ARRL

ARRL Propagation Bulletin ARLP036 (2002)

SB PROP @ ARL $ARLP036
ARLP036 Propagation de K7VVV

ZCZC AP36
QST de W1AW  
Propagation Forecast Bulletin 36  ARLP036
From Tad Cook, K7VVV
Seattle, WA  August 30, 2002
To all radio amateurs 

SB PROP ARL ARLP036
ARLP036 Propagation de K7VVV

Last week's rise in sunspot count couldn't last forever, and the
numbers this week show a drop.  Average daily sunspot count for the
week of August 22-28 (Thursday through Wednesday, for the
convenience of this bulletin schedule) declined 104 points and solar
flux was down by nearly 38 points when compared to the previous
week.

AA1LL wrote to ask if the renewed activity meant that there might be
a third peak to cycle 23.  I replied saying that I didn't think so,
but this is just based on observation of past cycles.  I don't know
of any way to really predict it, except that it would be outside the
standard variation for a sunspot cycle.  You can visualize the shape
of past cycles from 1700 to present at
http://www.wm7d.net/hamradio/solar/historical.shtml.  You can write
to the author of this bulletin at k7vvv@arrl.net.

AA6YQ asks us to check out Prop View, a very interesting free
program that is a graphical front end for IONCAP (Ionospheric
Communications Analysis Prediction) at http://www.qsl.net/propview/.
DXView (see http://www.qsl.net/dxview/) can be used with Prop View
to automate the selection of targets, as well as control antenna
rotators.  Prop View can be used with the NCDXF beacons (see
http://www.ncdxf.org/beacon.htm) to compare predictions with actual
on the air observations.  This also works with SpotCollector (see
http://www.qsl.net/spotcollector/), which gathers data from local
PacketCluster networks, the DX Summit spotting network, and up to
four additional telnet-accessible DX clusters.  You can get these
and additional software that works with Prop View at
www.qsl.net/dxlab.

A pair of NOAA links for solar and geomagnetic data listings
mentioned here in the past (and the source for 2/3 of the data
appearing at the end of each of our bulletins) have moved.
Occasionally NOAA moves these to another server, and then the old
links don't work.  The new URLs that do work are
http://www.sec.noaa.gov/ftpdir/indices/DGD.txt for geomagnetic
indices and http://www.sec.noaa.gov/ftpdir/indices/DSD.txt for solar
data.  The other 1/3 of the data at the bottom of these bulletins is
from Canada's Dominion Radio Astrophysical Observatory at
http://www.drao.nrc.ca/icarus/www/current.txt.  The flux values
presented here are the 2000 UTC daily measurements from the Observed
column.  2000 UTC is local noon in Penticton, British Columbia, the
location of the observatory.

The autumnal equinox is just a few weeks away.  This is a great time
for HF DX, as we pass from the summer season.  Sunspot 87 is
currently passing through an area where it is squarely aimed at
earth and poses a threat for developing powerful X-class solar
flares.  The current prediction is for moderate to unsettled
geomagnetic activity over the next few days, barring any upset from
sunspot 87.  Solar flux is expected to decline over the next few
days with Friday through Monday values around 170, 165, 155, and
150.  Solar flux is expected to reach a near term minimum near 125
around September 7, and then bounce back quickly.

One final note before putting this week's bulletin to bed.  This
bulletin is received by readers from various sources, but you can
see the complete text of this current bulletin as well as past
editions at http://www.arrl.org/w1aw/prop/.

Sunspot numbers for August 22 through 28 were 205, 207, 199, 136,
105, 133 and 87, with a mean of 153.1. 10.7 cm flux was 220.1,
224.5, 195.6, 178.6, 168.6, 161.4, and 163.2, with a mean of 187.4.
Estimated planetary A indices were 11, 11, 11, 9, 18, 15, and 10,
with a mean of 12.1.
NNNN
/EX