Solar Terrestrial Activity Report

Last major update issued on August 8, 2005 at 05:05 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 minor storm on August 7. Solar wind speed ranged between 560 and 907 (all day average 667) km/sec under the influence of a high speed stream from CH178.

Solar flux measured at 20h UTC on 2.8 GHz was 92.3. The planetary A index was 18 (STAR Ap - based on the mean of three hour interval ap indices: 18.1).
Three hour interval K indices: 35442223 (planetary), 34442223 (Boulder).

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

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

Region 10792 developed new penumbra to the north of the largest penumbra, otherwise slow decay was observed. Flare: C1.4 long duration event peaking at 12:49 UTC.
Region 10794 decayed slowly and quietly.
Region 10795 decayed slowly and quietly.
Region 10796 reemerged in the southwest quadrant.

Coronal mass ejections (CMEs)

August 6-7: No obvious partly or fully Earth directed CMEs were observed.
August 5: A filament eruption across the central meridian in the northern hemisphere was triggered by the C2 LDE in region 10792 during the morning. At least a partial halo CME was observed after this event.

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 small, elongated coronal hole (CH179) in the northern hemisphere was in an Earth facing position on August 5-6. CH179 apparently disappeared on August 6. A trans equatorial coronal (CH180) will rotate to an Earth facing position on August 8-9.

Processed SOHO/EIT 284 image at 01:06 UTC on August 8. The darkest areas on the solar disk are likely coronal holes.

Forecast

The geomagnetic field is expected to be quiet to active on August 8.  Quiet to unsettled is likely on August 9-10. 

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 to very poor. Propagation on long distance northeast-southwest paths is fair to good. Trans Atlantic propagation conditions are normally monitored every night on 1470 kHz. Dominant stations tonight: Radio Cristal del Uruguay, Radio Vibración (Venezuela)  and CPN Radio (Perú). Radio Santa Rosa (Perú) on 1499.93 had fair peaks before LSR. Radio Portales (Chile) on 1180 was good and Radio Nacional (Chile) and Radio Porlamar (Venezuela) were both audible on 1140 kHz. Quite a few frequencies had interesting stations (800, 830 kHz in particular) Most of the stations observed were from Brazil, Argentina and Venezuela. A few stations from Newfoundland (590, 640 and 930 kHz) had fair peaks as well.

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.