Solar Terrestrial Activity Report [Image] Last update March 20, 2001 at 05:40 UT. Minor update posted at 13:55 UT. [Solar and geomagnetic data - last 4 weeks (updated daily)] [Solar wind and electron fluence charts (updated daily)] [Solar cycles 21-23 (last update March 1, 2001) - Cycle 23 sunspot maximum was in April 2000] [Solar cycles 1-20] [Graphical comparison of cycles 21, 22 and 23 (last update March 1, 2001)] [Graphical comparison of cycles 10, 13, 17, 20 and 23 (last update March 1, 2001)] [Historical solar and geomagnetic data charts 1954-2000 (last update January 18, 2001)] Recent development The geomagnetic field was quiet to minor storm on March 19. Solar wind speed ranged between 277 and 551 km/sec. A solar wind shock was observed at ACE at 10:20 UT with solar wind speeds abruptly increasing from 320 to 400 km/sec. The source of the disturbance is likely the halo CME observed on March 15. Solar flare activity was low. Solar flux was 147.0, the planetary A index was 22 (3-hour K indices: 2233 4554, Boulder K indices: 2222 4544). Region 9373 developed a magnetic delta configuration in the trailer spot section and became more unstable. Minor M class flaring is likely. Region 9380 was spotless all day in all available images. Region 9384 decayed slowly and was quiet. Region 9386 decayed and was spotless by noon. New region 9387 emerged at the northeast limb. A couple of active regions are approaching the east limb, the one just behind the northeast limb appears to be the most interesting one. Comment added at 13:55 UT on March 20: The interplanetary magnetic field has gradually strengthened and swung further southwards since early today. Currently severe (K index 7) and even very severe (K index 8) storming is observed at high latitude stations. It is likely that the planetary A index for the 12-15 UT interval will significantly exceed 100. The current disturbance is much stronger than forecast and could last until sometime on March 21. Three new spotted regions are visible, one at the southeast limb, another one at the northeast limb (perhaps capable of minor M class flaring) and an emerging region in the northwest quadrant. Region 9384 is rapidly becoming spotless but was nonetheless the source of an M1.2 flare early today, region 9373 was the source of an M1.1 flare very early in the day. Flares and CMEs A total of 3 C class events were recorded on March 19. Region 9373 produced a C3.4 flare at 18:45 and a C3.2 flare at 23:27 UT. A filament eruption began at approximately 04:12 UT in the southern hemisphere and near the center of the solar disk. A weak full halo CME was observed later on in LASCO C3 images. A couple of minor M class flares have been observed early on March 20, both probably occurred in region 9373. The background x-ray flux is at the class B8 level. Coronal holes A small, well placed coronal hole in the northern hemisphere will rotate into a geoeffective position on March 19-20. Geomagnetic effects beyond a few unsettled to active intervals on March 22-23 are unlikely. Forecast The geomagnetic field is expected to be quiet to minor storm on March 20. A CME based disturbance will arrive on March 22 and cause unsettled to active conditions. Long distance medium wave (AM) band propagation along east-west paths over high and upper middle latitudes is 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 AreaClassification Comment sunspots midnight 9373 2001.03.09 21 S07W58 0270 FAI beta-gamma-delta 9374 2001.03.10 S17W62 plage 9376 2001.03.11 S13W30 plage 9379 2001.03.12 N31W51 plage 9380 2001.03.12 2 S12W29 0010 DSO actually spotless 9381 2001.03.13 S17W43 plage 9384 2001.03.14 8 N13W62 0100 FAO 9385 2001.03.17 S11E14 plage 9386 2001.03.18 1 N04W27 0010 HSX now spotless 9387 2001.03.19 3 N09E59 0030 CSO Total number of sunspots: 35 Monthly solar data Month Average solar International sunspot Smoothed sunspot flux number number 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) 2000.04 184.2 125.5 120.8 (+0.9) cycle 23 sunspot max. 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) 2000.08 163.0 130.5 118.6 (-1.2) 2000.09 182.1 109.7 (115.4 predicted, -3.2) 2000.10 167.4 100.1 (113.0 predicted, -2.4) 2000.11 178.8 106.5 (111.0 predicted, -2.0) 2000.12 173.6 104.5 (108.5 predicted, -2.5) 2001.01 166.6 95.7 (104.7 predicted, -3.8) 2001.02 146.6 80.1 (100.3 predicted, -4.4) 2001.03 148.6 (1) 71.3 (2) (96.8 predicted, -3.5) 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. ------------------------------------------------------------------------ Do you know about the survey which will be held this Summer among the listeners of WWV and WWVH? There is information about this survey at 16 minutes past the hour on WWV and at 47 minutes past the hour on WWVH. If you want to participate send an email with your name and address. ------------------------------------------------------------------------ [DX-Listeners' Club] [DX News] [StudyWeb]