Northern Lights Now – A long duration geomagnetic display gave aurora hunters a treat on the first three nights of September. Space weather conditions, under the influence of a large coronal hole on the Sun, were favorable for aurora borealis from late August 31st through September 3rd. KP reached G2 (moderate) storming levels for four 3-hour periods during that time. Strong storming is expected to continue for another 6-12 hours
— Tyler Collins (@tylerc0llins) September 3, 2016
September’s solar storm was caused by strong solar wind buffeting Earth. The solar wind is the stream of charged particles constantly flow outward from the Sun into the Solar System. At Earth, that stream travels at about 350-400 km/s under normal conditions. This weekend it has been flowing at 600-750 km/s. The magnetic fields of those particles interact with, and push on, the magnetic fields of Earth. Solar wind becomes enhanced as the result of CMEs or when coronal holes are pointed towards Earth.
The current enhanced solar winds are from a very large coronal hole in the northern hemisphere of the sun. It is visible as the dark area from AIA211 images taken by the SDO satellite:
Also visible in the above photograph is the longitudinal extent of the hole. As the Sun rotates, it takes about 14 days for a feature to move from the east lime (left side) to the west limb, the different portions of the hole are pointed towards earth. The longer portions of the hole are pointed towards Earth, the longer high solar wind speeds will impact earth and the longer the potential storm is. In today’s DSCOVR solar wind chart, notice that wind speeds have now been above 500km/s for over 48 hours, and above 650 km/s for over 6 hours:
The result of that long duration wind stream has been an epic solar storm. Over the last three days there have been four 3-hour periods where Boulder KP readings exceeded G2 storm levels, nine periods exceeded G1 levels and just 4 periods of KP less than three.
The Good Stuff
Below find several of our favorite tweets of pictures from this storm
A back of cam pic from the beginning of the storm in Finland:
— Thomas Kast (@thomas_kast) September 1, 2016
The next night in Wisconsin:
— Corinne (@AuroraNorthWI) September 3, 2016
— §nÖÖzy (@SussanSays) September 2, 2016
This Full sky display from over Lake Superior:
— harlanwallach (@harlanwallach) September 2, 2016
And of course, this author went out hunting in Colchester VT because we had clear skies:
— Northern Lights Now (@NorthLightAlert) September 2, 2016
More To Come
The official forecast shows this storm slowly decreasing in strength over the next 6-12 hours. There is still plenty of possibility for yet another night of display for Europe and the Eastern half of N. America. As long as wind speeds main enhanced, any disturbance traveling on the high speed wind stream could set off another substorm.