Last major update issued on May 31, 2005 at 04:10 UTC.
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The geomagnetic field was unsettled to severe storm on May 30. Solar wind speed ranged between 410 and 540 km/sec. The interplanetary magnetic field (at ACE) was very strongly southwards between 05 and 17h UTC, this caused minor to severe geomagnetic storming.
Solar flux measured at 20h UTC on 2.8 GHz was 94.9. The planetary
A
index was 67 (STAR Ap - based on the mean of three hour interval ap
indices: 66.8).
Three hour interval K indices: 43676754 (planetary), 33566554 (Boulder).
The background x-ray flux is at the class B1 level.
At midnight there were 4 spotted regions on the visible solar disk. The solar flare activity level was very low. No C class events were recorded during the day.
Region 10767 decayed slowly and quietly.
Region 10770 developed slowly and was quiet.
New region 10771 emerged in the northwest quadrant.
Spotted regions not numbered by NOAA/SEC:
[S552] This region emerged quickly after noon in the southeast quadrant in a hot plage area. The opposite polarity
fields are poorly separated and further development is likely.
May 28-30: No obviously fully or partly potentially geoeffective CMEs were 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 coronal hole (CH168) in the southern hemisphere was in an Earth facing position on May 29. A recurrent coronal hole (CH169) in the northern hemisphere will rotate into an Earth facing position on June 1-3.
Processed SOHO/EIT 284 image at 19:06 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 31. Unsettled to active conditions are possible on June 1-2 due to a high speed stream from CH168.
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 useless. Propagation along long distance north-south paths is excellent. Trans Atlantic propagation conditions are normally monitored every night on 1470 kHz. Dominant stations tonight: None, many stations from Brazil and Argentina were audible and of course Radio Cristal del Uruguay. Conditions were too good as it was difficult to get more than a few seconds of continuous audio from a single station. On 1540 kHz two stations from Argentina were noted, while other frequencies above 1350 kHz at times were stuffed by Brazilian stations.
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 |
---|---|---|---|---|---|---|---|
10765 | 2005.05.19 | N08W81 | plage | ||||
10766 | 2005.05.21 | N13W45 | plage | ||||
10767 | 2005.05.21 | 22 | 23 | S09W44 | 0240 | EAC |
beta-gamma classification was DAI at midnight, area 0150 |
10769 | 2005.05.28 | 4 | S08E49 | 0020 | BXO | spotless | |
10770 | 2005.05.29 | 7 | 11 | N12W14 | 0060 | DAO | |
10771 | 2005.05.30 | 3 | 4 | N24W33 | 0040 | BXO | classification was DSO at midnight |
S552 | emerged on 2005.05.30 |
6 | S18E61 | 0050 | DAO | ||
Total spot count: | 36 | 44 | |||||
SSN: | 76 | 84 |
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) |
2004.03 | 112.0 | 49.1 | 47.1 (-2.2) |
2004.04 | 101.2 | 39.3 | 45.5 (-1.6) |
2004.05 | 99.8 | 41.5 | 43.8 (-1.7) |
2004.06 | 97.4 | 43.2 | 41.6 (-2.2) |
2004.07 | 119.1 | 51.1 | 40.2 (-1.4) |
2004.08 | 109.6 | 40.9 | 39.2 (-1.0) |
2004.09 | 103.1 | 27.7 | 37.5 (-1.7) |
2004.10 | 105.9 | 48.0 | 35.9 (-1.6) |
2004.11 | 113.2 | 43.5 | (34.8 predicted, -1.1) |
2004.12 | 94.5 | 17.9 | (33.4 predicted, -1.4) |
2005.01 | 102.2 | 31.3 | (30.9 predicted, -2.5) |
2005.02 | 97.2 | 29.1 | (28.3 predicted, -2.6) |
2005.03 | 89.9 | 24.8 | (26.5 predicted, -1.8) |
2005.04 | 86.0 | 24.4 | (24.6 predicted, -1.9) |
2005.05 | 99.4 (1) | 62.8 (2) | (22.0 predicted, -2.6) |
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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