[HCDX] KN4LF Daily HF/MF Radio Propagation Outlook #2003-08
[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]
[HCDX] KN4LF Daily HF/MF Radio Propagation Outlook #2003-08
KN4LF Daily HF/MF Radio Propagation Outlook #2003-08
http://www.kn4lf.com/kn4lf5.htm
Date Format is YY/MM/DD
Published Wednesday 03/08/29 At 1800 UTC
PAST 24 HOUR SOLAR, SPACE WEATHER AND GEOMAGNETIC INDICES-
Solar Flux Readings- 118 119 118
Sunspot Number- 146
X-Ray Solar Flares- C-3 M-0 X-0
Averaged Background X-Ray Flux- B3.4
Energetic Protons >10 MeV (10+0)- None
Coronal Hole #054 which became geo-effective on 03/08/28 may impact the geo-magnetic field with minor storm conditions Kp-5 by 03/08/30-31.
In the past 24 hour period the Ap index has been at active levels, with a peak at 28.
In the past 24 hour period the Kp index has been at active levels, with a peak at 4.
For the balance of this week we should see periods of unsettled Kp-3 to active Kp-4 geomagnetic conditions, with some minor storm Kp-5 conditions possible towards the end of the week.
Here are some general guidelines concerning correlation of propagation indices to actual expected HF/MF propagation conditions.
1.) Dropping indices numbers are better, except for solar flux on HF.
2.) For medium frequencies a solar flux under 150, under 100 better, 70 is best for E layer multi hop. Keep in mind though that the 10.7 cm (2800 mhz) solar flux index is not a "reliable" gauge of ionization in our atmosphere, as the energy of photons at this frequency is to low on the order of one million times.
2a.) For high frequencies a solar flux of 100 is okay, 150 better, above 200 best for F layer multi hop.
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 C1 for several days consecutively for 160/120 meters and less then B9 for MF broadcast band.
8.) No current STRATWARM alert.
9.) IMF Bz with a (+) positive sign, indicates a lesser chance of high latitude path auroral absorption/unpredictable refraction or scattering of MF RF signals, when the Kp is above 3.
PROPAGATION LESSON-
MF Propagation Overview-
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 propagation is poor the majority of the time, especially past approximately 1100 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, mainly out of phase. The out of phase extra-ordinary ray represents a 50% power loss on the receive end of a propagation path.
B.) Why? 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 most of the time. I say most of the time because at high latitudes, during the winter season and especially at the low part of a sunspot cycle, penetration of RF signals through the weakened D-layer and then refraction via the E-layer does occur. However a fly-in-the-ointment is the fact that the D-layer does not totally disappear at night. Many books that deal with radio wave propagation erroneously state that the D and E-layers disappear after sunset, totally incorrect thanks to Galactic Cosmic Rays.
C.) Background electromagnetic radiation in the 1 to 10 Angstrom range (Hard X-Rays) is the main source of ionization of the day time D-layer, with our Sun as the source of Cosmic Rays, also playing a role. 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 region, radiation at 10 to 100 Angstroms (Soft X-rays), as well as Cosmic Rays ionize the E region. Galactic Cosmic Rays are the reason that the E-layer is "always" present at night time, the D-layer also. 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.
D.) Recently I saw a post on the Topband Reflector E-List, lamenting the seemingly unexplainable differences in 160 propagation on certain paths from night-to-night. 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, 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 MF 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 MF broadcast is always affected first followed by the upper half of the AM broadcast band, then 160 and 120 meters. If you learn nothing else on this website, remember this simple explanation and pass the word.
To be continued.
PROPAGATION OUTLOOK-
We should continue to see periods of unsettled Kp-3 to active Kp-4 geomagnetic conditions, with some minor storm Kp-5 conditions possible towards the end of the weekend.
GLOBAL HF 3000-30000 KC PROPAGATION CONDITIONS EXPECTED-
Low Latitude- Good
Mid Latitude- Good
High Latitude- Fair To Good
GLOBAL MF 300-3000 KC PROPAGATION CONDITIONS EXPECTED-
Expect fair to good "Northern Hemisphere" domestic propagation conditions on east-west paths.
Expect poor to fair domestic conditions on north "TO" south paths in the "Northern Hemisphere" out to approximately 1100 miles.
