by Ian O'Neill

March 31, 2014
from NewsDiscovery Website





The solar flare as observed by

NASA's Solar Dynamics Observatory in extreme ultraviolet light.





On Saturday, the sun erupted with an X-class solar flare, blasting Earth with powerful electromagnetic radiation.


Although we couldn't directly feel its effects on the ground, the impact of this event was measured as a dramatic radio blackout for several minutes, highlighting the fact that the sun isn't quite done with solar maximum yet.


The X1.0 flare erupted at 1:48 p.m. ET on March 29 and an armada of solar telescopes captured the event in all its glory. A solar flare occurs when highly-stressed magnetic field lines are forced together over regions of intense magnetic activity, descriptively known as "active regions."


These regions are often associated with sunspot clusters - this is why astronomers keep count of sunspots in an effort to record solar activity.


Although we are well protected from the worst effects of radiation from solar flares, ionizing X-ray and extreme ultraviolet radiation can have a disruptive impact on unshielded satellite electronics and can even give unprotected astronauts an increased radiation dose.


Our atmosphere is a thick shield that protects our biology from the sun's worst solar flares, but that's not to say that they can't impact our lives.


As reported by Spaceweather (below insert), the X1 flare, which was triggered above active region (AR) 2017, bathed our upper atmosphere in ultraviolet radiation, causing global ionization.




March 30, 2014

from Spaceweather Website


On Saturday, March 29, the magnetic canopy of sunspot AR2017 erupted, producing a brief but intense X1-class solar flare.


A flash of extreme UV radiation sent waves of ionization rippling through Earth's upper atmosphere and disturbed the normal propagation of terrestrial radio transmissions.


Radio engineer Stan Nelson of Roswell, NM, was monitoring WWV at 20 MHz when the signal wobbled then disappeared entirely for several minutes:




"The Doppler shift of the WWV signal (the 'wobble' just before the blackout) was nearly 12 Hz, the most I have ever seen," says Nelson.

The flare not only blacked out radio signals, but also produced some radio signals of its own.


The explosion above sunspot AR2017 sent shock waves racing through the sun's atmosphere at speeds as high as 4800 km/s (11 million mph). Radio emissions stimulated by those shocks crossed the 93 million mile divide to Earth, causing shortwave radio receivers to roar with static.


Here is a plot of the outburst detected by Nelson using a 20.1 MHz RadioJove receiver. Elsewhere, strong bursts were recorded at frequencies as high as 2800 MHz. It was a very broad band event.


NASA's Solar Dynamics Observatory recorded a beautiful movie of the flare:






The flash you just saw was extreme UV radiation, the type of radiation that ionizes the upper layers of our atmosphere. In this case, the ionizing action of the flare led to a rare magnetic crochet, measuring 17 nT at the magnetometer in Boulder, Colorado.


A magnetic crochet is a ripple in Earth's magnetic field caused by electrical currents flowing in air 60 km to 100 km above our heads. Unlike geomagnetic disturbances that arrive with CMEs days after a flare, a magnetic crochet occurs while the flare is in progress. They tend to occur during fast impulsive flares like this one.


The magnetic field of sunspot AR2017 is decaying now, but it still poses a threat for eruptions. NOAA forecasters estimate a 55% chance of M-class flares and a 20% chance of X-class flares on March 31st.


The aptly-named ionosphere is used for communications where radio waves are bounced around the globe.


This extensive ionization event caused the propagation of radio waves to wildly fluctuate, eventually blocking them all together. The blast was so powerful that the impulsive electrical currents generated in the ionosphere caused vast waves to ripple through our planet's magnetic field.


Radio engineer Stan Nelson located in Roswell, New Mexico, was monitoring the National Institute of Standards and Technology (NIST) WWV radio transmission (which transmits time and frequency information worldwide 24/7) during the flare and watched the signal oscillate wildly before being blocked all together.

"The Doppler shift of the WWV signal (the ‘wobble' just before the blackout) was nearly 12 Hz, the most I have ever seen," said Nelson.

The flare also generated its own radio signal; as the flare's shock wave blasted through the sun's corona (its atmosphere), an intense radio signal was generated and was recorded as powerful shortwave radio static.


The sun is currently experiencing the wane of solar maximum, the peak of its approximate 11-year solar cycle. Solar Cycle 24 has been a "below average" cycle exhibiting lower levels of magnetic activity - but as Saturday's flare proves, it's still capable of generating some impressive explosive displays.




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