Solar Terrestrial Activity Report

Last major update issued on June 13, 2004 at 03:35 UTC.

[Solar and geomagnetic data - last month (updated daily)]
[Solar wind and electron fluence charts (updated daily)]
[Solar cycles 21-23 (last update June 2, 2004)]
[Solar cycles 1-20]
[Graphical comparison of cycles 21, 22 and 23 (last update June 2, 2004)]
[Graphical comparison of cycles 2, 10, 13, 17, 20 and 23 (last update June 2, 2004)]
[Historical solar and geomagnetic data charts 1954-2004 (last update April 28, 2004)]
[Archived reports (last update June 7, 2004)]

Recent activity

The geomagnetic field was quiet to unsettled on June 12. Solar wind speed ranged between 297 and 393 km/sec.

Solar flux measured at 20h UTC on 2.8 GHz was 88.0. The planetary A index was 7 (STAR Ap - based on the mean of three hour interval ap indices: 7.9).
Three hour interval K indices: 12313222 (planetary), 22322211 (Boulder).

The background x-ray flux is at the class B2 level.

At midnight there were 4 spotted regions on the visible disk. The solar flare activity level was low. A total of 2 C class events was recorded during the day.

Region 10631 decayed slowly and quietly.
Region 10632 was unchanged and quiet.

Spotted regions not numbered by NOAA/SEC:
[S416] This region emerged in the southeast quadrant on June 12. Location at midnight: S05E50.
[S417] A fairly active region rotated partly into view at the northeast limb on June 12. This region is likely to produce C flares and maybe even minor M class flares. Location at midnight: N12E82. Flares: C1.9 at 18:41 and C1.1 at 19:43 UTC.

Coronal mass ejections (CMEs)

June 10-12: No fully or partly Earth directed CMEs observed.

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 coronal hole (CH101) in the southern hemisphere was in a geoeffective position on June 12. A recurrent trans equatorial coronal hole (CH102) will likely rotate into a geoeffective position on June 15.

Processed SOHO/EIT 284 image at 01:05 UTC on June 12. The darkest areas on the solar disk are likely coronal holes.

Forecast

The geomagnetic field is expected to be quiet to unsettled on June 13-14 becoming unsettled to active late on June 14 and on June 15 due to a high speed stream from coronal hole CH101.

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 poor. Propagation along long distance north-south paths is fair. Trans Atlantic propagation conditions are monitored every night on 1470 kHz. Dominant station tonight: Radio Vibración (Venezuela). At times Radio Cristal de Uruguay was noted as well. On other frequencies propagation favored stations from Venezuela and the most common stations from Brazil. A few stations from North America could be heard with 590 VOCM and 1510 WWZN having the best signals.

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.