KN4LF 7 Day Medium Frequency Radio Propagation Outlook #2003-01
Published 8:00 PM EST 02/12/28 For 02/12/28-03/01/03.
PROPAGATION-
Expect fair to good domestic propagation conditions on east-west paths and
poor to fair on north south paths in the northern hemisphere out to
approximately 1050 miles.
Expect fair domestic propagation conditions on east-west paths and poor on
north south paths in the southern hemisphere out to approximately 1050
miles.
"High latitude" northern hemispheric (TA) Trans Atlantic, (TP) Trans Pacific
and cross equatorial propagation conditions in excess of approximately 3000
miles should be poor becoming fair.
"High latitude" southern hemispheric (TA) Trans Atlantic, (TP) Trans Pacific
and cross equatorial propagation conditions in excess of approximately 3000
miles should be poor.
"Mid latitude" northern hemisphere (TA) Trans Atlantic, (TP) Trans Pacific
and cross equatorial propagation conditions in excess of approximately 3000
miles should be fair becoming good.
"Mid latitude" southern hemisphere (TA) Trans Atlantic, (TP) Trans Pacific
and cross equatorial propagation conditions in excess of approximately 3000
miles should be fair.
"Low latitude" northern hemisphere (TA) Trans Atlantic, (TP) Trans Pacific
propagation conditions in excess of approximately 3000 miles should be good.
"Low latitude" southern hemisphere (TA) Trans Atlantic, (TP) Trans Pacific
propagation conditions in excess of approximately 3000 miles should be fair.
QRN-
During the outlook period there will be "high" lightning induced QRN levels
in low latitude areas of the northern hemisphere due to proximity of the
Inter Tropical Convergence Zone (ITCZ).
Northern hemisphere mid latitude regions can expect "moderate to
occasionally high" lightning induced QRN tied to cold season thunderstorms,
cold/warm/occluded fronts and associated extra-tropical cold core low
pressure systems. These weather systems are currently being enhanced by the
moderate level El Nino ocean water temperature anomaly.
Northern hemisphere high latitude regions can expect "low to occasionally
moderate" lightning induced QRN tied to cold season thunderstorms,
cold/warm/occluded fronts and associated extra-tropical cold core low
pressure systems. These weather systems are currently being enhanced by the
moderate level El Nino ocean water temperature anomaly.
During the outlook period there will be "high" lightning induced QRN levels
in low latitude areas of the southern hemisphere tied to warm season
thunderstorms and tropical systems.
Southern hemisphere mid latitude regions can expect "moderate to high"
lightning induced QRN, tied to warm season thunderstorms and tropical
systems.
Southern hemisphere high latitude regions can expect "moderate" lightning
induced QRN, tied to warm season thunderstorms and tropical systems.
Here are some general guidelines concerning correlation of space weather and
propagation indices to actual expected HF/MF propagation conditions.
1.) Dropping indices numbers are better.
2.) Solar flux under 150 okay, under 100 better, 70 is best for E layer
multi hop.
2a.) For high frequencies (HF) solar flux of 100 is okay, 150 better, above
200 best.
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 C2 for several days consecutively
for 160/120 meters and less then C1 for MF broadcast band.
8.) No current STRATWARM alert.
9.) IMF Bz with a negative sign, indicates a better chance of high latitude
path auroral absorption/unpredictable refraction or scattering of MF RF
signals, when the Kp is above 3.
SPACE WEATHER INDICES DURING THE PAST 7 DAY PERIOD, SPACE WEATHER INDICES
EXPECTED DURING THE 7 DAY OUTLOOK PERIOD AND EXPLANATIONS OF THEIR IMPACT ON
ANTICIPATED PROPAGATION CONDITIONS.
ENERGETIC PROTON FLUX-
During the previous 7 day period no elevated energetic proton flux events of
10 MeV (10+0) occurred.
During the 7 day outlook period the probability of an elevated energetic
proton flux event >10 MeV (10+0) is placed at 10%.
An elevated energetic proton flux level greater then (10+0) on 160 meters
and greater then (10-1) on the medium frequency broadcast band creates
noticeably increased winter time day and year round night time D layer
absorption of medium wave frequencies, especially on high latitude
propagation paths but it can also negatively impact mid latitudes, depending
on the intensity of the event.
Elevated energetic proton events too small to be categorized as a Polar Cap
Absorption event (PCA) can still impact high and mid level medium frequency
propagation paths in the form of excessive D layer absorption. This fact is
still stubbornly opposed by some otherwise very knowledgeable space weather
physicists over dependent on high latitude threshold Riometer readings.
