Solar Terrestrial Activity Report [Image] Last update February 21, 2002 at 05:20 UTC. [Solar and geomagnetic data - last 4 weeks (updated daily)] [Solar wind and electron fluence charts (updated daily)] [Solar cycles 21-23 (last update February 2, 2002)] [Solar cycles 1-20] [Graphical comparison of cycles 21, 22 and 23 (last update February 2, 2002)] [Graphical comparison of cycles 10, 13, 17, 20 and 23 (last update February 2, 2002)] [Historical solar and geomagnetic data charts 1954-2001 (last update January 12, 2002)] Recent development The geomagnetic field was quiet to unsettled on February 20. Solar wind speed ranged between 357 and 449 km/sec. Solar flare activity was high. Solar flux was 193.4, the planetary A index was 8 (3-hour K indices: 2032 3223, Boulder K indices: 2132 3323). Region 9824 was quiet and stable. Region 9825 did not change much in what had been the main penumbral area. Explosive growth was observed early in the day in an area to the northwest of the region. It is not obvious if this development was in region 9825 or the rapid reemergence of region 9822. Anyway this development destabilized region 9825 which was the source of a C5 proton flare at 05:55 UTC. The remainder of the flare activity attributed to region 9825 occurred in the area with rapid flux emergence at the northwest limb. Region 9828 reemerged briefly early in the day with a couple of spots, the region was spotless again by 06h UTC. Region 9829 reemerged briefly with a single spot. Region 9830 decayed slightly losing some of the area in the leading penumbra. The region still has two strong magnetic delta structures and is capable of producing major flares. Region 9832 was quiet and stable. New region 9835 developed in the southwest quadrant and may be capable of producing C class flares. New region 9836 emerged briefly in the southwest quadrant and is now spotless. New region 9837 rotated into view at the northeast limb. Flares and CMEs A total of 9 C and 5 M class events were recorded on February 20. Region 9825 produced a C5 proton event at 05:55 UTC. Energetic electrons increased rapidly at ACE from 06:00 UTC and a weak above 10 pfu proton event followed. Region 9825 (or 9822) was the source of an M4.2 impulsive flare at 02:51 (SEC/NOAA places this event at N15W58, almost 30 degrees east of the actual flare site), a major impulsive M5.1/1N at 06:12 (which SEC/NOAA did not manage to separate from the C5 flare described above), a C2.5 flare at 07:44, an M4.3 flare at 09:59, a C7.5 flare at 11:07, a C4.5 flare at 11:39 and an M3.5 flare (placed by SEC/NOAA at S09W62 - region 9835. This placement is not supported by SOHO images, the event occurred just behind the limb with the source in the rapidly developing area northwest of region 9825) at 17:11 UTC. Region 9830 produced a C2.1 flare at 01:14, a C9.7/1N flare at 16:26 and an M2.4/1B flare at 21:07 UTC. Several CMEs were observed during the day, none of them appeared to be geoeffective. Type II and IV radio sweeps were recorded in association with the M flares at 02:51 and 06:12 UTC but the related CMEs were directed westwards. One CME behind the southwest limb and another behind the northeast limb just after the major flare at 06:12 contributed to the appearance of a halo CME. February 18: Region 9830 was the source of a long duration M1.0 event peaking at 21:15 UTC. A LASCO C3 difference movie indicates that a weak full halo CME was produced by this event. The CME will likely impact the Earth on February 21 or 22 and could cause unsettled to minor storm conditions. The background x-ray flux is at the class C1 level. Coronal holes No obvious coronal holes are currently approaching geoeffective positions. Forecast The geomagnetic field is expected to be quiet to unsettled most of February 21. A CME could arrive late in the day or on February 22 and cause unsettled to minor storm conditions. Long distance medium wave (AM) band propagation along east-west paths over high and upper middle latitudes is fair. Coronal holes (1) Coronal mass M and X class flares (3) ejections (2) [Coronal hole indicator][CME indicator] [M and X class flare indicator] 1) Effects from a coronal hole could reach earth within the next 5 days. 2) Material from a CME is likely to impact earth within 96 hours. 3) There is a possibility of either M or X class flares within the next 48 hours. Green: 0-20% probability, Yellow: 20-60% probability, Red: 60-100% probability. Active solar regions (Recent map) Solar Date Actual Location region numbered no. at Area Classification Comment sunspots midnight 9824 2002.02.09 1 N24W74 0100 HSX 9825 2002.02.09 6 N16W81 0150 DAO beta-gamma 9828 2002.02.11 2 S14W71 AXX now spotless 9829 2002.02.14 1 S06W01 0000 AXX now spotless 9830 2002.02.14 49 S20W07 0530 FKC beta-gamma-delta spot count too high 9832 2002.02.18 1 S15W03 0010 HSX 9833 2002.02.19 N11W29 plage 9834 2002.02.19 N03E42 plage 9835 2002.02.20 4 S09W61 0040 DSO 9836 2002.02.20 2 S02W26 0010 BXO now spotless 9837 2002.02.20 1 N07E69 0060 HSX Total number of sunspots: 67 Monthly solar data Month Average solar International sunspot Smoothed sunspot flux number number 2000.04 184.2 125.5 120.8 cycle 23 sunspot max. 2000.07 202.3 170.1 119.8 2000.12 173.6 104.4 112.0 (-0.7) 2001.01 166.6 95.6 108.7 (-3.3) 2001.02 146.6 80.6 104.1 (-4.6) 2001.03 177.7 113.5 104.8 (+0.7) 2001.04 177.7 107.7 107.6 (+2.8) 2001.05 147.1 96.6 108.7 (+1.1) 2001.06 173.0 134.0 109.8 (+1.1) 2001.07 131.3 82.2 111.7 (+1.9) 2001.08 162.9 106.8 (113.5 predicted, +1.8) 2001.09 233.2 150.7 (113.3 predicted, -0.2) 2001.10 207.6 125.6 (111.0 predicted, -2.3) 2001.11 210.6 106.5 (109.6 predicted, -1.4) 2001.12 235.1 131.8 (106.2 predicted, -3.4) 2002.01 226.6 113.9 (102.6 predicted, -3.6) 2002.02 207.3 (1) 140.4 (2) (101.2 predicted, -1.4) 1) Running average based on the daily 20:00 UT solar flux value at 2800 MHz. 2) Unofficial, accumulated value based on the Boulder (SEC/NOAA) sunspot number. The official international sunspot number is typically 25-40% less. This report has been prepared by Jan Alvestad. It is based partly on my own observations and interpretations, and partly on data from sources noted in solar links. Comments and suggestions are always welcome. ------------------------------------------------------------------------ [DX-Listeners' Club] [DX News]