Solar Terrestrial Activity Report

Last major update issued on February 9, 2005 at 03:50 UTC.

[Solar and geomagnetic data - last month (updated daily)]
[Solar wind and electron fluence charts (updated daily)]
[Solar cycles 21-23 (last update January 2, 2005)]
[Solar cycles 1-20]
[Graphical comparison of cycles 21, 22 and 23 (last update January 2, 2005)]
[Graphical comparison of cycles 2, 10, 13, 17, 20 and 23 (last update January 2, 2005)]
[Historical solar and geomagnetic data charts 1954-2004 (last update February 1, 2005)]
[Archived reports (last update February 1, 2005)]

Recent activity

The geomagnetic field was unsettled to major storm on February 8. Solar wind speed ranged between 587 and 877 km/sec under the influence of a high speed stream from CH144.

Solar flux measured at 20h UTC on 2.8 GHz was 108.2. The planetary A index was 34 (STAR Ap - based on the mean of three hour interval ap indices: 34.5).
Three hour interval K indices: 46434444 (planetary), 56434444 (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 10730 developed several trailing spots and was quiet.
Region 10732 developed as several spots emerged in the northern part. Decay was observed in the southwestern part where penumbra was lost on the leader spots. There is a small chance of a minor M class flare. Flare: C1.2 at 21:44 UTC.
Region 10733 was mostly unchanged and still has a small magnetic delta structure in the northern part of the single penumbra. A minor M class flare is possible. Flare: C1.9 at 15:27 UTC.

Spotted regions not numbered by NOAA/SEC:
[S508] This region rotated partly into view at the southeast limb late on February 8. Location at midnight: S04E80.

Coronal mass ejections (CMEs)

February 6-8: No obvious fully or partly 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 large recurrent coronal hole (CH144) in the northern hemisphere was in a geoeffective position on February 4-6.

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

Forecast

The geomagnetic field is expected to be quiet to active on February 9 due to a high speed stream from CH144, an isolated minor storm interval is possible. Quiet to unsettled is likely on February 10-11.

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 very poor. Propagation along long distance north-south paths is poor to fair. Trans Atlantic propagation conditions are normally monitored every night on 1470 kHz. Dominant stations tonight: Radio Vibración and Radio Cristal del Uruguay. Several stations from the US were heard. WWZN Boston on 1510 kHz had a fair to good signal while 1650, 1660, 1680, 1690 and 1700 kHz had poor to fair signals.

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
10730 2005.02.04 9 8 S20E20 0070 DSO  
10731 2005.02.06     S02E01     plage
10732 2005.02.06 10 9 N12E37 0050 FSO beta-gamma
classification was DSO at midnight
location: N17E39
10733 2005.02.07 4 4 S08E67 0240 HKX beta-delta
S508 visible on
2005.02.08
  1 S04E80 0050 HSX  
Total spot count: 23 22  
SSN: 53 62  

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)
2003.12 114.9 46.5 54.8 (-1.9)
2004.01 114.1 37.3 52.0 (-2.8)
2004.02 107.0 45.8 49.3 (-2.7)
2004.03 112.0 49.1 47.1 (-2.2)
2004.04 101.2 39.3 45.5 (-1.6)
2004.05 99.8 41.5 43.9 (-1.6)
2004.06 97.4 43.2 41.7 (-2.2)
2004.07 119.1 51.0 40.3 (-1.4)
2004.08 109.6 40.9 (38.9 predicted, -1.4)
2004.09 103.1 27.7 (36.6 predicted, -2.3)
2004.10 105.9 48.4 (34.4 predicted, -2.2)
2004.11 113.2 43.7 (32.5 predicted, -1.9)
2004.12 94.5 17.9 (30.2 predicted, -2.3)
2005.01 102.2 31.3 (27.6 predicted, -2.6)
2005.02 91.7 (1) 10.1 (2) (25.2 predicted, -2.4)

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% less.

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.


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