Solar Terrestrial Activity Report [Image] Last update April 5, 2001 at 03:55 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 minor storm on April 4. Solar wind speed ranged between 429 and 788 km/sec. A solar wind shock was observed at 14:20 UT at SOHO, solar wind speed increased abruptly from 470 to 659 km/sec. The source of the disturbance is the CME associated with the X22 flare on April 2. Prior to the shock a weak coronal stream had been in progress for most of the day. Solar flare activity was moderate. Solar flux was 204.8, the planetary A index was 15 (3-hour K indices: 2222 3452, Boulder K indices: 2211 4552). Region 9393 rotated completely off the visible disk early in the day, the region could still produce a major flare from just behind the west limb. Region 9395 rotated off the visible disk. Region 9397 decayed slowly and was quiet, the region will rotate over the west limb today. Region 9401 decayed slowly and was mostly quiet, the region will rotate out of view on April 6. Region 9404 decayed and was quiet. Regions 9406 and 9407 were quiet and stable. Region 9408 decayed slightly and could produce occasional minor M class flares. Region 9412 was quiet and stable. Region 9413 developed slowly and was quiet. Region 9414 was quiet and stable. Region 9415 was mostly unchanged, the region is capable of major flare production. Region 9416 was quiet and stable. Region 9417 decayed into spotless plage, then a new region emerged just to the east of region 9417 and was assigned the same region number. This new region developed quickly during the latter half of the day. New region 9418 rotated into view at the northeast limb, minor M class flares are possible. New region 9419 emerged in the northwest quadrant near the central meridian. Flares and CMEs A total of 5 C and 3 M class events were recorded on April 4. Region 9415 produced a C5.6/1F flare at 05:33 and an M1.6 long duration event peaking at 10:27 UT. Region 9401 generated an M1.1 flare at 11:59 UT. Region 9393 was the likely source of an M2.0 flare at 12:22 UT. The background x-ray flux is at the class C1 level. Coronal holes A trans equatorial coronal hole will be in a geoeffective position on April 5. Forecast The geomagnetic field is expected to be quiet to unsettled on April 5-6 with the chance of a few isolated active intervals. A fairly weak coronal stream could influence the field on April 8 and cause unsettled to active conditions. 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 no. Location at region numbered sunspots midnight Area Classification Comment 9393 2001.03.21 3 N18W94 0280 DSO 9395 2001.03.23 1 S13W85 0000 AXX 9397 2001.03.24 1 S07W78 0030 HSX 9401 2001.03.25 3 N24W70 0100 DAO 9403 2001.03.26 S15W61 plage 9404 2001.03.27 2 S03W46 0000 AXX 9406 2001.03.28 2 N27W22 0190 HAX 9407 2001.03.28 1 N11W28 0060 HSX 9408 2001.03.28 13 S08W59 0300 EAO 9410 2001.03.30 S36W21 plage 9411 2001.03.30 N08W18 plage 9412 2001.03.30 1 S14E12 0010 AXX 9413 2001.04.01 7 N11W57 0110 CAO 9414 2001.04.02 1 S22E31 0010 AXX 9415 2001.04.03 9 S21E60 0680 EKI beta-gamma 9416 2001.04.03 6 N17W32 0040 DSO 9417 2001.04.03 1 S09E33 0000 AXX 9418 2001.04.04 1 N23E69 0130 HSX 9419 2001.04.04 5 N08W08 0010 CSO Total number of sunspots: 57 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) 2001.04 228.4 (1) 31.9 (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]