SIDC Weekly Bulletin

Review of past solar and geomagnetic activity.
Source SIDC (RWC-Belgium)
Frequency Weekly
Format Plain text
Mail header SIDC Weekly Bulletin
SIDC code bul


Latest issue

:Issued: 2022 Aug 16 0957 UTC
:Product: documentation at
# SIDC Weekly bulletin on Solar and Geomagnetic activity             #
WEEK 1128 from 2022 Aug 08
Solar flaring activity was low at the start of the week when most regions
on disc where in decay or otherwise stable. There were 2 low-level C-class
flares in the afternoon of August 7 after which the X-ray flux remained
below C-level until August 11, when the newly emerging region NOAA 3077 as
well as new flux emergence in existing NOAA active region 3076 caused some
low C-class flares. Another newly emerging region (NOAA 3079) then was
responsible for most of the activity on August 12-13 and produced many
C-class flares, the strongest of which was a C6.8 flare peaking at 07:31UTC
on August 13.

A partial halo coronal mass ejection (CME) was observed in LASCO C2 from
around 12:48 UTC on August 14, with an estimated velocity of around 650
km/s. The CME is related to an on disc filament eruption in the
north-western quadrant and was associated to a long duration C2.4 flare, at
12:35 UT on August 14, with an associated observed type II radio emission.
The bulk of the CME was directed to the south-west, but a possible impact
at Earth was predicted for August 17.

The greater than 10 MeV proton flux was at nominal levels throughout the
The greater than 2 MeV electron flux first crossed the 1000 pfu threshold
on the afternoon of August 9 and remained enhanced for the remainder of the
The 24h electron fluence rose to moderate levels on August 9 and remained
at moderate levels throughout the rest of the week.

At the end of the week on August 14 a trans-equatorial negative polarity
coronal hole started transiting the central meridian.
During the week, the Earth was under the influence of the high-speed stream
from positive polarity equatorial coronal holes. By late August 7, the
solar wind speed rose to 600km/s and it remained at those levels for around
3 days. A very slow decline then set in and the speed reduced to just under
500km/s by the end of the week. On August 7 the magnitude of the
interplanetary magnetic field reached a value of almost 15nT in the
compression region. Bz was variable but mostly negative in the compression
region and reaching to -13nT. The orientation of the magnetic field
indicated a connection to a positive sector (field away from the Sun).

Geomagnetic conditions reached storm levels with the onset of the high
speed stream. Late on August 7, an isolated episode of moderate geomagnetic
storming was recorded. Over the rest of the week a downward trend was
observed, with quiet to unsettled conditions by the end of the week.
DATE           RC   EISN  10CM   Ak   BKG    M   X
2022 Aug 08   072    087   113   ///   B4.2   0   0   
2022 Aug 09   080    066   109   ///   B3.5   0   0   
2022 Aug 10   064    067   108   ///   B2.5   0   0   
2022 Aug 11   081    076   115   ///   B2.8   0   0   
2022 Aug 12   ///    110   120   ///   B3.2   0   0   
2022 Aug 13   ///    122   124   ///   B5.5   0   0   
2022 Aug 14   ///    119   126   ///   B4.3   0   0   
# 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)

# Solar Influences Data analysis Center - RWC Belgium                #
# Royal Observatory of Belgium                                       #
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This report is sent once a week, typically on a monday.
The weekly bulletin gives an overview of solar and geomagnetic activity of the past week and includes a noticeable solar events list.
Check the ISES code book for information on ISES codes.