[160m] KN4LF Medium Wave Radio Propagation Outlook #2002-3

[KN4LF, Thomas Giella]

KN4LF Medium Wave Radio Propagation Outlook
#2002-3 Published 11:00 PM EST 02/01/21 For 02/01/22-02/01/28

www.kn4lf.com

Note! Due to requests from our fellow radio brethren in the international
radio community I have adopted the date format of yy/mm/dd.

This outlook covers the upcoming CQ WW 160 Meter CW Contest which begins
02/01/25 through 02/01/27.

PREVIOUS FORECAST VERIFICATION-

Within outlook #2002-2 we discussed how solar region #'so 9773, 9775 and
9778 contained twisted delta class magnetic fields and were our best bet for
large M5 class or higher proton solar flares in coming days. Well the
magnetic fields collapsed shortly thereafter and my forecast of  an M5 class
or higher solar flare at 90% and X1 class or higher solar flare at 60%
during the upcoming 7 day outlook period did not verify.

I forecasted the solar flux to return to a peak above 250 (typo said 270)
but with the collapse of the magnetic structures of the above mentioned
sunspot groups, it only reached 241 but it was still high enough for some
lesser F2 openings?! on "magic band" 6 meters.

My forecast of an M 1-4 class solar flare at 100% did verify, as well as our
forecast of a Kp above 4.

We also forecasted High latitude (TA) Trans Atlantic and (TP) Trans Pacific
propagation to be poor on the AM broadcast band and fair on 160 meters.
improving to fair on the AM broadcast band and good on 160 meters, barring
any sudden proton event. This forecast did verify, with good to very good TA
and TP openings centered around UTC 17-18th. The opening to Florida on UTC
the 17th was the best so far this season. Unfortunately though a Kp index
above 3, tied to a coronal hole stream and short lived proton flux stream
above 10 MeV (10o), tied to a diffuse arriving proton ejection from an
unidentified sunspot group on the far side of the sun during the period UTC
18-19th, pretty much ended the good propagation.

As I've said on my "KN4LF Mediumwave Radio Propagation Theory Notes" sub
website, "The best way to look at medium wave frequencies as far as
propagation issues, is to accept the fact that the majority of the time
propagation is poor, especially past approximately 1050 miles, with
occasional short lived good periods as far as 3100 miles." Why? small upward
changes in night time D layer absorption ability, tied to proton streams
from C3 or higher solar flares, has a profound negative effect on medium
wave signal refraction.


PROTON FLUX-

Per our previous outlook, a short duration >10 MeV (10+1)  proton event
began on UTC 02/01/18 and ended UTC 02/01/19. More hard to predict short
lived proton flux streams above 10 MeV (10o), tied to a diffuse arriving
proton ejections from an unidentified sunspot group are possible.

A proton flux level above 10 MeV (10+1) creates elevated D absorption on
medium wave frequencies.

SOLAR FLUX-

Today's solar flux level is 225, after bottoming out at 188 on the 7th, the
first time below 200 since 02/08/07. A daily solar flux peak as high as 250
is possible in intervening days, which would be a boon to 6 meters ops.
looking for F2 propagation openings.

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. 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 increase
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
loss.

SUNSPOT REGIONS-

No solar regions currently contain twisted delta class magnetic fields which
would harbor potential for huge X1 class proton solar flares and our best
bet for smaller but still significant M5 class or higher proton solar flares
in coming days will be with solar region #'so 9785, 9788 and 9791.

All other solar regions are quiet and stable or slowly growing or decaying
at this moment.

SOLAR FLARES-

I place the likelihood of a C4 class or higher solar flare at 100%,  an M5
class or higher solar flare at 50% and X1 class or higher solar flare at
10%, during the upcoming 7 day outlook period.

An earthward facing M5 or higher class solar flare will move the proton flux
above 10o (10 MeV) and initiate large scale high latitude propagation path
absorption but even smaller C4 flares are the culprit behind hour to hour
and night to night variations in signal strength on the AM broadcast band
and 160 meters, both stateside and DX. as a transfer of increased density
and RF signal absorption from the day side D layer to night side of the
ionosphere occurs through high level neutral winds.

GEOMAGNETIC INDICES-

Per our previous outlook, the geomagnetic Kp index was elevated to a level
of 4 at times, with a peak of 5 during the previous 7 day period, as the
Earth entered a high-speed solar wind stream flowing from a coronal hole on
the Sun. No coronal holes are currently approaching geoeffective positions
but  a Kp index of 3 is still occurring due to residual effects from an old
coronal hole. Renewed elevation of the Kp index above 3 is possible  from
future coronal holes but is down from probable.


As the Kp index reaches 3 or higher, the aurora oval regions begin expanding
equatorward in magnetic latitude and generally begin have a possible
negative impact on mediumwave propagation. A Kp index of 5 or higher begins
to have a negative on high frequency shortwave propagation.

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, and polarization changes.

STRATOSPHERIC WARMING-

There is currently no stratospheric warming taking place and none is
expected during the 7 day period. However with Arctic air on the move again
in coming days across the north pole from Siberian Russia to North America
during the period, some increased D layer absorption of signals caused by
the stratospheric warming will may occur by day 10. Sporadic E  (Es)
propagation is also possible.

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 and moisture inversions are
involved with stratospheric warming. So it's possible that a mediumwave
signal could do any number of things when refracting off of a
temperature inversion, at any height.

Just as the E layer is the main refraction medium for medium wave signal
propagation within approximately 3100 miles, so is Sporadic E (Es). Like
stratospheric level warming and tropospheric level temperature and moisture
discontinuities, Sporadic E can depending on the circumstances absorb, block
and refract medium wave RF signals in an unpredictable manner.

OUTLOOK-

The bottom line for the next 7 days? Probably the best overall band
conditions for propagation of medium wave signals so far this season.

To start out expect good domestic propagation on the AM broadcast band and
good propagation on 160 meters out to approximately 3000 miles. High
latitude (TA) Trans Atlantic and (TP) Trans Pacific propagation will be fair
on the AM broadcast band and good on 160 meters.

High latitude (TA) Trans Atlantic and (TP) Trans Pacific propagation
conditions should then improve to good on the AM broadcast band and very
good on 160 meters, barring any sudden elevated proton event from an Earth
facing or diffuse far side of Sun solar flare or newly developed coronal
hole.

Most stateside AM broadcast band frequencies will contain co-channel North
and Central/South American stations, with northern latitude stations
dominating at times.

There will also be some occasional lightning induced QRN across the northern
hemisphere, with an endless series of winter time approaching cold fronts
and surface extra-tropical low pressure systems.


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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