Solar Terrestrial Activity Report [Image] Last update April 14, 2001 at 01:05 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 April 8, 2001)] Recent development The geomagnetic field was quiet to severe storm on April 13. Solar wind speed ranged between 561 and 889 km/sec. A solar wind shock was observed at SOHO at 07:05 UT. Solar wind speed initially increased from 620 to 710 km/sec, and later on increased to above 800 km/sec. The interplanetary magnetic field indicated this was a moderate solar wind shock, however, the disturbance caused minor to severe geomagnetic storming. The source of the disturbance is likely the halo CME observed on April 11. Solar flare activity was very low. Solar flux was 137.0, the planetary A index was 36 (3-hour K indices: 1137 6454, Boulder K indices: 1136 5443). Region 9415 decayed slowly and the magnetic delta configuration within the leading penumbra is not as strong as it has been. Although there is still a possibility of major flares from the region, these flares are likely to be less frequent and less intense than the ones we have seen over the last 10 days. Region 9417 was quiet and stable and will rotate off the visible disk today. Region 9418 was quiet and stable, as were regions 9420 and 9422. Region 9424 decayed slowly and was quiet. Regions 9426 and 9427 were quiet and stable. A new region has rotated into view at he northeast limb. Flares and CMEs No flaring of significance was observed on April 13. Sub flare activity did increase during the latter half of the day, but the source of this activity is not yet certain. April 12: Region 9415 produced an X2.0 long duration event peaking at 10:28 UT. The X flare was accompanied by a moderate type II sweep, a weak type IV sweep, as well as an increase in proton fluxes. A full halo CME was observed in LASCO images. The CME will likely reach Earth sometime between 00 and 18h UT on April 14 and cause active to major storm conditions, possibly with isolated severe storming. The background x-ray flux is at the class B5 level. Coronal holes An isolated coronal hole in the southern hemisphere will rotate into a geoeffective position on April 15 and could cause unsettled to active conditions on April 18. Forecast The geomagnetic field is expected to be unsettled to major storm on April 14, possibly with isolated severe storm intervals. 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 9414 2001.04.02 S23W84 plage 9415 2001.04.03 18 S22W59 0390 DKI beta-gamma-delta 9417 2001.04.03 7 S07W81 0120 DAO 9418 2001.04.04 5 N26W46 0120 ESO 9420 2001.04.05 3 S08W31 0040 CAO 9422 2001.04.06 6 S12W04 0050 DAO 9423 2001.04.07 N20W65 plage 9424 2001.04.08 6 S18W34 0030 DSO 9425 2001.04.09 S24W77 plage 9426 2001.04.11 6 S10E13 0060 DSO 9427 2001.04.11 7 S08W39 0060 DAO Total number of sunspots: 58 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 (115.4 predicted, -0.8) 2000.11 178.8 106.5 (114.2 predicted, -1.2) 2000.12 173.6 104.5 (111.7 predicted, -2.5) 2001.01 166.6 95.7 (108.0 predicted, -3.7) 2001.02 146.6 80.1 (103.5 predicted, -4.5) 2001.03 177.7 114.2 (100.0 predicted, -3.5) 2001.04 187.8 (1) 83.6 (2) (98.8 predicted, -1.2) 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]