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KN4LF DAILY LF/MF/HF/6M FREQUENCY RADIOWAVE PROPAGATION FORECAST #2008-35
Note! This propagation forecast is global in coverage. I’m publishing this forecast one day early due to personal obligations on Friday December 5, 2008.
Date Format is MM/DD/YYYY.
Published Thursday 12/04/2008 at 2100 UTC.
Valid 0000 UTC Saturday 12/06/2008 through 2359 UTC Friday 12/12/2008.
CONTEST INFORMATION-
Four contests are scheduled for the weekend of Saturday-Sunday 12/06-07/2008. The most popular ones are:
ARRL 160 Meter CW Contest and TARA RTTY Melee.
For more information on contests worldwide check out the WA7BNM website at http://www.hornucopia.com/contestcal/weeklycont.php and the SM3CER Contest Service website http://www.sk3bg.se/contest .
GLOBAL LF 30-300 KC PROPAGATION CONDITIONS EXPECTED WITH EMPHASIS ON LF AM BROADCAST BAND-
There exists a long distance “daytime” propagation medium between approximately 30-100 kc. The transmitted signal wave guides between the D layer and the surface of the Earth.
Some day time sky wave propagation does occur between approximately 100-300 kc via the E layer, especially at higher latitudes in the winter time and at the bottom of a solar cycle.
Reception is tied to the density of the D layer, as well as the E layer at radio Aurora altitude. Geomagnetic storming will suppress night time reception of signals but enhance day time reception of signals. High power broadcasters are more readily heard than low power ham radio signals.
Northern hemisphere- day time- FAIR night time- FAIR TO GOOD
Southern hemisphere- day time- FAIR night time- FAIR TO GOOD
Propagation Forecast Scales-
Excellent- +1 db Over S9 Or better
Good- S7-9
Fair- S4-6
Poor- S1-3
None- S0
GLOBAL MF 300-3000 KC PROPAGATION CONDITIONS EXPECTED WITH AN EMPHASIS ON 600 METERS, THE MF AM BROADCAST BAND, 160 METERS AND 120 METERS-
-Expect FAIR TO GOOD northern hemisphere domestic
propagation conditions on east-west paths out to approximately 1100 miles.
*Expect FAIR TO GOOD northern hemisphere domestic conditions on north to south
paths out to approximately 1100 miles.
+Expect FAIR TO POOR northern hemisphere domestic conditions on south to north paths out to approximately 1100 miles.
-Expect FAIR TO GOOD southern hemisphere domestic propagation conditions on east-west paths out to approximately 1100 miles.
*Expect FAIR TO GOOD southern hemisphere conditions on south to north paths out to approximately 1100 miles.
+Expect FAIR TO POOR southern hemisphere domestic conditions on north to south paths out to approximately 1100 miles.
-Expect FAIR TO GOOD equatorial domestic propagation conditions on east-west paths out to approximately 1100 miles.
High latitude northern hemisphere (TA) trans atlantic, (TI) trans indian, (TP) trans pacific and cross equatorial propagation conditions in excess of approximately 3200 miles will be FAIR TO GOOD.
High latitude southern hemisphere (TA) trans atlantic, (TI) trans indian, (TP) trans pacific and cross equatorial propagation conditions in excess of approximately 3200 miles will be FAIR TO GOOD.
Mid latitude northern hemisphere (TA) trans atlantic, (TI) trans indian, (TP) trans pacific and cross equatorial propagation conditions in excess of approximately 3200 miles will be GOOD.
Mid latitude southern hemisphere (TA) trans atlantic, (TI) trans indian, (TP) trans pacific and cross equatorial propagation conditions in excess of approximately 3200 miles will be GOOD
Low latitude northern hemisphere (TA) trans atlantic, (TI) trans indian, (TP) trans pacific propagation conditions in excess of approximately 3200 miles will be FAIR TO GOOD.
Low latitude southern hemisphere (TA) trans atlantic, (TI) trans indian, (TP) trans pacific propagation conditions in excess of approximately 3200 miles will be FAIR TO GOOD.