Expect good to fair domestic conditions on south "TO" north paths in the "Northern Hemisphere" out to approximately 1100 miles.
Expect good "Southern Hemisphere" domestic propagation conditions on east-west paths.
Expect good then becoming fair domestic conditions on north "TO" south paths in the "Southern Hemisphere" out to approximately 1100 miles+
Expect fair conditions on south "TO" north paths in the "Southern Hemisphere" 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 should be poor to fair.
"High latitude" Southern Hemisphere (TA) Trans Atlantic, (TI) Trans Indian, (TP) Trans Pacific and cross equatorial propagation conditions in excess of approximately 3200 miles should be fair.
"Mid latitude" Northern Hemisphere (TA) Trans Atlantic, (TI) Trans Indian, (TP) Trans Pacific and cross equatorial propagation conditions in excess of approximately 3200 miles should be fair to 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 should be good.
"Low latitude" Northern Hemisphere (TA) Trans Atlantic, (TI) Trans Indian, (TP) Trans Pacific propagation conditions in excess of approximately 3200 miles should be good.
"Low latitude" Southern Hemisphere (TA) Trans Atlantic, (TI) Trans Indian, (TP) Trans Pacific propagation conditions in excess of approximately 3200 miles should be good.
Propagation Forecast Scales-
Excellent- +1 db Over S9 Or better
Good- S7-9
Fair- S4-6
Poor- S1-3
NOISE (QRN) OUTLOOK-
GLOBAL SATELLITE DERIVED LIGHTNING STRIKE DATA
(See Where Your QRN Is Coming From)
http://aviationweather.gov/gcd
During the 24 hour outlook period there will be "high" lightning induced QRN levels in low latitude areas of the Northern Hemisphere due to the proximity of the Inter-Tropical Convergence Zone (ITCZ) and tropical cyclones.
Northern hemisphere mid latitude regions can expect "moderate to high" lightning induced QRN tied to summer season thunderstorms, cold/warm/occluded fronts and associated extra-tropical cold core low pressure systems and tropical cyclones.
Northern hemisphere high latitude regions can expect "moderate" lightning induced QRN tied to summer season thunderstorms, cold/warm/occluded fronts and associated extra-tropical cold core low pressure systems.
During the outlook period there will be "high" lightning induced QRN levels in low latitude areas of the Southern Hemisphere due to the proximity of the Inter Tropical Convergence Zone (ITCZ) and tropical cyclones.
Southern hemisphere mid latitude regions can expect "moderate" lightning induced QRN, tied to winter season thunderstorms cold/warm/occluded fronts and associated extra-tropical cold core low pressure systems.
Southern hemisphere high latitude regions can expect "low" lightning induced QRN tied to winter season thunderstorms, cold/warm/occluded fronts and associated extra-tropical cold core low pressure systems.
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 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
73 & GUD DX,
Thomas F. Giella, KN4LF
Plant City, FL, USA
KN4LF Daily Solar Space Weather & Geomagnetic Data Archive &
Daily HF/MF Radio Propagation Outlook http://www.kn4lf.com/kn4lf5.htm
KN4LF HF/MF Radio Propagation Theory Notes
http://www.kn4lf.com/kn4lf8.htm
KN4LF 160 Meter Amateur Radio Resources & More
http://www.kn4lf.com/kn4lf.htm
Florida Space & Atmospheric Weather Institute
http://www.kn4lf.com/fsawi.htm
---
Outgoing mail is certified Virus Free Thanks To Grisoft AVG.
Checked by AVG anti-virus system (http://www.grisoft.com).
Version: 6.0.512 / Virus Database: 309 - Release Date: 8/19/2003
---[Start Commercial]---------------------
World Radio TV Handbook 2003 is out! Order it now!
http://www.amazon.com/exec/obidos/ASIN/0823059677/hardcoredxcom
---[End Commercial]-----------------------
________________________________________
Hard-Core-DX mailing list
Hard-Core-DX@xxxxxxxxxxxxxxxx
http://dallas.hard-core-dx.com/mailman/listinfo/hard-core-dx
http://www.hard-core-dx.com/
_______________________________________________
THE INFORMATION IN THIS ARTICLE IS FREE. It may be copied, distributed
and/or modified under the conditions set down in the Design Science License
published by Michael Stutz at http://dsl.org/copyleft/dsl.txt