WARFA's Space Weather Pages
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Space Weather storms observed and expected are characterized using the NOAA Space Weather scales. The abbreviated table below shows the levels of activity that are included in the announcements and the associated terminology. The descriptor used to identify observed or expected conditions is the maximum level reached or predicted.
NOAA Space Weather Scales
|
Geomagnetic Storms |
Solar Radiation Storms |
Radio Blackouts |
Descriptor |
| G5 | S5 | R5 | Extreme |
| G4 | S4 | R4 | Severe |
| G3 | S3 | R3 | Strong |
| G2 | S2 | R2 | Moderate |
| G1 | S1 | R1 | Minor |
Geomagnetic storm levels are determined by the estimated 3-hourly Planetary K-indices derived in real time from a network of western hemisphere ground-based magnetometers.
Geomagnetic Storm Levels
| Planetary K indices | Geomagnetic storm level |
|
K = 5 |
G1 |
|
K = 6 |
G2 |
|
K = 7 |
G3 |
|
K = 8 |
G4 |
|
K= 9 |
G5 |
Solar Radiation storms levels are determined by the proton flux measurements made by NOAA's primary Geostationary Operational Environmental Satellite (GOES).
Solar Radiation Storm Levels
| Flux level of > 10 MeV particles | Solar Radiation Storm level |
| 10 | S1 |
| 102 | S2 |
| 103 | S3 |
| 104 | S4 |
| 105 | S5 |
Radio Blackout levels are determined by the x-ray level measured by the primary GOES satellite.
Radio Blackouts
| Peak x-ray level and flux | Radio Blackout level |
| M1 and (10-5) | R1 |
| M5 and (5 x 10-5) | R2 |
| X1 and (10-4) | R3 |
| X10 and (10-3) | R4 |
| X20 and (2 x 10-3) | R5 |
"When the sun is active, strong solar flares can occur that
will hit the Earth with hard X-rays on the sunlit side of the Earth.
They will penetrate to the D-region, release electrons which will
rapidly increase absorption causing a High Frequency (3-30 MHz) radio
blackout...
As soon as the X-rays end, the
sudden ionospheric disturbance (SID) or radio black-out ends as the
electrons in the D-region recombine rapidly and signal strengths
return to normal." - From Wikipedia's article on the ionosphere.
Every geophysical alert consists of three parts as shown in the two tables below. The first table describes the information contained in the geophysical alert. The second table provides example text from an actual message.
Information in Geophysical Alert Voice Message
| Section | Information in Voice Message |
| 1 | The solar-terrestrial indices for the day: specifically the solar flux, the A index, and the K index. Generally, the higher the solar flux number and the lower the Boulder K index, the better. |
| 2 | Space Weather storms observed during the previous 24 hours. Includes all observed geomagnetic storms, solar radiation storms (proton events) and Radio blackouts (class M1 and greater flares). |
| 3 | Space Weather expected during the following 24 hours. |
Example Text from Actual Geophysical Alert Message
| Section | Example of Actual Geophysical Alert Message |
| 1 | Solar-terrestrial indices for 08 November follow.
Solar flux 173 and Mid-Latitude A-index 14 The Mid-latitude K-index at 1500 UTC on 08 November was 3. |
| 2 | Space Weather for the past 24 hours has been severe.
Solar radiation storm(s) reaching the S4 level is in progress. Radio blackouts(s) reaching the R2 level occurred. |
|
Alternate section 2 |
No Space Weather storms have been observed during the past 24 hours. |
|
3 |
Space Weather for the next 24 hours is expected to be severe. Solar radiation storms reaching the S4 level are expected to continue. Radio blackouts reaching the R2 level are expected. |
|
Alternate section 3 |
No Space Weather storms are expected during the next 24 hours. |
The announcements include the descriptor of the largest space weather event observed (2) or expected (3) in the first line of each section. The remaining lines give the type of events and the level observed for each one. In the example above, no geomagnetic storm information is included because none was observed or is expected during the period. In the case where none of the three types of events are observed or expected, the announcement would contain section 1, plus alternate section 2 and alternate section 3.
To hear the current geophysical alert message by telephone, dial (303) 497-3235. Inquiries regarding these messages should be addressed to:
Space Weather Operations