Last major update issued on September 5, 2004 at 03:20 UTC.
[Solar and geomagnetic data - last month (updated daily)]
[Solar wind and electron fluence charts (updated daily)]
[Solar cycles 21-23 (last update September 2, 2004)]
[Solar cycles 1-20]
[Graphical comparison of cycles 21, 22 and 23 (last update September 2, 2004)]
[Graphical comparison of cycles 2, 10, 13, 17, 20 and 23 (last update September 2, 2004)]
[Historical solar and geomagnetic data charts 1954-2004 (last update August 28, 2004)]
[Archived reports (last update August 25, 2004)]
The geomagnetic field was quiet on September 4. Solar wind speed ranged between 289 and 351 km/sec.
Solar flux measured at 20h UTC on 2.8 GHz was 99.3. The planetary A
index was 4 (STAR Ap - based on the mean of three hour interval ap indices: 4.5).
Three hour interval K indices: 11012221 (planetary), 00111011 (Boulder).
The background x-ray flux is at the class B2 level.
At midnight there were 3 spotted regions on the visible disk. The solar flare activity level was very low. No C class events were recorded during the day.
Region 10667 was quiet and stable.
Region 10668 decayed slowly and quietly.
Spotted regions not numbered by NOAA/SEC:
[S450] A new region emerged in the southwest quadrant on September 4. Location at midnight: S01W34.
September 2-4: No obviously Earth directed CMEs were observed. Two full halo CMEs were observed on September 3, both from a centrally placed backsided source. Another full halo CME was observed on September 4, probably from the same backsided source. It will be interesting to see the region causing this activity when it rotates into view on Sept.10-11.
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 coronal hole (CH112) in the northern hemisphere was in a geoeffective position on September 3-5.
Processed SOHO/EIT 284 image at 01:06 UTC on September 5. The darkest areas on the solar disk are likely coronal holes.
The geomagnetic field is expected to be quiet on September 5. For September 6-8 unsettled to active conditions are possible due to a high speed stream from coronal hole CH112.
|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 at night and fair to good near local sunrise. Trans Atlantic propagation conditions are monitored every night on 1470 kHz. Dominant station tonight: Radio Vibración (Venezuela). Local sunrise propagation on September 4 was not as interesting as on the previous day. 1520 WVOZ had a good signal, as did a few other stations from Puerto Rico. Otherwise some stations from Venezuela, Argentina and Uruguay were noted.
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 HSX
at midnight, area 0210
classification was DAO
|Total spot count:||8||8|
flux at Earth
|International sunspot number||Smoothed sunspot number|
cycle 23 sunspot max.
|2004.03||112.0||49.1||(47.0 predicted, -2.3)|
|2004.04||101.2||39.3||(44.8 predicted, -2.2)|
|2004.05||99.8||41.5||(41.5 predicted, -3.3)|
|2004.06||97.4||43.2||(38.6 predicted, -2.9)|
|2004.07||119.1||51.0||(36.8 predicted, -1.8)|
|2004.08||109.6||40.9||(35.4 predicted, -1.4)|
|2004.09||95.0 (1)||3.0 (2)||(34.2 predicted, -1.2)|
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.