Solar Terrestrial Activity Report [Image] Last update July 22, 2002 at 06:10 UTC. Minor update posted at 06:41 UTC on July 23. Only occasional updates will be posted until August 3 due to vacation. [Solar and geomagnetic data - last 4 weeks (updated daily)] [Solar wind and electron fluence charts (updated daily)] [Solar cycles 21-23 (last update July 1, 2002)] [Solar cycles 1-20] [Graphical comparison of cycles 21, 22 and 23 (last update July 1, 2002)] [Graphical comparison of cycles 10, 13, 17, 20 and 23 (last update July 1, 2002)] [Historical solar and geomagnetic data charts 1954-2002 (last update April 13, 2002)] Recent development The geomagnetic field was quiet to active on July 21 with some magnetometers recording minor storm conditions during the first half of the day. Solar wind speed ranged between 448 and 639 km/sec. A minor solar wind shock was observed at ACE at 04:52 UTC on July 22 with a sudden increase in solar wind speed from 480 to 530 km/sec. Solar flare activity was low. Solar flux was 182.8, the planetary A index was 19 (3-hour planetary K indices: 4442 3332, Boulder K indices: 4552 3332). Region 10030 continued to decay quickly and by midnight had a penumbral area of just over 0100 mills. Most of the decay was observed in the leading spot section. The region is rotating quietly over the northwest limb. Region 10035 added several spots and could produce further C class flares. Region 10036 decayed slowly and quietly. A major flare is possible, however, the major part of the negative and positive polarity areas are well separated and there is only minor intermixing occurring in some areas. Region 10037 was quiet and stable. New region 10038 emerged in the northeast quadrant and developed at a moderate pace. Early on July 22 quite a few spots are visible at the southeast limb as an active region (the likely source of several large CMEs observed over the last days as well as the X3 flare on July 20) is rotating into view. Early magnetograms hint at a complex region but a more detailed evaluation of the flare potential will have to wait one or two days until the region rotates into better view. Comment added at 06:41 UTC on July 23: Region 10039 has rotated fully into view at the southeast limb. This region is complex and currently has two magnetic delta structures, one near the northern edge of the leading penumbra and a second one in the southern part of the main penumbral area. This region has the potential to produce occasional X10+ flares. At 00:35 UTC today a major X4.8/2B flare was recorded from region 10039. A large and fast full halo CME was observed. Although the fastest part of the CME headed eastwards, Earth should receive an impact on July 24. The CME was well defined even outside of its core and the geomagnetic field could be severely disturbed for 12-24 hours after the impact. Otherwise region 10036 has decayed significantly and is currently simply structured and has only a minor chance of producing an M class flare. I will try for another full update tomorrow. The Active Solar Regions and Forecast sections below have been updated. Flares and CMEs A total of 5 C class events was recorded on July 21. Region 10035 produced a C1.8 flare at 13:37 UTC. Other flares, including a C7.6 flare at 03:10 and C6.7 flares at 06:13 and 07:45 UTC, appeared to have their origin in the region at the southeast limb. The background x-ray flux is at the class B9 level. Coronal holes No obvious coronal holes are currently approaching geoeffective positions. Forecast The geomagnetic field is expected to be quiet to active on July 23 and intially on July 24. Sometime during July 24 a CME is likely to impact the magnetosphere causing active to severe storm conditions. The geomagnetic storm should last until July 25. Long distance medium wave (AM) band propagation along east-west paths over high and upper middle latitudes is poor to very 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 10030 2002.07.09 3 N20W89 0230 EAO 10031 2002.07.11 N12W78 plage 10035 2002.07.15 12 S09W32 0080 DAO 10036 2002.07.15 51 S07W15 0970 EKC 10037 2002.07.17 1 N13W06 0190 HSX 10038 2002.07.21 6 N17E37 0070 DAO beta-gamma-delta ridiculously low area 10039 2002.07.22 7 S12E68 0330 DAC estimate, was near 1000 mills at midnight Classification wrong, should be FKC 10040 2002.07.22 2 S22E01 0010 BXO 10041 2002.07.22 1 N16E22 0010 AXX 10042 2002.07.22 3 S18E38 0010 AXX Total number of sunspots: 86 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 2001.06 173.0 134.0 109.8 (+1.2) 2001.07 131.3 81.8 111.7 (+1.9) 2001.08 162.9 106.4 113.6 (+1.8) 2001.09 233.2 150.7 114.1 (+0.5) 2001.10 207.6 125.5 114.0 (-0.1) 2001.11 210.6 106.5 115.5 (+1.5) 2001.12 235.1 132.2 114.6 (-0.9) 2002.01 226.6 114.1 (112.7 predicted, -1.9) 2002.02 205.0 107.4 (111.3 predicted, -1.4) 2002.03 179.5 98.4 (106.6 predicted, -4.7) 2002.04 189.8 120.4 (100.7 predicted, -5.9) 2002.05 178.4 120.8 (96.3 predicted, -4.4) 2002.06 148.7 88.5 (91.7 predicted, -4.6) 2002.07 151.5 (1) 93.3 (2) (86.9 predicted, -4.8) 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]