Solar Terrestrial Activity Report

Last update issued on March 9, 2003 at 02:20 UTC. Minor update posted at 08:10 UTC.

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

Recent activity

The geomagnetic field was quiet to unsettled on March 8. Solar wind speed ranged between 393 and 451 km/sec.

Solar flux measured at 20h UTC on 2.8 GHz was 148.3. The planetary A index was 9 (STAR Ap - based on the mean of three hour interval ap indices: 9.4).
Three hour interval K indices: 11213332 (planetary), 22213432 (Boulder).

The background x-ray flux is at the class B3-B4 level.

At midnight there were 7 spotted regions on the visible disk. Solar flare activity was low. A total of 2 C class events were recorded during the day.

Region 10296 decayed further and lost most of the remaining small spots near the large penumbra as well as nearly all trailing spots.
Region 10297 developed in the leading spot section and could produce C flares.
Region 10301 decayed slowly and was mostly quiet. Flare: C1.0 at 01:16 UTC.
Region 10305 developed slowly and quietly.
Region 10306 was mostly quiet. C class flares are possible, as is a minor M class flare. Flare: C2.6 at 09:57 UTC.
New region 10307 emerged on March in the southeast quadrant and was numbered the next day. Only slow development was observed on March 8.
New region 10308 rotated into view at the northeast limb.

Comment added at 08:10 UTC on March 9: Changes to spotted regions noted so far today: Region 10305 has developed many new spots and could produce C flares. A new region has emerged in the southwest quadrant south of region 10297. Another new region emerged near the northwest limb. Region 10307 has become spotless.

The interplanetary magnetic field was weakly to moderately southwards between 02 and 04h UTC at ACE, and this caused an increase in geomagnetic activity to unsettled to active levels.

Coronal mass ejections (CMEs)

March 6-8: 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 well defined, large, recurrent coronal hole (CH25) is rotating into view at the southeast limb and will likely move into a geoeffective position on March 13-15.

Processed SOHO EIT 284 image at 19:06 UTC on March 8. Any black areas on the solar disk are likely coronal holes.

Forecast

The geomagnetic field is expected to be quiet to unsettled on March 9-12. Long distance medium wave (AM) band propagation along east-west paths over high and upper middle latitudes is poor, propagation along north-south paths is fair. [Trans Atlantic propagation conditions are currently monitored every night on 1470 kHz. Dominant station tonight: Radio Cristal del Uruguay]

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.