Increasing Solar Activity

ANOTHER X-FLARE ON MAY 15: When the week began, the sun hadn't unleashed an X-flare all year long. In only two days, sunspot AR1748 has produced four. The latest X-flare - X1 -from this active sunspot occurred on May 15th at 01.52 UT.  Although the sunspot is not directly facing Earth, this flare might have produced a CME with an Earth-directed component. We are waiting for coronagraph data from SOHO and the twin STEREO probes to check this possibility.

In summary, AR1748 has produced an X1.7-class flare (02.17 UT on May 13), an X2.8-class flare (16.09 UT on May 13), an X3.2-class flare (01.17 UT on May 14), and an X1-class flare (01.52 on May 15). These are the strongest flares of the year, and they signal a significant increase in solar activity. 

ION WAVES IN THE ATMOSPHERE: Although AR1748 is not directly facing Earth, its strong flares have nevertheless affected our atmosphere. UV and X-radiation hitting the top of the atmosphere ionizes atoms and molecules, creating ion waves over the dayside of the planet. Roberto Battaiola detected these waves on May 13th using a Sudden Ionospheric Disturbance monitor in Milan, Italy:

Sudden ionospheric disturbances--"SIDs" for short--make themselves known by the effect they have on low-frequency radio signals. When a SID passes by, the atmosphere overhead becomes a good reflector for radio waves, allowing signals to be received from distant transmitters. Battaiola monitored a faraway 21.75 kHz radio station to monitor the SIDs over his location.

More SIDS are in the offing as NOAA forecasters estimate an 80% chance of M-flares and a 50% chance of X-flares during the next 24 hours.                              www.spaceweather.com