((((Note, high latitude medium frequency radio propagation paths can still
be disturbed for days and up to weeks, following the end of an official >10
MeV (10+0) proton event.))))
SOLAR FLUX-
During the previous 7 day period the daily solar flux levels ranged between
198 and 115. The 115 is the lowest daily solar flux value to occur since
September 1999!
During the outlook period the daily solar flux values should range between
approximately 150 and 110.
Elevated background X-ray flux levels can impact propagation of medium
frequency signals in a negative manner. Background X-ray flux levels of C1
or greater creates increased D-layer absorption of 160 and 120 meter signals
and B9 or greater creates increased D-layer absorption of AM broadcast band
signals.
High solar flux values are generally considered to be detrimental to
propagation of medium frequency signals both domestic and Trans Atlantic
(TA) & Trans Pacific (TP), as more absorption can be present via the
transmitted signals' two trips through the D layer at the takeoff and
arrival points.
Most "strong" longer haul medium frequency DX signals in excess of 3000
miles is via the E Valley-F layer ducting and/or Chordal Hop propagation
modes. Therefore high solar flux values can aid in long haul medium
frequency propagation paths in excess of 3000 miles, as a high solar flux
value ensures a strong F layer part of the E Valley-F layer duct or Chordal
Hop propagation 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 Valley-F layer ducting mechanism. In a sense the E
Valley-F layer duct is closed on one or both ends of a propagation path and
the transmitted MF RF signal only propagates between the E layer and
land/ocean surface, with a higher angle and more loss.
SOLAR FLARES & SUNSPOT GROUP REGIONS-
During the previous 7 day period only one M class solar flares occurred. Ths
was an M1.1 solar flare on 02/12/22 at 0244-0304 UTC.
Amazingly no sunspot regions currently harbor even beta-gamma class magnetic
signatures that would harbor energy for large M class solar flares. Only
isolated M class solar flares are possible.
Solar flare forecast during the seven day period.
C- 100%
M- 30%
X- 01%
A C4 or higher class solar flare "can" elevate the proton flux above 10 MeV
(10+0) and initiate large scale high and mid latitude propagation path
absorption on the AM broadcast band, 160 and 120 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. Unfortunately even smaller C3 solar flares can create hour to
hour and night to night variations in signal strength on medium frequencies.
High and mid latitude Trans Atlantic (TA) and Trans Pacific (TP) propagation
paths tend to open up after a significant period of time passes without an
elevated energetic proton event of >10 MeV (10+0). This fact is still
stubbornly opposed by some otherwise very knowledgeable space weather
physicists over dependent on high latitude threshold Riometer readings.
Openings also occur when the solar background x-ray level falls back to
below C2 for 160 and 120 meters and below C1 for the AM broadcast band.
CORONAL MASS EJECTIONS/IONOSPHERIC STORMS/VISIBLE AURORA-
During the previous 7 day period no geo-effective (Earth facing) Coronal
Mass Ejections occurred. During the outlook period the probability of a
geo-effective (Earth facing) Coronal Mass Ejection (CME) is placed at 10%.
During the previous 7 day period a large recurring Coronal Hole was in a
geo-effective (Earth facing) position. It's related Solar Wind Stream
impacted the (IMF), for and extended period of time with a Kp index of 4
(Active) to 5 (Minor Storm), peaking at 6 (Moderate Storm) on 02/12/27.
During the outlook period the above mentioned large Coronal Hole will remain
in geo-effective (Earth facing) position and it's related Solar Wind Stream
will continue to impact the (IMF) for another 48-72 more hours.
The following related geomagnetic conditions will occur:
During the outlook period the probability of unsettled (Kp-3) geomagnetic
conditions is placed at 100%.
During the outlook period the probability of active (Kp-4) geomagnetic
conditions is placed at 90%.
During the outlook period the probability of at least a minor ionospheric
storm (Kp-5)(G1) is placed at 60%.
During the outlook period the probability of at least a moderate ionospheric
storm (Kp-6)(G2) is placed at 30%.
During the outlook period the probability of at least a strong ionospheric
storm (Kp-7+)(G3+) is placed at 20%.
G5 = Extreme - Kp = 9
G4 = Severe - Kp = 8
G3 = Strong - Kp = 7
G2 = Moderate - Kp = 6
G1 = Minor - Kp = 5
Active - Kp = 4
Unsettled - Kp = 3
During the outlook period the probability of a visible high latitude Aurora
display is placed at 100%, mid latitude 60%.
