Solar Terrestrial Activity Report [Image] Last update February 24, 2000 at 04:45 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 3, 2000)] [Solar cycles 1-20] [Graphical comparison of cycles 21, 22 and 23 (last update February 3, 2000)] [Graphical comparison of cycles 10, 13, 17, 20 and 23 (last update February 3, 2000)] [Historical solar and geomagnetic data charts 1954-1999] Recent development The geomagnetic field was quiet to active on February 23. Solar wind speed ranged between 355 and 534 km/sec. A coronal stream began influencing Earth just after 09h UTC. Solar flare activity was low. Solar flux was 185.1, the planetary A index was 10 (3-hour K indices: 3012 4422, Boulder K indices: 3112 3412). Region 8869 rotated off the visible disk. Region 8870 is rotating over the west limb. Region 8875 was mostly unchanged and quiet, the region could produce C flares and possibly even a minor M flare. Region 8879 developed several new spots and could possibly produce a minor M flare. Region 8881 developed slowly and was quiet. Region 8882 developed slowly and is capable of minor M class flaring. Region 8883 is developing and could soon become capable of M class flaring. Region 8884 was quiet and stable and will rotate off the visible disk today. New region 8885 emerged in the northwest quadrant. New region 8886 emerged in the southeast quadrant. Several interesting regions are at or just behind the east limb and will rotate into view over the next couple of days. 2 regions at the northeast limb and one at the southeast limb all appear capable of M class flaring, an X class flare is a possibility as well from one or two of these regions. Flares and CMEs 5 C flares were recorded on February 23, none of which were optically attributed to any of the numbered regions. An M1.1 flare was observed at 01:11 UTC on Feb.24, LASCO-EIT images indicate that the region at the southeast limb was the source of the flare. The background x-ray flux is at the class C2 level. Coronal holes A trans equatorial coronal hole was in a geoeffective position on February 21-25. This coronal hole is somewhat smaller than it has been over the last several months and is probably decaying. Forecast The geomagnetic field is expected to be quiet to minor storm on February 24 with a slight possibility of a major storm interval, unsettled to minor storm is expected on February 25 while quiet to active is likely on February 26-27. Long distance medium wave (AM) band propagation along east-west paths over high and upper middle latitudes is 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 no. Location at region numbered sunspots midnight Area Classification Comment 8870 1 N19W88 0030 HSX 8872 S31W73 plage 8874 S09W65 plage 8875 13 S23W54 0120 CAO beta-gamma 8876 S11W43 plage 8877 S22W55 plage 8879 20000217 11 N23E00 0250 CHO 8881 20000221 10 N20E24 0040 CSO 8882 20000221 14 S15E46 0320 DKO 8883 20000222 10 N13E47 0100 DSO 8884 20000222 2 S10W85 0060 DSO 8885 20000223 2 N11W43 0000 BXO 8886 20000223 2 S14E31 0000 BXO Total number of sunspots: 65 Monthly solar data Month Average solar International sunspot Smoothed sunspot flux number number 1999.01 140.6 62.4 82.6 (+4.8) 1999.02 141.9 66.1 84.6 (+2.0) 1999.03 126.3 69.1 83.8 (-0.8) 1999.04 117.2 63.9 85.4 (+1.6) 1999.05 148.4 106.3 90.4 (+5.0) 1999.06 169.8 137.7 93.0 (+2.6) 1999.07 165.6 113.5 94.4 (+1.4) 1999.08 170.7 93.7 (97.4 predicted, + 3.0) 1999.09 135.7 70.9 (102.4 predicted, +5.0) 1999.10 164.8 116.4 (107.5 predicted, +5.1) 1999.11 191.5 132.7 1999.12 169.8 86.4 2000.01 158.1 90.2 2000.02 163.7 (1) 121.0 (2) 1) Running average based on the daily 20:00 UTC solar flux value at 2800 MHz.. 2) Unofficial, accumulated value. The official value 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 in solar links. Comments and suggestions are always welcome. ------------------------------------------------------------------------ [DX-Listeners' Club] [DX News] [StudyWeb]