Solar Terrestrial Activity Report

Last major update issued on February 14, 2005 at 03:00 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 inactive to quiet on February 13. Solar wind speed ranged between 347 and 463 km/sec, generally decreasing all day.

Solar flux measured at 20h UTC on 2.8 GHz was 115.5. The planetary A index was 4 (STAR Ap - based on the mean of three hour interval ap indices: 3.8).
Three hour interval K indices: 11110121 (planetary), 21111111 (Boulder).

The background x-ray flux is at the class B1-B2 level.

At midnight there were 5 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 decayed further and could soon become spotless.
Region 10732 decayed significantly and could become spotless today.
Region 10733 decayed slowly. Flare: C2.7 at 10:47 UTC. A weak type II radio sweep was associated with this event and possibly even a small CME.
Region 10734 developed a small spot ahead of the previously single penumbra. Flare: C21.4 at 14:58 UTC.
Region 10735 was mostly unchanged and quiet.

Coronal mass ejections (CMEs)

February 11-13: 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 recurrent coronal hole (CH145) in the northern hemisphere will likely rotate to a geoeffective position on February 13-15. A small coronal hole (CH146) in the southern hemisphere was in a potentially geoeffective position on February 11.

Processed SOHO/EIT 284 image at 01:06 UTC on February 14. The darkest areas on the solar disk are likely coronal holes.

Forecast

The geomagnetic field is expected to be quiet to unsettled on February 14-15 with a chance of a few active intervals on February 14 due to a low speed stream from CH146. A high speed stream from CH145 could arrive on February 16 and cause unsettled to minor storm conditions until February 18.

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 fair. Propagation along long distance north-south paths is poor. Trans Atlantic propagation conditions are normally monitored every night on 1470 kHz. Dominant stations tonight: WLAM Lewiston ME and Radio Vibración (Venezuela). On other frequencies fewer stations from North America were heard compared to the previous night. Near local sunrise on February 13 XERF on 1570 kHz was heard above CFAV.

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 3 2 S19W44 0010 AXX classification was HRX at midnight
10731 2005.02.06     S02W64     plage
10732 2005.02.06 9 5 N12W30 0030 DSO classification was
CRO at midnight, area 0020
10733 2005.02.07 2 6 S09E01 0230 HAX classification was
CAO at midnight
10734 2005.02.09 1 2 S04E17 0080 HSX classification was
DSO at midnight
10735 2005.02.10 8 7 S09E34 0370 DHO  
S509 emerged on
2005.02.09
    S07W44     plage
S511 emerged on
2005.02.11
    S06E07     plage
Total spot count: 23 22  
SSN: 73 72  

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)
2005.02 100.2 (1) 24.1 (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.


[DX-Listeners' Club]