Northern Lights Now – The expected ICME has arrived. In the first hour since it arrived, solar wind data is indicating that is is oriented favorably to put on an aurora show.
The shock arrived at the DSCOVR satellite around 1:45am GMT on October 12, 2021. At the time of impact, Solar wind speed jumped from 350km/s to almost 500 km/s. Proton density and BT also jumped in synchrony. Bz is always the wildcard. It is hard to know how the B component will be oriented until it arrives. Tonight, it arrived with a strong negative orientation. This is the most favorable setup for producing aurora.
In the image below, the upper chart is a proxy for hemispheric power and can be seen on the DSCOVR solar wind page. The more bars and the longer the bars the higher the likelihood of aurora. As time goes on, if the favorable conditions persist, the bars will continue to grow. In the lower part of the image, you can see when the ICME shock arrived with the big jump in solar wind data.