Solar Terrestrial Activity Report

Last update issued on March 5, 2003 at 02:50 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 unsettled to minor storm on March 4. Solar wind speed ranged between 419 and 572 km/sec under the influence of a high speed stream from coronal hole CH23.

Solar flux measured at 20h UTC on 2.8 GHz was 146.0. The planetary A index was 26 (STAR Ap - based on the mean of three hour interval ap indices: 27.0).
Three hour interval K indices: 44545433 (planetary), 44545433 (Boulder).

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

At midnight there were 9 spotted regions on the visible disk, 2 of which have not yet been numbered by SEC/NOAA. Solar flare activity was very low.

Region 10294 decayed slowly and quietly and could become spotless today.
Region 10295 lost its trailing spot while slow development was observed in the leader spots.
Region 10296 developed slowly and quietly with all development occurring in the leading spot section. The trailing negative polarity spots decayed.
Region 10297 was quiet and stable.
Region 10298 decayed substantially and could become spotless today.
New region 10301 emerged in the northeast quadrant.
New region 10302 rotated into view at the northeast limb.

Spotted regions not yet numbered by SEC/NOAA:
[S118] A new region emerged in the southwest quadrant on March 4. Location at midnight: S26W37.
[S119] A new region emerged west of region 10297 in the southeast quadrant on March 4. Location at midnight: S15E15.

Coronal mass ejections (CMEs)

March 2 and 4: No obviously geoeffective CMEs observed.

March 3: A CME was observed after a long duration C2.4 event in and near region S117 late in the day. While most of the ejected material was observed off of the southeast limb, the LASCO C3 movie indicates that there was a full halo CME. It is difficult to tell whether or not there was a nearly simultaneous backsided CME which contributed to the apparent halo CME or if the CME associated with the LDE was the only source. In the latter case the CME would likely impact Earth on March 6.

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 coronal hole (CH24) in the southern hemisphere was in a geoeffective position on March 2-3.

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

Forecast

The geomagnetic field is expected to be unsettled to active until March 7 due to high speed streams from CH23 and CH24. Quiet to unsettled conditions are likely from March 8. 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 poor to fair. [Trans Atlantic propagation conditions are currently monitored every night on 1470 kHz. Dominant stations tonight: Radio Cristal del Uruguay and Radio Vibración]

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.