:Product: Weekly Highlights and Forecasts :Issued: 2003 Sep 16 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 08 - 14 September 2003 Solar activity ranged from very low to low levels. The period began with very low level activity on 08 – 10 September and again on 12 September. Low level activity was observed on 11 September and 13 – 14 September. Up until 12 September, all of the sunspot regions on the visible disk were relatively small and magnetically simple. Late on 11 September, a long duration B7 X-ray enhancement occurred at 2237 UTC and was correlated with the two disappearing solar filaments. The first DSF was five-degrees long and lifted off around 2100 UTC in the vicinity of S25E05. The second DSF followed the first and was along the same inversion line. This DSF was ten-degrees long and lifted off in the vicinity of S18E15. LASCO C2 imagery indicates a partial halo CME associated with the two DSF's. Region 456 (S07, L=221, class/area Dai/240 on 13 September) was in a slow gradual growth phase for most of the period and by 12 September had developed some polarity mixing in the intermediate spots. A beta-gamma-delta magnetic configuration developed for a brief period on 13 September. Activity from Region 456 consisted of a few mid level C-class flares, including the largest flare of the period, a C4/Sf on 14 September at 0127 UTC. Solar wind data were available from the NASA Advanced Composition Explorer (ACE) spacecraft for most of the summary period. Late on 08 September, a coronal hole high-speed flow rotated into a geoeffective position with the solar wind speed increasing to 700 km/s by 10 September. Wind speeds remained elevated above 600 km/s until late on 12 September. On 13 – 14 September, wind speed declined and by the close of the period was back to 400 km/s. The Bz component of the interplanetary magnetic field (IMF) was oscillating between –5nT and +8nT during most of the high speed flow with peak fluctuations near –10nT. Total IMF measurements were over 10nT on 08-09 September but then decreased to approximately 6nT for the duration of the high speed flow. There were no greater than 10 MeV proton events at geosynchronous orbit during the period. The greater than 2 MeV electron flux at geosynchronous orbit reached high levels on 08 September and again on 11 – 14 September. Geomagnetic activity ranged from quiet to isolated minor storm levels. The period began with quiet to unsettled conditions on 08 September. Late on 08 September, a coronal hole high-speed flow rotated into a geoeffective position producing mostly unsettled to active conditions on 09 – 11 September with one period of minor storm levels observed on 11 September. The remainder of the period (12 – 14 September) was at quiet to unsettled levels. Forecast of Solar and Geomagnetic Activity 17 September - 13 October 2003 Solar activity is expected to range from very low to low levels during the period. No greater than 10 MeV proton events at geosynchronous orbit are expected during the period. The greater than 2 MeV electron flux at geosynchronous orbit is expected to reach high levels on 19 – 23 September and again on 02 – 05 October. The geomagnetic field is expected to range from quiet to major storm levels during the period. A large coronal hole high speed flow is expected to return on 17 – 21 September with major storm levels possible. Another coronal hole is due to return on 01 – 03 October and is expected to produce mostly active conditions with isolated minor storm levels possible. A returning coronal hole on 05 – 08 October is expected to produce active to isolated minor storm levels.