Solar Terrestrial Activity Report [Image] Last update February 20, 2001 at 04:45 UT. [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, 2001) - Did cycle 23 peak in April 2000?] [Solar cycles 1-20] [Graphical comparison of cycles 21, 22 and 23 (last update February 2, 2001)] [Graphical comparison of cycles 10, 13, 17, 20 and 23 (last update February 2, 2001)] [Historical solar and geomagnetic data charts 1954-2000 (last update January 18, 2001)] Recent development The geomagnetic field was quiet to unsettled on February 19. Solar wind speed ranged between 280 and 350 km/sec. What was likely a weak coronal stream arrived at approximately 09 UT at ACE. Only a small increase in geomagnetic activity was observed following the arrival of this very minor disturbance. A weak solar wind shock was observed at 01 UT on February 20. Solar wind speed increased abruptly from 280 to 310 km/sec, and the interplanetary magnetic field has recently become stronger and swung southwards. This disturbance may have been related to the halo CME observed on Feb.15. Solar flare activity was low. Solar flux was 137.0, the planetary A index was 6 (3-hour K indices: 1122 2311, Boulder K indices: 0232 1211). Region 9349 was quiet and stable, as were regions 9350, 9352 and 9353. Region 9351 rotate off the visible disk. Region 9354 developed slowly and was mostly quiet. C and minor M class flares are possible Region 9355 decayed and was quiet, the region was spotless by early evening. Region 9356 decayed and was quiet, the region was spotless by early evening. Region 9357 was quiet and stable. Region 9358 developed slowly and appears to have some potential for further development. C class flares are possible. Flares and CMEs Only 1 C class event was observed on February 19, it was an optically uncorrelated long duration C5.4 event peaking at 21:00 UT. The background x-ray flux is at the class B4 level. Coronal holes No obvious coronal holes are currently approaching geoeffective positions. Forecast The geomagnetic field is expected to be quiet to unsettled on February 20-21. 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 no. Location at region numbered sunspots midnight Area Classification Comment 9347 2001.02.09 N05W67 plage 9349 2001.02.10 1 N28W56 0000 AXX 9350 2001.02.11 1 N18W36 0050 HSX 9351 2001.02.15 1 S21W92 0000 AXX 9352 2001.02.15 3 S21E14 0010 BXO 9353 2001.02.16 5 S22W24 0010 BXO 9354 2001.02.16 17 S09W06 0150 DAI 9355 2001.02.18 5 N20E21 0010 BXO 9356 2001.02.18 5 S13W23 0020 BXO 9357 2001.02.18 3 S25E19 0020 CRO 9358 2001.02.18 6 S08E33 0040 CRO Total number of sunspots: 47 Monthly solar data Month Average solar International sunspot Smoothed sunspot flux number number 1999.11 191.5 133.2 111.0 (+3.2) 1999.12 169.8 84.6 111.1 (+0.1) 2000.01 158.1 90.1 112.9 (+1.8) 2000.02 174.1 112.9 116.8 (+3.9) 2000.03 208.2 138.5 119.9 (+3.1) 120.8 (+0.9) 2000.04 184.2 125.5 cycle 23 peak candidate 2000.05 184.9 121.6 119.0 (-1.8) 2000.06 179.8 124.9 118.7 (-0.3) 2000.07 202.3 170.1 119.8 (+1.1) 2000.08 163.0 130.5 (119.5 predicted, -0.3) 2000.09 182.1 109.7 (117.9 predicted, -1.6) 2000.10 167.4 100.1 (116.3 predicted, -1.6) 2000.11 178.8 106.5 (114.4 predicted, -1.9) 2000.12 173.6 104.5 (111.8 predicted, -2.6) 2001.01 166.6 95.7 (108.2 predicted, -3.6) 2001.02 150.3 (1) 95.8 (2) 1) Running average based on the daily 20:00 UT 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 noted in solar links. Comments and suggestions are always welcome. ------------------------------------------------------------------------ [DX-Listeners' Club] [DX News] [StudyWeb]