Fw: ARLP041 Propagation de K7RA
>From: ARRL Web site <>
>Sent: Oct 14, 2011 1:20 PM
>Subject: ARLP041 Propagation de K7RA
>SB PROP @ ARL $ARLP041
>ARLP041 Propagation de K7RA
>QST de W1AW
>Propagation Forecast Bulletin 41 ARLP041
>From Tad Cook, K7RA
>Seattle, WA October 14, 2011
>To all radio amateurs
>SB PROP ARL ARLP041
>ARLP041 Propagation de K7RA
>Robust solar activity continues. Check http://www.spaceweather.com
>for daily images of the Sun, and you'll see it is full of spots. You
>can also use the archive feature to view the position of sunspots
>for previous days.
>The average daily sunspot number for the week (95.4) was about the
>same as last week (96.7) and the week before (96.1). The number
>hasn't stayed steady though, with daily variation as low as 82 and
>as high as 126 over the past two weeks. You can check
>http://www.swpc.noaa.gov/ftpmenu/forecasts/SRS.html for daily
>updates showing which numbered groups appeared and faded away, along
>with the relative area covered by each one.
>The latest forecast from USAF/NOAA has solar flux at 135 on October
>14-15, 130 on October 16-20, 125 on October 21 through November 2,
>120 on November 3-5, and 125 on November 6-8. The predicted
>planetary A index is 5 on October 14, 8 on October 15-17, 5 on
>October 18-27, 8 on October 28-30 and 5 on October 31 through
>Geophysical Institute Prague predicts quiet conditions on October
>14, quiet to unsettled October 15, unsettled October 16, quiet to
>unsettled October 17, and quiet October 18-20.
>Lots of 10 meter activity lately, and Jeff Hartley, N8II of
>Shepherdstown West Virginia sent this last week:
>"Today, Oct 7th, the SFI was only 125 and 10M was wide open to EU at
>1220Z (65 minutes after sunrise) with a very large amount of
>activity. As we move into October, a bit lower SFI will produce
>openings equivalent to those around the equinox 2 weeks ago with
>higher MUFs. I started off the day breaking a EU pile up calling
>7Z1TT in Saudi Arabia who was S9. I called one G running a vertical
>and 100W who was S9 and two stations called me when signing. Then I
>QSY'd up to 28530 kHz where there was still plenty of activity and
>ran off about 10 QSOs before having to QRT. 10 was wide open to the
>Moscow area and Great Britain which has been left out of many recent
>openings; M0RAD was S9+25 dB. XU7SSB (Cambodia) was worked on 15 CW
>S7 around 1300Z.
>"T32C has been good strength to loud on all bands in the past week
>and I've logged them on every HF band except 40M including both
>modes on 15, 12, and 10M. 10M is routinely open to the Rockies and
>west coast an hour or more after sunset and I was lucky enough to
>have VK4FAXA running 10W call in from McClay Island, IOTA OC-137, on
>10M last night. 10M conditions have been great except over the pole
>from here, not that many JA/Asia openings."
>Michael Gutman, K2CHM of Mashpee, Massachusetts writes, "10 meter
>propagation is certainly feeling a lot like 1958. I worked T32C on
>10/9 at 7:25 PM on 28.485 MHz and he was 59. It is impressive to me
>as I run only 100 watts to a dipole in the attic here at sea level
>on Cape Cod."
>Mark Lunday, WD4ELG of Greensboro, North Carolina wrote on October
>11, "Nothing gets the blood moving like a 10 meter opening at
>sunrise! BY, 4K, ZD7, VU, 4S, and of course tons of EU stations, all
>at 0800 local, and all audible on wire antennas. Feels almost like
>2001 all over again!
>"In fact, 10 and 12 have been spectacular this week. I am rapidly
>closing in on 9BDXCC using only LoTW...only 25 more to go on 12 and
>10, then that leaves just 160 for the final jewel in the crown."
>You can feel Mark's excitement! Check his blog at
>We also receive 6 meter reports. Anibal Dos Ramos, HK3R of Bogota,
>Colombia says that on Sunday, October 9 he made his longest distance
>6 meter contact yet. It was 2318 UTC when he contacted KH7Y on both
>SSB and CW, and he heard KH7Y for about 30 minutes with S9 signals.
>He estimates the distance was 8,897 km (5,528 miles) and he heard no
>other Pacific stations.
>There is much more on 6 meters and the recent meteor showers.
>Perhaps we can report on that next week.
