Last major update issued on May 11, 2004 at 05:10 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 8, 2004)]
The geomagnetic field was quiet to unsettled on May 10. Solar wind speed ranged between 361 and 426 km/sec. A weak flow from coronal hole CH95 arrived late in the day and has caused the geomagnetic field to become unsettled.
Solar flux measured at 20h UTC on 2.8 GHz was 93.0. The planetary A
index was 7 (STAR Ap - based on the mean of three hour interval ap indices: 7.8).
Three hour interval K indices: 12212233 (planetary), 22212213 (Boulder).
The background x-ray flux is at the class A6 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 10606 was quiet and stable.
Region 10608 developed early in the day, then decayed after noon.
May 8-9: No fully or partly Earth directed CME observed.
May 10: A slow partial halo CME was observed in LASCO C3 following a filament eruption in the southwest quadrant. This
eruption began at 03:36 UTC as observed in EIT images. The CME could reach Earth on May 13 and cause unsettled to active
conditions.
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 coronal hole in the northern hemisphere is probably located too far to the north to become geoeffective. A small coronal hole (CH95) in the northern hemisphere near the equator was in a geoeffective position on May 7.
Processed SOHO/EIT 284 image at 01:05 UTC on May 11. The darkest areas on the solar disk are likely coronal holes.
The geomagnetic field is expected to be mostly quiet on May 11-12. A CME could arrive on May 13 and cause unsettled to active conditions.
| 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. Trans Atlantic propagation conditions are monitored every night on 1470 kHz. Dominant stations tonight: Radio Cristal del Uruguay at first, then Radio Vibración (strong signal) with CPN Radio (Perú) occasionally noted. WWZN Boston on 1510 kHz had a fair signal].
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 spot count |
STAR spot count |
Location at midnight | Area | Classification | Comment |
|---|---|---|---|---|---|---|---|
| 10604 | 2004.05.03 | S18W41 | plage | ||||
| 10605 | 2004.05.04 | 1 | S11W84 | 0060 | HSX | rotated out of view | |
| 10606 | 2004.05.07 | 3 | 2 | S09E40 | 0140 | HKX |
classification was HAX at midnight |
| 10607 | 2004.05.09 | S11W13 | plage | ||||
| 10608 | 2004.05.09 | 10 | 6 | S04E52 | 0060 | DSO |
classification was CAO at midnight |
| 10609 | 2004.05.10 | 1 | S03E63 | 0000 | AXX | ||
| S399 | emerged on 2004.05.06 |
S16W64 | plage | ||||
| Total spot count: | 15 | 8 | |||||
| SSN: | 55 | 28 | |||||
| Month | Average solar flux at Earth |
International sunspot number | Smoothed sunspot number |
|---|---|---|---|
| 2000.04 | 184.2 | 125.5 | 120.8 cycle 23 sunspot max. |
| 2000.07 | 202.3 | 170.1 | 119.8 |
| 2001.12 | 235.1 | 132.2 | 114.6 (-0.9) |
| 2003.04 | 126.4 | 60.0 | 70.1 (-3.9) |
| 2003.05 | 115.7 | 55.2 | 67.6 (-2.5) |
| 2003.06 | 129.3 | 77.4 | 65.0 (-2.6) |
| 2003.07 | 127.7 | 83.3 | 61.8 (-3.2) |
| 2003.08 | 122.1 | 72.7 | 60.0 (-1.8) |
| 2003.09 | 112.2 | 48.7 | 59.5 (-0.5) |
| 2003.10 | 151.7 | 65.5 | 58.1 (-1.4) |
| 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 | 90.4 (1) | 15.5 (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.
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