2008
KN4LF DAILY LF/MF/HF/6M
FREQUENCY RADIOWAVE PROPAGATION FORECAST #17

KN4LF DAILY LF/MF/HF/6M FREQUENCY RADIOWAVE PROPAGATION FORECAST UPDATE #2008-17A

Date Format is MM/DD/YYYY.

Published Monday 04/28/2008 at 1500 UTC

I'm sure that this is old news for most by now but I was so busy over the weekend I did not have a chance to report on the event until now.

On Saturday 04/26/2008 a solar filament collapsed near 8 degrees north and 8 degrees east and produced a small B3.8 class solar flare beginning at 1408 UTC. The solar flare produced a weak and slow (velocity 466 km/s) full halo coronal mass ejection (CME).

A solar filament is a relatively cool and dense ribbon of gas held together by solar magnetic fields. From Earth they usually appear as relatively dark lines across the face of the Sun. At times the magnetic lines holding the filament open up creating a tremendous eruption similar in size and impact of a coronal mass ejection (CME). The collapse of solar filament is virtually impossible to forecast.

The geoeffective (Earth facing) CME should begin impacting Earth's geomagnetic field on 04/29/2008 in the form of unsettled (Kp-3) to active (Kp-4) geomagnetic conditions. A brief and minor geomagnetic storm (Kp-5) is possible at high latitudes.

Normally I would not report on a weak event such as this but as we have not seen an Earth directed CME in a long long time it is newsworthy.
 

KN4LF DAILY LF/MF/HF/6M FREQUENCY RADIOWAVE PROPAGATION FORECAST #2008-17

Date Format is MM/DD/YYYY.

Published Friday 04/25/2008 at 1630 UTC Valid Saturday-Friday 04/26-05/02/2008

CONTEST INFORMATION-

5 contests are scheduled for the weekend of Saturday-Sunday 04/26-27/2008.

The most popular one is the SP DX RTTY Contest.

For more information on contests worldwide check out the WA7BNM website at http://www.hornucopia.com/contestcal/weeklycont.php .

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 Night Time- POOR 04/26-27/2008, FAIR 04/28-30/2008, POOR 05/01-02/2008.

Southern Hemisphere Night Time- POOR 04/26-27/2008, FAIR 04/28-30/2008, POOR 05/01-02/2008.

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 THE MF AM BROADCAST BAND, 160 METERS AND 120 METERS-

-Expect POOR TO FAIR Northern Hemisphere domestic propagation conditions on east-west paths out to approximately 1100 miles.
 
*Expect POOR TO FAIR 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 POOR Southern Hemisphere domestic propagation conditions on east-west 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 Southern Hemisphere conditions on south to north paths out to approximately 1100 miles.

 -Expect FAIR 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 POOR 04/26-27/2008, FAIR 04/28-30/2008, POOR 05/01-02/2008.

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 POOR 04/26-27/2008, FAIR 04/28-30/2008, POOR 05/01-02/2008.

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 POOR 04/26-27/2008, FAIR 04/28-30/2008, POOR 05/01-02/2008.

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 FAIR 04/26-27/2008, GOOD 04/28-30/2008, FAIR 05/01-02/2008.

Low latitude Northern Hemisphere (TA) Trans Atlantic, (TI) Trans Indian, (TP) Trans Pacific propagation conditions in excess of approximately 3200 miles will be POOR 04/26-27/2008, FAIR 04/28-30/2008, POOR 05/01-02/2008.

Low latitude Southern Hemisphere (TA) Trans Atlantic, (TI) Trans Indian, (TP) Trans Pacific propagation conditions in excess of approximately 3200 miles will be FAIR 04/26-27/2008, GOOD 04/28-30/2008, FAIR 05/01-02/2008.

Equatorial region to Northern Hemisphere high latitude propagation conditions in excess of approximately 3200 miles will be POOR 04/26-27/2008, FAIR 04/28-30/2008, POOR 05/01-02/2008.

Equatorial region to Southern Hemisphere high latitude propagation conditions in excess of 3200 miles will be FAIR 04/26-27/2008, GOOD 04/28-30/2008, FAIR 05/01-02/2008.

Equatorial region to Northern Hemisphere mid latitude propagation conditions in excess of approximately 3200 miles will be POOR 04/26-27/2008, FAIR 04/28-30/2008, POOR 05/01-02/2008.

Equatorial region to Southern Hemisphere mid latitude propagation conditions in excess of approximately 3200 miles will be FAIR 04/26-27/2008, GOOD 04/28-30/2008, FAIR 05/01-02/2008.

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

Low Latitude- POOR 04/26-27/2008, FAIR 04/28-30/2008, POOR 05/01-02/2008 on 80-30 meters ham/90-31 meters shortwave.

