Register Account

Login Help

ARRL Propagation Bulletin ARLP023 (2003)

ARLP023 Propagation de K7RA

QST de W1AW  
Propagation Forecast Bulletin 23  ARLP023
From Tad Cook, K7RA
Seattle, WA  June 6, 2003
To all radio amateurs 

ARLP023 Propagation de K7RA

More crazy space weather this week. Average daily sunspot numbers
and solar flux were both down, and the average daily A index was up.
We've expressed a lot of angst about the solar wind, solar flares,
stormy conditions and resulting absorption. However, VHF operators
are loving it.

The average daily planetary A index compared to the previous week
was up over 50% to 37.1. The stormiest day was Thursday, May 29 with
a planetary A index of 89. Late in the day the planetary K index was
8, which is exceptional.

This week we received a number of comments and reports from fans of
VHF propagation. Bob Sluder, N0IS noted the displeasure expressed in
this bulletin over high A and K index numbers. He wrote, "It is very
obvious that you are not a VHF operator or you would LIKE those
numbers, because you know something is going to happen on VHF. Boy,
did it happen last week. 6-meters open around the clock and the
Aurora was magnificent (radio wise). Had a CW schedule with a friend
on 80-meters last Thursday evening and someone had thrown the big
low band switch to off, while the VHF one was set on GO."

Jon Jones, N0JK of Kansas wrote that there was a big aurora display
associated with coronal mass ejections on May 30. Following the
break up of the display, there was an all night E-skip opening on
6-meters from 0300-1800z. He noted it was unusual to hear YV1DIG
working California on 6-meters around 0600z.

Al Olcott, K7ICW wrote, "The CME events and related phenomena
enhanced VHF on Thursday 29 May briefly here in Las Vegas. We had a
rare aurora event covering a span of about 12 minutes. I had
contacts with 3 stations, KI7BP (DN13) Idaho, KB7WW (CN85) Oregon
and K7OFT (CN87) in Washington in a span of 2 minutes on 6-meters at
2255-2257z on SSB. Beam headings here were 45 degrees azimuth."

He continues, "At 2302z, an unidentified CW signal on 144.200 MHz
showed up for about 2 minutes in a DN grid, but no I.D. on the weak
signal.  Signals from N7IJ (DN44) in Idaho persisted on 6-meters
throughout our short opening here, but he didn't hear me. A
simultaneous E-skip opening during this period on 2-meters from the
Pacific Northwest states to California produced many interstate
contacts, but it is unknown which were aurora and which were E-skip.

"Reports from stations in Maine said that the aurora activity was
too far south for them for optimum participation. K0AWU (EN37) in
Minnesota reported to me that he worked 5 stations on 222 MHz via
the aurora at his northerly location. N0LL (EM09) in Kansas said he
worked a 222 E skip contact in grid EM83 during the aurora, a rare
event in itself!"

Ken Louks, WA8REI wrote about an aurora experience on HF from the
week before. "I worked the CQ WW WPX CW contest last weekend from a
QTH 720 feet above Lake Superior in Upper Michigan. The aurora both
Friday night (May 23) and Saturday night (May 24) was awesome!
Shades of green, blue, deep purple....some almost straight overhead,
and some way down at the horizon (to the north) of Lake Superior,
and even reflecting into the lake."

He continues, "I ran QRP (5 watts from a Yaesu FT-817), and even in
the bad conditions worked Japan, New Zealand and the Canary Islands.
The aurora seemed to reflect my signal south. I worked many South
America stations, but although I had a clear shot to Europe, I heard
virtually nothing from Europe until Sunday afternoon."

Note that Ken had propagation to the south, but not to the north
toward Europe. On HF his signals couldn't make it through a
near-polar path because of the stormy geomagnetic conditions, which
worsen toward the poles. Many people have thought that during
geomagnetic storms, north-south trans-equatorial propagation is
enhanced, but in reality, it only seems that way because this may be
the only remaining path that still works.

Chip Margelli, K7JA wrote in a May 30 email, "2-meters opened up
between southern California and Oregon/Washington/BC last night,
which obviously is unusual this far from the auroral zone, and
6-meters was going to some degree all night. Now, if we can just get
all this storminess to subside on the 27-day rotation, FD should be
in good shape! That big spot group is facing more away now, so that
should help."

The month of May is over, so let's look at the daily average solar
flux and sunspot numbers to spot any trends. The monthly averages of
daily solar flux numbers for January through May 2003 were 144,
124.5, 133.5, 126.8 and 116.6. Daily average sunspot numbers for the
same five months were 150, 87.9, 119.7, 114.3 and 89.6. To me the
trend appears downward.

What about conditions in the near future? It still looks stormy, so
have fun on 6-meters. We should enter a new solar wind stream over
this weekend, June 7 and 8. The predicted planetary A index for June
6-12 is 15, 20, 30, 30, 25, 20 and 15. Solar flux forecast for the
same days is 115, 118, 120, 120, 122, and 124. The summer solstice
is this month. As we move toward the longest day of the year, expect
daytime MUF to continue to decline. While 15-meters should decline
during the daytime, 20-meters should be good from North America
toward the Pacific late into the evening.

Sunspot numbers for May 29 through June 4 were 98, 62, 57, 66, 61,
54, and 74, with a mean of 67.4. 10.7 cm flux was 137.8, 117.2,
113.1, 112.3, 121.4, 114.5, and 105.6, with a mean of 117.4.
Estimated planetary A indices were 89, 49, 17, 19, 39, 26, and 21,
with a mean of 37.1.


Instragram     Facebook     Twitter     YouTube     LinkedIn