Solar Terrestrial Activity Report [Image] Last update March 31, 2001 at 02:40 UT. Minor update posted at 07:43 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)] [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 unsettled on March 30. Solar wind speed ranged between 381 and 476 km/sec. A weak solar wind shock was observed at 21:50 UT at ACE, solar wind speed increased only from 410 to 430 km/sec. The source of this shock was likely one of the halo CMEs observed on March 28. An extremely strong solar wind shock was observed at ACE at 00:23 UT. Solar wind speed increased abruptly from 430 to 660 km/sec. Solar wind density at SOHO incredibly reached 175 p/cm3, the highest density I can recall ever having observed. The interplanetary magnetic field strengthened dramatically and was for a few minutes initially very strongly southwards, then the IMF swung strongly northwards until approximately 02 UT when a strong southward excursion was observed. The source of this disturbance is highly likely the halo CME observed in connection with an X1 flare on March 29. WARNING: Extremely severe storming (K=9), particularly at high latitudes, is possible today. Solar flare activity was moderate. Solar flux was 256.8, the planetary A index was 10 (3-hour K indices: 1223 3333, Boulder K indices: 2223 4323). Region 9387 rotated off the visible disk early in the day. Regions 9389 and 9390 were quiet and stable. Region 9393 is a very large and complex region capable of producing major X class flares. Several strong magnetic deltas are distributed throughout the region. Another X class flare would likely be a large proton event as well. Region 9395 was quiet and stable. Region 9396 decayed and was quiet, the region has rotated over the west limb. Region 9397 developed slowly and was mostly quiet. Minor M class flares are possible. Region 9401 developed slowly and could produce M class flares. Region 9403 was quiet and stable. Region 9404 developed slowly and was mostly quiet. Regions 9406 and 9407 were quiet and stable. Region 9408 was mostly unchanged and quiet, a minor M class flare is possible. New region 9410 in the southeast quadrant at a high latitude was finally numbered. New region 9411 emerged in the northeast quadrant, the region appears to be spotless already. New region 9412 rotated into view at the southeast limb. Comment added at 07:43 UT on March 31: The geomagnetic field is currently extremely disturbed with several magnetometers around the world recording K9 fluctuations during the last couple of hours. The planetary A index was 92 for the 00-03h UT interval, and 224 for the 03-06 UT interval. Ap will likely exceed 300 for the 06-09 UT interval. The IMF has been exceptionally strongly southwards for several hours. Flares and CMEs A total of 4 C and 2 M class events were recorded on March 30. Region 9393 produced a C7.9 flare at 01:10, a C7.5 flare at 02:28, a C4.4 flare at 03:50, an M2.2/1N flare at 05:15 and an M1.0 flare at 09:28 UT. The background x-ray flux is at the class C2 level. Coronal holes A coronal hole in the northern hemisphere will rotate into a geoeffective position on March 31 and April 1 and could cause unsettled to active conditions on April 3-4. Forecast The geomagnetic field is expected to be minor to very severe storm on March 31 and quiet to minor storm April 1. Long distance medium wave (AM) band propagation along east-west paths over high and upper middle latitudes is useless. 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 9387 2001.03.19 1 N08W92 0060 HSX 9389 2001.03.20 8 S10W63 0050 BXO 9390 2001.03.20 1 N13W65 0050 HSX 9393 2001.03.21 63 N17W30 2240 FKC beta-gamma-delta 9394 2001.03.22 N08W33 plage 9395 2001.03.23 2 S13W17 0050 HSX 9396 2001.03.24 5 S06W85 0140 DAO 9397 2001.03.24 23 S09W06 0180 EAO beta-gamma 9398 2001.03.24 N21W65 plage 9399 2001.03.24 S31W73 plage 9400 2001.03.24 N10W57 plage 9401 2001.03.25 37 N21W11 0230 EKI beta-gamma 9402 2001.03.25 N18W60 plage 9403 2001.03.26 2 S13E06 0010 BXO 9404 2001.03.27 7 S05E23 0080 CAO 9405 2001.03.28 S13W47 plage 9406 2001.03.28 1 N26E41 0170 HAX 9407 2001.03.28 5 N11E41 0100 CSO 9408 2001.03.28 28 S09E11 0200 EKI 9410 2001.03.30 2 S36E38 0010 AXX 9411 2001.03.30 2 N07E49 0020 AXX 9412 2001.03.30 2 S14E79 0030 BXO Total number of sunspots: 189 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) 2001.03 175.5 (1) 156.2 (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]