SB PROP @ ARL $ARLP028 ARLP028 Propagation de K7RA ZCZC AP28 QST de W1AW Propagation Forecast Bulletin 28 ARLP028 >From Tad Cook, K7RA Seattle, WA July 16, 2010 To all radio amateurs
SB PROP ARL ARLP028 ARLP028 Propagation de K7RA Two new sunspot groups appeared in the last week, groups 1087 and 1088. 1088 lasted just one day, on July 13, 2010 with a relative area of 10 (millionths of a solar hemisphere). Sunspot group 1087 had a relative area from July 9-15 of 30, 100, 120, 130, 70, 100 and 60. Average daily sunspot numbers this reporting week (July 8-14) rose 2.9 points to 18.9, and average daily solar flux was up 6.4 points to 79.2. Predicted solar flux for July 16-23 is 76 on each day, then 74 on July 24-27. This is lower than recent forecasts predicted. Predicted planetary A index for July 16 is 10, followed by 5 for each day through July 22. The next rise in planetary A index is July 23-28, when it is predicted to be 18, 12, 10, 8, 15 and 10. Geophysical Institute Prague predicts quiet geomagnetic conditions July 16-21 and quiet to unsettled on July 22. On Wednesday, July 14 there was an interruption at http://stereo.gsfc.nasa.gov/ in the portion of the STEREO image that faces earth, but by early Thursday morning it was restored. On July 18 around 1000z the STEREO mission coverage will reach 91 percent of the sun's surface. In February 2011 the Solar Dynamics Observatory (http://sdo.gsfc.nasa.gov/) will provide the data to the STEREO online display that appears around the zero degree meridian, and solar coverage should be at 100 percent. Due to movement of the STEREO craft, as the gap closes on the far side, a new one facing earth will begin in January 2011. Eventually the two spacecraft will work their way around the sun and return to their original position by 2024. In another example of sporadic-e propagation, Erik Beck, who I think might be N7FYO, reports "As I was driving outside Providence Rhode Island, at about 9:00 AM I was able to pull in loud and clear on 90.1 MHz, WXVS, Waycross, GA. By far the longest DX FM station I have encountered! This with a car radio and an in-window antenna!" WXVS runs 79KW with a tower just north of the Okefenokee Swamp, around 1,000 miles from where Erik was driving. Vince Varnas, W7FA of Aloha, Oregon wrote to say this about E-skip: "As the Sporadic E skip distance on the lower frequencies shortens, the E skip on higher (VHF) frequencies appears and is longer in distance (single hop). Thus, VERY short skip on 10 meters means longer skip on 6 meters and probably E skip on 2 meters at a still longer distance". He says that one way to spot 6 meter openings is to watch ten meters. If you would like to make a comment or have a tip for our readers, email the author at, k...@arrl.net. For more information concerning radio propagation, see the ARRL Technical Information Service 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. Find more good information and tutorials on propagation at http://mysite.ncnetwork.net/k9la/index.html. 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 July 8 through 14 were 11, 12, 18, 25, 22, 28, and 16 with a mean of 18.9. 10.7 cm flux was 75.6, 80, 79.9, 82.6, 80, 78.5 and 77.7 with a mean of 79.2. Estimated planetary A indices were 3, 5, 2, 5, 5, 3 and 11 with a mean of 4.9. Estimated mid-latitude A indices were 2, 4, 0, 2, 2, 1 and 7 with a mean of 2.6. NNNN /EX ----------------------------------------------------------- To unsubscribe or subscribe to this list. Please send a message to imail...@njdxa.org In the message body put either unsubscribe dx-news or subscribe dx-news This is the DX-NEWS reflector sponsored by the NJDXA http://njdxa.org -----------------------------------------------------------