Last major update issued on June 19, 2004 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 June 2, 2004)]
[Solar cycles 1-20]
[Graphical comparison of cycles 21, 22 and 23 (last update June 2, 2004)]
[Graphical comparison of cycles 2, 10, 13, 17, 20 and 23 (last update June 2, 2004)]
[Historical solar and geomagnetic data charts 1954-2004 (last update April 28, 2004)]
[Archived reports (last update June 14, 2004)]
The geomagnetic field was quiet to unsettled on June 18. Solar wind speed ranged between 449 and 521 km/sec under the influence of a weak high speed stream from coronal hole CH102.
Solar flux measured at 20h UTC on 2.8 GHz was 107.8. The planetary A
index was 8 (STAR Ap - based on the mean of three hour interval ap indices: 9.4).
Three hour interval K indices: 12232322 (planetary), 22233333 (Boulder).
The background x-ray flux is at the class B2 level.
At midnight there were 3 spotted regions on the visible disk. The solar flare activity level was low. A total of 2 C class events was recorded during the day.
Region 10632 decayed slowly and quietly.
Region 10634 decayed with all intermediate and several trailing spots disappearing. The leading penumbra expanded slightly and a magnetic delta structure could form at the eastern edge of the large penumbra. Flare: C1.3 at 23:56 UTC.
Region 10635 developed further in the trailing spot section where a magnetic delta structure formed. The probability of a minor M class flare is increasing. The southeasternmost spots may be a separate region. Flare: C1.8 at 16:26 UTC.
June 16-18: No fully or partly Earth directed CMEs observed.
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 trans equatorial coronal hole (CH102) was in a geoeffective position on June 14-15.
Processed SOHO/EIT 284 image at 13:05 UTC on June 15. The darkest areas on the solar disk are likely coronal holes.
The geomagnetic field is expected to be quiet to unsettled on June 19-21.
|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) 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.
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 to fair. Trans Atlantic propagation conditions are monitored every night on 1470 kHz. Dominant stations tonight: Radio Cristal del Uruguay and Radio Vibración (Venezuela), both with weaker than usual signals. The only North American station noted was WWZN on 1510 kHz with a weak signal.
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|
became spotless early
in the day
area was 0050
|Total spot count:||78||56|
flux at Earth
|International sunspot number||Smoothed sunspot number|
cycle 23 sunspot max.
|2003.12||114.9||46.5||(54.4 predicted, -2.3)|
|2004.01||114.1||37.2||(50.5 predicted, -3.9)|
|2004.02||107.0||46.0||(46.2 predicted, -4.3)|
|2004.03||112.0||48.9||(43.5 predicted, -2.7)|
|2004.04||101.2||39.3||(41.4 predicted, -2.1)|
|2004.05||99.8||41.5||(38.2 predicted, -3.2)|
|2004.06||93.4 (1)||43.2 (2)||(35.3 predicted, -2.9)|
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.