SIDC Weekly Bulletin

:Issued: 2019 Dec 02 1245 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 987 from 2019 Nov 25
SOLAR ACTIVITY
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Solar activity was very low throughout the period. The Sun was spotless. No
earth-directed coronal mass ejections (CMEs) have been observed in
available coronagraphic imagery. The greater than 10 MeV proton flux was at
nominal values. A negative polarity coronal hole (CH) in the southern solar
hemisphere transited the central meridian on 24-25 November. A weak
extension of the southern polar CH transited the central meridian on 30
November.
GEOMAGNETIC ACTIVITY
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At the beginning of the period, solar wind parameters reflected the waning
influence of a positive polarity coronal hole (CH). Solar wind speed
gradually decreased from about 470 km/s late on 25 November to about 330
km/s late on 28 November (ACE). A sector boundary crossing (SBC) was
observed on 28 November, introducing a somewhat more enhanced solar wind
with speeds between mostly 350 and 400 km/s for the remainder of the week.
Following the SBC, the direction of the interplanetary magnetic field (phi
angle) switched from predominantly away (positive sector) to predominantly
towards the Sun (negative sector). Bz varied between -6 and +6 nT, with a
sustained negative stretch near -5 nT between 19-22UT on 29 November that
resulted in unsettled to active geomagnetic conditions during the 21-24UT
interval (Kp = 3; K Dourbes = 4). Otherwise, geomagnetic activity was
mostly at quiet levels.
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DAILY INDICES
DATE           RC   EISN  10CM   Ak   BKG    M   X
2019 Nov 25   000    ///   070   006   A8.2   0   0   
2019 Nov 26   000    ///   070   002   A8.0   0   0   
2019 Nov 27   ///    ///   072   004   A7.1   0   0   
2019 Nov 28   ///    ///   070   005   A7.8   0   0   
2019 Nov 29   000    ///   070   007   A7.8   0   0   
2019 Nov 30   ///    ///   070   004   A7.9   0   0   
2019 Dec 01   ///    000   071   003   A7.8   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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