KN4LF 7 Day Medium Frequency Radio Propagation Outlook
#2003-02 Published 11:00 PM EST 03/01/03 For 03/01/04-03/01/10.
PROPAGATION OUTLOOK-
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 to 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 to 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 OUTLOOK-
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 20%.
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 level ranged between
145 and 111. The 111 is the lowest daily solar flux value to occur since
January 1999!
During December 2002 the daily solar flux ranged between 245 and 111. During
2002 the daily solar flux ranged between 275 and 111. As a comparison, in
2001 it ranged between 294 and 123.
During the outlook period the daily solar flux values should range between
approximately 185 and 135.
During the previous 7 day period the daily "average" Background X-Ray Flux
level ranged between B2.6 and B1.7.
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.
Remember though that there are daily extremes of the Background X-ray flux
level. So even though the daily average might have been good at say B2.2,
the daily "extreme" maximum could have been C1.5, which would have been bad
and have cause a short period of increased D layer absorption.
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 no M class solar flares occurred.
Amazingly for the second week in a row, no sunspot group 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.
However sunspot group #'s 10224 and 10226 are due to rotate around the sun's
eastern limb by 03/01/08 and may be a source of renewed large M class solar
flare activity. Solar flare forecast during the outlook period.
C- 100%
M- 50%
X- 10%
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 20%.
During the previous 7 day period a small Coronal Hole was in a geo-effective
(Earth facing) position. It's related Solar Wind Stream impacted the (IMF)
for a three day period of time, with a Kp index of 4 (Active) to 5 (Minor
Storm).
During the outlook period a recurring Coronal Hole will rotate into
geo-effective (Earth facing) position and it's related Solar Wind Stream
will begin impacting the (IMF) on 03/01/06-07.
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 50%.
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 2028 UTC 03/01/03 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 03/01/03 at 2206 UTC the Bz was 2.4 nt north.
The Wang-Sheeley Interplanetary Magnetic Field (IMF) Model which predicts
the Sun's IMF polarity, forecasts a negative (-) polarity between
03/01/04-03/01/10.
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 past 7 day outlook period Stratospheric Warming did occur. 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 "probable".
As the SEC explains it:
Stratwarm: STRATWARM ALERT / SUNDAY / STRATWARM EXISTS INTENSE WARMING
COMTINUES IN THE UPPER STRATOSPHERE. WITHIN THE NEXT THREE DAYS: EASILY
WINDS AT 60N IN 1 HPA; REVERSED TEMPERATURE GRADIENT BETWEEN THE NORTH POLE
AND 60N FROM 10 TO 1 HPA; AN ELONGATION OF THE COLD POLAR VORTEX INTO TWO
CENTRES IN THE LOWER AND MID-STRATOSPHERE.
This occurence is tied to intense warming in the Stratosphere due to the
cold Circumpolar Vortex splitting and shifting in it's Arctic position.
A little related Meteorology:
Interrelated with the splitting and shifting of the Arctic Circumpolar
Vortex, is a Tropospheric level negative North Atlantic Oscillation (NAO)
and Pacific-North America Anomaly (PNA), mid and upper air height anomaly
pattern. This equates to a large high pressure ridge in Western North
America extending northward all the way into the Yukon region of Canada and
a deep trough in the Eastern North America, from the eastern U.S. extending
down into the Yucatan region of Mexico, with a second ridge in the western
North Atlantic Ocean. This pattern is also called a dual blocking ridge and
taps Siberian Arctic air, sending it across the North Pole into the eastern
2/3's of Canada and the U.S.,providing for very cold surface temperatures.
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
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
FL Meteorological & Climatic Institute:
http://www.kn4lf.com/sub/fmci.htm
FMCI 2002 Florida Daily Weather Discussion:
http://www.kn4lf.com/sub/fmci17.htm
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