Propagation Basics

SFI index Solar Flux Index: (the higher the number, the better HF propagation should be.)

< 70: propagation potentially bad.

80-90: propagation potentially are somewhat low

90-100: propagation tend to be average

100-150: propagation will tend to be good

>150: propagation will tend to be ideal

SN: Sunspot Numbers:

< 50: propagation conditions potentially very bad

50-75: propagation conditions attenuated

75-100: propagation conditions might be good

100-150: propagation conditions should be ideal

>150: propagation conditions possibly exceptional

Important:

Solar flux (SFI) and Sun spots (SN) numbers need to be high AND sustained to make a major impact on propagation. In other words, a single (1) day high numbers will have very little impact, but on the opposite end of things, high numbers sustained for more than 5-7 days will impact propagation very positively. The longer high numbers are sustained, better the propagation will become. So keep an eye on those numbers over the

period of several days!

The A Index:

Between 1 and 5: Best conditions on 10,12,15,17,20 meter bands.

Between 6 and 9: Average conditions on 10,12,15,17,20 meter bands.

From 10 and above: Very Bad conditions on 10,12,15,17,20 meter bands.

The Ap-index:

Between 1 and 5: Best conditions expected on 30,40,80,160 meter bands.

Between 6 and 9: Average conditions expected on 30,40,80,160 meter bands.

From 10 and above: Bad conditions expected on 30,40,80,160 meter bands.

The K-Index:

From 0 to 1: Best conditions for 10,12,15,17,20 meter bands.

From 2 to 3: Good conditions for 10,12,15,17,20 meter bands.

From 4 to 5: average conditions for 10,12,15,17,20 meter bands.

From 5 to 9: Very bad conditions for 10,12,15,17,20 meter bands.

The Kp-index:

Between 0 and 1: Best conditions expected on 30,40,80,160 meter bands.

Between 2 and 4: Good conditions expected on 30,40,80,160 meter bands.

Between 5 and 9: Bad conditions expected on 30,40,80,160 meter bands.

X-Ray:

NOAA reported value from A0.0 to X9.9. Intensity of hard x-rays hitting the earth’s

ionosphere. Impacts primarily the D-layer (HF absorption). The letter indicates the order of

magnitude of the X-rays (A, B, C, M and X), where A is the lowest. The number further

defines the level of radiation. Updated eight times daily.

304A:

 NOAA reported value from 0 to unknown. Relative strength of total solar radiation at a wavelength of 304 angstroms (or 30.4 nm), emitted primarily by ionized helium in the sun’s photosphere. Two measurements are available for this parameter, one measured by the Solar Dynamics Observatory, using the EVE instrument, and the other, using data from the SOHO satellite, using its SEM instrument. Responsible for about half of all the ionization of the F layer in the ionosphere. 304A does loosely correlate to SFI. Updated hourly.

Ptn Flx:

 NOAA reported value from 0 to unknown. Density of charged protons in the solar wind. The higher the numbers, the more the impact the ionosphere. Primarily impacts the E-Layer of the ionosphere. Updated hourly.

Elc Flx:

 NOAA reported value from 0 to unknown. Density of charged electrons in the solar wind. The higher the numbers (>1000), the more the impact the ionosphere. Primarily impacts the E-Layer of the ionosphere. Updated hourly.

N:

 NOAA reported value from 0 to 5. When <2.0, high confidence in Aurora measurement. When >2, low confidence. Updated hourly.