Equatorial region to northern hemisphere high latitude propagation conditions in excess of approximately 3200 miles will be FAIR TO GOOD.
Equatorial region to southern hemisphere high latitude propagation conditions in excess of 3200 miles will be FAIR TO GOOD.
Equatorial region to northern hemisphere mid latitude propagation conditions in excess of approximately 3200 miles will be GOOD.
Equatorial region to southern hemisphere mid latitude propagation conditions in excess of approximately 3200 miles will be GOOD.
Propagation Forecast Scales-
Excellent- +1 db Over S9 Or better
Good- S7-9
Fair- S4-6
Poor- S1-3
None- S0
GLOBAL F/F2 LAYER HF 3000-30000 KC PROPAGATION CONDITIONS EXPECTED-
Lower frequency HF (80-30 meters) propagation conditions are impacted in a negative manner not by variations in the maximum usable frequency (MUF) along a particular propagation path and time but rather due to geomagnetic storms that increase signal absorption via the E layer (the altitude of the radio aurora). Also increases in the lowest usable frequency (LUF) via D layer signal absorption due to elevated background solar flux levels and proton flux levels at energies greater than 10 MeV (10+0).
Higher frequency (20-10 meters) propagation conditions are impacted in a negative manner by variations in the maximum usable frequency (MUF) along a particular propagation path and time due to the current sunspot number and also due to geomagnetic storms. D layer signal absorption due to elevated proton flux at energies greater than 10 MeV (10+0) and elevated background solar flux levels, is usually but not always inconsequential on 20-10 meters.
Low: 0-25 degrees
Mid: 25-60 degrees
High: 60-90 degrees
Northern Hemisphere-
Low latitude- GOOD on 80-30 meters ham/90-31 meters shortwave broadcast.
Mid latitude- GOOD on 80-30 meters ham/90-31 meters shortwave broadcast.
High latitude- FAIR TO GOOD on 80-30 meters ham/90-31 meters shortwave broadcast.
Low latitude- GOOD on 20-17 meters ham/25-17 meters shortwave broadcast.
Mid latitude- GOOD on 20-17 meters ham/25-17 meters shortwave broadcast.
High latitude- FAIR TO GOOD on 20-17 meters ham/25-17 meters shortwave broadcast.
Low latitude- FAIR on 15 meters ham/13 meters shortwave broadcast.
Mid latitude- FAIR on 15 meters ham/13 meters shortwave broadcast.
High latitude- POOR TO FAIR on 15 meters ham/13 meters shortwave broadcast.
Low latitude- NONE TO POOR on 12-10 meters ham/11 meters shortwave broadcast.
Mid latitude- NONE TO POOR on 12-10 meters ham/11 meters shortwave broadcast.
High latitude- NONE on 12-10 meters ham/11 meters shortwave broadcast.
Southern Hemisphere-
Low latitude- GOOD on 80-30 meters ham/90-31 meters shortwave broadcast.
Mid latitude- GOOD on 80-30 meters ham/90-31 meters shortwave broadcast.
High latitude- FAIR TO GOOD on 80-30 meters ham/90-31 meters shortwave broadcast.
Low latitude- GOOD on 20-17 meters ham/25-17 meters shortwave broadcast.
Mid latitude- GOOD on 20-17 meters ham/25-17 meters shortwave broadcast.
High latitude- FAIR TO GOOD on 20-17 meters ham/25-17 meters shortwave broadcast.
Low latitude- FAIR on 15 meters ham/13 meters shortwave broadcast.
Mid latitude- FAIR on 15 meters ham/13 meters shortwave broadcast.
High latitude- POOR TO FAIR on 15 meters ham/13 meters shortwave broadcast.
Low latitude- NONE TO POOR on 12-10 meters ham/11 meters shortwave broadcast.
Mid latitude- NONE TO POOR on 12-10 meters ham/11 meters shortwave broadcast.
High latitude- NONE on 12-10 meters ham/11 meters shortwave broadcast.
