Last major update issued on May 6, 2004 at 02:50 UTC.
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[Solar cycles 21-23 (last update May 3, 2004)]
[Solar cycles 1-20]
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[Graphical comparison of cycles 2, 10, 13, 17, 20 and 23 (last update May 3, 2004)]
[Historical solar and geomagnetic data charts 1954-2004 (last update April 28, 2004)]
[Archived reports (last update April 30, 2004)]
The geomagnetic field was quiet to unsettled on May 5. Solar wind speed ranged between 376 and 670 km/sec under the influence of a high speed stream from coronal hole CH94. The interplanetary magnetic field was mostly northwards and caused only a weak geomagnetic disturbance.
Solar flux measured at 20h UTC on 2.8 GHz was 88.5. The planetary A
index was 13 (STAR Ap - based on the mean of three hour interval ap indices: 13.8).
Three hour interval K indices: 23333333 (planetary), 23343443 (Boulder).
The background x-ray flux is at the class A8 level.
At midnight there were 2 spotted regions on the visible disk. The solar flare activity level was very low. No C class events were recorded during the day.
Region 10604 was quiet and the only observation of interest was that the single penumbra split into two smaller
Region 10605 developed early in the day, then began to decay in the trailing and intermediate spot sections.
May 3-5: No fully or partly Earth directed CME 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 trans equatorial coronal hole (CH94) was in a geoeffective position on May 1 - May 4. The development of region 10605 caused a significant decrease in the southeasternmost part of the coronal hole on May 3-5.
Processed SOHO/EIT 284 image at 19:05 UTC on May 5. The darkest areas on the solar disk are likely coronal holes.
The geomagnetic field is expected to be quiet to active on May 6-7 due to a high speed stream from coronal hole CH94. Quiet to unsettled is likely on May 8-10.
|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. When the high speed stream has arrived
the color changes to green.
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.
Long distance low and medium frequency (below 2 MHz) propagation along east-west paths over high and upper middle latitudes is poor. Propagation along long distance north-south paths is poor to fair. Trans Atlantic propagation conditions are monitored every night on 1470 kHz. Dominant stations tonight: Radio Vibración (Venezuela) and Radio Cristal del Uruguay. A few stations from the easternmost parts of the USA (as usual with 1510 WWZN having the best signal) and Canada (590 VOCM and 930 CJYQ) were noted on other frequencies].
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. SEC active region numbers in the table below and in the active region map above are the historic SEC/USAF numbers.
|Active region||Date numbered||SEC
|Location at midnight||Area||Classification||Comment|
|10601||2004.04.30||2||S09W89||0150||CSO||rotated out of view|
|Total spot count:||17||16|
flux at Earth
|International sunspot number||Smoothed sunspot number|
cycle 23 sunspot max.
|2003.11||140.8||67.3||(56.5 predicted, -1.6)|
|2003.12||114.9||46.5||(53.5 predicted, -3.0)|
|2004.01||114.1||37.2||(49.1 predicted, -4.4)|
|2004.02||107.0||46.0||(44.8 predicted, -4.3)|
|2004.03||112.0||48.9||(42.1 predicted, -2.7)|
|2004.04||101.2||39.3||(40.0 predicted, -2.1)|
|2004.05||91.8 (1)||8.6 (2)||(36.8 predicted, -3.2)|
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 some of these solar data sources. All time references are to the UTC day. Comments and suggestions are always welcome.