Solar Terrestrial Activity Report

Last major update issued on August 14, 2005 at 05:50 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 13, 2005)]

Recent activity

The geomagnetic field was quiet to active on August 13. Solar wind speed ranged between 346 and 588 (all day average 503) km/sec, probably due to a high speed stream from CH180.

Solar flux measured at 20h UTC on 2.8 GHz was 75.4. The planetary A index was 16 (STAR Ap - based on the mean of three hour interval ap indices: 15.6).
Three hour interval K indices: 34233233 (planetary), 34333233 (Boulder).

The background x-ray flux is at the class A3 level.

At midnight there were 2 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 10797 developed during the latter half of the day adding many new spots. There is currently a minor degree of polarity intermixing. C flares are likely and further development will increase the possibility of a minor M class flare.

Spotted regions not numbered by NOAA/SEC:
[S582] A new region rotated into view at the southeast limb on August 12. Slow development was observed on August 13. Location at midnight: S08E64.

Coronal mass ejections (CMEs)

August 11-13: 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

Recurrent trans equatorial coronal hole (CH181) will be in an Earth facing position on August 13-15.

Processed SOHO/EIT 284 image at 01:06 UTC on August 14. The darkest areas on the solar disk are likely coronal holes.

Forecast

The geomagnetic field is expected to be quiet to active on August 14 and quiet to unsettled on August 15. A high speed stream from CH181 is likely to arrive on August 16 and cause unsettled to minor storm conditions until August 18.

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 on long distance northeast-southwest paths is good. Trans Atlantic propagation conditions are normally monitored every night on 1470 kHz. Dominant stations tonight: Radio Cristal del Uruguay and LT28 Rafaela Argentina. Conditions were poor before LSR and improved quickly to good at and after LSR. A large number of stations from Argentina were heard, there was audio even on frequencies like 560, 640, 800 and 730 kHz. Radio Universidad in Santa Fé on 1020 kHz was a surprise. Radio Belgrano on 950 and Radio Diez on 710 kHz were both at unusually good signal levels..

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.