Solar Terrestrial Activity Report [Image] Last update April 2, 2002 at 03:35 UTC. [Solar and geomagnetic data - last 4 weeks (updated daily)] [Solar wind and electron fluence charts (updated daily)] [Solar cycles 21-23 (last update April 2, 2002)] [Solar cycles 1-20] [Graphical comparison of cycles 21, 22 and 23 (last update April 2, 2002)] [Graphical comparison of cycles 10, 13, 17, 20 and 23 (last update April, 2002)] [Historical solar and geomagnetic data charts 1954-2001 (last update January 12, 2002)] Recent development The geomagnetic field was quiet to active on April 2. Solar wind speed ranged between 582 and 751 km/sec under the influence of a high speed solar coronal stream. Solar flare activity was low. Solar flux was 206.0, the planetary A index was 15 (3-hour K indices: 2444, Boulder K indices: 2443 2222). Region 9884 decayed slowly and quietly and only one spot was visible at the end of the day (SEC/NOAA amazingly observed 13 spots). Region 9885 decayed slowly and quietly. The region does not have mixed polarities any more. (SEC/NOAA managed to observe more spots than they did the day before despite the region decaying!). A minor M class flare is still possible. Region 9886 decayed slowly and quietly. (Again SEC/NOAA observed more spots (32) than on the previous day, in comparison Learmonth observed 12 spots in this region early on April 3). Region 9887 developed quickly early in the day with a magnetic delta structure forming briefly in the trailing spots section. The region has since simplified somewhat but is still capable of producing a major flare. (Not surprisingly SEC/NOAA observed significantly more spots than others even in this region.) Region 9888 decayed and lost several spots in the trailing section. (Not so according to SEC/NOAA which noted 10 more spots than on the previous day.) Region 9889 was quiet and stable. (Even in this small region SEC/NOAA incredibly increased their spot count from 2 to 7). New region 9890 in the southwest quadrant was finally numbered, the region is now spotless. New region 9891 emerged in the southwest quadrant near the central meridian. New region 9892 emerged quickly near the northeast limb between midnight and 06h UTC, the region has since decayed slowly. Flares and CMEs A total of 15 C class events were recorded on April 2. Region 9887 produced a C2.2 flare at 10:38, a C4.0 flare at 13:22, a C3.3 flare at 14:09, a C2.6 flare at 14:45, a C2.5 flare at 15:46, a C1.1 flare at 16:28 and a C2.8 flare at 17:01 UTC. The remainder of the flares, including a C9.4 flare at 00:50 UTC, were optically unaccounted. Numerous CMEs have been observed over the last couple of days, most of them from sources behind the southwest and northeast limbs. The background x-ray flux is at the class B7 level. Coronal holes A small coronal hole in the southern hemisphere may have been in a geoeffective position on April 2 and could cause a minor increase in geomagnetic activity on April 5. Forecast The geomagnetic field is expected to be quiet to unsettled on April 3-5. Long distance medium wave (AM) band propagation along east-west paths over high and upper middle latitudes is poor to very poor. 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 9882 2002.03.22 N16W77 plage 9883 2002.03.23 N07W62 plage 9884 2002.03.27 13 S18W39 0120 CSO area and spot count much too high 9885 2002.03.27 41 N13W14 0600 EKI spot count too high 9886 2002.03.29 32 N12E02 0110 DAI spot count too high 9887 2002.03.29 48 N02E11 0700 EKI beta-gamma spot count too high 9888 2002.03.29 24 S12E19 0250 DAI spot count too high 9889 2002.03.31 7 S19E18 0020 CAO spot count too high 9890 2002.04.02 1 S15W49 0000 AXX 9891 2002.04.02 1 S08W08 0000 AXX 9892 2002.04.02 5 N05E63 0090 CRO Total number of sunspots: 172 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 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) 2001.08 162.9 106.8 113.6 (+1.8) 2001.09 233.2 150.7 114.1 (+0.5) 2001.10 207.6 125.6 (112.7 predicted, -1.4) 2001.11 210.6 106.5 (111.5 predicted, -1.2) 2001.12 235.1 131.8 (108.2 predicted, -3.3) 2002.01 226.6 113.9 (104.8 predicted, -3.4) 2002.02 205.0 108.0 (103.4 predicted, -1.4) 2002.03 179.5 98.1 (99.1 predicted, -4.3) 2002.04 206.5 (1) 15.0 (2) (93.2 predicted, -5.9) 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 25-45% 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]