Note!!! At times propagation conditions on 12-10 meters ham/11 meters shortwave will be FAIR to GOOD, via the less predictable Sporadic E (Es) and trans equatorial (TE) propagation modes which involves the F2/3 layer.
Propagation Forecast Scales-
Excellent- +1 db Over S9 Or better
Good- S7-9
Fair- S4-6
Poor- S1-3
None- S0
GLOBAL HF 50-54 MC (6 METER) PROPAGATION MODES AND STRENGTHS EXPECTED-
F2- NO
Sporadic E (Es)- YES/GOOD
Aurora E high latitude- YES/GOOD
Aurora E mid latitude- NO
Troposphere ducting- YES/GOOD
Meteor Scatter- NO. Excluding occasional random meteors.
For more information about meteor shower events check out http://stardate.org/nightsky/meteors .
Note!!! At times propagation conditions on 6 meters will be FAIR to GOOD, via the less predictable trans equatorial (TE) propagation mode which involves the F2/3 layer.
Propagation Forecast Scales-
Excellent- +1 db Over S9 Or better
Good- S7-9
Fair- S4-6
Poor- S1-3
None-S0
For global real time information concerning 6 meter band openings check out the VHFDX website at:
http://www.vhfdx.net/spots/map.php?Frec=MUF
A good source of information concerning 6 meter band openings via troposphere ducting in the U.S. is at:
http://www.dxinfocentre.com/tropo.html
GLOBAL NOISE (QRN) OUTLOOK-
U.S. near real time lightning strike data:
http://thunderstorm.vaisala.com/explorer.html
A global view of near real time lightning strike data:
http://webflash.ess.washington.edu
Northern hemisphere low latitude regions can
expect HIGH TO MODERATE thunderstorm lightning induced QRN tied to the winter
season proximity of cold/warm/occluded fronts and associated extra-tropical cold
core low pressure systems.
Northern hemisphere mid latitude regions can expect MODERATE thunderstorm
lightning induced QRN tied to winter season cold/warm/occluded fronts and
associated extra-tropical cold core low pressure systems.
Northern hemisphere high latitude regions can expect LOW thunderstorm lightning induced QRN tied to winter season cold/warm/occluded fronts and associated extra-tropical cold core low pressure systems.
Southern hemisphere low latitude regions can
expect HIGH TO MODERATE thunderstorm lightning induced QRN tied to the summer
season proximity of the Inter Tropical Convergence Zone (ITCZ) and tropical warm
core low pressure systems.
Southern hemisphere mid latitude regions can expect MODERATE thunderstorm
lightning induced QRN tied to summer season cold/warm/occluded fronts and
associated extra-tropical cold core low pressure systems and tropical warm core
low pressure systems.
Southern hemisphere high latitude regions can expect LOW thunderstorm lightning
induced QRN tied to summer season cold/warm/occluded fronts and associated
extra-tropical cold core low pressure systems.
Lightning QRN will hamper receive conditions on 160/120 and 80/75 meters in the northern hemisphere.
Lightning QRN will hamper receive conditions on 160/120 and 80/75 meters in the southern hemisphere.
SOLAR, SPACE WEATHER AND GEOMAGNETIC CONDITIONS EXPECTED-
No recurrent coronal holes will be in geo-effective (Earth facing) position.
Formation of a new geo-effective (Earth facing) coronal hole is possible during the forecast period but is nearly impossible to forecast.
Globally with the daily sunspot number at ~00 and vaguely related solar flux level at ~68, decreased F layer MUFs will negatively impact 6, 10, 12 and 15 meters.
There will be Sporadic E (Es) propagation openings on 6-160 meters.
In the northern hemisphere due to seasonal chemical changes in the F layer of the ionosphere and therefore higher MUFs, there will be east-west F layer propagation on 17 and 15 meters. There will be intermittent east-west propagation openings on 12 and 10 meters.
