th had two relatively minor M-Class flares (M1.5) but produced very Large SID events. Guglielmo Fillipo (A93) sent me a copy of his SID data for that day and I was quite surprised at the magnitude of his response. A copy of that chart has been included in Cap Hossfields SID Report which follows. My chart recording for that date is at the top of the previous page. November 24/25 of course were the most active days of the month where 4 of the 5 X-ray events occurred.

I have noticed a couple of interesting points as I get more familiar with the analysis, and patterns are starting to form in my view of the data that I review. One is that sometimes an observer will not record an M-Class event and yet will record a lesser C-Class event. This points to the fact that the sensitivity of the ionosphere to these flares is dependent on factors other than the flare strength. It probably is due to localized conditions since other observers do detect the ones that others miss. Another interesting fact is that the SID events are not always directly related to an X-Ray flare event. If a reported event does not correspond to one of the Goes-8 X-Ray events, I then look at the entire event list for that day as published by NOAA. One interesting event was on Nov 25 at 1940 UT. The SID event was reported by two observers, A05 and A83. It did not correlate with an X-Ray event but upon examination it did correspond with a series of very strong Radio Outbursts from the sun from 1833 to 1942 UT. These were associated with the strong X-Ray event at 1840 UT but occurred at a later time. I looked at the correlation of these radio outbursts and realized that most M-Class events and all X-Class events are accompanied by them and that the strength of the outbursts are directly proportianal to that of the X-Ray flare events themselves. For the X-Ray event at 1840 UT there was a series of strong radio outbursts almost simultaneously and then another series an hour later. Both the X-Ray event and the strong radio outbursts later on resulted in a significant effect on our ionosphere and both events were detected by our observers.

I hope you all have a nice Holiday season. Thank you all again for your quick response in sending in data at the end of the month and for presenting data in the proper format.

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SOLAR BULLETIN of the American Association of Variable Star Observers. Vol. 56, No. 11, November, 2000

Casper H. Hossfield, SID Sup. Editor PO Box 23 New Milford, NY 10959, USA

SUDDEN IONOSPHERIC DISTURBANCES RECORDED DURING NOVEMBER , 2000

capaavso@aol.com Fax 973 853 2588

A new observer's recording of two nice SESs is shown below. He is Guglielmo Di Filippo, A-93, in Italy. Guglielmo lives near Teramo in Southern Italy and records GBZ in Criggons, Wales, UK transmitting on 19.6 kHz. He uses a Gyrator II receiver that he built himself and 75 cm square loop that is inductively coupled into the gyrator receiver. It produces a nice clean chart with beautiful sunrise and sunset patterns. Notice the two humps following the sunrise drop. These are typical of a signal west of the receiver and similar to the humps we get in the USA when we record NPM west of us in Hawaii. Guglielmo built his own MAX 186 A/D converter and used Joseph Lawrence's LOGGER software to compile a DAT file which was then plotted in XCL to make the chart below.

Charts below for 24, 25 and 26 November were made by Jerry Winkler, A-50 and show the solar flare activity those days as recorded on a Rustrack strip chart recorder and also as recorded ½ size and sent by email using that option in the new plotting program, Picklogger32D, that Al McWilliams recently wrote. The Rustrak charts were reduced to ½ size on a photocopy machine. This also reduces the thickness of the line to ½ its original thickness. The thickness of the trace line on the email charts is not reduced so they don't look as nice as the reduced to ½ size Rustrak charts. Next month we will have Jerry send the email charts normal Rustrak size and reduce them to ½ size on the photocopy machine and they should then have a nice thin trace line like the Rustrak charts. This is the sort of thing you learn by experience when using a new plotting program.

Jim Mandaville, A-91 also made a nice recording of the big X-class flare on the 26th. He records NPM in Hawaii transmitting on 21.4 kHz. The SES was recorded right after the sunrise pattern. Only a great flare can record so strong at that time.

Jim Just happened to be listening to BBC on 17.84 MHz when this big flare started. Here is his story of its short wave fade:

On 26 November around 1630 UTC I had BBC on 17.840 MHz, waiting for the news coming up at 1700. The relay on this frequency comes from stations in far eastern Canado or the southeastern U.S. As usual, the signal was very strong. Around 1645 I suddenly became aware of the fact that thesignal had totally disappeared. I went to the receiver to check the tuning for drift but found it right on. I then tuned down through the HF range to about 15 MHz and found that there were no signals whatever, except one weak fluttery SWBC station. I then looked over at my SID recorder and saw that the pen was in the middle of a very steep climb upward. This developed into a very strong SID with a duration of over two hours. Meanwhile I was monitoring 17.840 MHz, and BBC started to come back, weak and fluttery, around 1710 UTC. The signal continued to build, and was back to its normal, strong self by 1800. This was my first experience of an HF blackout coinciding with a SID.

Later I checked NOAA's Solar Events List and found that the GOES 8satellite had detected an X-class x-ray flare beginning at 1634 UTC. It's maximum was listed as 1648, about the time I noticed HF propagation loss. This was doubtless the big flare that I had detected starting at 1637 and which had coincided with the HF propagation blackout.

I then checked my magnetometer and saw that after several days of a very quiet field, a disturbance had started. This, over subsequent hours, developed into a fair to middlin' storm. The relationship between the flare and the magstorm is somewhat problematic, as a positive magnetic disturbance had started a few hours even before the flare affected the earth's ionosphere

J. M.

The above magnetogram is the one referred to above made at the time of the big X-class flare that caused the short wave fadeout on 26 November. The magnetogram below was made by Ed reed and shows a magnetic storm with sudden commencement on November 7. Both magnetograms were made with McWilliams torsion-balanced magnetometers.