Solar Terrestrial Activity Report

Last major update issued on August 10, 2005 at 04:20 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 August 3, 2005)]

Recent activity

The geomagnetic field was quiet to unsettled on August 9. Solar wind speed ranged between 443 and 686 (all day average 500) km/sec.

Solar flux measured at 20h UTC on 2.8 GHz was 82.5. The planetary A index was 10 (STAR Ap - based on the mean of three hour interval ap indices: 9.9).
Three hour interval K indices: 33222233 (planetary), 33223223 (Boulder).

The background x-ray flux is at the class A8 level.

At midnight there were 5 spotted regions on the visible solar disk. The solar flare activity level was very low. No C class events were recorded during the day.

Region 10792 decayed slowly as it rotated to the northwest limb.
Region 10794 decayed slowly and quietly.
Region 10795 decayed slowly and quietly.
Region 10796 decayed and was quiet. The region is rotating over the southwest limb.

Spotted regions not numbered by NOAA/SEC:
[S578] This region emerged in the northwest quadrant on August 9 and in the southwestern part of CH180. Location at midnight: N05W17.

Coronal mass ejections (CMEs)

August 7-9: 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

A trans equatorial coronal (CH180) was in an Earth facing position on August 8-9. When region S578 emerged CH180 lost most of its southwestern section. Recurrent trans equatorial coronal hole (CH181) will likely rotate to an Earth facing position on August 13-15.

Processed SOHO/EIT 284 image at 01:25 UTC on August 10. The darkest areas on the solar disk are likely coronal holes.

Forecast

The geomagnetic field is expected to be quiet to unsettled on August 10 becoming quiet to active on August 11-12 due to effects from CH180. Quiet conditions are likely on August 13-15.

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 fair. Trans Atlantic propagation conditions are normally monitored every night on 1470 kHz. Dominant stations tonight: Radio Cristal del Uruguay and CPN Radio (Perú). Again Radio Santa Rosa on 1499.93 kHz was heard well just after 03h UTC. After LSR most of the stations observed were from Argentina with Radio Cordoba on 700 and Radio Diez on 710 kHz having fair to good signals. Before LSR a few stations from North America, including the most usual Newfoundland stations and WWZN on 1510 kHz, were heard at poor signal levels. Rádio Olinda (Brazil) on 1030 kHz was surprisingly the best signal.

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.