Presto Alert - [Aurora Alert]

Issued: 2020 Nov 21 2339 UTC
:Product: documentation at www.sidc.be/products/presto
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# FAST WARNING ‘PRESTO’ MESSAGE from the SIDC (RWC-Belgium) #
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The in situ observations show the arrival of a shock wave registered in all solar wind parameters at 17:00UT on Nov 21st. The magnetic field magnitude decreased from 11 to 9 nT with the Bz component dropping from 7 nT to -9 nT. The solar wind speed Increased from 383 to 445 km/s. Related to the shock arrival the geomagnetic conditions remained globally unsettled and reached locally active conditions in Dourbes. The source for the observed shock is the arrival of a High-speed stream related to the positive polarity coronal hole CH 96, which first crossed the central meridian on Nov 19th. Currently the solar wind speed has Increased to 535 km/s, increasing the probability for minor geomagnetic storms.
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# Solar Influences Data analysis Center – RWC Belgium #
# Royal Observatory of Belgium #
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