Last update issued on April 1, 2003 at 03:10 UTC.
[Solar and geomagnetic data - last 4 weeks (updated daily)]
[Solar wind and electron fluence charts (updated daily)]
[Solar cycles 21-23 (last update March 3, 2003)]
[Solar cycles 1-20]
[Graphical comparison of cycles 21, 22 and 23 (last update March 3, 2003)]
[Graphical comparison of cycles 10, 13, 17, 20 and 23 (last update March 3, 2003)]
[Historical solar and geomagnetic data charts 1954-2002 (last update January 27, 2003)]
[Archived reports (last update March 31, 2003)]
The geomagnetic field was unsettled to major storm on March 31. Solar wind speed ranged between 459 and 647 km/sec under the influence of a high speed stream from coronal hole CH27.
Solar flux measured at 20h UTC on 2.8 GHz was 160.1. The planetary A
index was 31 (STAR Ap - based on the mean of three hour interval ap indices: 32.8).
Three hour interval K indices: 33346644 (planetary), 32445534 (Boulder).
The background x-ray flux is at the class B4 level.
At midnight there were 8 spotted regions on the visible disk, 1 of the regions has not yet been numbered by SE/NOAA. Solar flare activity was low. A total of 4 C class events was recorded during the day.
Region 10318 decayed slowly and was mostly quiet. Flares: C1.2 at 04:18 and a
C1.2 event which began at 23:52 UTC and peaked on April 1 at 00:16 UTC.
Region 10319 decayed slowly and was quiet.
Region 10321 decayed slowly and quietly.
Region 10323 decayed slightly in the trailing spot section while some development occurred in the intermediate spots. Flare: C1.6 at 16:22 UTC.
Region 10325 developed slowly and was quiet.
Region 10326 was unchanged and mostly quiet. Flare: C1.8 at 21:29 UTC.
New region 10327 emerged in the southwest quadrant near the central meridian.
Spotted regions not yet numbered by SEC/NOAA:
[S129] A new region emerged northwest of region 10324 in the southeast quadrant on March 30. Location at midnight: S11E06. Please note that SEC/NOAA now has this as region 10324!
March 29-31: 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 coronal hole (CH27) in the southern hemisphere was in a geoeffective position on March 25-27. A small coronal hole (CH28) in the northern hemisphere was in a geoeffective position on March 28 and closed on March 29-30. A coronal hole (CH29) in the southern hemisphere was in a geoeffective position on March 30-31.
Processed SOHO EIT 284 image at 19:06 UTC on March 31. Any black areas on the solar disk are likely coronal holes.
The geomagnetic field is expected to be quiet to minor storm until April 3 due to high speed streams from coronal holes CH27, CH28 and CH29. 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. [Trans Atlantic propagation conditions are currently monitored every night on 1470 kHz. Dominant station tonight: none, 3-4 weak unidentified stations from Brazil observed early on, then Radio Vibración (Venezuela) strongly at 03h UTC before Abril 1470 AM (Uruguay) emerged.]
|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 CAO
SEC has mistakenly
adopted the spots from
location should be
classification was CRO
no spots observed in
any available images,
no trace of region in
see comment for
|Total spot count:||75||88|
flux at Earth
|International sunspot number||Smoothed sunspot number|
cycle 23 sunspot max.
|2002.09||175.8||109.6||(94.7 predicted, -4.0)|
|2002.10||167.0||97.5||(91.2 predicted, -3.5)|
|2002.11||168.7||95.0||(86.0 predicted, -5.2)|
|2002.12||157.2||81.6||(81.6 predicted, -4.4)|
|2003.01||144.0||79.5||(78.6 predicted, -3.0)|
|2003.02||124.5||46.2||(73.6 predicted, -5.0)|
|2003.03||131.4 (1)||119.3 (2)||(67.9 predicted, -5.7)|
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 (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.