[ARRL-OK] (no subject)

[ClayMayrose at aol.com]

This was sent to me by the author with  the attached request.  Please 
forward to as many hams as possible
Clay  WA6LBU


From: k7ra at arrl.net
To: k7ra at arrl.net
Sent: 3/27/2010  5:49:46 P.M. Central Daylight Time
Subj: ARLP012



Probably due  to the troubled ARRL website upgrade, the propagation 
bulletin I sent to HQ 36  hours ago was never posted or forwarded.

So I am sending this out to  contacts, and please send it on to your ham 
contacts. Let's make this viral, at  least until Monday, March 29, 2010!

If you are not an amateur radio  operator, sorry to bother you.





SB PROP @ ARL  $ARLP012
ARLP012 Propagation DE K7RA
QST de W1AW
Propagation Bulletin  12 ARLP012
>From Tad Cook, K7RA
Seattle, WA March 26, 2010
To all radio  amateurs

Average daily sunspot numbers were down nearly five points this  week to 
24.6.

New sunspot group 1057 appeared on March 23, and by March  24 was 
thirty-eight times its original size. It covered ten one-millionths of  the solar 
hemisphere on Tuesday, and on Wednesday it grew to 380 one millionths.  On 
Thursday new sunspot group 1058 appeared, and the total area for both groups  
expanded to 401 millionths of the solar hemisphere. Total sunspot area has not 
 been this large since February 8, when the total was 460 one-millionths. 
(The  numbers given for Wednesday are a revision of the numbers for the same 
day given  in yesterday’s ARRL Letter).

The largest area covered during all of 2009  was 380 on October 29, 
followed by 310 on December 18. March 23 through April 3  2008 was a period of very 
strong sunspot activity, and on March 26-28 the area  covered by three 
sunspots was 520, 510 and 410 one-millionths of the solar  surface.

The spring equinox was last Saturday, March 20, and HF radio  conditions 
are good, with quiet geomagnetic conditions. NOAA and the U.S. Air  Force 
predict solar flux of 88 for today, March 26, and 89 for March 27-31. This  is 
higher than the average solar flux for this week, 84.2, and last week, 87.6,  
and the week before, 78.6. Our reporting week for data at the end of this  
bulletin is always Thursday through Wednesday, and we haven’t reported a 
weekly  average solar flux above 89 since ARLP007, which had 90.6 on February  
11-17.

NOAA predicts a bit more geomagnetic activity (but not much!),  rising from 
a planetary A index of 5 on March 26 to 7 on March 27 and 8 for  March 
28-31. Geophysical Institute Prague expects quiet to unsettled conditions  March 
26, quiet March 27-29, quiet to unsettled March 30-31, and a return to  
quiet for April 1, the day that NOAA predicts a planetary A index of  five.

Last week for the first time we presented the trailing 50-day  average of 
daily sunspot numbers, 27.34. This week it is 28.18.

This  weekend is the CQ World Wide WPX SSB Contest. HF conditions should be 
 good.

Harry Gross, KC2FYJ of Mineola, New York wrote in with questions  about the 
numbering of sunspot groups, which is different than the sunspot  number.

Harry asked, “First, what’s the scheme (e.g. why is a particular  group 
referred to as 1055, for example)? Is it the 55th group seen in 2010  perhaps? 
Or is it something more esoteric?”

“Second, how do you decide  that a particular group is ‘returning’? I 
presume it’s because it’s circled the  Sun and is returning on the other side 
again. However, how can you be certain  it’s the same group, since there is a 
wide (but now narrowing, thanks to STEREO)  area were we can’t observe on 
the far side of the SUN? Couldn’t the group have  disappeared, and a new one 
formed in its place?”

The sunspot groups are  numbered consecutively, starting with 0, and when 
group 9999 emerges, the next  new group will be 0 again. I have also seen 
them expressed as five digits, so  the current sunspot 1057 this week would be 
11057.

If you go to  http://spaceweather.com/ and look at the Archives section in 
the upper right,  change the date to June 15, 2002 and click View.

Note the numbers on the  solar image on the left side are up in the 9990+ 
range. Now click Forward on the  upper right to advance the date to June 16. 
Note the piece about Sunspot Zero. I  don't know why the image doesn't show 
sunspot 2. Perhaps it emerged, was  numbered, then faded in less than a day. 
Perhaps that is also why paging  backward does not produce sunspot 9999. 

