Last major update issued on August 1, 2004 at 03:50 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 31. Solar wind speed ranged between 449 and 534 km/sec.
Solar flux measured at 20h UTC on 2.8 GHz was 86.4. The planetary A
index was 9 (STAR Ap - based on the mean of three hour interval ap indices: 9.6).
Three hour interval K indices: 22223333 (planetary), 23213322 (Boulder).
The background x-ray flux is at the class B1 level.
At midnight there were 2 spotted regions on the visible disk. The solar flare activity level was low. A total of 3 C class events was recorded during the day. All flares had their origin in region 10652 behind the northwest limb: C2.8 at 01:04, very long duration C8.4 peaking at 06:57 and long duration C5.3 peaking at 11:01 UTC.
Region 10654 decayed as most of the intermediate spots disappeared.
Region 10655 developed slowly as some small trailing spots emerged.
July 29-31: No obvious Earth directed CMEs detected in LASCO images.
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
No obvious coronal holes are currently approaching geoeffective positions.
Processed SOHO/EIT 284 image at 19:06 UTC on July 31. The darkest areas on the solar disk are likely coronal holes.
The geomagnetic field is expected to be quiet to unsettled on August 1-4.
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 poor to fair. Trans Atlantic propagation conditions are monitored every night on 1470 kHz. Dominant stations tonight: Radio Cristal del Uruguay and Radio Vibración (Venezuela) with weak signals. After local sunrise several stations from Argentina were noted in the lower part of the MW band. No stations from North America were observed.
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 |
---|---|---|---|---|---|---|---|
10654 | 2004.07.25 | 14 | 7 | N08W28 | 0100 | DAO |
area was 0080 at midnight |
10655 | 2004.07.30 | 5 | 6 | S09E57 | 0170 | DAO |
classification was CAO at midnight, area 0110 |
Total spot count: | 19 | 13 | |||||
SSN: | 39 | 33 |
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 | 119.1 (1) | 87.2 (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.
[DX-Listeners' Club] |