Solar Terrestrial Activity Report

Last update issued on February 5, 2003 at 02:30 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 unsettled to minor storm on February 4. Solar wind speed ranged between 472 and 684 km/sec under the influence of a coronal stream.

Solar flux measured at 20h UTC on 2.8 GHz was 134.8. The planetary A index was 24 (STAR Ap - based on the mean of three hour interval ap indices: 24.5).
Three hour interval K indices: 34553333 (planetary), 34432332 (Boulder).

The background x-ray flux is at the class B4 level.

At midnight there were 8 spotted regions on the visible disk, 4 of which have not yet been numbered by SEC/NOAA. Solar flare activity was low. A total of 2 C class events was recorded during the day.

Region 10274 was quiet and stable.
Region 10276 decayed in the trailing spot section and lost its magnetic delta structure. An M class flare is still possible.
New region 10277 emerged near the southeast limb. Flare: C1.6 at 21:21 UTC.
New region 10278 rotated partly into view at the northeast limb. The negative and positive polarity areas appear to be narrowly separated, but it is too early to tell if there is a magnetic delta structure present. Minor M class flares are possible. Flare: C1.4 at 20:15 UTC.

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. Location at midnight: S04W23.
[S88] A new region emerged in the southeast quadrant on February 4. Location at midnight: S08E12.
[S89] A new region emerged just southeast of region S88 on February 4. Location at midnight: S12E15.
[S90] A new region emerged near the southeast limb on February 4. Location at midnight: S14E67.

Coronal mass ejections (CMEs)

February 2-4: 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 extension of the northern polar coronal hole was in a geoeffective position on February 1-3. A small coronal hole in the southern hemisphere was in a geoeffective position on February 4.

Processed SOHO EIT 284 image at 19:06 UTC on February 4. Any black areas on the solar disk are likely coronal holes.

Forecast

The geomagnetic field is expected to be quiet to active on February 5-7 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, propagation along north-south paths is good.

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.

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.

Monthly solar cycle data

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.