> :Issued: 2005 Apr 25 1318 UTC
> :Product: documentation at http://sidc.oma.be/products/bul
> #--------------------------------------------------------------------#
> # SIDC Weekly bulletin on Solar and Geomagnetic activity #
> #--------------------------------------------------------------------#
> WEEK 225 from 2005 Apr 18
>
> SOLAR ACTIVITY
> --------------
> The sun was very quiet during the entire week, with flaring activity not
> even reaching
> the C-class level (on some days not even B-flares were recorded). The
> largest flare of
> the week was a long-duration B8.0 flare on Apr 19, which was accompanied
> by a large
> eastward CME. This flare originated from Catania sunspot group 55 (NOAA
> 0755), which
> was the most active group this week, even though it only consisted of a
> few tiny spots.
> Towards the end of the week, while the surface of the sun was nearly
> spotless, the X-ray
> background increased significantly due to the appearance of the loop
> system of a new
> active region at the east limb.
>
> Besides the CME mentioned above, two other significant CMEs were seen,
> both on Apr 21.
> Early on this day a filament eruption at the west limb (also beautifully
> visible in EIT
> 304 images) caused the first one, while the second one late in the day
> came from behind
> the east limb. Several other small filaments erupted during the week (see
> e.g.
> http://sidc.oma.be/EITimages/EIT304_animator.html).
>
> GEOMAGNETIC ACTIVITY
> --------------------
> Once again, geomagnetic conditions were dictated by the presence (or not)
> of coronal
> holes near the solar equator. The week started with a slow solar wind and
> quiet
> geomagnetic conditions. On Apr 19, a small equatorial coronal hole that
> passed the
> central solar meridian on Apr 16 started to influence the earth. From the
> evening of
> Apr 19 onwards, the solar wind speed rapidly increased to about 550km/s.
> The highly
> variable IMF had short intervals of strong southwards orientation on Apr
> 19-20, leading
> to active conditions (K=4) in Niemegk. The NOAA estimated Kp index even
> reached 5 (minor
> storm) on Apr 20. The earth basically remained under coronal hole
> influence for the rest
> of the week, since the small equatorial hole was followed by a large
> trans-equatorial
> one. The solar wind speed did go down to 400 km/s late on Apr 21, but over
> the
> following days it increased again to 550km/s (by noon on Apr 23) and it
> currently still
> is near this value. However, the IMF was never strongly southwards after
> Apr 20, so the
> geomagnetic conditions remained mostly quiet from Apr 21 until the end of
> the week.
> ---------------------------------------------------------------------------
> DAILY INDICES
> DATE RC 10CM Ak BKG M X
> 2005 Apr 18 043 81 008 A4.8 0 0
> 2005 Apr 19 047 78 008 A3.5 0 0
> 2005 Apr 20 039 77 020 A2.5 0 0
> 2005 Apr 21 023 77 003 A1.5 0 0
> 2005 Apr 22 039 77 010 A2.6 0 0
> 2005 Apr 23 037 79 008 A5.5 0 0
> 2005 Apr 24 012 82 008 B1.1 0 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
> NONE
>
> #--------------------------------------------------------------------#
> # Solar Influences Data analysis Center - RWC Belgium #
> # Royal Observatory of Belgium #
> # Fax : 32 (0) 2 373 0 224 #
> # Tel.: 32 (0) 2 373 0 491 #
> # #
> # For more information, see http://sidc.oma.be. Please do not reply #
> # directly to this message, but send comments and suggestions to #
> # 'sidctech@oma.be'. If you are unable to use that address, use #
> # 'rvdlinden@spd.aas.org' instead. #
> #--------------------------------------------------------------------#
73 & GUD DX,
Thomas F. Giella, KN4LF
Retired Space & Atmospheric Weather Forecaster
Plant City, FL, USA
Grid Square EL87WX
Lat & Long 27 58 33.6397 N 82 09 52.4052 W
kn4lf@arrl.net
Contesting Propagation eReflector:
http://lists.contesting.com/mailman/listinfo/propagation
HC-DX Propagation Channel:
http://www.hard-core-dx.com/index.php?topic=Propagation
KN4LF Daily Solar Space Weather & Geomagnetic Data Archive:
http://www.kn4lf.com/kn4lf5.htm
KN4LF Daily LF/MF/HF 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/index.htm
--
No virus found in this outgoing message.
Checked by AVG Anti-Virus.
Version: 7.0.308 / Virus Database: 266.10.2 - Release Date: 4/21/2005
_______________________________________________
Propagation mailing list
Propagation@contesting.com
http://lists.contesting.com/mailman/listinfo/propagation
|