It looks like we went from group  321 to 1057 over the past seven years. If 
sunspot groups were to continue  emerging at the same rate, which has been 
slow recently, it could take us until  April 14, 2095 to reach group 0 
again, a pretty rough guess. That will be less  than a month and a half short of 
my birthday at age 143, perhaps around solar  cycle 32.

I get my information second hand regarding which groups are  returning, and 
do no direct observation myself. I think they can be recognized  possibly 
from magnetic signatures, and also the timing. It takes about 27.5 days  for 
a complete solar rotation, but it varies with latitude, because the sun is a 
 big ball of (very hot) gas. At the equator the period is less than 26 
days, and  toward the poles it is about 36 days. A few references on this are  
http://tinyurl.com/yhxjr5g, http://tinyurl.com/yktkwrq and  
http://tinyurl.com/ykguzeo.

John Buttolph, N1JB of Lake Elmore, Vermont  wrote in with information on a 
Navy map (see http://tinyurl.com/yhpfcwd) showing  letter designations for 
each time zone. Z or Zulu time as we all know is for the  prime meridian, or 
Greenwich Mean Time. But when it is 1200Z, it is 0400U on the  West Coast, 
and 0700R in Newington, Connecticut. Click on the map for greater  detail.

John wrote, “The world is divided into 24 time zones, and each is  assigned 
a letter. The U.S. Navy, as well as civil aviation, uses the letter "Z"  
(phonetically "Zulu") to refer to the time at the prime meridian. Proceeding  
eastward from Greenwich, the zones are designated with the Latin alphabet  
letters beginning with "A" or "Alpha" time. [I do not know why the prime  
meridian time zone was given the last letter of the alphabet rather than the  
first!] Not all letters of the alphabet are used. For various reasons having 
to  do with population centers and other cultural reasons, the time zones do 
not  strictly follow the meridian lines, and some time zones vary by the  
half-hour”.

Matt Pastorcich, KJ4NBM of Mobile, Alabama was surprised to  work VK2JB, 
John Baylis in Hobart, Tasmania last Saturday, March 20 at 1246z  using PSK31 
on 20 meters. That isn’t a promising time for that 9,300 mile short  path 
route, and Matt was even more surprised to learn that John was running 2  
watts into a loop antenna made for 80 meters. Matt uses a vertical. A better  
time would be 0500z-1000z, or even better would be 30 meters around 
0730z-1300z  or 40 meters 0800-1200z.

Wolf Urban, DK8MZ in Fuerstenfeldbruck Germany  wrote to comment on 15 
meters. Nearly two weeks ago, on Saturday, March 13 he  worked Rob Struppeck, 
V73RS on the southernmost island of Kwajalein Atoll. Wolf  uses a TH3 Yagi at 
12 meters high, and said that Rod had a very robust S9 signal  on 15 meter 
SSB. Wolf thinks this is a hopeful sign, and said, “I can’t remember  when I 
last heard such a strong signal from that part of the world, (the most  
difficult one for the Europeans on the high bands) even during periods of much  
higher solar activity!”

Don’t miss K9LA, Carl Luetzelschwab’s excellent  monthly propagation 
column in WorldRadio, available free, online at  
http://www.worldradiomagazine.com/. Just right-click on the image of the front  cover to download the PDF, 
and find Carl’s column on ionosphere modeling on page  36.


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, see the ARRL Technical 
Information Service at  http://www.arrl.org/tis/info/propagation.html. For a 
detailed explanation of the  numbers used in this bulletin, see 
http://www.arrl.org/tis/info/k9la-prop.html.  An archive of past propagation bulletins 
is at  http://www.arrl.org/w1aw/prop/.

Monthly propagation charts between four  USA regions and twelve overseas 
locations are at  http://www.arrl.org/qst/propcharts/.

Instructions for starting or ending  email distribution of this bulletin 
are at  http://www.arrl.org/w1aw.html#email.

Sunspot numbers for March 18 through  24 were 28, 24, 25, 25, 17, 26, and 
27 with a mean of 24.6. 10.7 cm flux was  85.8, 84.4, 83.5, 84.8, 82.5, 83.9, 
and 84.4 with a mean of 84.2. Estimated  planetary A indices were 5, 4, 7, 
2, 2, 2 and 3 with a mean of 3.6. Estimated  mid-latitude A indices were 4, 
2, 5, 0, 0, 0 and 2 with a mean of 1.9.
NNNN