Solar Terrestrial Activity Report [Image] Last update May 1, 2002 at 04:35 UTC. [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, 2002)] [Solar cycles 1-20] [Graphical comparison of cycles 21, 22 and 23 (last update April 2, 2002)] [Graphical comparison of cycles 10, 13, 17, 20 and 23 (last update April, 2002)] [Historical solar and geomagnetic data charts 1954-2002 (last update April 13, 2002)] Recent development The geomagnetic field was quiet to unsettled on April 30. Solar wind speed ranged between 411 and 553 km/sec, gradually decreasing all day. Solar flare activity was moderate. Solar flux was 153.4, the planetary A index was 8 (3-hour K indices: 2222 3331, Boulder K indices: 2222 3311). Region 9914 decayed slowly and was mostly quiet, only one spot was visible at the end of the day. The region is rotating over the northwest limb. Region 9915 decayed further and is about to lose the few remaining trailing spots. Region 9919 decayed further and was had only one spot left by late afternoon. Region 9922 was spotless all day in all available images, unfortunately the region was incorrectly reported by SEC/NOAA as having a single small spot. Region 9926 is developing slowly and could soon begin to produce flares. Region 9927 was quiet and stable. Region 9928 did not change much and was quiet. New region 9929 emerged in the northeast quadrant late on April 29, developed slowly early on April 30, then decayed and was spotless by the end of the day. SEC/NOAA failed to number a new region which is developing at the central meridian in the northern hemisphere. Another new region is emerging in the northeast quadrant just east of region 9929. A new region has rotated into view at the northeast limb. The positive magnetic areas belonging to one or two regions at the southeast limb are early on May 1 rotating into view. Spots should become visible later today. Flares and CMEs A total of 5 C and 1 M class events were recorded on April 30. Region 9919 produced a C3.2 flare at 06:53 UTC. Region 9914 generated a C3.2 flare at 11:18 UTC. An M1.3 flare occurred at 08:22 UTC and had its origin in a region just behind the southeast limb. This region was also the source of a C3.7 flare at 14:18 UTC. A large, fast and wide CME was first observed off the west limbs at 23:42 UTC in LASCO C3 images. The source of this event is likely a region several days behind the west limb. A proton enhancement is currently in progress and an above 10 MeV proton event could begin within the next few hours. The background x-ray flux is at the class B5 level. Coronal holes A coronal hole in the southern hemisphere was geoeffective on April 28-29. A well defined coronal hole in the northern hemisphere will rotate over the central meridian on May 2 but is likely too far to the north to be geoeffective. Another coronal hole, further east in the northern hemisphere, is currently poorly defined and will rotate into a geoeffective position on May 4-5. Forecast The geomagnetic field is expected to be quiet to active May 1-2 due to coronal hole effects. Long distance medium wave (AM) band propagation along east-west paths over high and upper middle latitudes is 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 9914 2002.04.19 3 N05W80 0110 CSO 9915 2002.04.21 6 N12W69 0150 DSO 9916 2002.04.21 S15W43 plage 9917 2002.04.22 S30W59 plage 9919 2002.04.22 6 N14W28 0070 CSO 9921 2002.04.23 N14W54 plage 9922 2002.04.23 2 N22W38 0010 BXO actually spotless 9926 2002.04.27 5 N14W15 0060 CAO 9927 2002.04.29 4 S29E55 0070 CSO 9928 2002.04.29 4 N18E61 0070 CSO 9929 2002.04.30 3 N22E16 0010 BXO now spotless Total number of sunspots: 33 Monthly solar data Month Average solar International sunspot Smoothed sunspot flux number number 2000.04 184.2 125.5 120.8 cycle 23 sunspot max. 2000.07 202.3 170.1 119.8 2001.02 146.6 80.6 104.0 (-4.7) 2001.03 177.7 113.5 104.8 (+0.8) 2001.04 177.7 107.7 107.5 (+2.7) 2001.05 147.1 96.6 108.6 (+1.1) 2001.06 173.0 134.0 109.8 (+1.2) 2001.07 131.3 82.2 111.7 (+1.9) 2001.08 162.9 106.8 113.6 (+1.8) 2001.09 233.2 150.7 114.1 (+0.5) 2001.10 207.6 125.5 (113.3 predicted, -0.8) 2001.11 210.6 106.5 (112.7 predicted, -0.6) 2001.12 235.1 132.2 (109.3 predicted, -3.4) 2002.01 226.6 113.9 (106.0 predicted, -3.3) 2002.02 205.0 108.0 (104.6 predicted, -1.4) 2002.03 179.5 98.1 (100.4 predicted, -4.2) 2002.04 189.8 (1) 195.0 (2) (94.5 predicted, -5.9) 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 25-45% 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. ------------------------------------------------------------------------ [DX-Listeners' Club] [DX News]