Last update issued on August 26, 2003 at 04:15 UTC.
[Solar and geomagnetic data - last month (updated daily)]
[Solar wind and electron fluence charts (updated daily)]
[Solar cycles 21-23 (last update August 18, 2003)]
[Solar cycles 1-20]
[Graphical comparison of cycles 21, 22 and 23 (last update August 18, 2003)]
[Graphical comparison of cycles 2, 10, 13, 17, 20 and 23 (last update August 18, 2003)]
[Historical solar and geomagnetic data charts 1954-2003 (last update July 23, 2003)]
[Archived reports (last update August 1, 2003)]
The geomagnetic field was unsettled to minor storm on August 25. Solar wind speed ranged between 552 and 749 km/sec under the influence of a high speed stream from coronal hole CH52.
Solar flux measured at 20h UTC on 2.8 GHz was 116.5. The planetary A
index was 21 (STAR Ap - based on the mean of three hour interval ap indices: 22.3).
Three hour interval K indices: 44533333 (planetary), 44533333 (Boulder).
The background x-ray flux is at the class B2 level.
At midnight there were 6 spotted regions on the visible disk. Solar flare activity was low with only 1 C class event recorded during the day.
Region 10436 decayed quickly and lost most of the leading spot section.
Region 10440 decayed further and was quiet.
Region 10441 decayed slowly and lost some of its penumbral area.
Region 10442 was unchanged and quiet. Flare: A long duration C3.6/1F event peaking at 02:59 and associated with an erupting filament.
New region 10444 emerged in the northeast quadrant.
New region 10445 emerged in the northeast quadrant south of region 10444.
August 23-25: No potentially 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 coronal hole (CH53) in the southern hemisphere may rotate into a geoeffective position on August 25. A coronal hole (CH54) in the northern hemisphere is rotating into view at the east limb.
Processed GOES SXI coronal structure image at 21:12 UTC on August 25. Base SXI image courtesy of NOAA/SEC. The darkest areas on the solar disk are likely coronal holes.
The geomagnetic field is expected to be quiet to unsettled on August 26-27. There is a chance of some geomagnetic effects from the northernmost extension of coronal hole CH53 on August 28-29.
Long distance low frequency (below 2 MHz) propagation along east-west paths over high and upper middle latitudes is poor. Propagation along north-south paths is fair to poor. [Trans Atlantic propagation conditions are currently monitored every night on 1470 kHz. Dominant stations tonight: Radio Vibración (Venezuela) and Radio Cristal del Uruguay. The Boston station on 1510 kHz was noted as well.]
|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 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.
|Solar region||Date numbered||SEC
|Location at midnight||Area||Classification||Comment|
classification was EAO
at midnight, area 0100
SEC used the same
region number for a
different, nearby region
on August 24
|Total spot count:||66||60|
flux at Earth
|International sunspot number||Smoothed sunspot number|
cycle 23 sunspot max.
|2003.02||124.5||46.0||(77.2 predicted, -3.8)|
|2003.03||131.4||61.1||(71.5 predicted, -5.7)|
|2003.04||126.4||60.0||(66.6 predicted, -4.9)|
|2003.05||115.7||55.2||(61.7 predicted, -4.9)|
|2003.06||129.3||77.4||(57.7 predicted, -4.0)|
|2003.07||127.7||85.0||(54.1 predicted, -3.6)|
|2003.08||123.2 (1)||90.4 (2)||(52.3 predicted, -1.8)|
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.