Issued: 2004 Aug 16 1308 UTC
SIDC Weekly bulletin on Solar and Geomagnetic activity
WEEK 189 from 2004 Aug 09
SOLAR ACTIVITY
--------------
The solar activity was dominated over the whole week by a major
active region, Catania#90 (NOAA10656), which was the source of
virtually all observed flares.
This active region experienced a fast growth between Aug.9 and 11,
acquiring a beta-gamma-delta magnetic configuration and reaching
an area of about 1350 millionth of an hemisphere. In the second
part of the week, the region grew further but at a slower rate.
In terms of eruptive activity, this region produced only C flares
until Aug.12, when it spawned a first M1 flare while the X-ray
background reached C1 level. For the last 3 days of the period,
the solar activity became high:
on Aug.13, 4 M flares and an X1 flare at 18:12UT, associated
with a 180sfu tenflare and a semi-halo CME
on Aug.14, 7 M flares, of which an M7 and an M5 (X-ray
background at C5)
on Aug.15, 5 M flares, including an M9.
Although active region #90 now shows some signs of decay, it may
still contribute a few major flares in the coming 3 days, before
it disappears at the West limb on Aug. 18. As the other active
regions on the disc are small and largely quiet, the solar
activity is expected to become low after Aug. 19.
GEOMAGNETIC ACTIVITY
--------------------
The geomagnetic field was mostly quiet to unsettled during the
whole week, except for two active to minor storm events, from
Aug. 9 18:00 to Aug. 10 02:00UT and from Aug.10 12:00 to
24:00UT. These events were associated with sector boundary
crossings and the entrance of the Earth into a high-speed
solar wind stream on Aug.10 (southward fluctuations of the
interplanetary magnetic field). The solar wind speed reached
a peak of 600km/s on Aug.11 at OO:OOUT and then steadily decayed
for the rest of the week, down to 350km/s. As the Bz component
of the IMF was predominently Northward, especially on the
last two days of the week, the geomagnetic field remained quiet.
However, several CMEs emerged from region Catania#90 or the
large filament channel located just to its South-West, in
particular over the last 3 days of the week. Still, given
their moderate speed and the source location far from central
meridian, they were either not Earth-directed or may only
induce small geomagnetic disturbances between Aug.16 and 18.
---------------------------------------------------------------------------
DAILY INDICES
DATE RC 10CM Ak BKG M X
2004 Aug 09 085 114 /// B3.8 0 0
2004 Aug 10 091 121 /// B3.3 0 0
2004 Aug 11 083 131 /// B4.9 0 0
2004 Aug 12 093 147 /// B6.9 1 0
2004 Aug 13 110 149 /// B6.8 4 1
2004 Aug 14 101 149 /// C2.0 7 0
2004 Aug 15 082 139 /// B7.0 5 0
# RC : Sunspot index from Catania Observatory (Italy)
# 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)
---------------------------------------------------------------------------
NOTICEABLE EVENTS
DAY BEGIN MAX END LOC XRAY OP TENCM TYPE Cat NOAA NOTE
12 0438 0505 0520 S14E02 M1.2 1F 90 0656
13 0636 0729 0738 S15W12 M1.2 1F 90 0656
14 1202 1209 1212 S13W19 M1.1 1F 90 0656
13 1807 1812 1815 S13W24 X1.0 1N 180 90 0656 Semi-halo CME
13 2314 2343 2346 S13W26 M3.0 90 0656
14 0410 0414 0417 S13W30 M2.4 SF 98 90 0656
14 0536 0544 0552 S11W28 M7.4 2N 96 90 0656
14 0751 0756 0759 S13W32 M2.3 1F 90 0656
14 0952 1007 1017 S14W30 M3.2 1F 25 90 0656
14 1331 1343 1350 S14W34 M5.6 2N 77 90 0656
14 1809 1818 1832 S13W36 M1.3 90 0656 GOES-12/SXI derived
location
14 2009 2016 2059 S13W39 M1.3 90 0656 GOES-12/SXI derived
location
15 0445 0506 0522 S12W44 M1.2 SF III/3 90 0656
15 0554 0600 0604 S12W42 M1.2 SF 90 0656
15 1123 1132 1148 S15W47 M2.6 2F 52 90 0656
15 1234 1241 1243 S15W45 M9.4 1N 90 0656
15 1837 1845 1850 S13W50 M1.2 III/2 90 0656 GOES-12/SXI derived
location
73,
Thomas F. Giella, KN4LF
Plant City, FL, USA
Grid Square EL87WX
Lat & Long 27 58 31 44N 82 09 51 98W
NWS Tampa Bay, FL SKYWARN Observer # HIL-249
SWFWMD Rainfall Network Observer #574 Thackery
CWOP Weather Station #CW2111
PODXS 070 PSK31 Club Member #349
KN4LF Solar Space Weather & Geomagnetic Data Archive:
http://www.kn4lf.com/kn4lf5.htm
KN4LF Daily HF/MF Radio Propagation Outlook: http://www.kn4lf.com/kn4lf6.htm
KN4LF HF/MF Radio Propagation Theory Notes: http://www.kn4lf.com/kn4lf8.htm
KN4LF Amateur & SWL Radio History: http://www.kn4lf.com
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