Last major update issued on May 31, 2004 at 03:30 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 30, 2004)]
The geomagnetic field was quiet to active on May 30. Solar wind speed ranged between 377 and 505 km/sec under the influence of a low speed stream from coronal hole CH98.
Solar flux measured at 20h UTC on 2.8 GHz was 99.6. The planetary A
index was 13 (STAR Ap - based on the mean of three hour interval ap indices: 13.3).
Three hour interval K indices: 32143334 (planetary), 32233334 (Boulder).
The background x-ray flux is at the class B2 level.
At midnight there were 3 spotted regions on the visible disk. The solar flare activity level was low. A single C class event was recorded during the day.
Region 10618 decayed slowly and is rotating over the southwest limb. Flare:
C1.2 at 19:34 UTC.
Region 10621 developed slowly and quietly.
New region 10622 rotated into view at the southeast limb.
May 28-30: 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 was in a geoeffective position on May 25-29. A recurrent trans equatorial coronal hole (CH99) will rotate to a geoeffective position on May 30.
Processed SOHO/EIT 284 image at 19:05 UTC on May 30. The darkest areas on the solar disk are likely coronal holes.
The geomagnetic field is expected to be quiet to active on May 31-June 3 due to effects from coronal holes CH98 and CH99.
|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 very poor. Propagation along long distance north-south paths is fair. Trans Atlantic propagation conditions are monitored every night on 1470 kHz. Dominant station tonight: Radio Cristal del Uruguay and Radio Vibración (Venezuela). One station of particular interest was an unidentified station from Brazil on 1590.05 kHz. The only stations from North America WWZN Boston on 1510 kHz and CJYQ on 930 kHz, both with fairly weak signals.
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|
classification was FAO
at midnight, area 0200
|Total spot count:||34||25|
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||100.0 (1)||75.6 (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.