Solar Terrestrial Activity Report

Last update issued on February 6, 2003 at 03:30 UTC.

[Solar and geomagnetic data - last 4 weeks (updated daily)]
[Solar wind and electron fluence charts (updated daily)]
[Solar cycles 21-23 (last update February 2, 2003)]
[Solar cycles 1-20]
[Graphical comparison of cycles 21, 22 and 23 (last update February 2, 2003)]
[Graphical comparison of cycles 10, 13, 17, 20 and 23 (last update February 2, 2003)]
[Historical solar and geomagnetic data charts 1954-2002 (last update January 27, 2003)]
[Archived reports (last update February 3, 2003)]

Recent activity

The geomagnetic field was quiet to active on February 5. Solar wind speed ranged between 489 and 667 km/sec under the influence of a coronal stream. A new coronal stream arrived early on February 6.

Solar flux measured at 20h UTC on 2.8 GHz was 140.1. The planetary A index was 12 (STAR Ap - based on the mean of three hour interval ap indices: 12.9).
Three hour interval K indices: 33224422 (planetary), 33222311 (Boulder).

The background x-ray flux is at the class B6 level.

At midnight there were 11 spotted regions on the visible disk, 7 of which have not yet been numbered by SEC/NOAA. Solar flare activity was low. A total of 3 C class events was recorded during the day.

Region 10274 was quiet and stable.
Region 10276 decayed in both the leading and trailing spots sections. The region was quiet.
Region 10277 decayed and became spotless by early afternoon. Just before midnight a single spot reemerged.
Region 10278 was mostly unchanged. The negative and positive polarity areas in the southern part of the region are fairly close and any development in this area could create a magnetic delta structure. Minor M class flares are possible. Flares: C1.1 at 19:24, C2.1 at 20:26 and C2.2 at 21:35 UTC.
New region 10279 emerged in the southeast quadrant on February 4 and was numbered the next day. The region decayed and was spotless before midnight.

Spotted regions not yet numbered by SEC/NOAA:
[S87] A new region emerged north of region 10274 on January 31. Initially it was not clear if this was a separate region and the spots were associated with region 10274. The region developed quickly on February 2 and it became obvious that regions 10274 and S87 were separate bipolar regions. Slow decay has been observed since February 4. Location at midnight: S04W36.
[S88] A new region emerged in the southeast quadrant on February 4. Location at midnight: S08W01.
[S91] A new region emerged in the southeast quadrant on February 5. The region is developing fairly quickly. Location at midnight: S09E42.
[S92] A new region emerged in the southeast quadrant between regions 10277 and S90 on February 5. Location at midnight: S17E56.
[S93] A new region emerged in the northeast quadrant, southwest of region 10278, on February 5. Location at midnight: N11E59.
[S94] A new region was rotating into view at the southeast limb late in the day. Location at midnight: S17E84.
[S95] A new region emerged in the southwest quadrant. Location at midnight: S17W41.

Coronal mass ejections (CMEs)

February 3-5: 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 small coronal hole in the southern hemisphere was in a geoeffective position on February 4.

Processed SOHO EIT 284 image at 01:06 UTC on February 6. Any black areas on the solar disk are likely coronal holes.


The geomagnetic field is expected to be quiet to active on February 6-7 due to a coronal stream and quiet to unsettled on February 8-9. Long distance medium wave (AM) band propagation along east-west paths over high and upper middle latitudes is very poor, propagation along north-south paths is good.

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)

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
Location at midnight Area Classification Comment
10274 2003.01.28 6 1 S07W33
0110 DSO classification was HSX
at midnight.
location corrected.
SEC spot count
includes that of region
10276 2003.02.01 21 22 S13E27 0180 EAI beta-gamma
classification was FAI
at midnight
10277 2003.02.04 2 1 S20E54 0020 BXO classification was AXX
at midnight
10278 2003.02.04 6 9 N19E65 0110 DSO classification was DAO
at midnight
10279 2003.02.05 4   S10E02 0010 BXO formerly region S89
now spotless
S84 emerged on
    N11W74     plage
S85 emerged on
    S13W74     plage
S86 emerged on
  S18W48     plage
S87 emerged on
  1 S04W38 0060 HSX split off from region
S88 emerged on
  2 S08W01 0010 AXX  
S90 emerged on
  S14E54     now spotless
S91 emerged on
  8 S09E42 0060 DAO  
S92 emerged on
  4 S17E56 0030 DSO  
S93 emerged on
  2 N11E59 0020 HRX  
S94 emerged on
  2 S17E84 0060 HAX  
S95 emerged on
  1 S17W41 0010 AXX  
Total spot count: 39 53
SSN: 89 163

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
2001.12 235.1 132.2 114.6 (-0.9)
2002.01 226.6 114.1 113.5 (-1.1)
2002.02 205.0 107.4 114.6 (+1.2)
2002.03 179.5 98.4 113.3 (-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 88.3 106.2 (-2.6)
2002.07 173.5 99.6 102.7 (-3.5)
2002.08 183.6 116.4 (99.7 predicted, -3.0)
2002.09 175.8 109.6 (96.7 predicted, -3.0)
2002.10 167.0 97.5 (93.2 predicted, -3.5)
2002.11 168.7 95.0 (88.0 predicted, -5.2)
2002.12 157.2 81.6 (83.6 predicted, -4.4)
2003.01 144.0 79.5 (80.6 predicted, -3.0)
2003.02 132.0 (1) 13.3 (2) (75.5 predicted, -5.1)

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. All time references are to the UTC day. Comments and suggestions are always welcome.

[DX-Listeners' Club]