Last major update issued on September 8, 2004 at 04:05 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 to active on September 7. Solar wind speed ranged between 412 and 495 km/sec under the influence of a fairly low speed stream from coronal hole CH112.
Solar flux measured at 20h UTC on 2.8 GHz was 118.9. The planetary A
index was 16 (STAR Ap - based on the mean of three hour interval ap indices: 16.1).
Three hour interval K indices: 34443323 (planetary), 44442222 (Boulder).
The background x-ray flux is at the class B3 level.
At midnight there were 3 spotted regions on the visible disk. The solar flare activity level was low. A total of 2 C class events was recorded during the day.
Region 10667 developed slowly in the trailing spot section. The large umbra within the leading penumbra split into two
Region 10669 developed slowly and quietly. The region is fairly compact and has a mostly east-west inversion line. A patch of positive polarity flux was observed inside the northern predominantly negative polarity area. A flare in this region could cause an event in region 10667 as well. Flare: C1.1 long duration event peaking at 07:38 UTC.
Region 10671 developed quickly. The trailing positive polarity penumbra in the northeast has negative polarity areas immediately to its south and west. C flares are possible and further development will increase the chance of an M class flare.
One or perhaps two closely spaced regions are approaching the northeast limb and could rotate into view late today or tomorrow. M class flares are possible. Flare: C2.8 long duration event peaking at 15:29 UTC.
September 5-7: No obviously Earth directed CMEs were observed. A full halo CME was observed after the C2 event behind the northeast limb on September 7.
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 3-6.
Processed SOHO/EIT 284 image at 01:06 UTC on September 8. The darkest areas on the solar disk are likely coronal holes.
The geomagnetic field is expected to be quiet to unsettled on September 8-10 with the possibility of a few active intervals on September 8 due to coronal hole effects.
|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 to occasionally fair. Propagation along long distance north-south paths is poor. Trans Atlantic propagation conditions are monitored every night on 1470 kHz. Dominant station tonight: Radio Vibración (Venezuela) with a poor signal. Most of the stations observed on other frequencies were from North America. Canada was represented on 590, 620, 640, 740, 750, 780, 930, 960, 1070 and 1140 kHz while US stations were noted on 1030, 1050, 1130, 1510, 1560, 1650, 1660 and 1690 kHz. WBBR 1130 and WWZN 1510 had the best signals.
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 CHO
at midnight, location
|10668||2004.09.03||1||S09W90||0010||AXX||rotated out of view|
these are the trailing
spots of region 10667,
this region should
classification was DAC
at midnight, area 0160
|Total spot count:||45||47|
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||101.2 (1)||10.9 (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.