Solar Influences Data Center (SIDC) / RWC Belgium Royal Observatory of Belgium E-mail: Pierre.Cugnon@oma.be http://sidc.oma.be SIDC WEEKLY BULLETIN -------------------- WEEK 118 from 2003 Mar 31 SOLAR ACTIVITY -------------- The week started fairly quiet regarding solar activity. Although both NOAA0319 and NOAA0323 had a beta-gamma magnetic configuration, they proved only capable of producing occasional C-flares. >From April 2 onwards, region NOAA0324 started a rapid development and became the dominant centre for solar activity. In the following days it unleashed many C-flares and also, on April 4, the first M-class solar flare since quite a few days. This flare was also accompanied by a partial halo CME. GEOMAGNETIC ACTIVITY -------------------- Although the beginning of the week saw a decrease of the solar wind speed, marking the end of the influence of a coronal hole, the geomagnetic conditions have remained unsettled throughout the week, with frequent brief excursions to minor storm levels. This was related to the fact that the solar wind remained motsly above 450km/s, and there were frequent intervals of southwards oriented interplanetary magnetic field. --------------------------------------------------------------------------- DAILY INDICES DATE RC 10CM Ak BKG M X 2003 Mar 31 /// 160 039 B3.8 0 0 2003 Apr 01 /// 153 019 B4.0 0 0 2003 Apr 02 /// 158 030 B5.1 0 0 2003 Apr 03 /// 156 020 B6.5 0 0 2003 Apr 04 /// 153 026 B8.5 1 0 2003 Apr 05 /// 137 030 B5.1 0 0 2003 Apr 06 /// 126 /// B3.3 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 10CM TYPE Cat NOAA NOTE 05 1905 2019 2038 S11W40 M2.1 1F 65 III/1 0324