Last update issued on February 25, 2003 at 01:50 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 to unsettled on February 24. Solar wind speed ranged between 439 and 553 km/sec, gradually decreasing all day.
Solar flux measured at 20h UTC on 2.8 GHz was 102.0 (adjusted to 1 AU this is the lowest solar flux level since April 23,
1999). The planetary A
index was 6 (STAR Ap - based on the mean of three hour interval ap indices: 7.1).
Three hour interval K indices: 21032222 (planetary), 21122321 (Boulder).
The background x-ray flux is at the class A8 level.
At midnight there were 3 spotted regions on the visible disk, 1 of which has not yet been numbered by SEC/NOAA. Solar flare activity was low. Only 1 C class flare was recorded during the day.
Region 10288 was mostly quiet and stable.
Region 10290 decayed further and lost a significant amount of penumbral area in both the leading and trailing spot sections. Flare: C1.1 at 11:36 UTC.
Spotted regions not yet numbered by SEC/NOAA:
[S107] A new region emerged near the center of the visible disk on February 24. The region has developed quickly initially. Location at midnight: S07E00.
February 22-24: 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 (CH21) will rotate into 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.
Processed SOHO EIT 284 image at 19:06 UTC on February 24. Any black areas on the solar disk are likely coronal holes.
The geomagnetic field is expected to be quiet to unsettled on February 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. Another high speed stream 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 to 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.]
|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 CSO
classification was EAO
at midnight, area 0160
|Total spot count:||24||23|
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||126.4 (1)||79.1 (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.