In the southern hemisphere due to seasonal chemical changes in the F layer of the ionosphere and therefore lower MUFs, there will be little east-west F layer propagation on 10, 12 and 15, meters. However there will be intermittent east-west propagation openings on 17 meters.
No sunspot groups will contain a twisted magnetic field capable of producing small sized C class, medium sized M class and large sized X class solar flares during the forecast period.
Formation of a new solar cycle 23 or 24 sunspot group is possible during the forecast period but is difficult to forecast. A tip off is a rising background solar flux level.
The following recurrent sunspot groups may rotate around the east limb of the Sun during the forecast period if they survived the back side transit- None.
Trans equatorial (TE) HF propagation between southern north and southern South America will occur, as well between southern Africa and Europe/West Asia and also Australia and Eastern Asia/Oceania.
There will be minor signal absorption on the MF AM broadcast band, 160 and 120 meters on high and low latitude propagation paths in the northern hemisphere. The minor absorption will degrade propagation conditions.
There will be minor signal absorption on the MF AM broadcast band, 160 and 120 meters on high and low latitude propagation paths in the southern hemisphere. The minor absorption will degrade propagation conditions.
There will be minor signal absorption on the LF band on high and low latitude paths in the northern hemisphere. The minor absorption will degrade propagation conditions.
There will be minor signal absorption on the LF band on high and low latitude propagation paths in the southern hemisphere. The minor absorption will degrade propagation conditions.
The following planetary geomagnetic conditions are forecasted:
12/06/2008 Kp 2-3 isolated 4, quiet to unsettled with isolated active geomagnetic conditions.
12/07-12/2008- Kp 0-3 quiet to unsettled geomagnetic conditions.
During the period quiet (Kp 0-2) geomagnetic conditions WILL OCCUR.
During the period unsettled (Kp- 3) geomagnetic conditions WILL OCCUR.
During the period active (Kp- 4) geomagnetic conditions MAY OCCUR.
During the period minor (Kp- 5) geomagnetic storming conditions WILL NOT OCCUR.
During the period moderate (Kp- 6) geomagnetic storming conditions WILL NOT OCCUR.
During the period strong (Kp- 7) geomagnetic storming conditions WILL NOT OCCUR.
During the period severe (Kp- 8) geomagnetic storming conditions WILL NOT OCCUR.
During the period extreme (Kp- 9) geomagnetic storming conditions WILL NOT OCCUR.
The chance of polar cap absorption on high latitude propagation paths due to excessive energetic protons >10 Mev (10+0) is LOW.
The chance of daylight side sudden ionosphere disturbances (SID) radio blackouts from solar flares is LOW.
The chance of a geoeffective (Earth facing) coronal mass ejection (CME) is LOW.
The chance of a partially geoeffective (Earth facing) coronal mass ejection (CME) is LOW.
The chance of a geoeffective (Earth facing) coronal hole is LOW.
Daily maximum/minimum solar flux index levels (SFI) should range between 70 and 67.
The probability of a small C class solar flare is LOW.
The probability of a large M class solar flare is LOW.
The probability of a huge X class solar flare is LOW.
When the interplanetary magnetic field (IMF) polarity is negative the probability of geomagnetic storming on Earth increases.
The NOAA/SWPC Wang-Sheeley-Arge model forecasts the interplanetary magnetic field (IMF) to be POSITIVE.
PROPAGATION LESSON-
From http://www.kn4lf.com/kn4lf8.htm
1.) Medium Frequency Radio Wave Propagation Overview-
Popular Myth- We don't understand medium frequency (300-529 kc long wave aviation and marine navigation beacon band, 530-1700 kc AM broadcast band, 160 meter amateur band and 120 meter shortwave tropical broadcast band) radio wave propagation conditions and therefore it can't be forecasted.
Fact- Yes
it can and is on a regular basis at KN4LF Daily LF/MF/HF/6M Frequency Radiowave
Propagation Forecast
http://www.kn4lf.com/kn4lf6.htm .
a.) Medium frequencies encompass 300 to 3000 kc. The simplest way to look at
medium frequencies with respect to propagation issues from a layman's point of
view, is to accept the fact that propagation is poor the majority of the time
(See definition #6. Electron Gyro Frequency Absorption), especially past
approximately 1250 miles (one refraction off of the E layer), with occasional
short-lived good periods as far as 3200 miles.
