HF Radio Communications
Monitor high-frequency (HF) radio propagation conditions in real-time. Solar X-ray events can cause D-region absorption, leading to radio blackouts affecting aviation, maritime, and amateur radio communications.
HF Radio Blackout Map
D-Region Absorption Prediction (D-RAP)
This map shows the D-Region Absorption Prediction (D-RAP), which indicates areas where high-frequency (HF) radio communications may be degraded or completely blacked out due to increased ionization caused by solar X-ray and particle events.
Red and orange areas indicate strong absorption where HF radio signals (3-30 MHz) will be significantly attenuated or completely absorbed, affecting aviation, maritime, and amateur radio communications.
GOES X-Ray Flux
Solar X-Ray activity from GOES satellite
M and X class flares can cause HF radio blackouts on the sunlit side of Earth.
Space Weather Alerts
Watches, Warnings & Alerts from NOAA SWPC
What is D-RAP?
The D-Region Absorption Prediction (D-RAP) model estimates high-frequency (HF) radio signal absorption in the ionosphere's D-layer due to enhanced ionization from solar X-ray and particle events.
When the Sun produces strong X-ray emissions (M or X-class flares), the increased ionization in the D-region absorbs HF radio signals, causing communication blackouts on the sunlit side of Earth.
Frequencies Affected: 3-30 MHz (HF band)
Who is Impacted: Aviation, maritime, amateur radio operators, emergency services, military communications
Radio Blackout Scale
Minor
Weak HF radio degradation on sunlit side
Moderate
Limited HF radio blackout on sunlit side
Strong
Wide area HF radio blackout for ~1 hour
Severe
HF radio blackout on most of sunlit side for 1-2 hours
Extreme
Complete HF radio blackout on entire sunlit side for hours
Data from NOAA Space Weather Prediction Center (SWPC) and GOES satellites