Solar Terrestrial Activity Report [Image] Last update July 25, 2002 at 04:45 UTC. 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 unsettled on July 24. Solar wind speed ranged between 402 and 478 km/sec. Early on July 25 there are still no signs of the expected CME, an impact will likely occur during the latter half of the day. Solar flare activity was moderate. Solar flux was 208.4, the planetary A index was 12 (3-hour planetary K indices: 3332 3332, Boulder K indices: 3332 2232). Region 10035 decayed further and had only a few small spots left by the end of the day, the region could become spotless within a couple of days. Region 10036 decayed significantly losing quite a bit of its penumbral area, particularly in the trailing spots section. The region remained simple with the positive and negative polarity areas well separated. slowly. C class flares are possible, as is a minor M class flare. Region 10037 began to develop new spots at the end of the day with most of the spots appearing north of the main penumbra. Region 10038 decayed slowly and quietly. Region 10039 did not change significantly and remains capable of producing very intense flares, including further X class flares. The region produced several C flares and a minor M class flare, most events had their origin near the magnetic delta in the northern part of the main penumbra. Region 10040 decayed and appeared to be spotless early on July 25. Region 10041 decayed and seems to be spotless early on July 25. Region 10042 developed slowly and quietly. Region 10043 continued to develop moderately quickly and could produce C class flares. Region 10044 developed further and has minor M class flare potential. New region 10045 in the northeast quadrant emerged on July 23 and was finally noticed by SEC/NOAA. The region has decayed slowly over the last day. New region 10046 emerged in the northeast quadrant. Flares and CMEs A total of 9 C and 1 M class events was recorded on July 24. Region 10039 generated a C4.5 flare at 03:21, a C6.1 flare at 12:56, an M1.2/1F long duration event peaking at 15:45 (and associated with a weak type IV radio sweep and a small CME off the east limb), a C3.2 flare at 18:13, a C2.2 flare at 18:48 and a C2.3 flare at 19:15 UTC. July 23: Region 10039 produced a major X4.8/2B flare at 00:35 UTC. A large and fast full halo CME was observed. Although the fastest part of the CME headed eastwards, Earth should receive an impact sometime on July 25. The CME was well defined even outside of its core and the geomagnetic field could be disturbed for 12-24 hours after the impact. Another full halo CME began after an eruption behind the northwest limb late in the day, the first image of the CME was visible in LASCO C3 images at 23:18 UTC. The background x-ray flux is at the class C1-C2 level. Coronal holes No obvious coronal holes are currently approaching geoeffective positions. Forecast The geomagnetic field is expected to be quiet to major storm on July 25-26 due to an expected CME impact. 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 10035 2002.07.15 9 S09W59 0070 EAO area too large 10036 2002.07.15 46 S07W42 0820 EKC 10037 2002.07.17 2 N14W32 0150 HSX now a CSO region 10038 2002.07.21 11 N16E12 0060 DAO 10039 2002.07.22 39 S15E48 0940 EKC beta-gamma-delta 10040 2002.07.22 6 S20W29 0020 CRO now spotless? 10041 2002.07.22 2 N17W04 0010 CRO now spotless? 10042 2002.07.22 6 S20E14 0030 CAO 10043 2002.07.23 9 N12E41 0080 DAO area too small 10044 2002.07.23 14 S20E43 0120 DAO area too small 10045 2002.07.24 4 N04E17 0020 CAO 10046 2002.07.24 2 N14E22 0010 CSO Total number of sunspots: 150 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) 2002.07 157.4 (1) 115.0 (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]