Last update issued on March 30, 2003 at 04:20 UTC.
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The geomagnetic field was unsettled to minor storm on March 29. Solar wind speed ranged between 366 and 478 km/sec. A disturbance which began during the latter half of March 28 continued until about 16h UTC when a high speed stream from coronal hole CH27 began to dominate the solar wind. Solar wind speed has been increasing slowly since the onset of the stream.
Solar flux measured at 20h UTC on 2.8 GHz was 155.1. The planetary A
index was 27 (STAR Ap - based on the mean of three hour interval ap indices: 28.0).
Three hour interval K indices: 55434434 (planetary), 45422334 (Boulder).
The background x-ray flux is at the class B4 level.
At midnight there were 8 spotted regions on the visible disk. Solar flare activity was low. A total of 8 C class events was recorded during the day.
Region 10318 developed quickly early in the day, produced several flares, then began to decay slowly as the magnetic
delta structure disintegrated. There is still some polarity intermixing and further C class flares are possible. Flares:
C7.2 at 10:15, C1.2 at 13:08 , C4.2 at 15:14, C8.2/1F at 18:39 and C1.3 at 20:51 UTC.
Region 10319 decayed slowly and quietly.
Region 10320 developed slowly and could produce occasional C flares.
Region 10321 decayed slowly and quietly.
Region 10323 developed quickly and has become the largest region on the visible disk. Polarities became mixed in the central part of the region and a negative polarity area emerged in the middle of the trailing positive polarity spots. A minor M class flare is possible. Flares: C1.1 at 04:07, C5.7 at 12:30 and C4.7 at 16:58 UTC.
Region 10324 was quiet and stable.
Region 10325 was quiet and stable.
Region 10326 was unchanged and quiet.
March 27-29: 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, this coronal hole is best defined in the section due west of region 10318. A small coronal hole (CH28) in the northern hemisphere was in a geoeffective position on March 28. A coronal hole (CH29) in the southern hemisphere will be in a possibly geoeffective position on March 29-30.
Processed SOHO EIT 284 image at 01:06 UTC on March 30. Any black areas on the solar disk are likely coronal holes.
The geomagnetic field is expected to be quiet to minor storm until April 2 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 poor. [Trans Atlantic propagation conditions are currently monitored every night on 1470 kHz. Dominant station tonight: none identified, only weak Latin American signals noted.]
|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 DAO
at midnight, area 0200
classification was DAO
at midnight, area 0060
classification was DAC
at midnight, area 0250
classification was HSX
at midnight, area 0040
only negative polarity
classification was HSX
at midnight, area 0220
|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||129.7 (1)||108.3 (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.