31st December

Solar wind speed at the ACE spacecraft decreased from 675 km/s to near
500 km/s over the period. Bt ranged from 1 nT to 5 nT while Bz was
variable and dipped as low as -5 nT. Phi angle was predominately
negative with a few short periods in a positive sector. These
observations suggest the waning of a high speed solar wind stream from
the southern crown coronal hole.

Leave a Reply