Solar Terrestrial Activity Report [Image] Last update March 28, 2001 at 03:40 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 minor storm on March 27. Solar wind speed ranged between 338 and 633 km/sec. A solar wind shock was observed at ACE at 01:10 UT. Solar wind speed increased abruptly from 350 to 440 km/sec. Another solar wind shock was observed at ACE at 17:18 UT, this time with a rapid increase in solar wind speed from 430 to 540 km/sec. The source of the latter shock was likely a halo CME observed during the afternoon of March 25. Solar flare activity was moderate. Solar flux was 273.4 (new high for cycle 23), the planetary A index was 18 (3-hour K indices: 3223 2345, Boulder K indices: 4223 2345). Region 9387 was quiet and stable. Region 9389 decayed and lost more than half of its spots. Region 9390 decayed and produced a few flares. Region 9393 developed further and is early on March 28 the largest region observed during cycle 23 covering an area of more than 2000 mils. The region is complex and could produce major flares any time. An X10+ proton flare is possible. Region 9394 was quiet and stable, as was region 9395. Region 9396 developed at a moderate pace and could produce M class flares. Region 9397 was mostly quiet and stable, M class flares are possible. Region 9398 decayed into spotless plage. Region 9399 was mostly unchanged and quiet. Region 9400 was quiet and stable. Region 9401 decayed slightly but could still produce M class flares. Region 9402 was mostly quiet and stable. Region 9403 developed slowly and could produce C class flares. New region 9404 rotated into view at the southeast limb. Early on March 28 a couple of spotted regions are rotating into view at the northeast limb (at least one of them appears to capable of M class flare production) and there is a region at a high latitude at the southeast limb as well. A couple of emerging regions, one in the southwest quadrant and another in the southeast quadrant could take the Boulder sunspot number close to 400 today. Flares and CMEs A total of 9 C and 1 M class events were recorded on March 27. Region 9390 produced a C4.2 flare at 00:55 and a C5.6 flare at 19:18 UT (the latter event was accompanied by a weak type II sweep. LASCO EIT images did not reveal any significant coronal activity). Region 9393 generated a C7.3 flare at 02:47, a C5.6 flare at 15:12 and a C4.2 flare at 18:31 UT. Region 9402 was the source of a C6.3 flare at 08:07 UT. Region 9401 produced a C4.5 flare at 12:22 and an M2.2/1N impulsive flare at 16:30 UT. A moderate type II sweep was recorded and there may have been a weak CME, however, LASCO C3 mages do not reveal any well defined coronal mass ejection. Region 9397 managed a C8.2 flare at 20:27 UT. The background x-ray flux is at the class C3 level. Coronal holes No obvious coronal holes are currently approaching geoeffective positions. Forecast The geomagnetic field is expected to be quiet to active on March 28-29. 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 9387 2001.03.19 1 N09W52 0130 HSX 9389 2001.03.20 13 S12W11 0080 EAO 9390 2001.03.20 9 N14W22 0110 ESO 9393 2001.03.21 55 N17E11 1590 FKC beta-gamma-delta 9394 2001.03.22 1 N09E09 0010 AXX 9395 2001.03.23 2 S12E21 0050 CSO 9396 2001.03.24 15 S06W44 0290 DAO beta-gamma 9397 2001.03.24 17 S09E35 0200 ESO 9398 2001.03.24 N21W39 plage 9399 2001.03.24 5 S29W35 0040 DSO 9400 2001.03.24 3 N10W10 0020 BXO 9401 2001.03.25 19 N22E30 0200 DAO 9402 2001.03.25 4 N14W11 0010 CRO 9403 2001.03.26 4 S12E48 0030 DRO 9404 2001.03.27 3 S06E66 0070 CSO Total number of sunspots: 151 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) 2001.03 165.6 (1) 123.5 (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]