Solar Terrestrial Activity Report

Last major update issued on February 16, 2005 at 04:10 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 quiet on February 15. Solar wind speed ranged between 336 and 436 km/sec. Early in the day the solar wind was under the influence of a low speed stream from CH146. Late in the day and early on February 16 the stream from CH145 arrived.

Solar flux measured at 20h UTC on 2.8 GHz was 121.7. The planetary A index was 5 (STAR Ap - based on the mean of three hour interval ap indices: 4.6).
Three hour interval K indices: 11201122 (planetary), 11211101 (Boulder).

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

At midnight there were 5 spotted regions on the visible solar disk. The solar flare activity level was low. A total of 1 C class event was recorded during the day.

Region 10733 decayed slowly and quietly.
Region 10734 was mostly unchanged. Flare: C1.1 at 19:48 UTC.
Region 10735 decayed and lost most of the penumbral area outside of the main penumbra.

Spotted regions not numbered by NOAA/SEC:
[S513] This region emerged to the northwest of region 10735 on February 15. This region has penumbra on both polarities. Location at midnight: S04E03.
[S514] A new region emerged in the southeast quadrant on February 15. Location at midnight: S08E56

Coronal mass ejections (CMEs)

February 13: A CME observed after a C2.7 flare in region 10733 at 10:47 UTC could have geoeffective components.
February 14-15:
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 was in a geoeffective position on February 13-15.

Processed SOHO/EIT 284 image at 13:06 UTC on February 15. The darkest areas on the solar disk are likely coronal holes.

Forecast

The geomagnetic field is expected to be quiet to active on February 16 due to effects from CH145. Unsettled to active conditions are likely on February 17-18 with a possibility of minor storm intervals.

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 along long distance north-south paths is poor. Trans Atlantic propagation conditions are normally monitored every night on 1470 kHz. Dominant station tonight: Radio Vibración (Venezuela). Only a few North American stations were noted with weak signals, amongst them WWZN on 1510 kHz.

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     S19W70     plage
10732 2005.02.06 4   N08W60 0020 BXO spotless for the second consecutive day
10733 2005.02.07 6 8 S08W26 0180 DAO  
10734 2005.02.09 4 7 S04W10 0070 CSO classification was
CAO at midnight
10735 2005.02.10 15 18 S08E06 0420 CKO beta-gamma
S509 emerged on
2005.02.09
    S07W70     plage
S511 emerged on
2005.02.11
    S06W19     plage
S512 emerged on
2005.02.14
    S04W57     plage
S513 emerged on
2005.02.15
  4 S04E03 0040 DAO  
S514 emerged on
2005.02.15
  2 S08E56 0010 BXO  
Total spot count: 29 39  
SSN: 69 89  

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)
2005.02 102.8 (1) 30.7 (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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