KN4LF Daily HF/LF/MF Radio Propagation Outlook #2004-005A
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Published Sunday 12/05/2004 At 1600 UTC Valid 12/05-09/2004
During the past three days geomagnetic indices have been very quiet. Also the
solar wind speed has been unusually slow at under 300 and the density also very
low. As a matter of fact most of the guideline parameters necessary to see good
propagation conditions have been met. The end result has been pretty good HF/MF
propagation conditions, actually the best in about a month.
Here are the general guideline parameters concerning correlation of propagation
indices to actual expected HF/MF propagation conditions.
1.) Dropping indices numbers are better.
2.) For medium frequencies a solar flux under 150, under 100 better, 70 is best
for E layer multi hop.
Keep in mind though that the 10.7 cm (2800 mhz) solar flux index is not a
"reliable" gauge of ionization in our atmosphere for F layer HF frequency
refractions, as the energy of photons at this frequency is to low on the order
of one million times. However most are used to solar flux and sunspot number
and it's a hard habit to break. A better indicator is the background x-ray
flux. See #7 below.
3.) Solar flux of at least 100 for E valley-F layer ducting mechanism.
4.) Previous 24 hour Ap index under 10, under 7 for several days consecutively
is best.
5.) Previous 3 hour Kp index under 3 for mid latitude paths, under 2 for high
latitude paths, 0-1 for several days consecutively is best.
6.) Energetic protons no greater then 10 MeV (10+0) for 160/120 meters and no
greater then (10-1) on MF broadcast band.
7.) Background x-ray flux levels less than C1 for several days consecutively
for 160/120 meters and less then B9 for MF broadcast band but A9 or less best.
8.) No current STRATWARM alert.
9.) IMF Bz with a (positive number) sign, indicates a lesser chance of high
latitude path auroral absorption/unpredictable refraction or scattering of MF
RF signals, when the Kp is above 3.
10.) A -50 or better towards a positive number Dst index during the recovery
time after a geomagnetic storm, as related to the Equatorial Ring Current.
On Friday 12/03/04 I predicted the chance of polar cap absorption on high
latitude propagation paths due to excessive energetic protons >10 Mev (10+0) as
low.
Only to have a brief period with excessive energetic protons >10 Mev (10+0) on
UTC 12/03-04/04, tied to the coronal mass ejection released by sunspot group #
10708 on Friday.
So I'm still a little rusty at forecasting space weather after returning from
my long sabbatical.
Note! From a standpoint of satellite component damage, energetic protons >10
Mev (10+0) is the threshold for warnings.
But as far as high latitude propagation path absorption, >(10-1) creates
absorption on the 530-1700 kc broadcast band and >(10+0) on 160 and 120 meters.
As previously forecasted, full halo CME #1 which was released in association
with the M1.2 solar flare by sunspot group #10708 on 12/01/04, arrived at the
ACE satellite at approximately 0700 UTC today. But as the Bz has initially
turned strongly northward, geomagnetic conditions have been at worst unsettled
(Kp-3) to active (KP-4).
As CME #2 arrives later today I still expect minor (Kp-5) to moderate (Kp-6)
geomagnetic storming to commence. There is also still a chance for major (Kp-7)
geomagnetic storming.
I see no need to update and or repeat publication of actual propagation path
forecasts contained in outlook #2004-05 at this time.
Standard Disclaimer-
Note! I use "RAW" public domain data from the NOAA Space Environment Center, as
well as other U.S. government organizations, to produce my "not for profit"
propagation forecast outlooks. This data is gathered and made public by the
U.S. Government using taxpayer $$$. However the forecast outlooks that I
produce from the "RAW" public domain data, is my personal intellectual
property. Therefore the propagation outlooks contained herein is copyrighted ©
1988-2004 by Thomas F. Giella and the Florida Space and Atmospheric Weather
Institute, all rights reserved. Reproduction of information herein is allowed
as long as proper credit is given.
Also space weather forecasting is still an inexact science. The discussions,
forecasts and outlooks are not official but for educational purposes only and
are subject to human error and acts of God, therefore no guarantee or warranty
implied.
73 & GUD DX,
Thomas F. Giella, KN4LF
Retired Space & Atmospheric Weather Forecaster
Plant City, FL, USA
Grid Square EL87WX
Lat & Long 27 58 33.6397 N 82 09 52.4052 W
kn4lf@arrl.net
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KN4LF Daily Solar Space Weather & Geomagnetic Data Archive:
http://www.kn4lf.com/kn4lf5.htm
KN4LF HF/MF Frequency Radio Propagation Theory Notes:
http://www.kn4lf.com/kn4lf8.htm
KN4LF Amateur & SWL Radio History: http://www.kn4lf.com/index.htm
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