Solar Terrestrial Activity Report

Last major update issued on February 28, 2004 at 04:30 UTC.

[Solar and geomagnetic data - last month (updated daily)]
[Solar wind and electron fluence charts (updated daily)]
[Solar cycles 21-23 (last update February 2, 2004)]
[Solar cycles 1-20]
[Graphical comparison of cycles 21, 22 and 23 (last update February 2, 2004)]
[Graphical comparison of cycles 2, 10, 13, 17, 20 and 23 (last update February 2, 2004)]
[Historical solar and geomagnetic data charts 1954-2003 (last update January 16, 2004)]
[Archived reports (last update February 26, 2004)]

Recent activity

The geomagnetic field was quiet to active on February 27. Solar wind speed ranged between 308 and 464 km/sec. The disturbance which began early in the day, caused unsettled to active conditions most of the day. The source of the disturbance may be the southeasternmost parts of coronal hole CH82, which was in a geoeffective position on February 23.

Solar flux measured at 20h UTC on 2.8 GHz was 122.2. The planetary A index was 11 (STAR Ap - based on the mean of three hour interval ap indices: 12.3).
Three hour interval K indices: 23132343 (planetary), 24322244 (Boulder).

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

At midnight there were 6 spotted regions on the visible disk. Solar flare activity was low. A total of 1 C class event was recorded during the day. 

Region 10563 decayed slowly and could become spotless today or tomorrow.
Region 10564 decayed with spots and penumbral area in the negative polarity area disappearing. The magnetic delta observed one day ago has become much weaker and the flare potential has decreased significantly. M class flares are still possible. Flare: C2.5 at 08:51 UTC.
Region 10565 decayed slowly and quietly.
New region 10567 emerged on February 26 in the southeast quadrant and was numbered the next day by SEC. The region developed quickly late on February 27.

Spotted regions not numbered by NOAA/SEC:
[S365] A new region emerged in the southwest quadrant on February 27. Location at midnight: S17W07.
[S366] This region emerged on February 27 just north of where spotless region 10562 is located. Location at midnight: S09W32.

Coronal mass ejections (CMEs)

February 25-27: No partly or fully earth directed CMEs 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 well defined  recurrent trans equatorial coronal hole (CH83) will rotate into a geoeffective position on February 26-28.

Processed SOHO/EIT 284 image at 01:06 UTC on February 28. The darkest areas on the solar disk are likely coronal holes.


The geomagnetic field is expected to be quiet to active on February 28. On February 29 - March 2 a high speed stream from coronal hole CH83 will likely cause unsettled to minor storm conditions.

Long distance low and medium frequency (below 2 MHz) propagation along east-west paths over high and upper middle latitudes is fair. Propagation along long distance north-south paths is poor. [Trans Atlantic propagation conditions are currently monitored every night on 1470 kHz. Dominant stations tonight: Radio Vibración (Venezuela) and WLAM Lewiston ME on WSW antenna while Radio Cristal del Uruguay was heard well on the southwesterly antenna. The Newfoundland stations were stronger than usual with signals in the range S9 to S9+20dB noted on 590, 620 and 800 kHz. Several other US and Canadian east coast stations had good signals too, particularly WBBR 1130 and WWZN 1510].

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.

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
Location at midnight Area Classification Comment
10562 2004.02.19     S12W35     plage
10563 2004.02.20 1 1 S23W27 0010 AXX  
10564 2004.02.21 29 37 N14W42 0870 EKC beta-gamma-delta
area was 1100
at midnight
10565 2004.02.23 15 15 S04W21 0190 DKO classification was DAO
at midnight
10566 2004.02.24   N05W21     plage
10567 2004.02.27 5 16 S13E50 0040 CSO formerly region S364
classification was DAI
at midnight
S358 emerged on
    S06W79     plage
S359 emerged on
    S14W77     plage
S365 emerged on
  7 S17W07 0050 DAO  
S366 emerged on
  1 S09W32 0000 AXX  
Total spot count: 50 77
SSN: 90 137

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)
2003.01 144.0 79.7 80.8 (-1.2)
2003.02 124.5 46.0 78.3 (-2.5)
2003.03 131.4 61.1 74.0 (-4.3)
2003.04 126.4 60.0 70.1 (-3.9)
2003.05 115.7 55.2 67.6 (-2.5)
2003.06 129.3 77.4 65.0 (-2.6)
2003.07 127.7 83.3 61.8 (-3.2)
2003.08 122.1 72.7 (59.4 predicted, -2.4)
2003.09 112.2 48.7 (57.6 predicted, -1.8)
2003.10 151.7 65.5 (54.9 predicted, -2.7)
2003.11 140.8 67.3 (52.2 predicted, -2.7)
2003.12 114.9 46.5 (49.6 predicted, -2.6)
2004.01 114.1 37.2 (45.4 predicted, -4.2)
2004.02 106.6 (1) 69.1 (2) (40.8 predicted, -4.6)

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 sources noted in solar links. All time references are to the UTC day. Comments and suggestions are always welcome.

[DX-Listeners' Club]