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Category | Radio Blackouts Use X-Ray |
Solar Radiation Storms Use Proton Flux |
Geomagnetic Storms Use K-Index/K-nT/ Aurora/Solar Wind/Bz |
Band Openings Use Solar Flux (SN) |
Electron Alert Use Electron Flux |
Extreme | X20 (1 per cycle) Complete HF blackout on entire sunlit side lasting hours |
1.0e+06 (1 per cycle) Complete HF blackout in polar regions |
K=9 (nT=>500) [Aur=10++] (SW=>800) [Bz=-40 -50] (4 per cycle) HF impossible. Aurora to 40°. Noise S30+. |
200-300 (SN=160-250) Reliable communications all bands up through 6m |
>1.0e+03 Alert Partial to complete HF blackout in polar regions |
Severe | X10 (8 per cycle) HF blackout on most of sunlit side for 1 to 2 hours |
1.0e+05 (3 per cycle) Partial HF blackout in polar regions |
K=8 (nT=330-500) [Aur=10+] (SW=700-800) [Bz=-30 -40] (100 per cycle) HF sporadic. Aurora to 45°. Noise S20-S30. |
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Strong | X1 (175 per cycle) Wide area HF blackout for about an hour on sunlit side |
1.0e+04 (10 per cycle) Degraded HF propagation in polar regions |
K=7 (nT=200-330) [Aur=10] (SW=600-700) [Bz=-20 -30] (200 per cycle) HF intermittent. Aurora to 50°. Noise S9-S20. |
150-200 (SN=105-160) Excellent conditions all bands up through 10m w/6m openings |
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Moderate | M5 (350 per cycle) Limited HF blackout on sunlit side for tens of minutes |
1.0e+03 (25 per cycle) Small effects on HF in polar regions |
K=6 (nT=120-200) [Aur=9] (SW=500-600) [Bz=-10 -20] (600 per cycle) HF fade higher lats. Aurora to 55°. Noise S6-S9. |
120-150 (SN=70-105) Fair to good conditions all bands up through 10m |
<1.0e+03 Active Degraded HF propagation in polar regions |
Minor | M1 (2000 per cycle) Occasional loss of radio contact on sunlit side |
1.0e+02 (50 per cycle) Minor impacts on HF in polar regions |
K=5 (nT=70-120) [Aur=8] (SW=400-500) [Bz=0 -10] (1700 per cycle) HF fade higher lats. Aurora to 56°. Noise S4-S6. |
90-120 (SN=35-70) Fair conditions all bands up through 15m |
<1.0e+02 Active Minor impacts on HF in polar regions |
Active | C1 Moderate Flare Low absorption of HF signals |
1.0e+01 Active Very minor impacts on HF in polar regions |
K=3-4 (nT=20-70) [Aur=6-7] (SW=200-400) [Bz=0-+50] Unsettled/Active Minor HF fade higher lats. Aurora 60-58°. Noise S2-S3. |
70-90 (SN=10-35) Poor to fair conditions all bands up through 20m |
<1.0e+01 Normal No impacts on HF |
Normal | A1-B9 No/Small Flare No or very minor impact to HF signals |
1.0e+00 Normal No impacts on HF |
K=0-2 (nT=0-20) [Aur=<5] (SW=200-400) [Bz=0-+50] Inactive/Quiet No impacts on HF. Aurora 67-62°. Noise S0-S2. |
64-70 (SN=0-10) Bands above 40m unusable |
<1.0e+00 Normal No impacts on HF |
VHF Conditions
Aur Lat (Auroral Latitude): Indicates lowest latitude from the current Aurora Activity measurement. Text color coded for low activity, hi-latitude, & mid-latitude.Aurora (Northern Auroral Activity): Band Closed = No/Low Auroral activity. High LAT AUR = Auroral activity >60°N. MID LAT AUR = Auroral activity 60° to 30°N. EsEU (Sporadic E - Europe): Band Closed = No Sporadic E (ES) activity. High MUF (2M only) = Cond support 2M ES. 50/70/144MHz ES = Respective band open EsNA (Sporadic E - North America): Band Closed = No Sporadic E activity. High MUF = Cond support 2M ES. 144MHz ES = Sporadic E reported >140 MHz. EME (Earth-Moon-Earth): Current EME degradation. Very Poor (>5.5dB), Poor (4dB), Moderate (2.5dB), Good (1.5dB), Very Good (1dB), Excellent (<1dB). Solar Flare Probability: Provides the probability of a solar flare (in %) for the net 24 hours. MUF (Max Usable Frequency Bar Color): No Sporadic E (ES) activity / ES reported @ 6M / ES reported @ 4M / Cond support 2M ES / ES reported @ 2M MS (Meteor Scatter) Activity Color bar: Provides meteor activity color coded MIN to MAX conditions (see the graph below the bar). ©N0NBH Paul L Herrman 2010 |