SIDC Weekly Bulletin

:Issued: 2018 Oct 15 1259 UTC
:Product: documentation at http://www.sidc.be/products/bul
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# SIDC Weekly bulletin on Solar and Geomagnetic activity             #
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WEEK 928 from 2018 Oct 08
SOLAR ACTIVITY
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The Sun was spotless in the first half of the week, until alpha regions
NOAA AR 2724 and 2725 rotated over the East limb. AR 2724 produced five B
flares, and the GOES X-ray flux background varied between about A0.5 and A2
level. There were no filament eruptions nor Earth-directed CMEs. The
greater than 10 MeV proton flux was at nominal levels throughout the week.
GEOMAGNETIC ACTIVITY
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A predicted high speed stream associated with a positive polarity
equatorial coronal hole (or rather the compression region in front of it)
arrived near Earth around 10h UT on October 7. Solar wind speed reached 600
km/s with Interplanetary Magnetic Field (IMF) intensities close to 20 nT,
and Bz went down to -15 nT. As a result, several minor storm intervals (K
Dourbes = 5 and NOAA Kp = 5) were registered on October 7. The solar wind
started its return to nominal speed levels on October 9. A minor storm
interval was registered on October 10 when IMF Bz was below -5 nT. The
arrival of a predicted high speed stream from a negative polarity
equatorial coronal hole was registered by DSCOVR around 13:50 UT on October
13, after a rise in density and Interplanetary Magnetic Field (IMF) had
marked the arrival of a compression region in front of the high speed
stream. Solar wind speed gradually rose from about 330 km/s to a maximum of
about 600 km/s. The IMF changed its direction from away from the Sun to
towards the Sun, and its magnitude reached a maximum of about 15 nT. Bz was
below -5 nT for a few hours on October 13, resulting in one minor storm
interval.
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DAILY INDICES
DATE           RC   EISN  10CM   Ak   BKG    M   X
2018 Oct 08   000    000   069   018   ////   0   0   
2018 Oct 09   000    000   070   018   ////   0   0   
2018 Oct 10   000    000   070   017   ////   0   0   
2018 Oct 11   012    007   071   012   ////   0   0   
2018 Oct 12   ///    013   072   007   ////   0   0   
2018 Oct 13   ///    026   072   014   ////   0   0   
2018 Oct 14   ///    023   072   008   ////   0   0   
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# RC   : Sunspot index (Wolf Number) from Catania Observatory (Italy)
# EISN : Estimated International Sunspot Number
# 10cm : 10.7 cm  radioflux (DRAO, Canada)
# Ak   : Ak Index Wingst (Germany)
# BKG  : Background GOES X-ray level (NOAA, USA)
# M,X  : Number of X-ray flares in M and X class, see below (NOAA, USA)
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NOTICEABLE EVENTS SUMMARY
DAY BEGIN MAX  END  LOC    XRAY OP  10CM Catania/NOAA RADIO_BURST_TYPES 
NONE
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