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Sunday, September 4, 2011

M3-Class Solar Flare Disrupting Radio Stations In Norway.


SOLAR FLARE: This morning at 1145 UT, an active region on the sun's western limb unleashed an M3-class solar flare. NASA's Solar Dynamics Observatory recorded the flash of extreme UV radiation:
Although the blast site was not directly facing Earth, radiation from the explosion nevertheless ionized Earth's upper atmosphere. This altered the propagation of radio signals around Europe, where it was high-noon at the time of the flare. "I detected a sharp change in signal levels from two radio stations on the VLF band," reports Rob Stammes of Lofoten, Norway.
In addition to the UV flash, the explosion also hurled a CME into space: SOHO movie. The cloud is not heading for Earth, so no auroras will result from this particular event. That's not to say, however, that no auroras are in the offing. Read on....http://www.spaceweather.com/
3-day Solar Xray Flux graph

NOAA Space Weather Scale for Radio Blackouts

Category
Effect
Physical measure
Average Frequency
(1 cycle=11 years)
Scale
Descriptor
Duration of event will influence severity of effects
  

Radio Blackouts

GOES X-ray peak brightness by class and by flux*
Number of events when flux level was met; (number of storm days)
R 5
Extreme
HF Radio:Complete HF (high frequency**) radio blackout on the entire sunlit side of the Earth lasting for a number of hours. This results in no HF radio contact with mariners and en route aviators in this sector.
Navigation: Low-frequency navigation signals used by maritime and general aviation systems experience outages on the sunlit side of the Earth for many hours, causing loss in positioning. Increased satellite navigation errors in positioning for several hours on the sunlit side of Earth, which may spread into the night side.
X20
(2 x 10-3)
Less than 1 per cycle
R 4
Severe
HF Radio: : HF radio communication blackout on most of the sunlit side of Earth for one to two hours. HF radio contact lost during this time.
Navigation: Outages of low-frequency navigation signals cause increased error in positioning for one to two hours. Minor disruptions of satellite navigation possible on the sunlit side of Earth.
X10
(10-3)
8 per cycle
(8 days per cycle)
R 3
Strong
HF Radio: Wide area blackout of HF radio communication, loss of radio contact for about an hour on sunlit side of Earth.
Navigation: Low-frequency navigation signals degraded for about an hour.
X1
(10-4)
175 per cycle
(140 days per cycle)
R 2
Moderate
HF Radio: Limited blackout of HF radio communication on sunlit side, loss of radio contact for tens of minutes.
Navigation: Degradation of low-frequency navigation signals for tens of minutes.
M5
(5 x 10-5)
350 per cycle
(300 days per cycle)
R 1
Minor
HF Radio: Weak or minor degradation of HF radio communication on sunlit side, occasional loss of radio contact.
Navigation: Low-frequency navigation signals degraded for brief intervals.
M1
(10-5)
2000 per cycle
(950 days per cycle)
* Flux, measured in the 0.1-0.8 nm range, in W·m-2. Based on this measure, but other physical measures are also considered.
** Other frequencies may also be affected by these conditions.


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