Medium frequency radio waves possess elliptical polarization, with the signal
splitting into ordinary and extra-ordinary rays. These rays can propagate in or
out of phase, more often out of phase. The out of phase extra-ordinary ray
represents a 50% power loss on the receive end of a path.
b.) Why is medium frequency propagation poor the majority of the time? D layer
absorption! At daytime the D layer which is at an approximate height of 30-60
miles in the mesosphere, totally absorbs medium frequency RF signals the
majority of the time. I say the majority of the time because at higher
latitudes, during the winter season and especially at the low part of a sunspot
cycle, daytime penetration of RF signals through the weakened D layer and then
refraction via the E layer and/or Sporadic E (Es) clouds does occur. Another
issue is the fact that the D layer does not totally
disappear at night. Many books that deal with wave propagation erroneously state
that the D and E layer's disappear after sunset, totally incorrect thanks to
Galactic X-Rays, Cosmic Rays and Lightning.
c.) Background electromagnetic radiation in the 1 to 10 Angstrom range (Hard
X-Rays) is a major source of ionization of the day time D layer, with our Sun as
the source of Cosmic Rays, also playing a role.
The following paragraph was contributed by Carl Luetzelschwab K9LA, a
scientist with a very good understanding of radiowave propagation.
.....A couple years ago I was playing with Proplab Pro on a one-hop 936km path
on 160m during daylight. I plotted absorption versus sunspot number. I expected
a nice monotonic increase as the sunspot number increased. But the plot showed
that absorption started at about 60dB at zero sunspots and was constant out to a
sunspot number of about 50. Then it started climbing, reaching 100dB at a
sunspot number of 150. This suggested that there was something other than hard
X-rays and cosmic rays as the source of daytime D region absorption. So I dug
into Davies 1990 (page 61), Hunsucker and Hargreaves (page 31), and Brekke (page
233). They all seem to point to the Lyman-alpha line of the solar spectrum at
1215 Angstroms ionizing NO as the main source of the quiet daytime D region. So
in terms of my absorption versus sunspot number plot, the flat portion up to a
sunspot number of 50 is probably due to the Lyman-alpha line ionizing NO. Then
above a sunspot number of 50 the hard X-rays start contributing as the Sun
becomes more active.....
Carl has produced two really good .pdf files on 160 meter propagation in 2003
and 2004. Read them here:
160 Meter Propagation
& Disturbances
To Propagation .
He also has a propagation website with allot of
good information on it at
K9LA's Amateur Radio
Propagation .
Also speaking of the ionosphere near and at the bottom of a +/- 11 year solar cycle, the ionosphere cools and shrinks in thickness. This shrinkage does increase D layer absorption and increase E layer and Sporadic E (Es) cloud refraction of medium frequency radio wave signals.
While I'm visiting the subject of electromagnetic radiation, our Sun emits electromagnetic radiation and matter, as a result of the nuclear fusion process. Electromagnetic radiation at wavelengths of 100 to 1000 Angstroms (Ultraviolet) ionizes the F layer, radiation at 10 to 100 Angstroms (Soft X-rays), as well as Cosmic Rays ionize the E layer. Galactic X-rays, Cosmic Rays and Lightning are the reason that the E layer is "always" present at night time, the D layer also. Background electromagnetic radiation in the 1 to 10 Angstrom range (Hard X-Rays) is a major source of ionization of the day time D layer,
Via K7RA's weekly ARRL Propagation Forecast Bulletin #46 published on November 9, 2007:
In last week's bulletin, Carl
Luetzelschwab K9LA said the closest measurement we have to radiation that
ionizes the F2 region is the GOES X-ray data at 0.1 to 0.8 nm. K9LA says that
is not correct- he received an e-mail from Michael Keane, K1MK, with the
following information:
"There does exist an instrument that measures solar EUV flux directly. That is
the SOHO Solar EUV Monitor (SEM) at
http://umtof.umd.edu/semflux. One SEM channel covers solar EUV in the
17-70 nm range. The other channel monitors just the 30.4 nm resonance line of
singly ionized helium. In most models, this 30.4 nm line by itself represents
25-50% of the energy input to the thermosphere/ionosphere."
