Last update issued on February 23, 2003 at 03:45 UTC.
[Solar and geomagnetic data
- last 4 weeks (updated daily)]
[Solar wind and electron fluence charts (updated daily)]
[Solar cycles 21-23 (last update February 2, 2003)]
[Solar cycles 1-20]
[Graphical comparison of cycles 21, 22 and 23 (last update February 2, 2003)]
[Graphical comparison of cycles 10, 13, 17, 20 and 23 (last update February 2, 2003)]
[Historical solar and geomagnetic data charts 1954-2002 (last update January 27, 2003)]
[Archived reports (last update February 17, 2003)]
The geomagnetic field was quiet to active on February 21. Solar wind speed ranged between 507 and 631 km/sec under the influence of a high speed stream.
Solar flux measured at 20h UTC on 2.8 GHz was 106.6 (adjusted to 1 AU this is the lowest solar flux level since April 25,
1999). 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: 23233421 (planetary), 23233412 (Boulder).
The background x-ray flux is at the class B1 level.
At midnight there were 2 spotted regions on the visible disk. Solar flare activity was low. A total of 6 C class events was recorded during the day. A C1.5 flare at 10:52 UTC had an origin behind the northwest limb.
Region 10288 decayed slowly and quietly.
Region 10290 lost most of its remaining small spots and simplified. The leading penumbra increased its area. A minor M class flare is possible. Flares: C4.3 at 02:03, C4.7 at 05:10, C5.8 at 09:29, C2.1 at 10:44 and C1.7 at 12:20 UTC.
February 20-22: No obviously geoeffective 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 will rotate into a geoeffective position on February 23-24.
Processed SOHO EIT 284 image at 01:06 UTC on February 23. Any black areas on the solar disk are likely coronal holes.
The geomagnetic field is expected to be quiet to unsettled on February 23-25. A high speed stream originating in CH21 will likely reach Earth either late on February 25 or early on February 26 and cause a disturbance lasting until February 27 with the geomagnetic field becoming unsettled to active. Long distance medium wave (AM) band propagation along east-west paths over high and upper middle latitudes is very poor, propagation along north-south paths is fair to good. [Propagation conditions are currently monitored every night. Main monitoring frequency: 1470 kHz. Dominant station tonight: Radio Cristal del Uruguay, after c/d at 02:03 UTC a few unidentified stations from Brazil]
|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.
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 SEC/NOAA. 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.
|Solar region||Date numbered||SEC
|Location at midnight||Area||Classification||Comment|
classification was DKI
|Total spot count:||23||17|
flux at Earth
|International sunspot number||Smoothed sunspot number|
cycle 23 sunspot max.
|2002.08||183.6||116.4||(99.7 predicted, -3.0)|
|2002.09||175.8||109.6||(96.7 predicted, -3.0)|
|2002.10||167.0||97.5||(93.2 predicted, -3.5)|
|2002.11||168.7||95.0||(88.0 predicted, -5.2)|
|2002.12||157.2||81.6||(83.6 predicted, -4.4)|
|2003.01||144.0||79.5||(80.6 predicted, -3.0)|
|2003.02||128.5 (1)||76.0 (2)||(75.5 predicted, -5.1)|
1) Running average based on the daily 20:00 UT observed solar flux value at 2800
2) Unofficial, accumulated value based on the Boulder (SEC/NOAA) sunspot number. The official international sunspot number is typically 25-45% less.
This report has been prepared by Jan Alvestad. It is based partly on my own observations and interpretations, and partly on data from sources noted in solar links. All time references are to the UTC day. Comments and suggestions are always welcome.