Last update December 27, 2002 at 04:50 UTC.
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The geomagnetic field was quiet to active on December 26. Solar wind speed ranged between 389 and 557 km/sec. A strong coronal stream began to dominate the solar wind after 15h UTC and early on Dec.27 solar wind speed has increased further to near 700 km/sec. The interplanetary magnetic field has at times been strongly southwards.
Solar flare activity was low. Solar flux was 127.4 (slightly enhanced by a long duration B level enhancement caused by an
erupting filament at the northeast limb. 123.1 was the
value obtained at 18h UTC - this is the lowest measured solar flux since the first days of August, 2001), the planetary A
index was 15 (STAR Ap - based on the mean of three hour ap indices: 16.1).
Three hour interval K indices: 22244434 (planetary), 12233434 (Boulder).
The background x-ray flux is at the class B3 level.
At midnight there were 3 spotted regions on the visible disk. A total of 3 C class events were recorded during the day. A C1.9 flare at 08:35 UTC apparently had its source just behind the southwest limb, probably in old region 10224.
Region 10229 decayed and became spotless early in the day.
Region 10230 added a few small spots while the main penumbra was mostly unchanged. Flares: C1.0
at 01:08 and C1.4 at 02:01 UTC.
Region 10231 did not not change much and remained mostly quiet.
Region 10234 was quiet and stable.
Region 10235 decayed and was spotless by early afternoon.
December 24-26: No obviously geoeffective CMEs observed.
Coronal hole history (since late October 2002)
Compare today's report with the situation one solar rotation ago: 28
days ago
27 days ago 26 days ago
A large and well defined trans equatorial coronal hole was in a geoeffective position on December 24-25.
Processed SOHO EIT 284 image at 01:06 UTC on December 27. Any black areas on the solar disk are likely coronal holes.
The geomagnetic field is expected to be active to minor storm on December 27 with a chance of an isolated major storm interval. Unsettled to active is likely on December 28-29 due to a coronal stream. Long distance medium wave (AM) band propagation along east-west paths over high and upper middle latitudes is very poor.
| Coronal holes (1) | Coronal mass ejections (2) | M and X class flares (3) |
 |
|
|
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.
Composite image based on a SOHO/MDI continuum image and overlaid by a coronal hole image. Region numbering has been included. Compare to the previous day image.
Data for all numbered solar regions according to the Solar Region Summary provided by SEC/NOAA. Comments are my own, as is the STAR spot count (spots observed at or inside a few hours before midnight) and data for regions not numbered by SEC or where SEC has observed no spots.
| Solar region | Date numbered | SEC spot count |
STAR spot count |
Location at midnight | Area | Classification | Comment |
|---|---|---|---|---|---|---|---|
| 10229 | 2002.12.14 | 1 | N27W90 | 0010 | AXX |
became spotless early in the day |
|
| 10230 | 2002.12.17 | 3 | 4 | S07W63 | 0120 | CAO |
classification was HSX at midnight |
| 10231 | 2002.12.19 | 3 | 3 | S24W77 | 0110 | CSO |
area was near 0050 at midnight |
| 10232 | 2002.12.21 | N13W73 | plage | ||||
| 10233 | 2002.12.23 | N13E01 | plage | ||||
| 10234 | 2002.12.24 | 2 | 3 | N17E45 | 0060 | CAO | |
| 10235 | 2002.12.25 | 3 | N14E15 | 0010 | BXO | now spotless | |
| Total spot count: | 12 | 10 | |||||
| SSN: | 62 | 40 | |||||
| Month | Average solar flux at Earth |
International sunspot number | Smoothed sunspot number |
|---|---|---|---|
| 2000.04 | 184.2 | 125.5 | 120.8 cycle 23 sunspot max. |
| 2000.07 | 202.3 | 170.1 | 119.8 |
| 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 | 113.5 (-1.1) |
| 2002.02 | 205.0 | 107.4 | 114.7 (+1.2) |
| 2002.03 | 179.5 | 98.4 | 113.4 (-1.3) |
| 2002.04 | 189.8 | 120.7 | 110.5 (-2.9) |
| 2002.05 | 178.4 | 120.8 | 108.8 (-1.7) |
| 2002.06 | 148.7 | 88.3 | (106.4 predicted, -2.4) |
| 2002.07 | 173.5 | 99.9 | (102.8 predicted, -3.6) |
| 2002.08 | 183.6 | 116.4 | (99.6 predicted, -3.2) |
| 2002.09 | 175.8 | 109.3 | (96.6 predicted, -3.0) |
| 2002.10 | 167.0 | 97.5 | (93.1 predicted, -3.5) |
| 2002.11 | 168.7 | 95.0 | (87.8 predicted, -5.3) |
| 2002.12 | 165.2 (1) | 135.8 (2) | (83.5 predicted, -4.3) |
1) Running average based on the daily 20:00 UT observed 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.
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