Last major update issued on August 8, 2004 at 05:10 UTC.
[Solar and geomagnetic data - last month (updated daily)]
[Solar wind and electron fluence charts (updated daily)]
[Solar cycles 21-23 (last update August 2, 2004)]
[Solar cycles 1-20]
[Graphical comparison of cycles 21, 22 and 23 (last update August 2, 2004)]
[Graphical comparison of cycles 2, 10, 13, 17, 20 and 23 (last update August 2, 2004)]
[Historical solar and geomagnetic data charts 1954-2004 (last update April 28, 2004)]
[Archived reports (last update August 1, 2004)]
The geomagnetic field was quiet to minor storm on August 7. Solar wind speed ranged between 323 and 510 km/sec under the influence of a low to medium high speed stream from coronal hole CH107.
Solar flux measured at 20h UTC on 2.8 GHz was 94.6. The planetary A
index was 20 (STAR Ap - based on the mean of three hour interval ap indices: 21.1).
Three hour interval K indices: 33544323 (planetary), 33544222 (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 10655 decayed further with no trailing spots having penumbra, quite a few small spots disappeared.
Region 10656 developed slowly adding penumbra to a few trailing spots.
Region 10657 was quiet and stable.
New region 10658 emerged early in the day to the northwest of region 10656. Penumbra was visible on a single spot, then the region decayed and only a single tiny spot was visible at the end of the day.
August 5-7: No obviously Earth directed CMEs were 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
The northernmost extension of a coronal hole (CH108) in the southern hemisphere may have been in a geoeffective position on August 7. The southernmost extensions of a poorly defined coronal hole (CH109) in the northern hemisphere will be in geoeffective positions on August 8-9.
Processed SOHO/EIT 284 image at 01:06 UTC on August 8. The darkest areas on the solar disk are likely coronal holes.
The geomagnetic field is expected to be quiet to unsettled on August 8-9 with conditions becoming quiet to active on August 10-12 due to effects from coronal holes CH108 and CH109.
|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 poor to fair. Trans Atlantic propagation conditions are monitored every night on 1470 kHz. Dominant stations tonight: Radio Vibración (Venezuela) and Radio Cristal del Uruguay. Some stations from Brazil were noted before local sunrise with the most interesting signal from Floresta AM on 1590 kHz. Only a few stations from North America could be heard, WWZN Boston on 1510 kHz had a fair and stable signal for a long time.
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
|Location at midnight||Area||Classification||Comment|
classification was CAI,
area 0140 at midnight
classification was DAO,
area 0150 at midnight
area was 0040
classification was AXX,
area 0000 at midnight
|Total spot count:||31||27|
flux at Earth
|International sunspot number||Smoothed sunspot number|
cycle 23 sunspot max.
|2004.02||107.0||45.8||(49.1 predicted, -2.9)|
|2004.03||112.0||49.1||(46.5 predicted, -2.6)|
|2004.04||101.2||39.3||(44.3 predicted, -2.2)|
|2004.05||99.8||41.5||(41.0 predicted, -3.3)|
|2004.06||97.4||43.2||(38.2 predicted, -2.8)|
|2004.07||119.1||51.0||(36.3 predicted, -1.9)|
|2004.08||87.8 (1)||11.4 (2)||(34.9 predicted, -1.4)|
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.