Solar Terrestrial Activity Report

Last update issued on June 13, 2003 at 03:15 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 quiet to unsettled on June 12. Solar wind speed ranged between 456 and 567 km/sec.

Solar flux measured at 20h UTC on 2.8 GHz was 163.5. The planetary A index was 11 (STAR Ap - based on the mean of three hour interval ap indices: 11.6).
Three hour interval K indices: 22323333 (planetary), 11113123 (Boulder). [Curiously, SEC is reporting their own K index as: 32324454, an exact replica of the K index for (high latitude magnetometer at) College, Alaska. Looking back at recent K indices data for Boulder, there was a problem even for June 11 when the reported 43434443 should have been 22223232. Prior to that the data seems to be OK.]

The background x-ray flux is at the class C3 level.

At midnight there were 6 spotted regions on the visible disk. Solar flare activity was high. A total of 12 C and 4 M  class events was recorded during the day.

Region 10375 decayed in the trailing and intermediate spot sections while the leading spots rotated out of view at the northwest limb. Another major flare is possible while the region is at and just behind the limb during the next 2-3 days. Flares: M7.3/1N at 01:30, C6.1 at 07:13, C7.2 at 08:14, C5.0 at 08:55, C4.1 at 10:04, C8.1 at 10:27, M1.0 at 14:03, C2.9 at 14:47, M1.1 at 17:12, C3.2 at 19:22, C3.2 at 19:59, C8.5 at 20:14, M2.6 at 21:27, C7.1 at 22:49 UTC.
Region 10377 decayed further and lost nearly all trailing and intermediate spots.
Region 10380 decayed slightly as the large penumbra lost some of its area. A major flare is still possible, however, the magnetic delta structure in the main penumbra has weakened and could soon disappear. Flare: C8.4 at 08:33 UTC.
Region 10381 decayed in the trailing spot section while the leader spots developed slowly.
Region 10382 developed slowly and quietly.
New region 10384 emerged early in the day in the northwest quadrant. The region has mixed polarities. Any further development could cause the formation of a magnetic delta structure.

Coronal mass ejections (CMEs)

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. The CME could reach Earth and cause a geomagnetic disturbance on June 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. A recurrent trans equatorial coronal hole (CH44) will likely rotate into a geoeffective position on June 17.

Processed SOHO EIT 284 image at 19:06 UTC on June 12. Any black areas on the solar disk are likely coronal holes.

Forecast

The geomagnetic field is expected to be quiet to unsettled on June 13. Late on June 13 or sometime on June 14 a CME could impact Earth and cause unsettled to minor storm conditions. If no CME arrives a high speed stream from coronal hole CH43 will likely dominate the solar wind on June 14-15 and cause unsettled to active conditions.

Long distance medium wave (AM) band propagation along east-west paths over high and upper middle latitudes is very poor and will likely be very poor until at least June 17. 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.