Last major update issued on September 7, 2004 at 03:10 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 6. Solar wind speed ranged between 347 and 474 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 106.5. The planetary A
index was 14 (STAR Ap - based on the mean of three hour interval ap indices: 14.4).
Three hour interval K indices: 22443323 (planetary), 22343322 (Boulder).
The background x-ray flux is at the class B2 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 10667 was mostly unchanged and quiet.
Region 10668 decayed further and will rotate out of view today.
Region 10669 developed slowly and quietly.
New region 10671 emerged in the southwest quadrant.
September 4-5: 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.
No new LASCO images have become available since early on September 5.
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 19:06 UTC on September 6. The darkest areas on the solar disk are likely coronal holes.
The geomagnetic field is expected to be quiet to active on September 7-8 due to coronal hole effects. Quiet to unsettled is likely on September 9-10.
| 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 Cristal del Uruguay on the sloping inverted L (pointed WSW), Radio Vibración (Venezuela) on the EWE (aimed NNW). From North America Newfoundland was noted on 620 (poor), 750 (poor), 800 (fair) and 930 kHz (good). WWZN on 1510 was weak.
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 |
|---|---|---|---|---|---|---|---|
| 10666 | 2004.08.29 | N16W74 | plage | ||||
| 10667 | 2004.09.01 | 10 | 5 | S11E09 | 0240 | DAO |
classification was CAO at midnight, location S12E12 |
| 10668 | 2004.09.03 | 1 | 1 | S10W76 | 0050 | HSX |
classification was HRX at midnight, area 0010 |
| 10669 | 2004.09.05 | 12 | 12 | S07E19 | 0050 | DSO |
classification was DAO at midnight, area 0060 |
| 10670 | 2004.09.05 | 4 | S13E19 | 0010 | AXX |
these are the trailing spots of region 10667, this region should be deleted |
|
| 10671 | 2004.09.06 | 5 | 9 | S10W29 | 0040 | DSI |
classification was DAO at midnight |
| S449 | emerged on 2004.08.30 |
S14W54 | plage | ||||
| S450 | emerged on 2004.09.04 |
S01W60 | plage | ||||
| Total spot count: | 32 | 27 | |||||
| SSN: | 82 | 67 | |||||
| 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) |
| 2003.07 | 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 | 52.0 (-2.8) |
| 2004.02 | 107.0 | 45.8 | 49.3 (-2.7) |
| 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 | 98.3 (1) | 7.7 (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.
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