Cosmic Rays are not rays at
all, but particles. They are ionized atoms, atoms with missing electrons ranging
from a single proton up to an iron nucleus and beyond but typically protons and
alpha particles, which have 2 protons and 2 neutrons. They originate from deep
space, being produced by a number of different sources, such as other stars, and
more exotic objects, such as supernova, which are exploding stars and their
remnants, neutron stars, black holes, and distant galaxies. Cosmic Ray particles
travel very close to the speed of light, and are highly energetic.
While on the subject of distant galactic objects, on 12/27/2004 more than a dozen spacecraft recorded the brightest event from outside the solar system ever observed in the history of astronomy. This gamma and x-ray producing super flare was emitted by a Magnetar star named SGR 1806–20. This star is an estimated 50,000 light years distant in the constellation Sagittarius on the far side of the Milky Way galaxy and obscured behind dense interstellar clouds. A similar event also occurred in 1998.
Upon arrival at Earth the X-rays were powerful enough to increase absorption in the D layer of our ionosphere and create a dayside Sudden Ionospheric Disturbance (SID) and a blackout of radio signals, amazing!!! To read more about this rare event check out this link at: http://skyandtelescope.com/news/article_1464_1.asp and http://www.sciencedaily.com/releases/2006/02/060221084628.htm .
d.) Recently I saw a post
on the Topband Reflector lamenting the seemingly unexplainable differences in
160 propagation on certain paths from night-to-night. is there a reasonable
explanation? Yes, unfortunately small increases in the density of the night time
D layer over short periods of time, caused by smaller solar flares and also the
general variability of the solar background X-Ray flux level of greater than A0,
can have a profound negative impact on propagation in the form of increased
absorption of high and even mid latitude medium frequency signal paths, both on
the medium frequency AM broadcast band, 160 and 120 meters. Why? It only takes
10 electron volts (ev) of energy to ionize the atmosphere and 1-10 Angstrom
x-ray photons energize the atmosphere at a factor of 100. This translates into D
layer absorption of medium frequency signals. The lower half of the medium
frequency broadcast is always affected first followed by the upper half of the
medium frequency AM broadcast band, then 160 and 120 meters. If you learn
nothing else on this website, remember this simple explanation and pass the
word.
e.) After much personal observational research over a 35 year period, I've come
to the conclusion that high and mid latitude TA and TP propagation paths tend to
open up only after an approximate three day period of time passes with an
energetic proton event of no greater then (10+0) on the medium frequency AM
broadcast band, 160 and 120 meters.
f.) Also there are daily
extremes of the background x-ray flux level. So even though the daily average
might have been pretty good at say A1.1, the daily "extreme" maximum could have
been C1.5, which would have been bad and would have caused a short period of
increased D layer absorption.
g.) Though high latitude paths on the day light side of the Earth are primarily
effected, night time high latitude paths can also be impacted by higher
intensity energetic proton events. This fact is still stubbornly opposed by some
otherwise very knowledgeable space weather physicists hung up on high latitude
threshold Riometer data tied to Polar Cap Absorption (PCA).
h.) Another wrench in the gears preventing consistent good propagation on medium
frequencies is related to Sporadic-D (Ds) absorption. Sporadic-D (Ds)
occurrences have an inter-relationship with brief but intense Sun based and
Galactic Cosmic Rays, extremely large positive cloud to ground lightning strokes
and interrelated Elves. Very large bursts of Gamma Rays have also been observed
to occur in conjunction with Sprites.
i.) Also there is another unavoidable problem, Magneto Ionic Power Coupling.
