Last update issued on August 18, 2003 at 08:00 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 very quiet to minor storm on August 17. Solar wind speed ranged between 444 and 558 km/sec. A moderate strong solar wind shock was observed at ACE at 13:40 UTC. The interplanetary magnetic field was mostly northwards for the remainder of the day. The IMF swung strongly southwards early on August 18 causing minor to severe storm conditions. The source of this disturbance is a full halo CME which was observed early on August 15 following a C7.7 long duration event in region 10431 which peaked at 00:18 UTC that day.
Solar flux measured at 20h UTC on 2.8 GHz was 119.3. The planetary A
index was 15 (STAR Ap - based on the mean of three hour interval ap indices: 15.6).
Three hour interval K indices: 21014445 (planetary), 21114434 (Boulder).
The background x-ray flux is at the class B4 level.
At midnight there were 6 spotted regions on the visible disk. Solar flare activity was low. A total of 2 C class events was recorded during the day.
Region 10431 decayed quickly and simplified. Flares: C2.1 at 04:26 and C1.9 at 08:44
Region 10432 developed slowly and quietly.
Region 10433 was quiet and stable.
Region 10435 decayed slowly and could soon become spotless.
Region 10436 rotated fully into view and was mostly quiet.
Spotted regions not numbered by NOAA/SEC:
[S230] A new region emerged on August 17 near the center of the visible disk. Location at midnight: S03E05.
August 16-17: 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 large coronal hole (CH51) in the northern hemisphere will be in a geoeffective position on August 17-21.
Processed GOES SXI coronal structure image at 23:53 UTC on August 17. 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 active to severe storm on August 18 and quiet to active on August 19. A high speed stream from coronal hole CH51 will likely arrive on August 20 and cause mostly unsettled to minor storm conditions until August 24.
Long distance low frequency (below 2 MHz) propagation along east-west paths over high and upper middle latitudes is useless. Propagation along north-south paths is poor. [Trans Atlantic propagation conditions are currently monitored every night on 1470 kHz. Dominant station tonight: Radio Vibración (Venezuela)]
|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. [Not yet available]
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 0130
|Total spot count:||53||66|
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||126.0 (1)||62.7 (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.