Solar Terrestrial Activity Report

Last update issued on June 26, 2003 at 04:00 UTC.

[Solar and geomagnetic data - last month (updated daily)]
[Solar wind and electron fluence charts (updated daily)]
[Solar cycles 21-23 (last update June 3, 2003)]
[Solar cycles 1-20]
[Graphical comparison of cycles 21, 22 and 23 (last update June 3, 2003)]
[Graphical comparison of cycles 2, 10, 13, 17, 20 and 23 (last update June 3, 2003)]
[Historical solar and geomagnetic data charts 1954-2003 (last update April 13, 2003)]
[Archived reports (last update June 23, 2003)]

Recent activity

The geomagnetic field was unsettled to active on June 25. Solar wind speed ranged between 510 and 576 km/sec under the influence of a high speed stream from a southern hemisphere coronal hole..

Solar flux measured at 20h UTC on 2.8 GHz was 116.3. The planetary A index was 19 (STAR Ap - based on the mean of three hour interval ap indices: 18.9).
Three hour interval K indices: 33433444 (planetary), 32443433 (Boulder).

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

At midnight there were 7 spotted regions on the visible disk. Solar flare activity was low. A total of 2 C class events was recorded during the day. Both events, C3.7 at 16:32 and C1.2 at 21:55 UTC, were long duration events and had their origin behind the northeast limb where old region 10375 soon will be rotating into view. 

Region 10386 decayed slowly and quietly most of the day. The northern negative polarity spot increased its area late in the day.
Region 10387 decayed slowly and was quiet.
Region 10390 was quiet and stable.
Region 10391 developed slowly and quietly. An emerging positive polarity area at the western edge of the trailing negative polarity spot area could create a magnetic delta structure.
Region 10392 was quiet and stable.
Region 10393 decayed slowly in the trailing spot section and was quiet.

Spotted regions not numbered by NOAA/SEC:
[S193] A new region rotated into view at the northeast limb early on June 25. Location at midnight: N11E76.

Coronal mass ejections (CMEs)

June 23: No obviously geoeffective CMEs observed.
June 24-25: No LASCO images available as there is a serious problem with the SOHO high gain antenna.

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 huge, recurrent coronal hole (CH46) mainly in the southern hemisphere and with a large leading trans equatorial extension will rotate into a geoeffective position from late on June 24 until July 2. The trans equatorial extension has become much larger over the last solar rotation.

Processed GOES SXI coronal structure image at 21:40 UTC on June 25. The darkest areas on the solar disk are likely coronal holes.

Forecast

The geomagnetic field is expected to be unsettled to active on June 26 and early on June 27. After noon on June 27 a high speed stream from coronal hole CH46 will cause unsettled to major storm conditions until July 1 becoming unsettled to active on July 2-4.

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 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 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.

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 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.