Solar Terrestrial Activity Report [Image] Last update April 4, 2001 at 03:50 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 quiet to unsettled on April 3. Solar wind speed ranged between 446 and 551 km/sec. Solar flare activity was high. Solar flux was 223.1, the planetary A index was 5 (3-hour K indices: 2111 2322, Boulder K indices: 2110 3322). Region 9393 was less active than on the previous day but could still produce further X class flares while rotating over the west limb. Region 9395 decayed and was quiet. Region 9397 decayed slowly and was quiet. Region 9401 decayed slowly and was mostly quiet. Region 9404 decayed and was quiet. Regions 9406 and 9407 were quiet and stable. Region 9408 was mostly unchanged and quiet, the region could produce M class flares. Region 9412 decayed slowly and could soon become spotless. Region 9413 developed slowly and was quiet. Region 9414 was quiet and stable, the region could become spotless within a couple of days. New region 9415 rotated into view at the southeast limb revealing a large and complex spot group. Further major flaring is possible. New region 9416 emerged in the northwest quadrant. New region 9417 emerged in the southeast quadrant but could soon become spotless. A new region is rotating into view at the northeast limb. Flares and CMEs A total of 3 C, 3 M and 1 X class events were recorded on April 3. Region 9415 produced a long duration X1.2/1N event peaking at 03:57 UT. A weak type IV sweep was associated with the event, as was a partial halo CME. Region 9393 generated an M2.4/2F flare at 12:34 UT. Region 9401 was the source of a C8.5 flare at 17:42 UT. April 2: Region 9393 produced an X17.1 flare peaking at 21:51 UT. Type II and IV sweeps were recorded and an extremely fast full halo CME was observed. With the source of the CME near the west limb it is difficult to estimate the actual arrival of the solar wind shock, it could be anytime on April 4 or early on April 5. 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 April 1 and could cause unsettled to active conditions on April 4. Forecast The geomagnetic field is expected to be quiet to severe storm on April 4 and unsettled to major storm on April 5. 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 Area Classification Comment sunspots midnight 9393 2001.03.21 17 N18W82 1080 FKC beta-gamma-delta 9394 2001.03.22 N08W85 plage 9395 2001.03.23 1 S12W72 0010 AXX 9397 2001.03.24 5 S07W65 0060 DAO 9401 2001.03.25 6 N25W58 0160 CAO 9403 2001.03.26 S15W48 plage 9404 2001.03.27 9 S05W31 0030 CSO 9406 2001.03.28 2 N26W09 0160 HSX 9407 2001.03.28 4 N13W15 0100 CSO 9408 2001.03.28 20 S08W46 0360 EKI beta-gamma 9410 2001.03.30 S36W08 plage 9411 2001.03.30 N08W05 plage 9412 2001.03.30 2 S15E25 0010 AXX 9413 2001.04.01 9 N11W44 0110 CAO 9414 2001.04.02 1 S23E44 0010 AXX 9415 2001.04.03 5 S22E72 0470 DKO beta-gamma 9416 2001.04.03 6 N17W18 0040 DSO 9417 2001.04.03 1 S10E43 0000 AXX Total number of sunspots: 88 Monthly solar data Month Average solar International sunspot Smoothed sunspot flux number number 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) 2001.04 236.2 (1) 24.9 (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]