The Aurora Index at 1812 UTC 02/12/28 is a 7.
The NOAA POES historical database that was used to construct statistical
patterns of auroral power flux for each of the 10 levels of auroral activity
as defined by total power dissipation as illustrated in the following table.
Total Power Dissipation in Gigawatts/Activity Index Kp Index/Aurora Index
04-06/3/1+
10-16/5/2+
24-39/7/3+
61-96/9/5-
On 02/12/28 at 2046 UTC the Bz was 1.8 nt south.
The Wang-Sheeley Interplanetary Magnetic Field (IMF) Model which predicts
the Sun's IMF polarity, forecasts a positive (+) polarity between
02/12/28-03/01/03.
When the polarity of the IMF is negative a visible mid latitude Aurora
display is likely when a CME strikes the Earth's magnetic field. When the
polarity of the IMF is positive a visible mid latitude Aurora display is
unlikely as a CME strikes the Earth's magnetic field.
A Geomagnetic or Ionospheric Storm is a worldwide disturbance of the earth's
magnestosphere induced by the Sun's interplanetary magnetic field (IMF),
distinct from regular diurnal variations.
A Coronal Mass Ejection is the name given to an ejection of a large amount
of matter from the Sun's outer atmosphere or corona. These ejections
typically comprise millions of tons of material in the form of charged
particles, and can be seen because the material reflects sunlight. When one
of these ejections is directed towards the Earth (or conversely, directly
away from the Earth), it looks like a roughly circular "halo" surrounding
the Sun.
The "Halo CME's" then are those CME's which are more likely to impact the
Earth than those which are shot out at right angles to the Earth-Sun line.
Energetic protons emitted during CME's play a major role in increased day
time and night-time D-layer absorption of mediumwave frequencies.
Coronal Mass Ejections were once thought to be completely initiated by solar
flares. However it is now known that many (CME's) are not associated with
Solar Flares. If a (CME) collides with the Earth, it can excite a
Geomagnetic Storm if the polarity of the IMF has a negative sign. We must be
vigilant in watching for geoeffective (CME's), in order to not be caught by
surprise with a seemingly sudden and unexpected Geomagnetic Storm.
As the Kp index reaches 3-4, the aurora oval begins expanding equatorward in
magnetic latitude and generally begins having a negative impact on high
latitude medium frequency propagation paths. A Kp index of 5 or higher
begins to have a negative impact on high latitude high frequency shortwave
propagation paths. However at times skewed path propagation conditions can
compensate for high latitude propagation path auroral absorption.
STRATOSPHERIC WARMING-
During the outlook period increased winter like day and year round night
time D layer absorption of medium frequency signals tied to stratospheric
warming in the northern hemisphere is possible, due to a large scale
movement of Arctic air across the North Pole from Siberian Russia into
Canada.
In the nearer term of 7-14 days we will return to a negative North Atlantic
Oscillation (NAO) and Positive West Negative East (PNA) upper air height
anomaly pattern. This means a big ridge in the west all the way into the
Yukon region of Canada and a deep trough in the eastern U.S.down into the
Yucatan region of Mexico and another ridge in the western North Atlantic
Ocean. This pattern is also called a dual blocking ridge. This pattern taps
Siberian Arctic air across the North Pole and sends it rushing south,
increasing the chances of stratospheric warming.
As the stratosphere lies below the ionosphere, which is at mesosphere and
thermosphere height, you would not expect to see stratospheric warming
effect medium frequency propagation in any way BUT medium frequency signals
do propagate off of temperature inversions and moisture discontinuities and
a temperature inversion is involved with stratospheric warming. So it's
probable that a medium frequency signal could do any number of things when
scattering off of a temperature inversion, at any height. Unfortunately
though some otherwise very knowledgeable Physicists stubbornly resist this
concept.
Also stratospheric warming (STRATWARM) has a negative effect on medium
frequency propagation, due to increasing medium frequency radio wave
absorption by the D layer, via upward propagating Internal Gravity Waves
(IGW).
This phenomenon also occurs in southern hemisphere winter but seems to be
less pronounced.
73,
Thomas Giella,
KN4LF/NNN0HUS-T
Plant City, FL, USA
KN4LF 160 Meter Amateur Radio Resources And More:
http://www.kn4lf.com
KN4LF Daily Solar Space Weather Geomagnetic Data Plus MF Propagation
Outlook:
http://www.kn4lf.com/kn4lf5.htm
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