Last update issued on April 2, 2003 at 03:15 UTC.
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[Graphical comparison of cycles 21, 22 and 23 (last update April 2, 2003)]
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[Archived reports (last update April 1, 2003)]
The geomagnetic field was quiet to minor storm on April 1. Solar wind speed ranged between 452 and 561 km/sec under the influence of a high speed stream from coronal hole CH27 early in the day, then from CH28.
Solar flux measured at 20h UTC on 2.8 GHz was 153.1. The planetary A
index was 12 (STAR Ap - based on the mean of three hour interval ap indices: 16.3). The large discrepancy in Ap is because
SEC/NOAA has used only the last 7 intervals as the basis for their calculation. The first 3 hour interval (00-03 UTC) was the one
with minor storm conditions and leaving that one caused their daily Ap value to become much lower than it should have been.
Three hour interval K indices: 54132333 (planetary), 44223333 (Boulder).
The background x-ray flux is at the class B4 level.
At midnight there were 9 spotted regions on the visible disk. Solar flare activity was low. A total of 2 C class events was recorded during the day.
Region 10318 decayed slowly and could become spotless today. Flare: C2.3 at 14:45
Region 10319 decayed slowly and quietly, the region will soon rotate over the northwest limb.
Region 10321 lost most of its leader spots while new spots emerged to the north of the large trailing penumbra.
Region 10323 decayed slowly with some of the penumbrae splitting into smaller penumbrae. Flare: C1.9 at 02:52 UTC.
Region 10324 reemerged with a few small spots. Because SEC/NOAA previously failed to number region S129 and instead reused region number 10324 for that region, they now had to create a new region number for the reemerged region 10324. So, what should have been region 10324 has now become region 10328 ... What a mess SEC/NOAA has created here!
Region 10325 decayed slightly with several of the smaller spots disappearing.
Region 10326 was mostly unchanged and quiet.
Region 10327 developed slowly and quietly.
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: S12W08. Please note that SEC/NOAA has this as region 10324!
March 30-April 1: 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 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 April 1. Any black areas on the solar disk are likely coronal holes.
The geomagnetic field is expected to be quiet to active April 2-4 due to high speed streams from coronal holes 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: 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 BXO
at midnight, area 0010
SECs spots are those
of region S129
classification was BXO
at midnight, area 0000
this is actually region
see comment for
regions 10324, 10328
|Total spot count:||71||80|
flux at Earth
|International sunspot number||Smoothed sunspot number|
cycle 23 sunspot max.
|2002.10||167.0||97.5||(91.0 predicted, -3.6)|
|2002.11||168.7||95.0||(85.7 predicted, -5.3)|
|2002.12||157.2||81.6||(81.3 predicted, -4.4)|
|2003.01||144.0||79.5||(78.3 predicted, -3.0)|
|2003.02||124.5||46.2||(73.3 predicted, -5.0)|
|2003.03||131.4||61.5||(67.6 predicted, -5.7)|
|2003.04||153.0 (1)||5.4 (2)||(62.7 predicted, -4.9)|
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.