:Product: Weekly Highlights and Forecasts :Issued: 2002 Oct 08 2212 UTC # Prepared by the US Dept. of Commerce, NOAA, Space Environment Center # Product description and SEC contact on the Web # http://www.sec.noaa.gov/weekly.html # # Weekly Highlights and Forecasts # Highlights of Solar and Geomagnetic Activity 30 September - 06 October 2002 Solar activity ranged from low to high levels. Activity reached high levels on 04 – 05 October with the largest event an M5 flare, on 05 October, from Region 139 (N12, L=336, class/area Dkc/680 on 05 October). A Type II radio sweep measuring 325 km/s was associated with the M5 flare. For flare times and magnitudes, please refer to Energetic Flare and Optical Flare Lists. Region 139 exhibited rapid growth on 03-05 October and developed a magnetic delta configuration on 04 October, which only lasted a day. Region 139 produced two M-class events, on 04 October, each with an associated Type II radio sweep. Region 137 (S19, L=40, class/area Eki/310 on 03 October) produced four M-class flares on 04 October, with the largest an M4/1n at 04/0538 UTC. Region 137 showed signs of mixing polarities in the trailing spot on 03 October, but maintained only a beta-gamma magnetic configuration. On 04 October, Region 137 entered a gradual decay phase. Region 139 entered a gradual decay phase on 06 October, but still had signs of a weak delta configuration in the leader spot. Solar wind data were available from the NASA Advanced Composition Explorer (ACE) spacecraft for most of the summary period. A CME shock was recorded at ACE at 30/0730 UTC with an IMF Bz deflection to –18 nT. Late on 30 September, Bz went from a maximum positive value of 26 nT to a maximum negative value of –24 nT in a six-hour period. Solar Wind velocities jumped to about 360 km/s due to the initial CME shock on 30 September and continued a gradual increase into the next day with peak values near 425 km/s. Solar wind velocities increased to near 550 km/s on 02-03 October then began a variable decrease, ending the period near 360 km/s. The Bz component of the IMF was predominantly negative throughout the summary period. Average Bz values were near –5 nT from 02-06 October. There were no greater than 10 MeV proton events at geo-synchronous orbit during the summary period. The greater than 2 MeV electron flux at geo-synchronous orbit reached normal to high levels. High levels were observed on 05-06 October. Geomagnetic field activity ranged from quiet to severe storm levels. On 30 September, two sudden impulses were recorded on the Boulder magnetometer, a 22 nT deflection at 30/0822 UTC and an 11 nT deflection at 30/1928 UTC. Resulting activity reached major storm levels and is believed to have originated from the M-class events that occurred on 27 September. Activity on 01-02 October reached severe storm conditions. The source of this activity is unclear but NASA/ACE data revealed a slow moving transient signature. Late on 03 October and early on 04 October, geomagnetic activity reached minor to severe storm levels and was probably due to CME activity observed on 30 September. Active to minor storm activity on 05-06 October was the result of predominantly southward Bz component of the IMF, which was most likely due to CME activity on 03-04 October. Forecast of Solar and Geomagnetic Activity 09 October - 04 November 2002 Solar activity is expected to be low to moderate during the forecast period. Moderate activity is possible early in the period due to Region 139 and the return of old Region 119 (S14, L=228). Moderate activity is possible late in the period with the Return of Region 134 and Region 137 on 19 October and 23 October, respectively. There is a slight chance of a greater than 10 MeV proton event during the forecast period. The greater than 2 MeV electron flux at geo-synchronous orbit may reach event threshold on 10-12 October due to coronal hole effects. The geomagnetic field is expected to be quiet to active levels. Coronal hole effects are expected on 09-10 October and weak coronal hole effects are possible on 03-04 November. .