Solar Terrestrial Activity Report

Last major update issued on June 5, 2005 at 04:45 UTC.

[Solar and geomagnetic data - last month (updated daily)]
[Solar wind and electron fluence charts (updated daily)]
[Solar cycles 21-23 (last update June 4, 2005)]
[Solar cycles 1-20]
[Graphical comparison of cycles 21, 22 and 23 (last update June 4, 2005)]
[Graphical comparison of cycles 2, 10, 13, 17, 20 and 23 (last update June 4, 2005)]
[Historical solar and geomagnetic data charts 1954-2004 (last update February 1, 2005)]
[Archived reports (last update June 4, 2005)]

Recent activity

The geomagnetic field was quiet to minor storm on June 4. Solar wind speed ranged between 351 and 541 km/sec. A high speed stream from CH169 began to dominate the solar wind after 13h UTC.

Solar flux measured at 20h UTC on 2.8 GHz was 96.9. The planetary A index was 18 (STAR Ap - based on the mean of three hour interval ap indices: 18.3).
Three hour interval K indices: 21323454 (planetary), 22224543 (Boulder).

The background x-ray flux is at the class B3 level.

At midnight there were 5 spotted regions on the visible solar disk. The solar flare activity level was low. A total of 8 C class events was recorded during the day.

Region 10772 developed in the trailing spot section and has a weak magnetic delta structure. M class flaring is possible. Flares: C2.0 at 00:39, C4.9 at 00:55, C2.0 at 01:50, C2.2 at 06:43, C1.1 at 08:48, C1.3 at 11:40 and C1.3 at 16:56 UTC.
Region 10773 was mostly unchanged and quiet.
New region 10774 emerged in the northeast quadrant on June 3 and was numbered the next day by SEC. The region decayed slightly on June 4.
New region 10775 rotated into view at the northeast limb.

Spotted region not numbered by NOAA/SEC:
[S554] This region rotated partly into view at the southeast limb on June 4. Location at midnight: S05E84. Flare: C2.8 at 22:25 UTC.

Coronal mass ejections (CMEs)

June 2-4: No obvious fully or partly potentially geoeffective CMEs were observed in LASCO images.

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 large, recurrent coronal hole (CH169) in the northern hemisphere with a trans equatorial extension was in an Earth facing position on June 1-3.

Processed SOHO/EIT 284 image at 01:06 UTC on June 5. The darkest areas on the solar disk are likely coronal holes.

Forecast

The geomagnetic field is expected to be unsettled to minor storm on June 5 and quiet to active on June 6 due to a high speed stream from CH169. Quiet to unsettled conditions are likely on June 7-8.

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. When the high speed stream has arrived the color changes to green.
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.

Propagation

Long distance low and medium frequency (below 2 MHz) propagation along east-west paths over high and upper middle latitudes is very poor. Propagation along long distance north-south paths is fair to poor. Trans Atlantic propagation conditions are normally monitored every night on 1470 kHz. Dominant station tonight: Radio Cristal del Uruguay. There were several weak carriers (and occasionally audio) near 1470 kHz from Brazilian stations. On other frequencies several weak signals from Brazil and Argentina were noted, with the strongest signal from an unidentified station from Brazil on 1060 kHz.

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. SEC active region numbers in the table below and in the active region map above are the historic SEC/USAF numbers.

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 analysis, and partly on data from some of these solar data sources. All time references are to the UTC day. Comments and suggestions are always welcome.