Solar Terrestrial Activity Report

Last update issued on June 28, 2003 at 04:10 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 major storm on June 27. Solar wind speed ranged between 611 and 768 km/sec under the influence of a high speed stream from coronal hole CH46.

Solar flux measured at 20h UTC on 2.8 GHz was 123.9. The planetary A index was 28 (STAR Ap - based on the mean of three hour interval ap indices: 28.6).
Three hour interval K indices: 44644443 (planetary), 45654333 (Boulder).

The background x-ray flux is at the class B4 level.

At midnight there were 9 spotted regions on the visible disk. Solar flare activity was low. A total of 7 C class events was recorded during the day.

Region 10387 decayed further and appears to be losing all trailing spots.
Region 10390 was quiet and stable.
Region 10391 decayed and lost most of the trailing spots as well as some penumbral area on the leading spots.
Region 10392 was quiet and stable.
Region 10393 decayed slowly and quietly.
Region 10394 developed slowly and was quiet. Some polarity intermixing is evident and the region could soon become more interesting.
Region 10395 was quiet and stable.
New region 10396 emerged quickly on June 26 and was numbered by SEC the next day. The region is still developing and is capable of producing C class flares.
New region 10397 rotated partly into view on June 26 and was numbered the following day by SEC. Flares: C3.9 at 03:21, C1.2 at 05:20, C1.4 at 05:53, C2.6 at 07:06, C1.1 at 07:35, C1.5 at 17:43 and C1.0 at 21:13 UTC.

Coronal mass ejections (CMEs)

June 25-27: No LASCO images available. There is a serious problem with the SOHO high gain antenna. Current LASCO images and other SOHO data is expected to be unavailable until about July 14.

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 June 30. The trans equatorial extension has become much larger over the last solar rotation.

Processed GOES SXI coronal structure image at 21:56 UTC on June 27. The darkest areas on the solar disk are likely coronal holes.

Forecast

The geomagnetic field is expected to be unsettled to major storm until July 1, unsettled to active is likely 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 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.