Solar Terrestrial Activity Report

Last major update issued on March 16, 2004 at 04:20 UTC.

[Solar and geomagnetic data - last month (updated daily)]
[Solar wind and electron fluence charts (updated daily)]
[Solar cycles 21-23 (last update March 2, 2004)]
[Solar cycles 1-20]
[Graphical comparison of cycles 21, 22 and 23 (last update March 2, 2004)]
[Graphical comparison of cycles 2, 10, 13, 17, 20 and 23 (last update March 2, 2004)]
[Historical solar and geomagnetic data charts 1954-2003 (last update January 16, 2004)]
[Archived reports (last update March 11, 2004)]

Recent activity

The geomagnetic field was quiet to active on March 15. Solar wind speed ranged between 452 and 546 km/sec.

Solar flux measured at 20h UTC on 2.8 GHz was 101.4. The planetary A index was 13 (STAR Ap - based on the mean of three hour interval ap indices: 13.3).
Three hour interval K indices: 43233332 (planetary), 54234332 (Boulder).

The background x-ray flux is at the class B1 level.

At midnight there were 4 spotted regions on the visible disk. Solar flare activity was very low. No C class events were recorded during the day. 

Region 10570 decayed slowly and quietly. Occasionally small spots were visible in the trailing positive polarity area, however, at midnight only the two leading negative polarity spots were visible.
Region 10572 decayed slowly and quietly.
Region 10573 did not change much. The single penumbra could be splitting into two smaller penumbrae.

Spotted region not numbered by NOAA/SEC:
[S372] This region rotated into view at the southeast limb late on March 15. Location at midnight: S02E83.

Coronal mass ejections (CMEs)

March 13-15: No partly or fully earth directed 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 coronal hole in the northeast quadrant appears to be too far to the north to become geoeffective.

Processed SOHO/EIT 284 image at 01:06 UTC on March 16. The darkest areas on the solar disk are likely coronal holes.

Forecast

The geomagnetic field is expected to be quiet to unsettled on March 16-19.

Long distance low and medium frequency (below 2 MHz) propagation along east-west paths over high and upper middle latitudes is poor. Propagation along long distance north-south paths is poor. [Trans Atlantic propagation conditions are currently monitored every night on 1470 kHz. Dominant station tonight: Radio Vibración (Venezuela). Sunrise propagation on March 15 was much improved over the previous days with trans Atlantic signals on nearly all  frequencies between 1350 and 1700 kHz].

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. When the high speed stream has arrived the color changes to green.
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 NOAA/SEC. 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. SEC active region numbers in the table below and in the active region map above are the historic SEC/USAF numbers.

Monthly solar cycle data

1) Running average based on the daily 20:00 UTC observed solar flux value at 2800 MHz.
2) Unofficial, accumulated value based on the Boulder (NOAA/SEC) sunspot number. The official international sunspot number is typically 30-50% less.

This report has been prepared by Jan Alvestad. It is based partly on my own observations and analysis, and partly on data from some of these solar data sources. All time references are to the UTC day. Comments and suggestions are always welcome.