Last major update issued on May 27, 2004 at 03:25 UTC.
[Solar and geomagnetic data - last month (updated daily)]
[Solar wind and electron fluence charts (updated daily)]
[Solar cycles 21-23 (last update May 3, 2004)]
[Solar cycles 1-20]
[Graphical comparison of cycles 21, 22 and 23 (last update May 3, 2004)]
[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 May 18, 2004)]
The geomagnetic field was quiet to unsettled on May 26. Solar wind speed ranged between 374 and 428 km/sec.
Solar flux measured at 20h UTC on 2.8 GHz was 103.3. The planetary A
index was 6 (STAR Ap - based on the mean of three hour interval ap indices: 7.0).
Three hour interval K indices: 11213322 (planetary), 11111223 (Boulder).
The background x-ray flux is at the class B2 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 10615 was quiet and stable and will rotate over the northwest limb on May 28.
Region 10618 decayed in the trailing and leading spot sections. New development occurred in a penumbra to the southeast of the main penumbra, here a magnetic delta structure formed. A minor M class flare is possible. This region is increasingly looking like two separate regions.
May 24-26: 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 recurrent elongated coronal hole (CH98) in the northern hemisphere will likely be in a geoeffective position on May 25-29. A recurrent trans equatorial coronal hole (CH99) will probably rotate to a geoeffective position on May 31. Both coronal holes are less well defined compared to one rotation ago.
Processed SOHO/EIT 284 image at 19:05 UTC on May 26. The darkest areas on the solar disk are likely coronal holes.
The geomagnetic field is expected to be quiet to unsettled on May 27 and quiet to active on May 28-June 1 due to effects from coronal hole CH98.
|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 to fair. Propagation along long distance north-south paths is fair. Trans Atlantic propagation conditions are monitored every night on 1470 kHz. Dominant station tonight: none except at and after local sunrise when Radio Vibración (Venezuela) was clearly the best. Before that several weak stations were noted. On other frequencies an interesting unidentified Spanish talking station was observed on 1509.90 kHz. East coast North American stations had improved signals over the last day with, as usual, WWZN Boston on 1510 kHz having the best signal. Fair signals noted from several Newfoundland stations (560, 590, 600, 640, 740 and 930 kHz).
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|
|10613||2004.05.13||2||S09W94||0060||HSX||rotated out of view|
classification was FAI
at midnight, area 0260
|Total spot count:||39||42|
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||99.8 (1)||68.0 (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.