Solar Terrestrial Activity Report

Last update issued on June 16, 2003 at 03:10 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 10, 2003)]

Recent activity

The geomagnetic field was unsettled to minor storm on June 15. Solar wind speed ranged between 473 and 583 km/sec. The high speed stream from coronal hole CH43 ended early in the evening. At about 19h UTC a new and short lived disturbance arrived as solar wind speed increased and ACE EPAM data indicated the arrival of a CME. This disturbance has not been particularly geoeffective so far with the interplanetary magnetic field nearly constantly northwards.

Solar flux measured at 20h UTC on 2.8 GHz was 128.7. The planetary A index was 20 (STAR Ap - based on the mean of three hour interval ap indices: 21.0).
Three hour interval K indices: 45333343 (planetary), 34123233 (Boulder). [SEC have since June 11 been reporting faulty values for the Boulder K indices. They are using the data from the high latitude magnetometer at College, Alaska instead of the ones recorded at Boulder by USAF. The USAF K indices are used in this report.]

The background x-ray flux is at the class B7 level.

At midnight there were 4 spotted regions on the visible disk. Solar flare activity was high. A total of 7 C and 1 X  class events was recorded during the day. Old region 10375 behind the northwest limb produced a C2.3 flare at 02:20, a C1.2 flare at 08:43, a C1.7 flare at 09:58 and a C1.3 flare at 12:28 UTC.

Region 10380 decayed further and has only a few spots left.
Region 10381 decayed slowly and quietly.
New region 10385 emerged in the northeast quadrant early on June 14 and was numbered by SEC the next day. The region developed slowly on June 15.
New region 10386 (S184) rotated partly into view at the southeast limb late in the day. This region could produce further major flares and probably has a complex layout. Location at midnight: S07E85. Flares: C3.3 long duration event peaking at 14:57, C2.1 at 22:38 and X1.3 long duration event peaking at 23:56 UTC.

Coronal mass ejections (CMEs)

June 13: No obviously geoeffective CMEs observed. A filament across the central meridian in the northern hemisphere began to erupt late in the day and may have been associated with a small CME.

June 14: The erupting filament noted late on June 13 may have triggered activity in and near region 10380. SOHO EIT images display an apparent sequence of activity beginning with the filament eruption in the north, then an eruption in region 10380 and finally a filament eruption to the east southeast of region 10380. A faint full halo CME was observed in LASCO C3 images early in the day and may have been related to this activity. The distribution of the ejected material correlates fairly well with the location of the activity, however, we cannot disregard the possibility that the CME could be related to backside activity.

June 15: No obviously geoeffective CMEs observed. While the X1 flare in region S184 late in the day was associated with a CME, the CME is not likely to be geoeffective.

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 recurrent well defined trans equatorial coronal hole (CH44) will rotate into a geoeffective position on June 16-17.

Processed SOHO EIT 284 image at 19:06 UTC on June 15. Any black areas on the solar disk are likely coronal holes.

Forecast

The geomagnetic field is expected to be quiet to active early on June 16. If the CME noted early on June 14 had a frontside source, it will likely arrive on June 16 and could cause active to minor storm conditions. A high speed stream from coronal hole CH44 should dominate the solar wind from late on June 18 until  June 21 and cause unsettled to minor storm 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 22. 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.