Last major update issued on May 30, 2004 at 04:30 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 18, 2004)]
The geomagnetic field was quiet to active on May 29. Solar wind speed ranged between 349 and 459 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 101.2. The planetary A
index was 14 (STAR Ap - based on the mean of three hour interval ap indices: 14.4).
Three hour interval K indices: 33343323 (planetary), 43343333 (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 very low. No C class events were recorded during the day.
Region 10618 decayed slowly and was mostly quiet.
New region 10621 rotated into view at the southeast limb on May 28 and was numbered the next day by SEC. The region
developed on May 29 and added several spots with penumbra.
Spotted regions not numbered by NOAA/SEC:
[S409] A new region emerged in the southeast quadrant on May 29. Location at midnight: S01E47.
May 27-29: 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 01:05 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 30-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 poor. Propagation along long distance north-south paths is good to excellent. Trans Atlantic propagation conditions are monitored every night on 1470 kHz. Dominant station tonight: Radio Cristal del Uruguay. Radio Vibración (Venezuela) was noted only after local sunrise, earlier Radio Rafaela (Argentina) was noted at times. On other frequencies propagation was particularly good towards Argentina and Uruguay with Argentine stations noted on a number of frequencies including 1610, 1620, 1630 and 1660 kHz. A few stations from North America were observed before local sunrise: WWZN Boston on 1510 kHz and Newfoundland stations on 590, 620, 640, 650 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 spot count |
STAR spot count |
Location at midnight | Area | Classification | Comment |
|---|---|---|---|---|---|---|---|
| 10618 | 2004.05.20 | 32 | 19 | S10W60 | 0520 | FKC |
beta-gamma classification was FAI at midnight, area 0280 |
| 10620 | 2004.05.23 | S15W42 | plage | ||||
| 10621 | 2004.05.29 | 5 | 13 | S14E62 | 0110 | DAI |
formerly region S407 area was 0080 at midnight |
| S406 | emerged on 2004.05.24 |
S14W56 | plage | ||||
| S408 | emerged on 2004.05.28 |
N13W25 | plage | ||||
| S409 | emerged on 2004.05.29 |
2 | S01E47 | 0000 | BXO | ||
| Total spot count: | 37 | 34 | |||||
| SSN: | 57 | 64 | |||||
| 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 | 100.0 (1) | 73.5 (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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