Yesterday (24. August) there was an X-ray event on the sun. Such events ionize the dayside ionosphere above “normal” levels and may cause blackouts. Here is the Alert issued by SWPC:
Space Weather Message Code: SUMXM5
Serial Number: 119
Issue Time: 2014 Aug 24 1256 UTC
SUMMARY: X-ray Event exceeded M5
Begin Time: 2014 Aug 24 1200 UTC
Maximum Time: 2014 Aug 24 1217 UTC
End Time: 2014 Aug 24 1225 UTC
X-ray Class: M5.9
Optical Class: 2b
NOAA Scale: R2 – Moderate
Comment: Impulsive M5/2b flare from new Region 2151 near the SE limb. Type II (593 km/s) and Tenflare (409 sfu) radio emissions associated with this event.
Potential Impacts: Area of impact centered primarily on sub-solar point on the sunlit side of Earth.
Radio – Limited blackout of HF (high frequency) radio communication for tens of minutes.
And indeed effects were seen on the ground. Here are the raw riometer data from Skibotn and Ny-Ålesund. A riometer measures the power of the background cosmic radiation. When the ionosphere increase in density at its lowest altitudes this radiation is absorbed and absorption is observed in the curve. I will at a later point write a post about the excellent instrument of riometers.
Notice at 12 UT there is a small dip in the curves lasting for a little less than half an hour. That is the effect of the x-ray event and indicates some absorption of HF signals at 30 and 40 MHz. Now, both Skibotn and Ny-Ålesund are at hight latitudes, if one moved closer to the sub-solar point one would probably see even more absorption.
The event was also seen to affect geomagnetic conditions a little at most latitudes of the TGO magnetometer network, see the simultanous dip in the curves at 12 UT in the stackplot.
Nothing dramatic about this space weather event, but it illustrates quite nicely one of the ways the Sun may affect conditions here on Earth