Asunto:  [dxcolombia] ARLP014 Propagation de K7RA  Fecha:  Viernes, 8 de Abril, 2005 17:42:30 (0500)  Autor:  Dxcolombia <dxcolombia @.........co>

SB PROP @ ARL $ARLP014 ARLP014 Propagation de K7RA
ZCZC
AP14 QST de W1AW Propagation Forecast Bulletin 14
ARLP014 From Tad Cook, K7RA Seattle, WA April 8, 2005 To all
radio amateurs
SB PROP ARL ARLP014 ARLP014 Propagation de
K7RA
Sunspots, solar flux and geomagnetic numbers all averaged out to
a slight rise this past week over the previous period. Average
daily sunspot numbers rose over five points to 39.4, and average
daily solar flux was up over two points to 82.5.
The most active
geomagnetic day was Tuesday, April 5, when the planetary A index was 48 and
the midlatitude A index was 30. This was triggered by a solar wind stream
and a southpointing interplanetary magnetic field. The field pointing north,
as it was on April 3 offers some protection, but when it points south
the earth is vulnerable to the effects of flares and coronal
holes.
Sunspot numbers and solar flux are expected to decline very
slowly for the rest of April. Sunday, April 10 looks like a day
for possibly unsettled to active geomagnetic conditions. Spring is a great
time of year for propagation, but we wish there were more sunspots. Comparing
the average daily sunspot number for the past week with monthly averages for
April in years past, this week was 34% below 2004, 66% below 2003, and 80%
below 2002.
Tim Young, WB7UVH of Washougal, Washington wrote, "Some time
ago I used a graphing program that imported data from your reports
to graph flux values. Is that program still available?"
Yes, it is
available, and the data file has just been updated. Tim is remembering the
WA4TTK Solar Data Plotting Utility, which has worked in conjunction with this
bulletin for nearly a dozen years. It is freeware written generously by Scott
Craig, and you can find it on Scott's web site at http://www.craigcentral.com/. Just
click on the link, "Download Freeware Software I Have Written."
Scott
updated the GRAPH.dat data file through April 6, 2005, and you can find a
link for this below the software download link. Scott has programs working
with all Windows versions beginning with 3.1, and even one that works with
MSDOS. The program can update by automatically grabbing the sunspot and
solar flux data from a text file version of this bulletin, or it can download
the data from ARRL servers over the net.
Andy Gudas, N7TP of Nevada,
sent in this question. "On the packet spotting nets they report SFI, A, K,
and R. What is R?"
R is the sunspot number. It is calculated by
multiplying the number of visible sunspot groups by ten, then adding the
number of individual sunspots. So if four sunspot groups are observed,
and there are 29 individual sunspots visible, the sunspot number would be
69. That is the simple explanation. What really happens is observations are
made from multiple sites, and then there is a K factor, sort of a fudge
factor, that the number is multiplied by. That K factor is different for each
observatory, and is used to make the resulting numbers approximately
equivalent. All of the results are averaged to yield the daily sunspot
number.
By the way, SFI is the Solar Flux Index, which is a measurement
of 10.7 cm (about 2.8 GHz) energy with an antenna pointed at the sun. We
get our solar flux numbers from a Canadian observatory in Penticton, British
Columbia.
You can find the definition for R and many other terms in
the Glossary of SolarTerrestrial Terms, hosted by the High
Altitude Observatory at the National Center for Atmospheric Research. Look
it up at, http://www.hao.ucar.edu/public/education/glossary.html.
The
story in last week's Propagation Forecast Bulletin ARLP013 about the Novice
license and the red sweater provoked a huge email response. Thanks to
everyone who wrote.
If you would like to comment or have a tip, email the
author at, k7ra@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.
Sunspot
numbers for March 31 through April 6 were 22, 26, 30, 38, 54, 56 and 50 with
a mean of 39.4. 10.7 cm flux was 76.7, 78.3, 80.2, 81.1, 84.8, 88.3 and 88,
with a mean of 82.5. Estimated planetary A indices were 9, 8, 4, 6, 17, 48
and 11 with a mean of 14.7. Estimated midlatitude A indices were 5, 6, 1, 4,
11, 30 and 7, with a mean of 9.1. NNNN /EX