Antenna polarization plays a large role in the success of a long haul DX
contact. As a medium frequency RF signal traverses Earth's magnetic lines of
force in a perpendicular manner on high and mid latitude paths say between W3
land and SM, higher angle horizontally polarized signals are more readily
absorbed than lower angle vertically polarized signals. On other propagation
paths on the globe opposite results can be found, i.e., horizontally polarized
signals suffer less absorption on a propagation path between VK6 and W6 or S9
and W4.
Magneto Ionic Power Coupling expert NM7M
Robert Brown, PhD. has a good educational thread on this bugaboo on the May 2002
Topband Reflector. The thread can read in its entirety by going to this link
Topband Reflector May 2002 Archives Layer
.
Also an excellent but more technically oriented website covering 160 meter propagation and more is the "HF Propagation Tutorial" by NM7M Bob Brown, Ph.D. and hosted by ON4SKY Thierry Lombry and can be found at: http://www.astrosurf.com/luxorion/qsl-hf-tutorial-nm7m.htm .
j.) Geological effects such
as earthquakes and volcanic eruptions, as well as meteorological effects such as
troposphere originating
Internal Buoyancy/Gravity Waves (IBGW), stratospheric level Quasi-Biennial
Oscillations (QBO) and stratospheric warming (See definition #20 on
Stratospheric Warming) have a negative effect on medium frequency RF signals in
the form of small to medium increased absorption variations of medium frequency
RF signals via the D layer caused by traveling ionospheric disturbances (TID's).
Also temperature and moisture discontinuities (frontal inversions) can
refract/scatter medium frequency radio signals in unpredictable ways, most
notably on high transmitted RF power levels.
k.) The Quasi-Biennial Oscillation (QBO) is a wind shift in the equatorial
stratosphere, an oscillation from easterly to westerly and back on the time
scale of approximately two years (26 months) and is a source of Internal
Buoyancy/Gravity Waves (IBGW's) which create absorptive perturbations in the D
and E layers.
l.) A note, the E-valley/F layer ducting propagation mechanism does not exist
only during grayline periods. Internal Buoyancy/Gravity Waves (IBGW's) are a
source of the ducting mechanism and allow for occurrences of ducting along any
propagation path in total darkness. Measurement of the timing of arrival of
propagated medium frequency RF signals demonstrates the existence of the ducting
mechanism, versus conventional numerous E layer land/ocean surface hops which,
would allow for approximately 40 db of attenuation on a North America to Europe
propagation path.
Another note! When it comes to 160 meter vertical antenna's you can get a lower take off angle (TOA) from a full 1/4 wave vertical or electrical 1/4 wave tee vertical of 10-20 deg., versus ~30 deg. with the inverted L. However it's a moot point as the night time E layer MUF blocks 160 meter low angle transmitted radio signals from ever reaching the F layer to be propagated. So unlike with high frequency propagation, medium frequency propagation success does not require the lowest of take off angles.
Also higher take off angles of 30-40 deg. via the inverted L are better able to take advantage of the low signal loss E valley-F layer propagation duct mechanism, a form of Chordal Hop propagation.
m.) Yet another mechanism
to deal with that impacts medium frequency radio wave propagation in a negative
fashion is the D Layer Mid Winter Anomaly. It is a period of increased medium
frequency radio wave absorption at high and mid latitudes occurring in mid
winter and is associated with sudden stratospheric warming and the Quasi
Biennial Oscillation (QBO).
n.) The HAARP ionospheric research program, earthquakes, volcanic eruptions,
thunderstorms, lightning (especially positive cloud to ground strokes), elves,
tornadoes, hurricanes and even man made activities such as rocket launches
including the space shuttle, are all sources of (IBGW's). Many times I've heard
ham's lament that propagation was going to go to crap due to another space
shuttle launch, in a sense they are correct.
o.) Another issue facing
medium frequency AM broadcast Band DXers and 160 meter operators are lower
latitude propagation path absorption due to the Equatorial Ring Current. This
phenomenon acts as a repository for precipitated electrons and the end result is
unpredictable medium frequency RF signal blockage absorption and refraction.