Mid Latitude- FAIR 04/26-27/2008, GOOD 04/28-30/2008, FAIR 05/01-02/2008 on 80-30 meters ham/90-31 meters shortwave.

High Latitude- POOR 04/26-27/2008, FAIR 04/28-30/2008, POOR 05/01-02/2008 on 80-30 meters ham/90-31 meters shortwave.

Low Latitude- FAIR TO GOOD on 20-17 meters ham/25-17 meters shortwave.

Mid Latitude- FAIR TO GOOD on 20-17 meters ham/25-17 meters shortwave.

High Latitude- POOR TO FAIR on 20-17 meters ham/25-17 meters shortwave.

Low Latitude- POOR TO FAIR on 15 meters ham/13 meters shortwave.

Mid Latitude- POOR TO FAIR on 15 meters ham/13 meters shortwave.

High Latitude- POOR on 15 meters ham/13 meters shortwave.

Low Latitude- NONE TO POOR on 12-10 meters ham/11 meters shortwave.

Mid Latitude- NONE TO POOR on 12-10 meters ham/11 meters shortwave.

High Latitude- NONE TO POOR on 12-10 meters ham/11 meters shortwave.

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 (TEP) propagation modes.

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- YES/GOOD

Auroral E- YES/GOOD

Tropospheric Ducting- YES/GOOD

Meteor Scatter- NO

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 tropospheric 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 MODERATE TO HIGH thunderstorm lightning induced QRN tied to the Spring season proximity of cold/warm/occluded fronts and associated extra-tropical cold core low pressure systems, as well as the Inter Tropical Convergence Zone (ITCZ).

Northern Hemisphere mid latitude regions can expect MODERATE TO HIGH thunderstorm lightning induced QRN tied to Spring season cold/warm/occluded fronts and associated extra-tropical cold core low pressure systems.
 
Northern Hemisphere high latitude regions can expect MODERATE thunderstorm lightning induced QRN tied to Spring 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 Fall season proximity of cold/warm/occluded fronts and associated extra-tropical cold core low pressure systems, Inter Tropical Convergence Zone (ITCZ) and tropical warm core low pressure systems.

Southern Hemisphere mid latitude regions can expect HIGH TO MODERATE thunderstorm lightning induced QRN tied to Fall season cold/warm/occluded fronts and associated extra-tropical cold core low pressure systems, as well as tropical warm core low pressure systems.

Southern Hemisphere high latitude regions can expect MODERATE TO LOW thunderstorm lightning induced QRN tied to Fall season cold/warm/occluded fronts and associated extra-tropical cold core low pressure systems.

The lightning QRN will hamper receive conditions on 160/120, 80/75, 40/41 and 30/31 meters in the Northern Hemisphere.

The lightning QRN will hamper receive conditions on 160/120, 80/75 and 40/41 in the Southern Hemisphere.

END OF FORECAST

SOLAR, SPACE WEATHER AND GEOMAGNETIC CONDITIONS EXPECTED-

For 04/26-05/02/2008-

Recurrent transequatorial Coronal Hole #322 (old #319) will become geo-effective (Earth facing) and the associated high velocity solar wind stream emanating from it will be strong (>700 m/s) and the impact to propagation conditions moderate (Kp-6).

Globally with the daily sunspot number at ~00 and vaguely related solar flux level at ~70, decreased F layer MUFs will negatively impact 6, 10, 12, 15, 17 and 20 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 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.

In the Southern 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, 15 and 12 meters. There will be intermittent east-west propagation openings on 10 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.

The following old sunspot groups may rotate around the east limb of the Sun during the forecast period if they survived the back side transit- None

Some new solar cycle 23/24 sunspot groups may form but it is nearly impossible to forecast. A tip off is a rising background solar flux level.

Trans Equatorial (TEP) HF propagation between North and South America will occur, as well between southern Africa to Europe/West Asia and also Australia to Eastern Asia/Oceania.

There will be minor to moderate signal absorption on the MF AM broadcast band, 160 and 120 meters on high, mid and low latitude propagation paths in the Northern Hemisphere. The minor to moderate 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 to moderate signal absorption on the LF band on high, mid and low latitude paths in the Northern Hemisphere. The minor to moderate 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 will occur:

04/26/2008- Kp 4-1. 04/27-30/2008 Kp 3-0, 05/01-02/2008 Kp 5-3, isolated 6.

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 WILL OCCUR.

During the period minor (Kp- 5) geomagnetic storming conditions WILL OCCUR.

During the period moderate (Kp- 6) geomagnetic storming conditions MAY 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 Ionospheric 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 HIGH.

Daily maximum/minimum solar flux index levels (SFI) should range between 72 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 NEGATIVE.

