Solar Conditions & Ham Radio Propagation

Solar activity, governed by the solar cycle, plays a crucial role in radio wave propagation on Earth. When solar activity is high, an increase in sunspots enhances the ionosphere's ability to reflect radio waves. Conversely, during periods of low solar activity, a decrease in sunspots diminishes this reflective capacity, negatively impacting global communication. Consequently, the success of ham radio operations is highly contingent upon the careful selection of appropriate frequency bands.

Amateur radio operators use solar indices to predict radio wave behavior and adjust communication strategies.

See for example the following banner courtesy of Paul L Herrman, N0NBH:

The banner displays numerical indices, which are explained below:

SFI - Solar Flux, 2800MHz (10.7cm)

(SFU units) correlates with F2-region ionization; higher value better HF conditions.

SN - Daily Sunspot Number is a measure of the solar activity; like SFI it correlates with enhanced F2-region i.e. better HF conditions

K-Index

: Geomagnetic Disturbance; good conditions K < 3 | A -Index ref.

: 24 hours Average; good conditions A < 10

304 Å: Total Solar Radiation at SEM (Solar EUV Monitor) wavelenth: 304 Ångstroms (30.4nm) that affects F-region ionization

Ptn - Proton Flux Density | Elc - Electron Flux Density in the Solar Wind; both impact E-region

Aurora indicates the strength of the ionization of the F-region in the polar regions

MUF Boulder - Maximum Usable Frequency (MHz) at Boulder, CO, USA, updated every 15 minutes.

GeoMag - Calculated - Earth`s Geomagnetic based on K-Index. Updated every 3 hours.

Sig Noise - Calculated every ½ hour: S-units (Solar Wind and Geomagnetic Activity)

The project "Understanding HF Propagation" provides a detailed overview and tutorials on HF propagation.

Ham radio solar weather

Current HF Band Conditions

Current Ham radio conditions

Find Your Opening on the Map

Current Ham Radio Propagation

Real time radio propagation map

Current solar conditions Ham radio

Current Ham Radio HF Propagation

HF Radio Propagation Search Terms

Current HF Band Conditions Online Map

Current Ham Radio Propagation Conditions

Real-time watching of worldwide ham activity

Real-time watching of worldwide hams' activity

Current HF Bands Conditions Charts for Radio Hams

Current HF Band Conditions Maps For Radio Operators