Solar Terrestrial Activity Report

Last update December 25, 2002 at 04:30 UTC.

[Solar and geomagnetic data - last 4 weeks (updated daily)]
[Solar wind and electron fluence charts (updated daily)]
[Solar cycles 21-23 (last update December 2, 2002)]
[Solar cycles 1-20]
[Graphical comparison of cycles 21, 22 and 23 (last update December 2, 2002)]
[Graphical comparison of cycles 10, 13, 17, 20 and 23 (last update December 2, 2002)]
[Historical solar and geomagnetic data charts 1954-2002 (last update October 13, 2002)]
[Archived reports (last update December 23, 2002)]

Recent activity

The geomagnetic field was quiet to active on December 24. Solar wind speed ranged between 468 and 574 km/sec. A weak solar wind shock was observed at ACE at 13:18 UTC. Solar wind speed increased abruptly from 470 to 520 km/sec and the interplanetary magnetic field was at times moderately southwards after the shock.

Solar flare activity was low. Solar flux was 147.3, the planetary A index was 18 (STAR Ap - based on the mean of three hour ap indices: 18.6).
Three hour interval K indices: 32334433 (planetary), 32334433 (Boulder).

The background x-ray flux is at the class B7 level.

At midnight there were 6 spotted regions on the visible disk, 1 of which has not yet been numbered. A total of 8 C class events were recorded during the day. C2.7 flares at 18:21 and 23:36 were optically uncorrelated.

Region 10223 decayed and became spotless in the early morning.
Region 10224 decayed fairly quickly as the region rotated to the southwest limb. Flares: C5.8 at 05:27, C1.6 at 13:29 and C5.8 at 14:51 UTC.
Region 10229 decayed further and had only a single spot left by the end of the day.
Region 10230 decayed quickly in the trailing spot section where only two tiny spots could be observed at the end of the day.
Region 10231 decayed in the leading spot section while the main trailing  spot increased its area.
Region 10233 decayed and was spotless by early afternoon.
New region 10234 rotated into view at the northeast limb early in the day.

Spotted regions not yet numbered by SEC:
[S60] A new region began to emerge in the northeast quadrant late on December 24. Location at midnight: N11E40.

Coronal mass ejections (CMEs)

December 22: A CME was observed off of the northwest limb early in the day after an M1.1 flare and an associated filament eruption in region 10223. The CME does not appear to be geoeffective.

December 23-24: No obviously geoeffective CMEs observed.

Coronal holes

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 will be in a geoeffective position on December 24-25.

Processed SOHO EIT 284 image at 19:06 UTC on December 24. Any black areas on the solar disk are likely coronal holes.

Forecast

The geomagnetic field is expected to be quiet to unsettled on December 25-26. A coronal stream will likely arrive early on Dec.27 and cause unsettled to minor storm conditions. 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 ejections (2) M and X class flares (3)
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)

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
10223 2002.12.12 1   N24W83 0020 AXX now spotless
10224 2002.12.12 10 5 S14W81 0230 DAO  
10225 2002.12.13     N17W85     plage
10226 2002.12.13 4   S28W89 0110 EAO rotated out of view
10228 2002.12.14     S14W65     plage
10229 2002.12.14 4 1 N25W63 0050 DSO classification was HSX
at midnight, area 0030
10230 2002.12.17 9 4 S08W34 0170 DSO  
10231 2002.12.19 5 3 S25W53 0050 DAO classification was CAO
at midnight
10232 2002.12.21     N13W47     plage
10233 2002.12.23 5 N13E27 0030 CRO now spotless
10234 2002.12.24 1 1 N18E73 0040 HSX  
S60 emerged on
2002.12.24
1 N11E40 0000 AXX  
Total spot count: 39 14
SSN: 119 74

Monthly solar cycle data

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)
2002.12 168.1 (1) 131.3 (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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