PAST SOLAR, SPACE WEATHER AND GEOMAGNETIC CONDITIONS-

For 04/19-25/2008-

Per forecast #2008-16 the period saw propagation conditions ranging from poor to fair on LF, MF and HF frequencies.

Globally with the daily sunspot number as low as 00 and vaguely related solar flux level as low as 66, the Maximum Usable Frequency (MUF) did not rise high enough to give 6, 10, 12, 15, 17 and 20 meters a boost in propagation conditions via the F2 layer.

The following propagation modes and strengths were observed on 6 meters.

F2- NO

Sporadic E- YES/GOOD

Auroral E- YES/GOOD due to a high latitude K index of 6.

Tropospheric Ducting- YES/GOOD

Meteor Scatter- YES/GOOD due to the Lyrids meteor shower on 04/21-22/2008

A good source of information on meteor showers is Star Date Online at: http://stardate.org/nightsky/meteors

Propagation Forecast Scales-
Excellent- +1 db Over S9 Or better
Good- S7-9
Fair- S4-6
Poor- S1-3

None-S0

There were some 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 lower MUFs, there was little significant east-west F layer propagation on 15, 12 and 10 meters. There were intermittent east-west propagation openings on 17 meters.

In the Southern Hemisphere due to seasonal chemical changes in the F layer of the ionosphere and therefore higher MUFs, there was significant east-west F layer propagation on 17 and 15 meters. There were intermittent east-west openings on 12 and 10 meters.

There were 5 days with visible sunspot groups and 2 days without visible sunspot groups on the Earth facing side of the Sun. Sunspot groups had been visible on the far side of the Sun via the SOHO GONG holographic image.

No sunspot groups had a twisted magnetic field capable of producing small sized C class, medium sized M class and large sized X class solar flares.

During the period the following solar cycle 23 sunspot groups were visible-

10991 (old 10989) with a beta magnetic field.

10992 with a beta magnetic field.

Recurrent northern hemisphere Coronal Hole #320 (old #317) became geo-effective (Earth facing) during the forecast period and the associated high velocity solar wind stream emanating from them was moderate (665 m/s) and the impact to propagation conditions minor (Kp-5).

Recurrent transequatorial Coronal Hole #321 (old #318) became geo-effective (Earth facing) during the forecast period and the associated high velocity solar wind stream emanating from them was moderate (622 m/s) and the impact to propagation conditions minor (Kp-4).

Trans Equatorial (TEP) HF propagation between North and South America occurred, as well as between southern Africa to Europe/West Asia and also Australia to Eastern Asia/Oceania.

There was moderate signal absorption on the MF AM broadcast band, 160 and 120 meters on high and low latitude propagation paths in the Northern Hemisphere. The moderate absorption degraded propagation conditions.

There was minor absorption on the MF AM broadcast band, 160 and 120 meters on high, medium and low latitude propagation paths in the Southern Hemisphere. The minor absorption degraded propagation conditions.

There was moderate signal absorption on the LF band on high and low latitude paths in the Northern Hemisphere. The moderate absorption degraded propagation conditions.

There was minor signal absorption on the LF band on high, medium and low latitude propagation paths in the Southern Hemisphere. The minor absorption degraded propagation conditions.

High lightning QRN (static) hampered receive conditions on 160/120, 80/75, 40/41, 30/31 and 20/22 meters in the Northern Hemisphere.

High lightning QRN (static) hampered receive conditions on 160/120, 80/75 and 40/41 in the Southern Hemisphere.

Max/Min Solar Flux Readings- 71.6 to 66.1.

Max/Min Background Solar Flux Readings- A0.0 to A0.0.

Max/Min SWPC Sunspot Number- 13 to 00.

Max/Min Solar Wind Speed- 665 to 322.

Max/Min DST via Kyoto- -41 to +19.

Max/Min DST via G3YNK- -62 to -10.

Solar Flares- C-0 M-0 X-0

Elevated Energetic Protons >10 MeV (10+0)- None.

Geoeffective (Earth Facing) Coronal Mass Ejections- None.

Partially geoeffective (Earth Facing) Coronal Mass Ejections- None

Polar cap absorption on high latitude propagation paths due to excessive energetic protons >10 Mev (10+0)- None.

The Ap index had been at quiet geomagnetic levels to major geomagnetic storming levels, with a range of 00-56.

The Kp index had been at quiet geomagnetic levels to minor geomagnetic storming levels, with a range of 0 to 5.

The Boulder CO mid latitude K index had been at quiet geomagnetic levels to minor geomagnetic storming levels, with a range of 0 to 5.

The Fredericksburg, MD mid latitude K index had been at quiet to active geomagnetic levels, with a range of 0 to 4.

The College, AK high latitude K index had been at quiet geomagnetic levels to moderate geomagnetic storming levels, with a range of 0 to 6. 