Absorption is similar to higher latitude Auroral absorption.
p.) LF propagation theory is out of my realm from a standpoint of formal
education. Alan Melia G3YNK is studying LF propagation and has made some very
interesting observations and put forth some fascinating theories.
SPACE WEATHER SCALES-
Kp Indices-
G5 = Extreme Storm - Kp = 9
G4 = Severe Storm - Kp = 8
G3 = Strong Storm - Kp = 7
G2 = Moderate Storm - Kp = 6
G1 = Minor Storm - Kp = 5
Active - Kp = 4
Unsettled - Kp = 3
Ap Indices-
Ap 100-400 Severe Storm
Ap 50-99 Major Storm
Ap 30-49 Minor Storm
Ap 16-29 Active
Ap 8-15 Unsettled
Ap 0-7 Quiet
Correlation Of Kp To Ap Indices-
K- 0= A- 0
K- 1= A- 3
K- 2= A- 7
K- 3= A- 15
K- 4= A- 27
K- 5= A- 48
K- 6= A- 80
K- 7= A- 140
K- 8= A- 240
K- 9= A- 400
GENERAL
GUIDELINES CONCERNING CORRELATION OF PROPAGATION INDICES TO ACTUAL MF/HF
PROPAGATION CONDITIONS-
NOTE!!! The propagation indices "interpretations" are my personal intellectual
property. Therefore the propagation indices interpretations contained herein is
copyrighted © 1988-2008 by Thomas F. Giella, KN4LF, all rights reserved.
Reproduction of information herein is allowed without permission in advance as
long as proper credit is given.
1.) Dropping indices numbers are better.
2.) A solar flux of 150 or higher, 200+ best, for medium frequencies under 100, under 70 best.
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 medium 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 150 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).
7.) Background x-ray flux levels less than A1 for several days consecutively.
8.) No current STRATWARM alert.
9.) Interplanetary magnetic field (IMF) Bz with a (positive number) sign,
indicates a lesser chance of high latitude path Aurora absorption/unpredictable
refraction or scattering of medium frequency RF signals, when the Kp is above 3.
10.) A -20 or better towards a positive number Dst index during the recovery
time after a Geomagnetic Storm, as related to the equatorial ring current. A
positive number is best.
11.) Rising positive T index number. The T Index tracks with the F2 layer critical frequency (foF2) and sunspot number (SSN) and indicates the capability of the F2 layer to refract RF signals.
Standard Disclaimer-
Note! I use error prone RAW public domain data from the NOAA Space Environment Center, as well as other U.S. government organizations, to produce my propagation forecasts. This data is gathered and made public by the U.S. Government using taxpayer $$$. However the forecast that I produce from the RAW public domain data is my personal intellectual property. Therefore the propagation outlooks contained herein is copyrighted © 1988-2008 by Thomas F. Giella, KN4LF. Reproduction of and distribution of information herein is allowed without advanced permission as long as proper credit is given.
Also space weather forecasting is still an inexact science. The forecasts are not official but for hobby related purposes only and are subject to human error and acts of God, therefore no guarantee or warranty implied.
73 & God Bless,
Thomas F. Giella, KN4LF
Lakeland, FL, USA
kn4lf@arrl.net
KN4LF Daily Solar Space Weather & Geomagnetic Data Archive: http://www.kn4lf.com/kn4lf5.htm
KN4LF Daily LF/MF/HF/6M Frequency Radiowave Propagation Forecast & Archive: http://www.kn4lf.com/kn4lf6.htm
KN4LF 160 Meter Radio Propagation Theory Notes: http://www.kn4lf.com/kn4lf8.htm
LF/MF/HF/VHF Frequency Radiowave Propagation Email Reflector: http://montreal.kotalampi.com/mailman/listinfo/kn4lf Harmful Man Induced Climate Change (Global Warming) Refuted: http://www.kn4lf.com/globalwarminglie.htm