Solar Terrestrial Activity Report

Last major update issued on February 10, 2010 at 05:35 UTC.

[Solar and geomagnetic data - last month (updated daily)]
[Solar wind and electron fluence charts (updated daily)
[Solar cycles 21-23 (last update October 4, 2007)]
[Solar cycles 1-20]
[Graphical comparison of cycles 21, 22 and 23 (last update October 4, 2007)]
[Graphical comparison of cycles 2, 10, 13, 17, 20 and 23 (last update October 4, 2007)]
[Historical solar and geomagnetic data charts 1954-2006 (last update April 5, 2007)]
[Archived reports (last update January 3, 2010)]

Recent activity

The geomagnetic field was quiet on February 9. Solar wind speed ranged between 279 and 360 km/s.

Solar flux measured at 20h UTC on 2.8 GHz was 91.4. The planetary A index was 3 (STAR Ap - based on the mean of three hour interval ap indices: 3.1). Three hour interval K indices: 10101201 (planetary), 01110111 (Boulder).

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

At midnight there were 3 spotted regions on the visible solar disk.

Region 11045 decayed further but could still produce occasional C flares.
Region 11046 developed slowly and was quiet.
Region  11047 decayed and could soon become spotless.

Coronal mass ejections (CMEs)

February 7: A full halo CME was observed following an M6 flare in region 11045.
February 8: A small CME was observed after an M4 flare in region 11045.
February 9: No obvious Earth directed CMEs were observed in LASCO images

Coronal holes

Coronal hole history (since late October 2002)
Compare today's report to the situation one solar rotation ago: 28 days ago 27 days ago 26 days ago

A recurrent coronal hole (CH390) in the northern hemisphere was in an Earth facing position on February 6-7. A coronal hole (CH391) in the southern hemisphere may have closed before reaching an Earth facing position.

Processed SOHO/EIT 195 image at 23:36 UTC on February 9. The darkest areas on the solar disk are likely coronal holes.

Propagation

Long distance low and medium frequency (below 2 MHz) propagation along paths north of due west over high and upper middle latitudes is good. Propagation on long distance northeast-southwest paths is poor.

Forecast

The geomagnetic field is expected to be quiet to active on February 10-11 due to CME and coronal hole effects.

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) Effects from a CME are likely to be observed at 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.

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/SWPC. 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 SWPC or where SWPC has observed no spots. SWPC active region numbers in the table below and in the active region map above are the historic SWPC/USAF numbers.

Active region Date numbered SWPC
spot
count
STAR
spot
count
Location at midnight Area SWPC
Classification
Comment
S749 2010.02.05     N19W50     plage
11045 2010.02.06 25 23 N23W26 0300 FKC area was 0170 at midnight, classification FAI
11046 2010.02.07 7 7 N24E42 0010 BXO classification was DSO at midnight, area 0050
11047 2010.02.08 1 1 S17E61 0010 AXX  
Total spot count: 33 31  
SSN: 63 61  

Monthly solar cycle data

Month Average measured solar flux International sunspot number (SIDC) Smoothed sunspot number Average Ap
(3)
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)  
2008.07 65.7 0.5 2.8 (-0.4)  
2008.12 69.2 0.8 1.7 (-)
sunspot minimum
3.25
2009.01 69.8 1.3 1.8 (+0.1) 3.70
2009.02 70.0 1.4 1.9 (+0.1) 4.68
2009.03 69.2 0.7 2.0 (+0.1) 4.85
2009.04 69.7 1.2 2.2 (+0.2) 4.52
2009.05 70.5 2.9 2.3 (+0.1) 4.75
2009.06 68.6 2.6 2.7 (+0.4) 5.22
2009.07 68.2 3.5 3.6 (+0.9) 5.49
2009.08 67.3 0.0 (4.5 predicted, +0.9) 5.70
2009.09 70.5 4.2 (5.5 predicted, +1.0) 3.88
2009.10 72.6 4.6 (6.6 predicted, +1.1) 3.66
2009.11 73.6 4.2 (7.8 predicted, +1.2) 2.45
2009.12 76.7 10.6 (9.2 predicted, +1.4) 1.41 / 1.92
2010.01 81.1 13.1 (11.0 predicted, +1.8) 2.93
2010.02 82.2 (1) 10.2 (2) (13.0 predicted, +2.0) (4.77)

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/SWPC) sunspot number. The official international sunspot number is typically 30-50% lower.
3) Running average based on the daily SWPC ap indices. Values in red are based on official NGDC records.

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.