Solar Terrestrial Activity Report [Image] Last update April 2, 2001 at 04:20 UT. Last minor update posted at 13:10 UT. [Solar and geomagnetic data - last 4 weeks (updated daily)] [Solar wind and electron fluence charts (updated daily)] [Solar cycles 21-23 (last update April 2, 2001)] [Solar cycles 1-20] [Graphical comparison of cycles 21, 22 and 23 (last update April 2, 2001)] [Graphical comparison of cycles 10, 13, 17, 20 and 23 (last update April 2, 2001)] [Historical solar and geomagnetic data charts 1954-2000 (last update January 18, 2001)] Recent development The geomagnetic field was unsettled to major storm level on April 1. Solar wind speed ranged between 566 and 861 km/sec. Solar flare activity was high. Solar flux was 257.5, the planetary A index was 30 (3-hour K indices: 4563 3344, Boulder K indices: 5552 2244). Regions 9389 and 9390 rotated off the visible disk. Region 9393 decayed slightly but is still a complex region capable of major flare production. Region 9395 was quiet and stable. Region 9397 decayed slowly and was quiet. Region 9401 decayed slowly and quietly. Region 9402 once again decayed into spotless plage. Region 9403 decayed and was spotless by early evening. Region 9404 was quiet and stable, as were regions 9406 and 9407. Region 9408 developed slowly and was quiet. Regions 9410 and 9411 were spotless all day in all available images. Region 9412 was quiet and stable. New region 9413 emerged in the northwest quadrant. An interesting region is just behind the southeast limb, the region is capable of generating major flares. Comment added at 10:19 UT on April 2: Region 9393 generated an X1.4 flare at 10:14 UT. An update will follow within a few hours when LASCO images have been analysed. The region has been very active today and further major flares are possible. Comment added at 11:40 UT: The above flare does not appear to have produced a significant CME. Another and more interesting event is currently in progress. A long duration X1.1 flare has just peaked. Further details to follow. Comment added at 13:10 UT: The X1.1 flare which peaked at 11:36 produced a coronal mass ejection, the first observation in LASCO C2 images was at 11:26 UT at the west limb. The CME so far does not appear to have been very wide and it is uncertain if it will be geoeffective. Proton fluxes have begun to increase slowly. Flares and CMEs A total of 2 C and 3 M class events were recorded on April 1. Region 9393 produced a C9.9 flare at 19:07, an M4.0/1F flare at 19:49, a C9.0 flare at 22:32 and an M1.2 flare at 23:01 UT. The most energetic flare of the day, a major M5.5 long duration event peaking at 12:17 UT had its origin just behind the southeast limb, intense post flare loops were observed for many hours after the flare. A full halo CME was observed in LASCO C3 images, no terrestrial impact is expected. The background x-ray flux is at the class C3 level. Coronal holes A coronal hole in the northern hemisphere was in 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 quiet to active and April 2-4. Long distance medium wave (AM) band propagation along east-west paths over high and upper middle latitudes is very poor to 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 AreaClassification Comment sunspots midnight 9389 2001.03.20 1 S12W86 0050 HSX 9390 2001.03.20 1 N11W91 0030 HSX 9393 2001.03.21 53 N16W56 1700 FKC beta-gamma-delta 9394 2001.03.22 N08W59 plage 9395 2001.03.23 1 S13W46 0020 HSX 9397 2001.03.24 16 S08W36 0090 EAO 9400 2001.03.24 N10W83 plage 9401 2001.03.25 19 N20W39 0180 EAO 9402 2001.03.25 N20W70 plage 9403 2001.03.26 3 S15W22 0010 BXO 9404 2001.03.27 22 S06W04 0080 DAI 9405 2001.03.28 S13W73 plage 9406 2001.03.28 3 N25E16 0160 HAX 9407 2001.03.28 7 N11E13 0110 CSO 9408 2001.03.28 34 S10W18 0340 EKI beta-gamma 9410 2001.03.30 1 S36E26 0000 AXX actually spotless! 9411 2001.03.30 2 N08E35 0000 AXX actually spotless! 9412 2001.03.30 3 S14E51 0040 DSO 9413 2001.04.01 4 N09W17 0020 CAO Total number of sunspots: 170 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) 2000.09 182.1 109.7 116.2 (-2.4) 2000.10 167.4 100.1 (114.6 predicted, -1.6) 2000.11 178.8 106.5 (112.6 predicted, -2.0) 2000.12 173.6 104.5 (110.1 predicted, -2.5) 2001.01 166.6 95.7 (106.3 predicted, -3.8) 2001.02 146.6 80.1 (101.9 predicted, -4.4) 2001.03 177.7 114.2 (98.4 predicted, -3.5) 2001.04 257.5 (1) 10.7 (2) (97.1 predicted, -1.3) 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]