Solar Terrestrial Activity Report

Last major update issued on August 2, 2005 at 04:40 UTC.

[Solar and geomagnetic data - last month (updated daily)]
[Solar wind and electron fluence charts (updated daily)]
[Solar cycles 21-23 (last update August 2, 2005)]
[Solar cycles 1-20]
[Graphical comparison of cycles 21, 22 and 23 (last update August 2, 2005)]
[Graphical comparison of cycles 2, 10, 13, 17, 20 and 23 (last update August 2, 2005)]
[Historical solar and geomagnetic data charts 1954-2004 (last update February 1, 2005)]
[Archived reports (last update July 19, 2005)]

Recent activity

The geomagnetic field was quiet to active on August 1. Solar wind speed ranged between 436 and 628 (all day average 529) km/sec. A fairly weak solar wind shock was observed at 06:09 UTC at SOHO. This was the arrival of the full halo CME observed two days earlier.

Solar flux measured at 20h UTC on 2.8 GHz was 111.2. The planetary A index was 16 (STAR Ap - based on the mean of three hour interval ap indices: 16.5).
Three hour interval K indices: 41343333 (planetary), 42344323 (Boulder).

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

At midnight there were 5 spotted regions on the visible solar disk. The solar flare activity level was moderate. A total of 2 C and 1 M class events was recorded during the day.

Region 10791 decayed slowly and quietly and will rotate out of view at the northwest limb late today.
Region 10792 decayed slowly as some penumbra and a few spots were lost in the leading spot section. The large trailing penumbra split as well and currently there is just one small magnetic delta structure. The region could still produce a major flare. Flares: C1.4 at 05:19 and a long duration M1.0 event peaking at 13:51 UTC. The latter event was associated with a weak type IV sweep and a small CME off of the east limb.
Region 10793 developed slowly and quietly.
Region 10794 added a few spots and has at least C class flare potential. Flare: C5.8 at 12:21 UTC.
Region 10795 was quiet and stable.

Coronal mass ejections (CMEs)

July 31 - August 1: No obvious partly or fully Earth directed CMEs were 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

No obvious coronal holes are currently in or near Earth facing positions.

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

Forecast

The geomagnetic field is expected to be quiet to active on August 2 and quiet to unsettled on August 3-4.

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 on long distance northeast-southwest paths is poor. Trans Atlantic propagation conditions are normally monitored every night on 1470 kHz. Dominant station tonight: Radio Cristal del Uruguay. Both Radio Vibración (Venezuela) and an unidentified Brazilian with religious programming were heard. The post LSR opening to Uruguay and Argentina was weaker than usual. During the hour before LSR several stations from Newfoundland were noted with weak to fair signals on these frequencies: 540, 560, 590, 600, 620, 640, 710, 740, 750, 790, 800 and 930 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% 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.