Solar Terrestrial Activity Report

Last update December 27, 2002 at 04:50 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 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.

Coronal mass ejections (CMEs)

December 24-26: 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 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.

Forecast

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)
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
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

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)
2002.12 165.2 (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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