Last major update issued on June 2, 2004 at 04:15 UTC.
[Solar and geomagnetic data - last month (updated daily)]
[Solar wind and electron fluence charts (updated daily)]
[Solar cycles 21-23 (last update June 2, 2004)]
[Solar cycles 1-20]
[Graphical comparison of cycles 21, 22 and 23 (last update June 2, 2004)]
[Graphical comparison of cycles 2, 10, 13, 17, 20 and 23 (last update June 2, 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 unsettled to active on June 1. Solar wind speed ranged between 496 and 586 km/sec under the influence of a high speed stream from coronal hole CH98.
Solar flux measured at 20h UTC on 2.8 GHz was 90.0. The planetary A
index was 16 (STAR Ap - based on the mean of three hour interval ap indices: 17.0).
Three hour interval K indices: 33433333 (planetary), 43434333 (Boulder).
The background x-ray flux is at the class B1 level.
At midnight there were 4 spotted regions on the visible disk. The solar flare activity level was very low. No C class events were recorded during the day.
Region 10621 developed slowly and was quiet.
Region 10622 decayed and could soon become spotless.
New region 10623 emerged in the northwest quadrant before noon and developed fairly quickly initially. By the evening the
region was already decaying and lost several small spots before midnight.
New region 10624 rotated into view at the southeast limb on May 31 and was numbered by SEC the next day.
May 30-June 1: No fully or partly Earth directed CMEs 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 trans equatorial coronal hole (CH99) was in a geoeffective position on May 30-31.
Processed SOHO/EIT 284 image at 01:05 UTC on June 2. The darkest areas on the solar disk are likely coronal holes.
The geomagnetic field is expected to be quiet to active on June 2-4 due to a high speed stream from coronal hole 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 stations tonight: Radio Cristal del Uruguay and Radio Vibración (Venezuela). Several stations from Brazil were observed on other frequencies, Rádio Metropolitana on 930 kHz had an impressive signal. The only station from North America was WWZN Boston on 1510 kHz with a very weak 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 |
|---|---|---|---|---|---|---|---|
| 10618 | 2004.05.20 | 1 | S08W89 | 0030 | HRX | rotated out of view | |
| 10620 | 2004.05.23 | S15W81 | plage | ||||
| 10621 | 2004.05.29 | 18 | 23 | S16E25 | 0070 | DSO |
classification was DAI at midnight, area 0100 location S14E23 |
| 10622 | 2004.05.30 | 2 | 2 | S12E46 | 0030 | CAO |
classification was HRX at midnight, area 0020, same polarity spots |
| 10623 | 2004.06.01 | 4 | 2 | N07W23 | 0020 | CAO |
classification was DSO at midnight, location N08W21 |
| 10624 | 2004.06.01 | 1 | 1 | S09E64 | 0030 | HSX | formerly region S410 |
| S408 | emerged on 2004.05.28 |
N13W64 | plage | ||||
| S409 | emerged on 2004.05.29 |
S01E08 | plage | ||||
| Total spot count: | 26 | 28 | |||||
| SSN: | 76 | 68 | |||||
| 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 | 56.7 (-1.4) |
| 2003.12 | 114.9 | 46.5 | (54.4 predicted, -2.3) |
| 2004.01 | 114.1 | 37.2 | (50.5 predicted, -3.9) |
| 2004.02 | 107.0 | 46.0 | (46.2 predicted, -4.3) |
| 2004.03 | 112.0 | 48.9 | (43.5 predicted, -2.7) |
| 2004.04 | 101.2 | 39.3 | (41.4 predicted, -2.1) |
| 2004.05 | 99.8 | 41.5 | (38.2 predicted, -3.2) |
| 2004.06 | 90.0 (1) | 2.5 (2) | (35.3 predicted, -2.9) |
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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