October 5, 2022

Astronomy & Astrophysics 101: Solar Flares (Radio Blackouts)

R1.
M1.
0.00001.
Minor.

R4.
X10.
0.001.
Severe.

Radio Blackout
X-ray Flare
Flux (W/m2).
Intensity Descriptor.

Solar flare intensities cover a big variety and are classified in terms of peak emission in the 0.1– 0.8 nm spectral band (soft x-rays) of the NOAA/GOES XRS. The X-ray flux levels start with the “A” level (nominally starting at 10-8 W/m2). The next level, ten times higher, is the “B” level (≥ 10-7 W/m2); followed by “C” flares (10-6 W/m2), “M” flares (10-5 W/m2), and lastly “X” flares (10-4 W/m2).
Radio blackouts are classified utilizing a five-level NOAA Space Weather Scale, straight related to the flares max peak in soft X-rays reached or anticipated. SWPC presently anticipates the likelihood of C, x-class, and m flares and relates it to the probability of an R1-R2, and R3 or higher events as part of our 3-day projection and forecast discussion items. When an M5 (R2) flare takes place, swpc also releases an alert.
The table listed below offers the correlation in between radio blackouts, solar flares, nominal energy flux (watts per square meter), and the designated severity occasion descriptor.

R5.
X20.
0.002.
Extreme.

The next level, 10 times greater, is the “B” level (≥ 10-7 W/m2); followed by “C” flares (10-6 W/m2), “M” flares (10-5 W/m2), and finally “X” flares (10-4 W/m2).

R2.
M5.
0.00005.
Moderate.

Solar flares are big eruptions of electromagnetic radiation from the Sun lasting from minutes to hours. When a strong enough solar flare occurs, ionization is produced in the lower, more thick layers of the ionosphere (the D-layer), and radio waves that communicate with electrons in layers lose energy due to the more regular accidents that occur in the higher density environment of the D-layer. Solar flares normally take location in active regions, which are areas on the Sun marked by the presence of strong magnetic fields; generally associated with sunspot groups. These include electro-magnetic radiation, which are observed as solar flares.

Solar flares– like this one captured by a NASA satellite orbiting the Sun– eject substantial quantities of radiation. Credit: NASA
Solar flares are large eruptions of electromagnetic radiation from the Sun lasting from minutes to hours. The abrupt outburst of electro-magnetic energy travels at the speed of light, for that reason any result upon the sunlit side of Earths exposed outer atmosphere takes place at the very same time the event is observed. The increased level of X-ray and extreme ultraviolet (EUV) radiation results in ionization in the lower layers of the ionosphere on the sunlit side of Earth.
Under normal conditions, high frequency (HF) radio waves are able to support interaction over cross countries by refraction via the upper layers of the ionosphere. When a strong sufficient solar flare happens, ionization is produced in the lower, more dense layers of the ionosphere (the D-layer), and radio waves that communicate with electrons in layers lose energy due to the more regular accidents that occur in the greater density environment of the D-layer. This can cause HF radio signals to become degraded or completely absorbed. This results in a radio blackout– the absence of HF interaction, mostly impacting the 3 to 30 MHz band. The D-RAP (D-Region Absorption Prediction) product associates flare strength to D-layer absorption strength and spread.
Solar flares typically happen in active regions, which are locations on the Sun marked by the existence of strong electromagnetic fields; normally connected with sunspot groups. As these magnetic fields progress, they can reach a point of instability and release energy in a range of forms. These consist of electro-magnetic radiation, which are observed as solar flares.

R3.
X1.
0.0001.
Strong.

Leave a Reply

Your email address will not be published. Required fields are marked *