>Roger Harrison, VK2ZRH sent an interesting email about propagation
>of VHF signals from Dubai in the Middle East to the Far East. He
>"Over September 12-16, United Arab Emirates TV signals from Dubai on
>48.25 - 53.75 MHz, were being copied in Shenzhen in south-east
>China, Hong Kong and the Philippines, which are all in the UTC+8
>time zone; Dubai is UTC+4. Dan VR2HF is the HK contact, while George
>DU1GM is located 80 km south of Manila.
>"The 48.25 MHz video signal typically reached S9+20 dB on peaks.
>The 53.75 MHz sound channel was received for short periods when the
>"Optimum reception time was around 1200-1300 UTC, although sometimes
>signals were received in Hong Kong as early as 1130 UTC (1930 HK
>"The propagation path ranges from about 5900 km to 7200 km and is
>generally in daylight in mid-September. As this is the equinoctial
>season, when the occurrence of sporadic E is a minimum, I thought
>the propagation was most likely to be F2, requiring two hops of
>about 3000 km each to Shenzhen/Hong Kong, and about 3600 km to DU1
>"Dubai is located about 18 degrees N geomagnetic latitude, while
>Shenzhen and Hong Kong are at about 11-12 degrees N geomagnetic
>latitude. Manila is directly beneath the geomagnetic equator.
>"The propagation path is largely beneath the northern Equatorial
>Ionospheric Anomaly (also known as the Appleton anomaly) in the F2
>region, which lies generally between 10 and 20 degrees geomagnetic
>latitude north (another forms south of the geomagnetic equator). It
>is the region of high electron density that forms late morning local
>time, builds during the day and can last 6-7 hours into early
>"For the Dubai to Shenzhen/Hong Kong path, the first F2 reflection
>point would be 1500 km east of Dubai, near the northern extent of
>the EIA, and in the UTC+5 time zone. The second F2 reflection point
>would be about 4500 km east of Dubai, in the UTC+7 time zone and
>near the middle of the EIA. To support 48 MHz propagation, foF2 at
>each F2 reflection would need to be above 14.5 MHz as a 3000 km F2
>skip has an M-factor of about 3.3.
>"The only vertical incidence ionosonde with available online data
>that I could locate in the EIA zone is at Guangzhou, about 100 km
>northwest of Shenzhen, and 140 km northwest of Hong Kong. Although
>at the propagation path's eastern end, the growth of the EIA
>"follows the Sun" westward and the Guangzhou foF2 values provide a
>good guide as to how the EIA develops during the day, from which we
>can infer likely foF2 values west along the propagation path. NOAA's
>Space Weather Prediction Center lists the Guangzhou ionosonde's
>"For September 13, foF2 was above 16 MHz from 0500 to 1100 UTC,
>which implies that the highest electron density of the EIA covered a
>longitudinal extent of 6 hours. The 1st F2 reflection point will
>determine when the path opens as the 2nd reflection point will be
>well covered by the EIA. As the openings commenced around 1130-1200
>UTC, the foF2 at the 1st reflection point must have reached 14.5 MHz
>at 0830-0900 UTC, which is 3.5 hrs after foF2 hit 16 MHz at
>Guangzhou. The discrepancy can be put down to the fact the 1st
>reflection point is closer to the northern edge of the EIA, where
>the electron density would take more time to accumulate to the high
>values found near the middle of the EIA.
>"Undoubtedly, the propagation experienced was supported by 2-hop F2
>skip east-west along the EIA.
>"The Dubai-DU1GM path is reported to experience longer durations and
>higher signal strengths than the Dubai-Shenzhen/HK path. Each skip
>is about 3600 km, just shorter than the maximum F2 skip of about
>4000 km. For F2 skips of this length, the M-factor is about 4, so
>foF2 only needs to reach 12 MHz to support 48 MHz propagation, and
>the EIA achieves this earlier and sustains it longer.
>"For the record, the 10.7 cm flux over September 12-16 was 124, 129,
>143, 141, 143, and the A index was 17, 11, 5, 4, 2 (NOAA weekly
>If you would like to make a comment or have a tip for our readers,
>email the author at, .
>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. Find more good
>information and tutorials on propagation at
>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 October 6 through 12 were 99, 88, 61, 71, 87,
>113, and 149, with a mean of 95.4. 10.7 cm flux was 123.9, 122,
>118.4, 121, 126.4, 130.1, and 134.1, with a mean of 125.1. Estimated
>planetary A indices were 7, 7, 7, 13, 3, 4, and 6, with a mean of
>6.7. Estimated mid-latitude A indices were 6, 4, 5, 8, 2, 3, and 4
>with a mean of 4.6.
Randy Allen, KA0AZS
bulletins mailing list