:Product: Weekly Highlights and Forecasts :Issued: 2004 Mar 02 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 23 - 29 February 2004 Solar activity ranged from very low to high levels with all of the significant activity occurring on 26 February. Region 564 (N14, L=160, class/area, Ekc/650 on 26 February) was responsible for all of the major flare activity during the summary period with an X1.1/2n at 26/0203 UTC and an M5.7/1n at 26/2230 UTC. Both events were very impulsive; LASCO imagery did not show CME activity associated with either flare. Since forming on the disk on 21 February, Region 564 exhibited rapid growth, forming a complex magnetic structure (beta-gamma-delta) that contributed to the increase in activity on the 26th. Since the activity on 26 February, Region 564 exhibited slow decay as it approached the west limb. The only other regions of interest this period were Region 565 (S05, L=140, class/area, Dai/130 on 26 February) that formed on the disk on 23 February and Region 567 (S13, L=070, class/area, Dao/120 on 29 February) that formed on the disk on 27 February. Region 567 produced two weak C-class flares on 28 February. Solar wind data were available from the NASA Advanced Composition Explorer (ACE) spacecraft during most of the summary period. The period began with solar wind speeds slightly elevated between 400 – 450 km/s and declined to about 325 km/s by 26 February. A solar sector boundary crossing was observed on ACE mid-day on the 26th as phi switched from a towards orientation to an away orientation. Early on 27 February, the wind speed began a steady increase reaching 800 km/s by mid-day on 29 February. The increased solar wind speeds were driven by a small, favorably positioned, recurrent coronal hole. The Bz component of the interplanetary magnetic field did not vary beyond +/- 5 nT from 23 to 27 February. Increased variability of +/- 15 nT was evident after 27 February due to the influence of the high-speed stream There were no greater than 10 MeV proton events at geosynchronous orbit during the summary period. The greater than 2 MeV electron flux at geosynchronous orbit remained below threshold levels every day of the summary period but the 24th where high levels were recorded. The geomagnetic field ranged from quiet to minor storm levels during the period. Mostly quiet to unsettled levels were observed on 23 to 27 February with one isolated active period recorded late on the 27th. Quiet to minor storm levels occurred on 28 and 29 February. The increase on 27 – 29 February was due to a coronal hole driven high-speed solar wind stream. Forecast of Solar and Geomagnetic Activity 03 - 29 March 2004 Solar activity is expected to be low with a chance for moderate levels until 03 March when Region 564 is due to rotate off the west limb. Predominantly very low to low activity levels are expected from 03 March through the middle of March. By 15 March, low to moderate level activity may return due to the return old of Region 564. No greater than 10 MeV proton events are expected during the period. The greater than 2 MeV electron flux at geosynchronous orbit is expected to reach high levels on 03 – 04 March and again on 10 – 16 March due to recurrent coronal holes. Geomagnetic activity is expected to range from quiet to minor storm levels. A large, recurrent coronal hole high-speed stream is due to return on 09 – 14 March and is expected to produce active to minor storm conditions. A second, weak coronal hole high-speed stream is due to return on 19 – 20 March and is expected to produce quiet to active conditions.