Solar Terrestrial Activity Report

Last update December 31, 2002 at 04:00 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 30, 2002)]

Recent activity

The geomagnetic field was unsettled to slightly active on December 30. Solar wind speed ranged between 458 and 560 km/sec.

Solar flux was 113.8 (the lowest solar flux level since September 9, 1999).
The planetary A index was 15 (STAR Ap - based on the mean of three hour interval ap indices: 15.0).
Three hour interval K indices: 43333433 (planetary), 42432232 (Boulder).

The background x-ray flux is at the class B1-B2 level.

At midnight there were 3 spotted regions on the visible disk, 1 of which has not yet been numbered. Solar flare activity was very low.

Region 10234 was quiet and stable.
Region 10239 developed slowly and may be capable of C class flaring.

Spotted regions not yet numbered by SEC:
[S64] A new region emerged quickly late on December 30 just east of region 10239. The region should be capable of C class flaring. Location at midnight: S09E34.

Coronal mass ejections (CMEs)

December 28-30: 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 recurrent trans equatorial coronal hole will rotate into a geoeffective position on December 31-January 1.

Processed SOHO EIT 284 image at 01:06 UTC on December 31. Any black areas on the solar disk are likely coronal holes.

Forecast

The geomagnetic field is expected to be quiet to unsettled on December 31 - January 2. A coronal stream will likely arrive on January 3 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 fair to 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 and a contrast enhanced white light image. Region numbering has been included. Compare to the previous day's 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
10233 2002.12.23   N13W51     plage
10234 2002.12.24 2 1 N18W08 0030 HSX  
10235 2002.12.25 3   N14W35 0020 CSO  now spotless
10236 2002.12.27     N16W66     plage
10237 2002.12.28   S26W26     plage
10238 2002.12.28   N09W11     plage
10239 2002.12.29 9 11 S10E24 0040 DSO classification was DAO
at midnight
S63 emerged on
2002.12.29
  S15W28     plage
S64 emerged on
2002.12.30
  5 S09E34 0030 DAO  
Total spot count: 14 17
SSN: 44 47

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)
2002.12 158.6 (1) 143.2 (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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