Last major update issued on May 14, 2004 at 03:50 UTC. (While the reports have been ready at the usual time, problems at my Internet provider has prevented uploading of the reports until about 06h UTC the last two days.)
[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 8, 2004)]
The geomagnetic field was quiet to active on May 13. Solar wind speed ranged between 370 and 428 km/sec. A sustained moderately southward swing of the interplanetary magnetic field caused some magnetometers to register minor storm levels 06-09h UTC.
Solar flux measured at 20h UTC on 2.8 GHz was 100.8. The planetary A
index was 13 (STAR Ap - based on the mean of three hour interval ap indices: 14.9).
Three hour interval K indices: 23433333 (planetary), 33522433 (Boulder).
The background x-ray flux is at the class B1-B2 level.
At midnight there were 6 spotted regions on the visible disk. The solar flare activity level was low. A total of 3 C class events was recorded during the day.
Region 10606 developed several small trailing spots early in the day, then lost these spots again during the latter half
of the day.
Region 10608 decayed and could soon become spotless.
Region 10609 developed quickly and more than doubled the penumbral area. A minor M class flare is possible. Flares: C1.7 at 07:45, C1.3 at 09:40 and C7.7 at 13:34 UTC.
New region 10612 emerged in the northeast quadrant.
New region 10613 rotated into view at the southeast limb.
Spotted regions not numbered by NOAA/SEC:
[S402] This region emerged near the center of the visible disk on May 13, 6 degrees longitude to the west of now spotless region 10610 and further north. Location at midnight: N02W02.
May 11-13: 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 coronal hole in the southern hemisphere will likely rotate into a geoeffective position on May 17..
Processed SOHO/EIT 284 image at 19:05 UTC on May 13. The darkest areas on the solar disk are likely coronal holes.
The geomagnetic field is expected to be quiet to active on May 14 and quiet to unsettled on May 15-16.
|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 fair to poor. Trans Atlantic propagation conditions are monitored every night on 1470 kHz. Dominant station tonight: Radio Vibración, CPN Radio (Perú) was noted with a weak signal. Near local sunrise the Puerto Rico stations on 1480 and 1600 were audible, as were a few other stations in the Caribbean. WWZN Boston on 1510 kHz was the only USA station heard and had a weak signal, while a few of the usual Newfoundland stations made it across the Atlantic as well.
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 HAX
at midnight, area 0180
classification was AXX
at midnight, area 0010
area was 0280
classification was CSO
at midnight, area 0020
area was 0070
|Total spot count:||47||44|
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)||23.1 (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.