Solar Bulletin August, 2002

• Sudden Ionospheric Disturbance Report
• Sudden Ionospheric Disturbances Supplement

Click image to enlarge. Fig.1.10 cm Solar Flux and Comparison of Ri (provisional) and Ra Estimates for August (r=0.981). (Ri Source: http://sidc..oma.be/index.php3) (10cm Source: http://www.drao.nrc.ca/icarus)

Click image to enlarge. Fig.2 Maximum, Mean, and Minimum Ra Values for Each Month from January 2001 to Present.

Michael Hill, SID Analyst 114 Prospect St Marlborough, MA 01752 USA noatak@aol.com

Observer Code Station(s) monitored A Clerkin A29 NAA J Winkler A50 NAA D Toldo A52 HWU NAA NWC J Ellerbe A63 ICV W Moos A83 NAA W Moos A84 FTA,ICV,DHJ M Hill A87 NAA G DiFillipo A93 HWU T Poulos A95 NAA J Wallace A97 NAA M King A99 HWU P Campbell A100 NLK S Bressan A101 HWU F Steyn A102 NAA NWC D Welch A104 NAA E Smith A105 DHO

The events listed above meet at least one of the following criteria Event reported by two or more observers within +/- 5 minutes Event matched to GOES-8 XRA event to within +/- 15 minutes and event time < 1000 UT Reported by observer with a high quality rating > 8 (scale 1-10)

Solar Events

You may note a difference in the reporting criteria just below the data table. This is due to a major change in the method of analysis I now use. I have written a program that does all the analysis automatically. It uses slightly different, although comparable event detection criteria. It is based for the most part on observer-observer correlations which are made to ±5 minutes. The reported peak time and importance rating are an average of all correlated entries for a given event. After this I use the GOES-8 X-RAY data set and try to match events that were not correlated with another observer but do match an X-Ray event to within 15 minutes. I only use events found under this criteria if the time of the event is < 1000 UT. This effectively allows me to accept events reported by observers that see those early hours but are not correlated with others because there are not as many observers overseas as there are here in the United States. Lastly, I maintian quality statistics for each observer that accumulate over time and reflect the number of events reported that go uncorrelated with another observer. The quality rating is a number from 1 - 10 where 10 indicates all events reported were matched to another observer and 1 means that none of them were. As a final event acceptance criteria, if an observer has a quality rating > 8 then all reported events from that observer are included. If you tend to report every little blip on your chart resulting in a lot of uncorrelated events, your quality rating will be low. If you only report very definite events, it will be high. I have been using this method for two months and have verified the results with a parallel manual analysis for two previous months. These comparisons allowed me to refine my correlation criteria which resulted in a very good match to events recored in the manual vs. the automated mode. The analysis task is now much more efficient and accurate. It event generates the AAVSO database file that is posted to the web site and the file to be sent to the NGDC data center.

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