Solar Terrestrial Activity Report [Image] Last update March 29, 2001 at 04:00 UT. Last minor update posted at 12:40 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 major storm on March 28. Solar wind speed ranged between 560 and 672 km/sec. The major storm intervals were caused by two significant southerly excursions of the interplanetary magnetic field, at ACE these intervals were from 07 until 08:30 UT and from 11 until 12:30 UT. Solar flare activity was high. Solar flux was 273.5 (new high for cycle 23), the planetary A index was 31 (3-hour K indices: 2246 6434, Boulder K indices: 2255 5423). Region 9387 was quiet and stable. Regions 9389 and 9390 decayed slowly and were quiet. Region 9393 continues to develop and is without comparison the largest sunspot group observed during cycle 23. Several M flares had their origin in region 9393 and the region will continue to produce M class flares. The chance of an X class proton flare is fairly high as well. Region 9394 was quiet and stable, as was region 9395. Region 9396 was mostly unchanged and quiet. M class flares are possible. Region 9397 developed slowly and could produce occasional M class flaring. Region 9399 decayed slowly and was quiet. Region 9400 decayed and was quiet. Region 9401 was mostly unchanged and could produce minor M class flares. Region 9402 decayed and was quiet. Region 9403 was mostly unchanged could produce C class flares. Region 9404 was quiet and stable. New region 9405 emerged in the southwest quadrant. New regions 9406 and 9407 rotated into view at the northeast limb. New region 9408 emerged in the southeast quadrant and initially developed quickly. SEC/NOAA failed to number a region at a high latitude near the southeast limb, this region was spotted all day. Comment added at 10:23 UT on March 29: Region 9393 has finally produced its first X class flare. The flare peaked at the class X1.7 level at 10:15 UT. A significant earth directed coronal mass ejection will likely result from this event, further details will be posted within the next few hours. Comment added at 12:40 UT: A full halo CME is in progress. Although it's a bit early to tell the CME appears to be fairly fast and could reach Earth within the next 2 days. The flare does not appear to have been a significant proton flare. Flares and CMEs A total of 6 C and 6 M class events were recorded on March 28. Region 9403 produced a C7.1 flare at 00:50 UT. Region 9401 generated a C5.6 flare at 01:38 UT. Region 9393 was the source of an M1.1 flare at 01:58, a C5.7 flare at 06:40, an M1.3 flare at 09:47, a long duration M4.3 event peaking at 12:40 UT, an M1.6 flare at 19:09, an M1.6/1N flare at 22:47 and an M2.2/1F flare at 23:30 UT. Region 9397 produced a C9.9 flare at 10:47 UT. Region 9408 generated a C8.2 flare at 09:18 UT. Two full halo CME were observed during the day, the halos were similar in appearance, brightness and velocity and may have had the same source. The first halo was observed in LASCO C2 images beginning at 01:27 UT while the second was first observed at 12:50 UT. LASCO EIT images unfortunately do not point conclusively to a source for either of the CMEs. The long duration M4.3 event in region 9393 may have contributed to the latter halo, however, there is a possibility both events may have a backside origin. If both or one of the CMEs had a frontside origin Earth will receive an impact sometime between noon on March 30 and noon on March 31. 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 29-30. A CME could arrive during the latter half of March 30 and cause major storming. Another CME associated with the X1 flare on March 29 could impact the magnetosphere on March 31 and cause severe geomagnetic storming. 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 4 N08W66 0150 CSO 9389 2001.03.20 13 S12W34 0050 CRO 9390 2001.03.20 8 N13W38 0080 CSO 9393 2001.03.21 51 N13E00 2240 FKC beta-gamma-delta 9394 2001.03.22 1 N09W05 0010 AXX 9395 2001.03.23 4 S13E08 0060 CSO 9396 2001.03.24 12 S06W59 0330 DSO beta-gamma 9397 2001.03.24 17 S09E19 0260 EAI beta-gamma 9398 2001.03.24 N21W52 plage 9399 2001.03.24 3 S30W49 0030 CRO 9400 2001.03.24 1 N10W29 0000 AXX 9401 2001.03.25 20 N22E17 0160 CAO 9402 2001.03.25 3 N18W25 0010 AXX 9403 2001.03.26 5 S13E36 0020 BXO 9404 2001.03.27 1 S05E50 0070 HAX 9405 2001.03.28 14 S13W20 0040 BXO 9406 2001.03.28 1 N25E67 0150 HAX 9407 2001.03.28 1 N11E64 0080 HSX 9408 2001.03.28 13 S08E38 0090 CAO Total number of sunspots: 172 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) 2001.03 169.5 (1) 134.8 (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]