K7RA Propagation Bulletin #36 (updated on: 04/Sep/15)
SB PROP @ ARL $ARLP036 ARLP036 Propagation de K7RA ZCZC AP36 QST de W1AW Propagation Forecast Bulletin 36 ARLP036 From Tad Cook, K7RA Seattle, WA September 4, 2015 To all radio amateurs SB PROP ARL ARLP036 ARLP036 Propagation de K7RA The Australian Space Forecast Centre issued a geomagnetic warning at 0009 UTC on September 4: "The IMF Bz has been strongly southward over the last 3 hours (2100 UTC on September 3 to present). However, the current solar wind speeds are at moderate levels, which are unfavourable to cause any major geomagnetic disturbance. If the solar wind speeds elevate in the coming 24 hours, active to minor storm conditions are possible. If this happens, there is chance that aurora would be visible during the local night hours of the 4 Sep from Tasmania and other southern most regions of Australia. "Increased geomagnetic activity expected due to coronal hole high speed wind stream for September 4, 2015." The IMF Bz refers to the interplanetary magnetic field: http://spaceweather.com/glossary/imf.html Over this reporting week, August 27 through September 2, the average daily sunspot number was 48.3, which is 21.4 points lower than the previous seven days. Similarly, average daily solar flux declined 22.7 points to 97. New sunspot groups appeared on August 27, 29, 30, 31, September 1 and 3. But activity is still very weak and the sunspots are not magnetically complex or strong. Now that we are in early September, we can look at recent monthly averages for sunspot numbers. For May through August monthly averages of daily sunspot numbers were 83, 77.4, 68.5 and 61.7. As you can see, there has been a steady decline in activity. For our three-month moving average of daily sunspot numbers, the past three months, June 1 through August 31 averaged 69.1. This is centered on July, 2015. For the past 12 months, the three month moving averages of daily sunspot numbers were 108.4, 107, 104.7, 107.8, 98.2, 78.1, 68.2, 72.4, 77.7, 76.3 and 69.1. According to our same figures, the current sunspot cycle peaked between January and April 2014, when the three month moving averages centered on those months were 138.5, 146.4, 148.2 and 129.6. The latest predicted solar flux values for the near term from NOAA/USAF forecasters are 85 on September 4, 90 on September 5-8, 85 on September 9-10, then 95 and 105 on September 11-12, 115 on September 13-22, then 110, 105 and 100 on September 23-25, 90 on September 26-28, and then bottoming out at 85 on September 29 through October 7. Although this is a long way out, predicted flux values then rise to 115 on October 10-18. Planetary A index predictions show values of 8, 10 and 9 on September 4-6, then 10, 12 and 9 on September 7-9, then 5 on September 10-11, then 12, 15 and 10 on September 12-14, then 8, 10 and 5 on September 15-17, then 8, 20 and 10 on September 18-20, 5 on September 21-23, and 15, 10, 5, 8, 20 and 22 on September 24-29. A quiet period with planetary A index at 5 is predicted for October 4-8. Petr Kolman, OK1MGW of the Czech Propagation Interest Group predicts geomagnetic conditions will be quiet to unsettled on September 4-5, mostly quiet September 6-8, quiet on September 9-10, quiet to active September 11-13 (with the possibility of disturbed conditions on September 11), quiet to unsettled September 14, quiet to active September 15-16 (possibly disturbed September 15), quiet to unsettled September 17-18, active to disturbed September 19, mostly quiet September 20-21, quiet to active September 22, active to disturbed September 23- 24, quiet to unsettled September 25, quiet September 26-28, mostly quiet September 29 and quiet to unsettled September 30. Petr expects increased solar wind on September 10-13, 15-16, 19, and 22-24. http://www.spaceweather.com reports that 156 years ago this week, on September 2, 1859 the huge Carrington Event occurred, the monster geomagnetic storm in which a billion ton CME smashed into Earth, setting fire to telegraph stations around the world. Check Spaceweather.com, using the archive feature in the upper right corner of the site to select September 2, 2015. David Moore sent a link to a dramatic video from the Solar Dynamics Observatory of sunspot group 2403 breaking up in the past week: https://shar.es/1vl5Yp David sent another link about solar activity and aurora over the past week: https://shar.es/1vluPQ Slate has an animation created by stringing together a long series of hand drawn sunspot maps: http://bit.ly/1hGQP4r If you would like to make a comment or have a tip for our readers, email the author at, email@example.com. For more information concerning radio propagation, see the ARRL Technical Information Service web page at, http://arrl.org/propagation-of-rf-signals. For an explanation of the numbers used in this bulletin, see http://arrl.org/the-sun-the-earth-the-ionosphere. An archive of past propagation bulletins is at http://arrl.org/w1aw-bulletins-archive-propagation. More good information and tutorials on propagation are at http://k9la.us/. My own archives of the NOAA/USAF daily 45 day forecast for solar flux and planetary A index are in downloadable spreadsheet format at http://bit.ly/1VOqf9B and http://bit.ly/1DcpaC5 . Click on "Download this file" to download the archive and ignore the security warning about file format. Pop-up blockers may suppress download. I've had better luck with Firefox than Internet Explorer. Monthly propagation charts between four USA regions and twelve overseas locations are at http://arrl.org/propagation. Instructions for starting or ending email distribution of ARRL bulletins are at http://arrl.org/bulletins. Sunspot numbers for August 27 through September 2 were 46, 52, 50, 50, 50, 49, and 41, with a mean of 48.3. 10.7 cm flux was 110.2, 109.1, 100.1, 91.6, 91, 89, and 88.2, with a mean of 97. Estimated planetary A indices were 53, 43, 16, 5, 6, 6, and 7, with a mean of 19.4. Estimated mid-latitude A indices were 26, 28, 13, 5, 5, 7, and 10, with a mean of 13.4.
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