Solar wind shock arrival

Monday, 8 January 2018 13:58 UTC

A coronal hole solar wind stream was expected but not of this magnitude due to the high latitude of the coronal hole. Such clear shocks with a very sharp increase in the solar wind speed/IMF (Bt) are usually associated with the arrival of an interplanetary magnetic cloud, also better known as a coronal mass ejection. The catch is: there were no known coronal mass ejections on the way to Earth.

Nonetheless, whatever this may be, it is worth to keep an eye on the stats right now. The north-south direction of the IMF (Bz) has been mostly northward but did turn southward about 2 hours ago and the solar wind speed is also increasing to about 440km/s. Active geomagnetic conditions (Kp4) are possible later today should the current conditions hold.