Last major update issued on December 28, 2003 at 03:55 UTC.
[Solar and geomagnetic data - last month (updated daily)]
[Solar wind and electron fluence charts (updated daily)]
[Solar cycles 21-23 (last update December 2, 2003)]
[Solar cycles 1-20]
[Graphical comparison of cycles 21, 22 and 23 (last update December 2, 2003)]
[Graphical comparison of cycles 2, 10, 13, 17, 20 and 23 (last update December 2, 2003)]
[Historical solar and geomagnetic data charts 1954-2003 (last update October 15, 2003)]
[Archived reports (last update December 17, 2003)]
The geomagnetic field was quiet to active on December 27. Solar wind speed ranged between 354 and 501 km/sec. A weak and unexpected solar wind shock was observed at SOHO (and ACE) at 09:18 UTC with a sudden increase in solar wind speed from 354 to 410 km/sec. The interplanetary magnetic field was moderately southwards between 19h and 2230 UTC, this caused the geomagnetic field to become active.
Solar flux measured at18h UTC on 2.8 GHz was 126.6 (the 20h UTC measurement was faulty). The planetary A
index was 12 (STAR Ap - based on the mean of three hour interval ap indices: 12.9).
Three hour interval K indices: 33233334 (planetary), 23232333 (Boulder).
The background x-ray flux is at the class B2-3 level.
At midnight there were 2 spotted regions on the visible disk. Solar flare activity was very low.
Region 10528 was mostly unchanged and quiet. A minor M class flare is
Region 10532 decayed slowly and was quiet.
December 25-27: No partly or fully 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 (CH73) will rotate into a geoeffective position on December 28-29.
Processed SOHO/EIT 284 image at 19:06 UTC on December 26. The darkest areas on the solar disk are likely coronal holes.
The geomagnetic field is expected to be quiet to unsettled until December 31. That day and on January 1 a high speed stream from coronal hole CH73 is likely to cause unsettled to minor storm conditions.
Long distance low frequency (below 2 MHz) propagation along east-west paths over high and upper middle latitudes was poor. Propagation along long distance north-south paths is fair. [Trans Atlantic propagation conditions are currently monitored every night on 1470 kHz. Dominant station tonight: Radio Vibración (Venezuela). WWZN Boston on 1510 and CJYQ St.John's on 930 both had good signals, otherwise reception of North American stations was considerably poorer compared to the previous nights].
|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.
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|
classification was FKI
|Total spot count:||27||26|
flux at Earth
|International sunspot number||Smoothed sunspot number|
cycle 23 sunspot max.
|2003.06||129.3||77.4||(65.1 predicted, -2.5)|
|2003.07||127.7||83.3||(61.8 predicted, -3.3)|
|2003.08||122.1||72.7||(58.8 predicted, -3.0)|
|2003.09||112.2||48.7||(56.9 predicted, -1.9)|
|2003.10||151.7||65.6||(54.1 predicted, -2.8)|
|2003.11||140.8||67.2||(51.4 predicted, -2.7)|
|2003.12||115.4 (1)||71.5 (2)||(48.9 predicted, -2.5)|
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.