[South Florida DX Association] ARLP020 Propagation de K7RA

[Bill Marx]

 SB PROP ARL ARLP020
> ARLP020 Propagation de K7RA
> 
> Our Sun is in another period of spotless days. Since Monday, May 15,
> no spots are visible, through Thursday so far. We don't have access
> to an actual sunspot prediction model for the next week, but the
> U.S. Air Force does issue a daily 45 day outlook for solar flux and
> planetary A index. The forecast shows a steady solar flux of 75
> until May 26, when it jumps 10 points to 85.
> 
> The solar flux on these four spotless days ranged from 71.5 to 73.5,
> and rises slightly over the period. With a prediction of solar flux
> at 75 over the next week, that suggests low sunspot numbers or
> perhaps even more days with no sunspots. Currently sunspot 884 (a
> small one) is just beginning to peek around our Sun's eastern limb.
> We should see some daily sunspot number until it either fades away
> or completes a transit of the Earth-facing side of our sun.
> 
> As the sunspot cycle continues its descent, we will see long
> stretches with no visible spots. Nearly a decade ago, 38 consecutive
> days, from September 13, 1996 through October 20, 1996 had no
> sunspots.
> 
> You can look at projected smoothed sunspot numbers for the next year
> on page 11 at http://www.sec.noaa.gov/weekly/pdf/prf1602.pdf. This
> prediction hasn't changed for several years. It shows a smoothed
> sunspot number of 11 for May 2006, so according to this chart, in
> September 2007 we should see more sunspots than we do now. Next
> month we can observe that in July 2007 we should have more sunspots
> than June 2006.
> 
> Earth has been within a solar wind stream from a coronal hole. As a
> result, late on May 18 both the planetary and mid-latitude K index
> reached 4, and the high-latitude college A index went to 5. For May
> 19 the planetary A index is predicted to be 20. Conditions quiet
> down in the following days, and the A index is not predicted to rise
> again to that level until early June.
> 
> Geophysical Institute Prague predicts unsettled to active conditions
> for May 19, unsettled on May 20-21, quiet to unsettled on May 22,
> quiet on May 23-24, and quiet to unsettled on May 25. With no
> sunspots, MUF for most long-range propagation paths is lower, so 10,
> 12 and 15 meters are not yielding results as they were when there
> was at least some sunspot activity.
> 
> Ever wonder exactly where these geomagnetic observatories used for
> the various A and K indexes are located? Here is a table of recent
> observations: http://www.sec.noaa.gov/ftpdir/indices/DGD.txt . Jim
> Henderson, KF7E of Queen Creek, Arizona (southeast of Phoenix) sent
> a page from USGS devoted to magnetic observatories:
> http://geomag.usgs.gov/observatories/. Click on the link for
> Newport, and you can see photos of the observatory buildings, this
> one near the Idaho border in Eastern Washington. Note the arcane
> latitude/longitude numbers. To convert those to the normal
> coordinates we are used to, subtract the co-latitude number from 90,
> and the longitude from 360. You can then enter these numbers (40.27
> N, 117.12 W) in an online map, such as Google Maps at
> http://maps.google.com/. Note if you zoom in far enough you will see
> that the buildings are just off Geophysical Observatory Road, near
> the town of Newport, Washington.
> 
> On the Daily Geomagnetic Data page (the table mentioned in the
> previous paragraph), you'll see that our middle-latitude K and A
> index come from Fredericksburg. Click on the FRD link on the USGS
> page mentioned above, and you can do the same location calculations,
> which yield 38.2 N, 77.37 W. The map shows this is near another
> Observatory Road, this time near the western perimeter of Fort A.P.
> Hill Military Reservation (not named on this map), southeast of
> Fredericksburg, Virginia. There is another link from the USGS page
> (CMO), which shows the home of the college A and K index in
> Fairbanks, Alaska, and another for the Boulder observatory, source
> of the numbers heard on WWV. Recent indices from Boulder are at
> http://www.sec.noaa.gov/alerts/k-index.html.
> 
> Don Eiler, WA4PLD of Knoxville, Tennessee sent in a couple of links
> with information on the IMF (Interplanetary Magnetic Field). The
> first is one this bulletin has mentioned before:
> http://www.spaceweather.com/glossary/imf.html. The second,
> http://pluto.space.swri.edu/image/glossary/IMF.html, is new to me.
> 
> If you would like to make a comment or have a tip for our readers,
> email the author at, k7ra at arrl.net.
> 
> For more information concerning radio propagation and an explanation
> of the numbers used in this bulletin, see the ARRL Technical
> Information Service propagation page at,
> http://www.arrl.org/tis/info/propagation.html. An archive of past
> propagation bulletins is at, http://www.arrl.org/w1aw/prop/.
> 
> Sunspot numbers for May 11 through 17 were 36, 38, 24, 11, 0, 0 and
> 0 with a mean of 15.6. 10.7 cm flux was 76.4, 75.7, 73.5, 72, 71.7,
> 71.5, and 72, with a mean of 73.3. Estimated planetary A indices
> were 18, 16, 11, 8, 4, 2 and 5 with a mean of 9.1. Estimated
> mid-latitude A indices were 21, 10, 9, 6, 3, 0 and 4, with a mean of
> 7.6.
> NNNN
> /EX
> 
>