Solar Terrestrial Activity Report

Last major update issued on July 9, 2005 at 05:25 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 July 8. Solar wind speed ranged between 301 and 388 (all day average 338) km/sec. A weak disturbance, possibly coronal hole related, began early on July 9.

Solar flux measured at 20h UTC on 2.8 GHz was 110.4. The planetary A index was 5 (STAR Ap - based on the mean of three hour interval ap indices: 5.1).
Three hour interval K indices: 22111222 (planetary), 22111212 (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 total of 2 C class events was recorded during the day.

Region 10783 decayed quickly losing spots and penumbral area. Flare: C1.9 at 05:20 UTC.
Region 10786 decayed moderately quickly and simplified magnetically. There is still a chance of a minor M class flare.  Flare: C1.6 long duration event peaking at 16:18 UTC.
Region 10788 decayed slowly and was quiet.
Region 10789 was mostly unchanged and quiet.

Coronal mass ejections (CMEs)

July 8: The C1 long duration event in region 10786 during the afternoon was apparently associated with (at least) a very faint partial halo CME. This CME was observed in LASCO C3 images during the evening and early on July 9.
July 7: A filament eruption which started at approximately 11h UTC just south of region 10786 was the likely source of a full halo CME observed in LASCO C3 images beginning at 14:42 UTC. Another full halo CME was observed in LASCO C3 images beginning at 18:18 UTC. Its source was likely the M4.9 flare in region 10786. The CME was not very impressive. 
July 6: 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

An extension of a coronal hole (CH174) in the southern hemisphere may have been in an Earth facing position on July 5-6.

Processed SOHO/EIT 284 image at 01:06 UTC on July 9. The darkest areas on the solar disk are likely coronal holes.

Forecast

The geomagnetic field is expected to be quiet to active on July 9 due to a weak stream from CH174. Two CMEs could arrive late on July 9 or early on July 10 and cause unsettled to minor storm conditions. If the CME observed late on July 8 / early on July 9 had a visible disk source, the CME could arrive late on July 11.

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 along long distance north-south paths is fair. Trans Atlantic propagation conditions are normally monitored every night on 1470 kHz. Dominant stations tonight: Radio Cristal del Uruguay and Radio Vibración (Venezuela). Like on the previous two mornings propagation was best during the hour after local sunrise. Radio América (Argentina) on 1190 had a fair signal and there were a number of interesting stations on frequencies like 1480, 1500, 1510 and 1560 kHz. North America was represented by 930 CJYQ (fair and very stable signal), 1510 WWZN and 1660 WWRU, all heard during the hour before local sunrise.

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.