[160m] Mediumwave Propagation Outlook #2002-1 Published 11:00 PM EST

[KN4LF, Thomas Giella]

Outlook #2002-1 Published 11:00 PM EST 01/04/02 For 01/05/02-01/11/02
http://www.kn4lf.com/kn4lf5.htm

The long running >10 MeV (10+3) proton event that began on 01/30/01 at
approximately 0245 UTC and peaked at 108 pfu on 01/31/01 at approximately
1620 UTC, continues to slowly decay and barring any new earthward directed
M5 class or higher solar flares should reach a 10o-1 level within 48 hours.
A proton flux level above 10 MeV (10+1) creates increased D absorption on
medium wave frequencies.

Solar flux values are still in excess of 200 with a peak of 285 on 01/27/01.
Ver recent values have in the low 200's and slowly falling. We may be on a
trend of seeing the daily solar flux level fall below 200 for the first time
since 11/28/01 when it dropped to 199. We have not seen a daily solar flux
value below 150 since 08/19/01 when it dropped to 145.

High solar flux values are generally considered to be detrimental to
propagation of medium wave signals both domestic and TA/TP, as more
absorption can be present via the transmitted signals' two trips through the
D layer near sunrise and sunset. Most long haul medium wave DX signals in
excess of 3000 miles is via the E/F layer ducting and/or E valley
propagation modes. Therefore high solar flux values can aid in long haul
medium wave propagation paths in excess of 3000 miles, as a high solar flux
value ensures a strong E and F layer duct mechanism. However high solar
activity in the form of increased ionization created by ultraviolet and
x-ray radiation can fill in the E Valley region and interfere with the E/F
layer ducting mechanism. In a sense the E/F layer duct is closed and the
transmitted RF signal only propagates between the E layer and land/ocean
surface, with a higher angle and more hops, therefore more loss.

Solar region # 9767 is basically unchanged and represents the best chance
for an M class or higher proton solar flare. This sunspot group was
responsible for the X3 class proton solar flare on 12/28/01. Solar region #
9773 is rotating into view at the northeast limb and is also a solar flare
threat in future days. All other solar regions are quiet and stable or
slowly decaying at this moment.

The geomagnetic Kp index may be elevated to a 3 at times especially before
01/08/02. As the Kp index reaches 3 or higher, the aurora oval regions begin
expanding southward in magnetic latitude and generally begin to have a
possible negative impact on high latitude mediumwave propagation paths. A Kp
index of 5 or higher begins to have a negative on high latitude shortwave
propagation paths. If the path over which you are communicating lies along
or inside one of the auroral ovals, you will experience degraded propagation
in one of several different forms: strong signal absorption, brief periods
of strong signal enhancement, which is mainly caused by tilts in the
ionosphere that allow signals to become focused at your location or very
erratic signal behavior in the form of strong and rapid fading, etc., caused
by a variety of effects such as multipathing, anomalous and rapid variations
in absorption, non-great-circle propagation (skewed) and polarization
changes.

Some continued increased D layer absorption of signals caused by
stratospheric warming will also effect the AM broadcast band and 160 meters
during the outlook period. As the stratosphere lies below the ionosphere,
which is at mesosphere and thermosphere height, you might not normally
expect to see stratospheric warming effect the AM broadcast band and 160
meter propagation in any way BUT mediumwave frequency signals do refract off
of temperature inversions and moisture discontinuities and temperature
inversions are involved with stratospheric warming. So it's possible that a
mediumwave signal signal could do any number of things when refracting off
of a temperature inversion, at any height.

I place the likelihood of an M 1-4 class solar flare at 100%, an M5 class or
higher solar flare at 70% and X1 class or higher solar flare at 30% during
the upcoming 7 day outlook period.

The bottom line for the next 7 days? Good stateside propagation on the
broadcast band and 160 meters out to approximately 3100 (two hops) miles,
with high latitude (TA) Trans Atlantic and (TP) Trans Pacific propagation
poor on the AM broadcast band and fair on 160 meters and improving to fair
on the AM broadcast band and good on 160 meters, barring any sudden proton
events. There will also be some occasional lightning induced QRN across
North America, with a series of approaching cold fronts and surface
extra-tropical low pressure systems. Most stateside AM broadcast band
frequencies will contain co-channel North and Central/South American
stations, with either dominating at times.


73,
Thomas Giella, KN4LF

Plant City, FL
Grid Square- EL88wx
CQ Zone 5
ITU Zone 8

KN4LF 160 Meter Amateur Radio Resources And More:
http://www.kn4lf.com

Florida Meteorological & Climatic Institute:
http://64.176.157.9/sub/fmci.htm

Giella Website Designs:
http://www.giellawoodsignandwebsitedesigns.com


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