Solar Terrestrial Activity Report

Last update issued on March 15, 2003 at 02:40 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 10, 2003)]

Recent activity

The geomagnetic field was quiet to major storm on March 14. Solar wind speed ranged between 468 and 667 km/sec under the influence of a high speed coronal hole stream. Some high latitude stations recorded major to severe storm conditions 11-14h UTC. While magnetometers at all other latitudes recorded unsettled to active conditions at the same time, the storm conditions at high latitudes caused the planetary A index to reach 63 during the 12-15h UTC interval.

Solar flux measured at 20h UTC on 2.8 GHz was 138.9. The planetary A index was 25 (STAR Ap - based on the mean of three hour interval ap indices: 25.5).
Three hour interval K indices: 22446343 (planetary), 22434343 (Boulder).

The background x-ray flux is at the class B2-B3 level.

At midnight there were 5 spotted regions on the visible disk, 1 region has not yet been numbered by SEC/NOAA. Solar flare activity was very low. A C1.8 event which began at 23:59 UTC, peaked at 00:09 UTC on March 15 and did not reach the C level until a few minutes after midnight. The source of this event was an active region which is about to rotate into view at the northeast limb.

Region 10306 is splitting off some spots at the northeastern part of the huge penumbra, otherwise the region is mostly unchanged.
Region 10311 developed slowly adding a few spots.
Region 10313 developed slowly and quietly.
New region 10314 emerged on March 13 and was numbered the next day. The region has developed moderately quickly and could produce C class flares.

Spotted regions not yet numbered by SEC/NOAA:
[S123] A new region emerged in the northwest quadrant early in the day. Location at midnight: N02W60.

Coronal mass ejections (CMEs)

March 12-14: 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, huge, recurrent coronal hole (CH25) mainly in the southern hemisphere will be in a geoeffective position on March 11-19. This coronal hole has developed in the northwestern and northeastern trans equatorial parts.

Processed SOHO EIT 284 image at 01:06 UTC on March 15. Any black areas on the solar disk are likely coronal holes.

Forecast

The geomagnetic field is expected to be mostly unsettled to active until March 22 due to a high speed coronal hole stream, occasional quiet or minor storm intervals are likely. The strongest part of the disturbance will probably occur on March 18-21. 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 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.