Solar Terrestrial Activity Report

Last update issued on June 12, 2003 at 03:00 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 10, 2003)]

Recent activity

The geomagnetic field was unsettled to active on June 11. Solar wind speed ranged between 561 and 751 km/sec under the influence of a high speed stream from coronal hole CH42 until about 16h UTC when the stream appeared to be ending.

Solar flux measured at 20h UTC on 2.8 GHz was 192.9. The planetary A index was 15 (STAR Ap - based on the mean of three hour interval ap indices: 15.6).
Three hour interval K indices: 33433333 (planetary), 43434443 (Boulder).

The background x-ray flux is at the class C5 level.

At midnight there were 6 spotted regions on the visible disk. Solar flare activity was high. A total of 4 C, 9 M and 1 X class events was recorded during the day.

Region 10375 decayed in the intermediate spot section while the trailing spot section was mostly unchanged. The leading penumbra became larger. The region is very hot and is flaring nearly continuously. Further major flaring is likely. Flares: M7.8 flare at 00:25, M1.8 at 03:06, C8.1 at 04:53, C6 at 05:40, C3.8 at 07:52, C8.3 at 08:30, M1.1 at 10:33, M1.4 at 11:09, M2.8/1N at 13:21, M3.9 long duration event peaking at 15:27, M4.8/1F at 16:36, X1.6/1N at 20:14, M2.9 at 21:51 and C9.9 at 23:41 UTC. A major M7.3 flare at 01:30 UTC on June 12 had its source in this region.
Region 10377 decayed significantly in the trailing and intermediate spot sections.
Region 10380 was mostly unchanged and remains capable of producing a major flare. Flare: M1.8/1F long duration event peaking at 17:47 UTC.
Region 10381 developed slowly and quietly.
Region 10382 developed slowly adding penumbra to both polarities.
New region 10383 emerged early on June 10 in the northeast quadrant and was numbered by SEC the next day. The region decayed during the day and could soon become spotless.

Coronal mass ejections (CMEs)

June 9: A partial halo CME was observed in LASCO images late in the day after the X1 event in region 10375. The major part of the ejected material was observed off of the northwest limb. The CME could reach Earth during the latter half of June 11 and cause major geomagnetic storming.

June 10: A full halo CME was observed in LASCO C3 images before noon. The distribution of the ejected material and lack of supporting frontside activity suggests that the source of this CME was several days behind the east limb. Otherwise slow and continuous mass ejection was observed off of the northwest limb, probably because of the ongoing activity in region 10375. Any CMEs in association with the major flares during the latter half of the day could not be observed as LASCO has shut its doors awaiting a SOHO spacecraft maneuver. No new LASCO images will become available until late on June 13.

June 11: A CME was observed in SXI images in association with the M4 event in region 10375 peaking at 15:24 UTC. A much larger CME was observed following an M1.8 event in region 10380 (peaking at 17:47 UTC). This flare triggered a large filament eruption south and southwest of the region. This CME could reach Earth and cause major geomagnetic storming on June 13-14.

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 coronal hole (CH43) mainly in the northern hemisphere and with a trans equatorial extension, was in a geoeffective position on June 11.

Processed SOHO EIT 284 image at 19:06 UTC on June 11. Any black areas on the solar disk are likely coronal holes.

Forecast

The geomagnetic field is expected to be quiet to active on June 12 and early on June 13. On June 13 a CME could impact Earth and cause active to major storm conditions late that day and on June 14. On June 14-15 a high speed stream from coronal hole CH43 will likely dominate the solar wind and cause unsettled to active conditions.

Long distance medium wave (AM) band propagation along east-west paths over high and upper middle latitudes is useless and will likely be very poor to useless until at least June 17. Propagation along north-south paths is fair to good. [Trans Atlantic propagation conditions are currently monitored every night on 1470 kHz. Dominant station tonight: none, several stations noted including Radio Cristal del Uruguay and two unidentified from Argentina.]

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.