Last major update issued on July 29, 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 July 2, 2004)]
[Solar cycles 1-20]
[Graphical comparison of cycles 21, 22 and 23 (last update July 2, 2004)]
[Graphical comparison of cycles 2, 10, 13, 17, 20 and 23 (last update July 2, 2004)]
[Historical solar and geomagnetic data charts 1954-2004 (last update April 28,
2004)]
[Archived reports (last update July 1, 2004)]
The geomagnetic field was quiet to unsettled on July 28. Solar wind speed ranged between 567 and 968 km/sec, decreasing quickly early in the day. A weak high speed stream from coronal hole CH106 appeared to be influencing the field most of the day.
Solar flux measured at 20h UTC on 2.8 GHz was 100.7. The planetary A
index was 14 (STAR Ap - based on the mean of three hour interval ap indices: 15.0).
Three hour interval K indices: 33333323 (planetary), 33323233 (Boulder).
The background x-ray flux is at the class B4 level.
At midnight there were 2 spotted regions on the visible disk. The solar flare activity level was moderate. A total of 8 C and 1 M class events were recorded during the day.
Region 10652 decayed further losing penumbral area and spots. There is still a chance of M class flares while the region
rotates over the northwest limb today and tomorrow. Flares: C2.0 at 03:03, very long duration
C4.8 event peaking at 06:15, C6.3 at 08:11 (superimposed on the C4 LDE), C3.0 at 11:47, C1.2 at 13:38, C3.6 at 15:34, C3.3 at
16:27, C1.6/1F at 21:33 and M2.0 (beginning at 23:45) at 00:06 (peak on July 29) UTC.
Region 10654 decayed slowly and quietly.
July 26-27: No obvious Earth directed CMEs observed.
July 28: A partial halo CME was observed after a very long duration event in region 10652 early in the day. There is a
chance that some effects from this CME could be observed at Earth on July 30.
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
The northernmost extensions of a coronal hole (CH106) in the southern hemisphere were in a geoeffective position on July 25.
Processed SOHO/EIT 284 image at 01:06 UTC on July 29. The darkest areas on the solar disk are likely coronal holes.
The geomagnetic field is expected to be mostly quiet to unsettled on July 29-31. There is a chance of unsettled to active conditions on July 30 if the CME observed on July 27 reaches Earth.
| 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 to useless. Propagation along long distance north-south paths is good. Trans Atlantic propagation conditions are monitored every night on 1470 kHz. Dominant station tonight: Radio Cristal del Uruguay. A couple of Brazilian stations were heard as well. Post sunrise conditions were good towards Uruguay (610, 1410 and 1590 kHz) and Argentina (580, 590, 710, 790, 870, 950, 970 ++ kHz). No signs of any stations from North America.
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 |
|---|---|---|---|---|---|---|---|
| 10652 | 2004.07.16 | 20 | 17 | N08W76 | 0830 | EKC |
beta-gamma classification was EAC at midnight, area 0400 |
| 10653 | 2004.07.17 | 9 | S12W76 | 0020 | BXO | spotless | |
| 10654 | 2004.07.25 | 7 | 7 | N08E11 | 0110 | DAO |
classification was DSO at midnight, area 0090 |
| Total spot count: | 36 | 34 | |||||
| SSN: | 66 | 54 | |||||
| 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) |
| 2003.06 | 129.3 | 77.4 | 65.0 (-2.6) |
| 2003.07 | 127.7 | 83.3 | 61.8 (-3.2) |
| 2003.08 | 122.1 | 72.7 | 60.1 (-1.7) |
| 2003.09 | 112.2 | 48.7 | 59.6 (-0.5) |
| 2003.10 | 151.7 | 65.5 | 58.2 (-1.4) |
| 2003.11 | 140.8 | 67.3 | 56.8 (-1.4) |
| 2003.12 | 114.9 | 46.5 | 54.8 (-2.0) |
| 2004.01 | 114.1 | 37.7 | (51.1 predicted, -3.7) |
| 2004.02 | 107.0 | 45.8 | (46.9 predicted, -4.2) |
| 2004.03 | 112.0 | 49.1 | (44.1 predicted, -2.8) |
| 2004.04 | 101.2 | 39.3 | (42.1 predicted, -2.0) |
| 2004.05 | 99.8 | 41.5 | (38.8 predicted, -3.3) |
| 2004.06 | 97.4 | 43.2 | (36.0 predicted, -2.8) |
| 2004.07 | 122.0 (1) | 83.8 (2) | (34.2 predicted, -1.8) |
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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