Solar Terrestrial Activity Report

Last major update issued on February 22, 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 18, 2004)]

Recent activity

The geomagnetic field was quiet to unsettled on February 21. Solar wind speed ranged between 309 and 424 km/sec.

Solar flux measured at 20h UTC on 2.8 GHz was 98.2. The planetary A index was 7 (STAR Ap - based on the mean of three hour interval ap indices: 8.9).
Three hour interval K indices: 21123322 (planetary), 21013222 (Boulder).

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

At midnight there were 3 spotted regions on the visible disk. Solar flare activity was very low. No C class events was recorded during the day. 

Region 10562 decayed slowly and quietly.
Region 10563 was quiet and stable.
New region 10564 emerged in the northeast quadrant on February 20 and was numbered by SEC the following day. The region developed quickly on February 21 and has two magnetic delta structures, one each in the leading and central penumbrae. Further development in this region will increase the likelihood of minor M class flares.

Coronal mass ejections (CMEs)

February 19-21: 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

The southernmost parts of a coronal hole (CH82) in the northern hemisphere will rotate into geoeffective positions on February 22-23. A coronal hole (CH83) is currently rotating into view at the east limb.

Processed SOHO/EIT 284 image at 19:06 UTC on February 21. The darkest areas on the solar disk are likely coronal holes.

Forecast

The geomagnetic field is expected to be quiet to unsettled until February 24. On February 25-26 a high speed from coronal hole CH82 could arrive and may cause unsettled to active conditions.

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 currently monitored every night on 1470 kHz. Dominant stations tonight: Radio Vibración (Venezuela) on the inverted L pointing WSW with a good to excellent signal. Occasionally WLAM Lewiston ME was heard and there were a couple of weak unidentified Spanish speaking stations as well. On other frequencies most of the usual stations from Newfoundland and Nova Scotia had fair to good signals].

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
spot
count
STAR
spot
count
Location at midnight Area Classification Comment
10555 2004.02.09     S16W87     plage
10558 2004.02.13     S16W71     plage
10560 2004.02.15     S17W48     plage
10561 2004.02.15 2   N02W15 0020 AXX spotless
10562 2004.02.19 2 1 S13E45 0020 BXO classification was HSX
at midnight
10563 2004.02.20 1 2 S24E51 0020 AXX classification was HAX
at midnight, area 0040
10564 2004.02.21 7 24 N14E42 0020 BXO beta-gamma-delta
formerly region S361
classification was DAI
at midnight, area 0150
S357 emerged on
2004.02.17
    N10W77     plage
S358 emerged on
2004.02.18
    S06W14     plage
S359 emerged on
2004.02.18
    S14W12     plage
Total spot count: 12 27
SSN: 52 57

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)
2004.02 104.8 (1) 51.4 (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.


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