Current Solar/Ionospheric Data
Interpretation of Data
A-INDEX 1-6 Best; 7-10 Fair; 11+ Bad: This represents the global level of ionospheric
geomagnetic disturbance over the previous 24-hour period.
K-INDEX 0-1 Best; 2 Okay; 3-4 Bad; 5+ Very Bad: This is the level of geomagnetic
ionospheric disturbance averaged around the planet over the past 3 hours. Values >4
indicate the presence of geomagnetic storms and noise levels on all HF bands increase
appreciably. With values >6 overall HF conditions degrade significantly. Generally, HF
conditions are best when the A-Index is 10 or lower and the K-Index is 3 or lower.
SFI (SOLAR FLUX INDEX) 70 Not Good; 80 Good; 90 Better; 100+ Best: This is a measure
of the total radio emissions from the sun. A higher SFI generally suggests better propagation
on the 10, 12, 15, 17, & 20 meter Bands. It rarely affects the 30, 40, 60, 80, & 160
meter bands. When it is >70 then 20m opens and when it is >90 then 15m opens.
SN (SUNSPOT NUMBER) The higher the SN, the higher the level of UV and X-ray radiation
that is striking our atmosphere and producing ionization in the D, E and F layers. As
ionization increases, the MUF goes up. The higher bands (15M, 12M, 10M and 6M) become active
with good propagation when there is a high SN
X-RAY Strong solar X-Ray emissions will cause shortwave fadeouts and radio blackouts.
Classification from weak to strong X-Ray emissions is A, B, C, M, X.
Thanks to Barry Siegfried, K2MF, for these explanations.
The banner is provided by Paul Herrman, N0NBH, via his website at http://www.hamqsl.com/solar.html. Steve Saint Andrea, AG1YK, offers more details in an article, "Solar Banners - A Propagation Resource," p. 78 of QST for February 2014.