Last major update issued on April 5, 2004 at 03:35 UTC.
[Solar and geomagnetic data - last month (updated daily)]
[Solar wind and electron fluence charts (updated daily)]
[Solar cycles 21-23 (last update April 2, 2004)]
[Solar cycles 1-20]
[Graphical comparison of cycles 21, 22 and 23 (last update April 2, 2004)]
[Graphical comparison of cycles 2, 10, 13, 17, 20 and 23 (last update April 2, 2004)]
[Historical solar and geomagnetic data charts 1954-2003 (last update January 16, 2004)]
[Archived reports (last update March 28, 2004)]
The geomagnetic field was quiet to minor storm on April 4. Solar wind speed ranged between 382 and 525 km/sec. After 03h UTC the interplanetary magnetic field was northwards and from 16h UTC strongly northwards and this caused a considerable decrease in geomagnetic activity.
Solar flux measured at 20h UTC on 2.8 GHz was 108.9. The planetary A
index was 12 (STAR Ap - based on the mean of three hour interval ap indices: 13.0).
Three hour interval K indices: 53212213 (planetary), 63312323 (Boulder).
The background x-ray flux is at the class B2 level.
At midnight there were 7 spotted regions on the visible disk. The solar flare activity level was low. A single C class event was recorded during the day.
Region 10581 was quiet and stable.
Region 10582 was quiet and stable.
Region 10587 decayed slowly and quietly.
Region 10588 was quiet and stable.
Spotted regions not numbered by NOAA/SEC:
[S380] This region emerged on April 3 as a reversed polarity group just south of region 10588. The region developed moderately quickly on April 4 and is becoming increasingly complex. A magnetic delta structure has formed in the largest penumbra. A minor M class flare is possible. Location at midnight: S16E38. Flare: C3.0 at 16:26 UTC.
[S381] This region rotated into view at the northeast limb on April 4. Location at midnight: N11E70.
[S382] A new bipolar region emerged to the east of region 10582 late on April 4. Location at midnight: N15W54.
April 2-4: 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
An elongated, recurrent trans equatorial coronal hole (CH88) will be in a geoeffective position on April 1-7.
Processed SOHO/EIT 284 image at 00:12 UTC on March 18. The darkest areas on the solar disk are likely coronal holes.
The geomagnetic field is expected to be quiet to minor storm on April 5-6 due to a high speed stream from coronal hole CH88 becoming quiet to active on April 7-10.
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 poor. [Trans Atlantic propagation conditions are currently monitored every night on 1470 kHz. Dominant stations tonight: Radio Cristal del Uruguay before 02:30 UTC, then Radio Vibración (Venezuela) became increasingly more dominant. A weak signal from WWZN on 1510 was the only noted station from North America].
|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.
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|
area was 0070
SEC spot count,
area and classification
include region S380
split off from region
|Total spot count:||29||31|
flux at Earth
|International sunspot number||Smoothed sunspot number|
cycle 23 sunspot max.
|2003.10||151.7||65.5||(58.0 predicted, -1.5)|
|2003.11||140.8||67.3||(55.9 predicted, -2.1)|
|2003.12||114.9||46.5||(53.3 predicted, -2.6)|
|2004.01||114.1||37.2||(49.1 predicted, -4.2)|
|2004.02||107.0||46.0||(44.5 predicted, -4.6)|
|2004.03||112.0||48.9||(41.7 predicted, -2.8)|
|2004.04||109.3 (1)||11.2 (2)||(39.6 predicted, -2.1)|
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.