Solar Terrestrial Activity Report

Last major update issued on July 2, 2005 at 05:10 UTC.

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

Recent activity

The geomagnetic field was quiet to active on July 1. Solar wind speed ranged between 342 and 745 (all day average 424) km/sec. A high speed stream from CH173 arrived after noon.

Solar flux measured at 20h UTC on 2.8 GHz was 114.6. The planetary A index was 16 (STAR Ap - based on the mean of three hour interval ap indices: 15.9).
Three hour interval K indices: 22213444 (planetary), 22213534 (Boulder).

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

At midnight there were 8 spotted regions on the visible solar disk. The solar flare activity level was low. A total of 2 C class events was recorded during the day.

Region 10781 was quiet and stable.
Region 10782 added some penumbral area. The separation between the opposite polarities has increased and, unless new flux emerges, the region is likely to begin decaying soon. Flare: C1.2 at 12:56 UTC.
Region 10783 developed moderately quickly to become the largest region on the visible disk. There is some polarity intermixing and C flares are possible.
Region 10784 decayed slowly and quietly.
Region 10785 developed slowly and quietly.
New region 10786 rotated into view at the northeast limb. This region is complex with a high degree of polarity intermixing and possibly a magnetic delta structure. A minor M class flare is possible. Flare: C5.3 at 05:02 UTC. A weak type II radio sweep was associated with this event.
New region 10787 emerged in the southwest quadrant on June 30 and was numbered the next day by SEC. Slow development was observed on July 1. A small positive polarity area has emerged between two negative polarity areas.

Spotted regions not numbered by NOAA/SEC:
[S566] A new region rotated into view at the southeast limb late on July 1. Location at midnight: S05E81.

Coronal mass ejections (CMEs)

June 29 - July 1: No obvious fully or partly Earth directed CMEs were observed in available 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 trans equatorial coronal hole (CH173) was in an Earth facing position on June 28-30.

Processed SOHO/EIT 284 image at 01:06 UTC on July 2. The darkest areas on the solar disk are likely coronal holes.

Forecast

The geomagnetic field is expected to be unsettled to minor storm on July 2, quiet to active on July 3 and quiet to unsettled on July 4-5.

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 poor to very poor. Trans Atlantic propagation conditions are normally monitored every night on 1470 kHz. Dominant station tonight: Radio Cristal del Uruguay. On 1510 kHz Rádio Nordeste AM (Brazil) had a fair to strong signal for some time, otherwise there was not much interesting to listen to.

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% lower.

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.