The Troms, Norway high latitude K index had been at quiet geomagnetic levels to moderate geomagnetic storming levels, with a range of 0 to 6. 

The Australia Region K index had been at quiet to active geomagnetic levels, with a range of 0 to 4. 

PROPAGATION LESSON-

From http://www.kn4lf.com/kn4lf8.htm

8.) E Valley/F Layer Propagation Ducting Mechanism/Chordal Hop Propagation-

Antenna polarization plays a large role in the success of a long haul DX contact. As a medium frequency RF signal traverses our planets 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 then lower angle vertically polarized signals. On other paths on the globe opposite results can be found, i.e. horizontally polarized signals suffer less absorption on a propagation path between VK6 and W4.

You would expect a true long path QSO on 160 to be theoretically possible but improbable on most paths during any season. However a G to VK long path might be possible if the E Valley/F layer ducting propagation mechanism or the Chordal Hop propagation mechanism is involved. A 160 meter signal can traverse a daylight path via these propagation modes if the transmitted signal enters/exits at each end of the path at or near sunrise/sunset when the D layer ionization is weak (ionospheric tilting).

The downward tilt of ionospheric layers is eastward at sunrise. As a result, signals coming from the west are refracted downward at steeper angles and are therefore heard better on higher angle antennas. The opposite is true at local sunset.

A note though, the E-valley/F layer ducting propagation mechanism does not exist only during greyline 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.

The majority of the time medium frequency RF signals in excess of approximately 3200 miles propagate via the E Valley/F Layer propagation mechanism or via the Chordal Hop (mostly on HF near local sunrise and sunset) propagation mechanism. High solar flux values above 150 can aid in long haul medium frequency propagation, as high solar flux values ensure a strong F layer half of the E Valley/F Layer duct mechanism. Typically the majority of transmit antenna's radiation must be focused between 40-60 deg. to enter the E Valley/F Layer duct. (See definition #23.) The Greyline/Greyline Propagation).

Well Known Chordal Hop LP Routes Courtesy Of Larry Duncan K4WLS

Here are some well known Chordal Hop LP routes from the East Coast and Mid-West:

Late Afternoon, Mid-February to Mid-March - Western Australia and beyond, and Southern Malaysia: Predominately 20M.

0700-1000 Local, Early to Late Summer - Eastern and Southern Africa, and Indian Ocean: 20, 15, 17, 12, and 10M (17 through 10M depending on Solar Flux).

0800-1000 Local, Early Fall - Western Australia and S.E. Indian Ocean: 20M

0500-0700 Local, * December - Malaysia, Indonesia, and S.E. Asia: 40M

Sunset to 1 Hour Before, Fall to Mid-December - Middle and Eastern Asia: 40M

0700-0800 Local, Mid-December - Middle East: Predominately 20M

Sunset to 1 Hour Before, Mid-December - Northern Middle and Eastern Asia: 20 and 40M (20M depending on Solar Flux).

* Sporadically as late as early March

If one is lucky enough to be on the receive end of a ducted medium frequency signal due to an IBGW or two, a change in the vertical and/or horizontal electron gradient will allow the RF to drop out of the duct at your QTH.

A note, high solar activity in the form of increased ionization created by ultraviolet and X-ray radiation, can fill in the E Valley/F Layer ducting region with medium frequency absorptive ionization and interfere with the E Valley/F Layer ducting mechanism. In a sense the E/F layer duct is shut down and the medium frequency RF signal can only propagate between the E layer and land/ocean surface, at a higher angle and with more signal loss. This closing of the duct can be reciprocal on each end of the propagation path or one way only. (((((When closing of the duct occurs the advantage of a low angle vertical radiator is lost, with a higher takeoff angle horizontal dipole making the contact still possible, albeit maybe weaker.)))))

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 propagation path.

As follows is a recent experience I had in Florida with this propagation mode on 160 meters.

I began listening for DX on 160 meters at 5:00 pm EST this evening February 05-06, 2006. I was watching the OH2AQ spot and the stations in ME to VA were working stations in Europe and Africa. I could hear the stateside stations real well but not a peep out of any DX.

Then right at my local sunset which was at 6:15 pm EST it was like flipping a switch as all the DX stations just showed up. It was a classic example of the E Valley-F Layer ducting mechanism propagation mode with the duct opening up right over Florida as the ionized layers changed height with the arrival of the grey line terminator.

Once the DX showed up I heard oodles of CW DX stations including VQ9LA and 6W/G4WFQ who were 55 on the receive loop. MM0SJH, G3FPQ and I7RIZ showed up on phone between 1841 and 1849 kc and they were 57. I didn't bother to work anything this time as the only countries I heard that I've never worked were VQ9LA and 6W/G4WFQ and I couldn't break the pileups with 100 watts.

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 Auroral 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,

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