Last update issued on February 26, 2003 at 03:00 UTC. Minor update posted at 09:31 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 24, 2003)]
The geomagnetic field was quiet on February 25. Solar wind speed ranged between 362 and 452 km/sec.
Solar flux measured at 20h UTC on 2.8 GHz was 101.6 (adjusted to 1 AU this is the lowest solar flux level since April 23,
1999). The planetary A
index was 5 (STAR Ap - based on the mean of three hour interval ap indices: 6.3).
Three hour interval K indices: 21122221 (planetary), 22122112 (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.
Region 10288 decayed slowly and quietly.
Region 10290 decayed quickly losing nearly all remaining trailing spots.
New region 10292 emerged on February 24 near the center of the visible disk and was numbered the next day. The region decayed slowly on Feb.25.
Comment added at 09:31 UTC on February 26:The expected high speed stream arrived at ACE at approximately 03:15 UTC. The disturbance has caused the geomagnetic field to become unsettled to active. Solar wind speed is currently near 480 km/sec.
February 23-24: No obviously geoeffective CMEs observed. No new LASCO images will become available until Feb.27 or 28 thus preventing CME analysis.
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 (CH21) was in a geoeffective position on February 23-24. The northernmost part of a coronal hole (CH22) in the southern hemisphere could become geoeffective on February 26-27. A coronal hole (CH23) in the northern hemisphere will rotate into a geoeffective position on March 1.
Processed SOHO EIT 284 image at 01:06 UTC on February 26. Any black areas on the solar disk are likely coronal holes.
The geomagnetic field is expected to be initially quiet on February 26. A high speed stream originating in CH21 will likely reach Earth during the day and cause a disturbance lasting until February 27 or 28 with the geomagnetic field becoming unsettled to active. Another high speed stream (from CH22) could arrive on February 28 or March 1 and prolong the unsettled to active conditions. Long distance medium wave (AM) band propagation along east-west paths over high and upper middle latitudes is poor, propagation along north-south paths is good. [Propagation conditions are currently monitored every night. Main monitoring frequency: 1470 kHz. Dominant station tonight: Radio Cristal del Uruguay. After Cristals s/off on February 25 Radio Abril from Melo (Uruguay) was the best station.]
|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|
area was 0030
classification was DAO
at midnight, area 0100
formerly region S107
classification was CSO
at midnight, area 0020
|Total spot count:||18||15|
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||125.4 (1)||80.8 (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.