:Issued: 2023 Sep 13 1103 UTC
:Product: documentation at http://www.sidc.be/products/presto
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# FAST WARNING 'PRESTO' MESSAGE  from the SIDC (RWC-Belgium)         #
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A solar wind shock was observed on September 12 at 11:22 UTC in the solar wind
parameters as recorded by DSCOVR. The total interplanetary magnetic field (Bt) jumped
from 11 nT to 18 nT, the solar wind speed also jumped from 361 km/s to 409 km/s. The
signature of the solar wind shock was also visible in the southward component (Bz)
and the solar wind density. Then, the total interplanetary magnetic field (Bt)
increased up to 20 nT, the southward component (Bz) reached -19 nT, and the solar
wind speed rose up to 440 km/s. This solar wind shock is associate to a relatively
slow solar structure (with a maximum speed of 440 km/s). It can be associated with
the arrival of the glancing of a partial halo coronal mass ejection (CME) that was
observed on September 07.

Following the solar wind enhancement, a geomagnetic storm was observed (Kp=6- and
K_BEL=5) on September 12 at 15:00 UTC.
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