Last major update issued on April 16, 2006 at 05:15 UTC.
geomagnetic data - last month (updated daily)]
[Solar wind and electron fluence charts (updated daily)]
[Solar cycles 21-23 (last update April 1, 2006)]
[Solar cycles 1-20]
[Graphical comparison of cycles 21, 22 and 23 (last update April 1, 2006)]
[Graphical comparison of cycles 2, 10, 13, 17, 20 and 23 (last update April 1, 2006)]
[Historical solar and geomagnetic data charts 1954-2005 (last update March 3, 2006)]
[Archived reports (last update April 3, 2006)]
The geomagnetic field was unsettled to minor storm on April 15. Solar wind speed ranged between 524 and 704 (all day average 595) km/sec under the influence of a strong high speed stream from CH220.
Solar flux measured at 20h UTC on 2.8 GHz was 78.4. The planetary A index
was 29 (STAR Ap - based on the mean of three hour interval ap
Three hour interval K indices: 35443543 (planetary), 34543433 (Boulder).
The background x-ray flux is at the class A4 level.
At midnight there were 3 spotted regions on the visible solar disk. The solar flare activity level was very low. No C class events were recorded during the day.
Region 10871 was quiet and stable.
Region 10872 decayed and could become spotless today.
Region 10873 decayed slowly and could become spotless today.
April 13-15: No partly or fully Earth directed CMEs were observed in LASCO imagery.
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 (CH220) was in an Earth facing position on April 11-14.
Processed SOHO/EIT 284 image at 13:06 UTC on April 15. The darkest areas on the solar disk are likely coronal holes.
The geomagnetic field is expected to be quiet to active on April 16 under the influence of a high speed stream from CH220 becoming quiet to unsettled on April 17-18.
|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) Effects from a CME are likely to be observed at 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 useless. Propagation on long distance northeast-southwest paths is poor to very poor. Trans Atlantic propagation conditions are normally monitored every night on 1470 kHz. Dominant station tonight: Radio Cristal del Uruguay with a weak signal, Radio Vibración (Venezuela) was noted after LSR. During the night only a few very weak signals were detected. Near LSR a few stations from Argentina, Colombia and Venezuela were audible.
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|
|10871||2006.04.10||6||2||S06W18||0060||CAO||classification was HSX at midnight, area 0040|
|10872||2006.04.11||8||1||S08E21||0060||BXO||classification was AXX at midnight, area 0010|
|10873||2006.04.11||1||2||S03W05||0020||HSX||classification was BXO at midnight, area 0000|
|Total spot count:||15||5|
flux at Earth
|International sunspot number||Smoothed sunspot number|
cycle 23 sunspot max.
|2005.10||77.0||8.5||(24.8 predicted, -1.0)|
|2005.11||86.3||18.0||(22.7 predicted, -2.1)|
|2005.12||90.7||41.2||(19.8 predicted, -2.9)|
|2006.01||83.4||15.4||(16.7 predicted, -3.1)|
|2006.02||76.5||4.7||(13.6 predicted, -3.1)|
|2006.03||75.4||10.8||(11.4 predicted, -2.2)|
|2006.04||89.9 (1)||33.6 (2)||(10.7 predicted, -0.7)|
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% lower.
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.