RRADIO BLACKOUT
R—Reading X-rays…
HELIOPHYSICS · OPERATIONAL DATA
FROM THE SUN TO THE POLES
Follow the full space-weather chain: eruptions, X-rays, solar wind, interplanetary magnetic field, magnetosphere, aurora and communication impacts.
01 · OPERATIONAL SUMMARY
Three phenomena, three scales
The NOAA scales distinguish radio blackouts R, solar radiation storms S and geomagnetic storms G. They do not describe the same mechanism.
SSOLAR RADIATION
S—Reading protons…
GGEOMAGNETIC
G—Reading Earth’s field…
F10.7 SOLAR FLUX—sfu
KP INDEX—/ 9
SOLAR WIND—km/s
BZ FIELD—nT
X-RAYS—GOES
PROTONS ≥10 MeV—pfu
02 · SOLAR OBSERVATORY
The Sun now
Three wavelengths reveal different structures. These are near-real-time images, generally updated by SDO every fifteen minutes.
AIA 193 ÅHot corona and coronal holes
Large dark regions can identify coronal holes, possible sources of high-speed solar-wind streams.
Images: courtesy of NASA/SDO and the AIA, EVE and HMI science teams. A missing image indicates a source outage, not an absence of solar activity.
03 · ERUPTIONS AND RADIATION
When the Sun strikes at light speed
X-rays from a flare reach Earth in about eight minutes. They ionize the sunlit hemisphere and can suddenly absorb HF signals in the D layer.
GOES · LAST 6 HOURS
X-ray flux
CURRENT CLASS—
ABCMX
Reading the GOES sensor…
Flare risk
—Class C+
—Class M+
—Class X
Each letter is a factor of ten. An X1 flare produces ten times the X-ray flux of an M1 flare.
VISIBLE PHOTOSPHERE
—Active solar regions
Reading NOAA-numbered regions…
04 · INTERPLANETARY MEDIUM
Solar wind measured upstream of Earth
Spacecraft near the L1 Lagrange point sample the plasma before it reaches Earth. Speed, density and especially negative Bz determine how efficiently energy can enter the magnetosphere.
SUN
≈ 1 AU · 149.6 million km
L1upstream measurement
≈ 1.5 million km
EARTH
—
Potential dynamic pressure
Interplanetary plasma
IMF magnitude
—
At measured speed
Speed and density
SpeedDensity
Interplanetary field Bt / Bz
BtBz
The L1 lead time is a geometric estimate, not an alert. A CME requires analysis of its direction, speed and magnetic structure; space weather can never be reduced to one number.
05 · EARTH’S MAGNETIC SHIELD
The magnetosphere under pressure
The dayside is compressed by solar wind while the magnetotail stretches far behind Earth. When the interplanetary field points south, magnetic reconnection transfers energy more efficiently.
Bow shockMagnetopauseAuroral ovalMagnetotail
KP—
- Current ap index
- —
- Contributing stations
- —
- Bz coupling
- —
- Storm level
- —
Calculating magnetospheric response…
06 · AURORAL OVAL AND POLAR REGIONS
Northern lights: where energy descends into the atmosphere
The OVATION model estimates northern-lights probability in the Northern Hemisphere. Particles follow field lines toward the pole and excite oxygen and nitrogen in the upper atmosphere.
Marieville
LOWHIGH
Oxygen · green
The dominant 557.7 nm emission, often around 100–150 km altitude.
Oxygen · red
The 630.0 nm emission, higher in the thermosphere and often more diffuse.
Nitrogen · blue/violet
Molecular emissions associated with more energetic particles and lower altitudes.
07 · OUTLOOK AND WATCH
What may happen next
The outlook combines F10.7 radio flux and the geomagnetic ap index. NOAA watches, alerts and warnings take precedence when an event is detected.
NOAA FORECAST · 7 DAYS
—Solar and geomagnetic activity
F10.7ap
Official probabilities
- M-class or greater
- —
- X-class flare
- —
- Protons ≥10 MeV
- —
- Polar cap absorption
- —
A probability describes risk over a period, not the exact time of an event.
OPERATIONAL MESSAGES
NOAA alert centre ↗Recent watches and alerts
Reading official messages…
TECHNOLOGICAL IMPACTS
What these indices actually change
Canada’s high latitudes make some infrastructure more sensitive. Effects vary with time, latitude, frequency and signal path.
3–30 MHz radio
X-rays strengthen the D layer on the dayside and increase absorption. Geomagnetic storms can degrade or move ionospheric paths for hours.
GPS and navigation
Total electron-content gradients and ionospheric scintillation can cause delays, position errors and temporary loss of lock.
Satellites
Energetic particles, charging, electronic errors and upper-atmosphere expansion can disrupt electronics and increase drag in low Earth orbit.
Grids and pipelines
Rapid geomagnetic variations induce currents in long infrastructure. Quebec suffered a major blackout during the March 1989 storm.
08 · SCIENTIFIC GUIDE
Understand the Sun–Earth chain
No single index is sufficient. A sound reading connects the solar source, travel time, magnetic orientation and ionospheric response.
- 1Solar magnetic energy
Fields in active regions twist and store energy. Reconfiguration can produce a flare, a CME or both.
- 2Three distinct speeds
Light and X-rays arrive in 8 min 20 s; energetic particles in tens of minutes to hours; a CME generally in one to several days.
- 3Measurement at L1
Upstream observatories measure speed, density and IMF before impact. Southward Bz favours reconnection with Earth’s field.
- 4Magnetospheric response
Dayside compression, energy storage in the tail, auroral currents and the ring current alter the field measured at ground level.
- 5Ionosphere and poles
Deposited energy changes ionization, produces aurora and disturbs radio propagation, navigation and some electrical systems.
Solar flare
A burst of electromagnetic radiation. Its GOES class A, B, C, M or X is based on 0.1–0.8 nm soft X-ray flux; each letter is ten times the previous class.
Coronal mass ejection · CME
A massive cloud of magnetized plasma. Only CMEs whose path intersects Earth can cause a major geomagnetic impact.
Coronal hole
A region of open magnetic field in the corona. It can feed a high-speed stream and cause recurring activity with solar rotation.
Kp index
A quasi-logarithmic planetary index from 0 to 9 calculated over three hours from several observatories. Kp 5 marks the G1 threshold.
ap index
A linearized measure of geomagnetic activity. It is easier to average and forecast than the quasi-logarithmic Kp index.
IMF Bt and Bz
Bt is total interplanetary field magnitude. Bz is its north–south component in GSM coordinates; sustained negative values are often more geoeffective.
Radiation storm
An energetic proton event measured notably above 10 MeV. Effects are stronger near the poles, at altitude and outside the magnetosphere.
Auroral oval
A ring around the magnetic pole where particles precipitate. It expands toward lower latitudes as geomagnetic activity increases.
Solar cycle
Sunspot number and activity follow an average cycle of about eleven years. During every cycle the Sun’s magnetic poles reverse polarity.
Space weather and climate
Space weather describes minute-to-day variations in the Sun–Earth environment. It is distinct from terrestrial weather and atmospheric climate.