Solar Terrestrial Activity Report

Last update issued on March 16, 2003 at 03:15 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 unsettled to minor storm on March 15. Solar wind speed ranged between 571 and 702 km/sec under the influence of a high speed coronal hole stream.

Solar flux measured at 20h UTC on 2.8 GHz was 130.7. The planetary A index was 24 (STAR Ap - based on the mean of three hour interval ap indices: 23.9).
Three hour interval K indices: 54444343 (planetary), 54343333 (Boulder).

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

At midnight there were 6 spotted regions on the visible disk. Solar flare activity was low. A C1.8 event at 00:09 UTC had a source behind the northeast limb. At 00:03 UTC on March 16 a C1.3 flare was recorded in region  10306.

Region 10306 decayed slightly and was mostly quiet.
Region 10308 reemerged with a few spots.
Region 10311 decayed losing most of its spots and penumbral area.
Region 10313 decayed slowly and quietly.
Region 10314 has quickly become the most interesting region on the visible disk. A fairly strong magnetic delta formed in the large trailing penumbra. Many new spots have emerged and the region is capable of M class flaring. Flares: C3.7 at 15:30 and a long duration C8 event peaking at 20:18 UTC (see NOAA/SEC SXI image).
New region 10315 emerged early on March 14 in the northwest quadrant and was numbered the next day. The region is decaying and could become spotless before rotating out of view.

Coronal mass ejections (CMEs)

March 13-15: No obviously geoeffective CMEs observed. Late on March 15 a fast CME was observed off of the northeast limb. It was associated with a long duration class B8 xray enhancement and probably had the same origin as the C1.8 flare recorded at the start of the day.

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. After the emergence of region 10314 the central part of CH25 has weakened considerably, further development of region 10314 could completely close off the western part of CH25.

Processed SOHO EIT 284 image at 01:06 UTC on March 16. 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.