Solar Terrestrial Activity Report

Last major update issued on August 30, 2005 at 04:50 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 29. Solar wind speed ranged between 354 and 425 (all day average 372) km/sec.

Solar flux measured at 20h UTC on 2.8 GHz was 89.2. The planetary A index was 9 (STAR Ap - based on the mean of three hour interval ap indices: 8.6).
Three hour interval K indices: 24212111 (planetary), 34311111 (Boulder).

The background x-ray flux is at the class B1 level.

At midnight there were 4 spotted regions on the visible solar disk. The solar flare activity level was low. A total of 3 C class events was recorded during the day.

Region 10801 was quiet and stable.
Region 10803 lost most of its penumbral area while a few new leader spots emerged.
Region 10805 was quiet and stable.
New region 10806 emerged in the southeast quadrant on August 30. The region has mixed polarities and further C class flaring is likely. Flares: C1.3 at 17:03, C6.5 at 21:55 and C1.2 at 00:01 UTC (the flare began at 23:55 and therefore belongs to August 29 and not August 30).

Coronal mass ejections (CMEs)

August 27-29: No obvious partly or fully Earth directed CMEs were observed. A large full halo CME was observed from a source behind the southwest limb. A minor increase in the above 10 MeV proton flux was probably caused by this event as well.

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 recurrent coronal hole (CH184) in the southern hemisphere was likely in an Earth facing position on August 27-28.

Processed SOHO/EIT 284 image at 19:06 UTC on August 29. The darkest areas on the solar disk are likely coronal holes.

Forecast

The geomagnetic field is expected to be quiet initially on August 30. A high speed stream from CH184 could reach Earth during the latter half of August 30 and cause unsettled to minor storm conditions until August 31 with quiet to active likely on September 1.

Coronal holes (1) Coronal mass ejections (2) M and X class flares (3)
Coronal hole indicator CME indicator M and X class flare indicator

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 poor. Trans Atlantic propagation conditions are normally monitored every night on 1470 kHz. Dominant station tonight: Radio Cristal del Uruguay. More stations and somewhat better signals were noted both before and after LSR on August 30. WWZN on 1510 was again audible while several stations from the Buenos Aires area had fair signals after LSR.

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.

Active region Date numbered SEC
spot
count
STAR
spot
count
Location at midnight Area Classification Comment
10800 2005.08.19 2   N16W87 0030 CAO rotated out of view
10801 2005.08.20 2 1 N09W57 0020 CSO classification was HSX at midnight, area 0010
10802 2005.08.24     S12W52     plage
10803 2005.08.24 13 8 N11E14 0050 DAO beta-gamma
10804 2005.08.25 2   N11W39 0010 BXO spotless
10805 2005.08.27 3 3 S08E47 0090 DAO classification was HAX at midnight, area 0060
only negative polarity spots
10806 2005.08.29 6 11 S17E50 0070 DAI beta-gamma
Total spot count: 28 23  
SSN: 88 63  

Monthly solar cycle data

Month Average solar
flux at Earth
International sunspot number Smoothed sunspot number
2000.04 184.2 125.5 120.8
cycle 23 sunspot max.
2000.07 202.3 170.1 119.8
2001.12 235.1 132.2 114.6 (-0.9)
2004.06 97.4 43.2 41.6 (-2.2)
2004.07 119.1 51.1 40.2 (-1.4)
2004.08 109.6 40.9 39.2 (-1.0)
2004.09 103.1 27.7 37.5 (-1.7)
2004.10 105.9 48.0 35.9 (-1.6)
2004.11 113.2 43.5 35.3 (-0.6)
2004.12 94.5 17.9 35.2 (-0.1)
2005.01 102.2 31.3 34.6 (-0.6)
2005.02 97.2 29.2 (33.5 predicted, -1.1)
2005.03 89.9 24.5 (32.1 predicted, -1.4)
2005.04 86.0 24.4 (30.2 predicted, -1.9)
2005.05 99.3 42.6 (27.6 predicted, -2.6)
2005.06 93.7 39.6 (26.1 predicted, -1.5)
2005.07 96.4 39.9 (25.1 predicted, -1.0)
2005.08 90.9 (1) 61.8 (2) (23.2 predicted, -1.9)

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.


[DX-Listeners' Club]