Last update issued on September 5, 2003 at 03:45 UTC.
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The geomagnetic field was unsettled to active on September 4. Solar wind speed ranged between 524 and 778 km/sec under the influence of a high speed stream from coronal hole CH54.
Solar flux measured at 20h UTC on 2.8 GHz was 112.2. The planetary A
index was 19 (STAR Ap - based on the mean of three hour interval ap indices: 19.3).
Three hour interval K indices: 33443334 (planetary), 34343344 (Boulder).
The background x-ray flux is at the class B3-B4 level.
At midnight there were 3 spotted regions on the visible disk. Solar flare activity was low. A single C class event was recorded during the day, a C1.4 long duration event peaking at 14:49 UTC from a source near the southwest limb.
Region 10450 decayed in the trailing spot section while slow development was observed in the leader spots.
New region 10453 emerged on September 3 in the southwest quadrant and was numbered the next day by SEC. The region developed moderate quickly on September 4 with the most of the development occurring in the trailing penumbra. The positive polarity area in this penumbra has negative polarity areas immediately to the northwest and southwest.
New region 10454 emerged on September 3 in the southeast quadrant, developed early on Sept.4, then decayed slowly as the positive and negative polarity areas drifted apart.
September 2-4: No potentially geoeffective CMEs observed.
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 large recurrent coronal hole (CH54) in the northern hemisphere and with a trans equatorial extension, was in a geoeffective position on August 29 - September 3. A trans equatorial coronal hole (CH55) will rotate into a geoeffective position on September 7-8.
Processed SOHO/EIT 284 image from 20:06 UTC on September 4. The darkest areas on the solar disk are likely coronal holes.
The geomagnetic field is expected to be unsettled to active until September 6 under the influence of a high speed stream from coronal hole CH54. Quiet to active is expected for September 7-9.
Long distance low frequency (below 2 MHz) propagation along east-west paths over high and upper middle latitudes is poor to fair. Propagation along north-south paths is fair. [Trans Atlantic propagation conditions are currently monitored every night on 1470 kHz. Dominant station tonight: Radio Vibración (Venezuela)].
|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.
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.
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.
|Solar region||Date numbered||SEC
|Location at midnight||Area||Classification||Comment|
formerly region S249
classification was DAO
at midnight, area 0130
|10454||2003.09.04||6||5||S10E22||0030||CSO||formerly region S250|
|S09W82||rotated out of view|
|Total spot count:||29||27|
flux at Earth
|International sunspot number||Smoothed sunspot number|
cycle 23 sunspot max.
|2003.03||131.4||61.1||(74.2 predicted, -4.3)|
|2003.04||126.4||60.0||(69.3 predicted, -4.9)|
|2003.05||115.7||55.2||(64.4 predicted, -4.9)|
|2003.06||129.3||77.4||(60.4 predicted, -4.0)|
|2003.07||127.7||85.0||(56.9 predicted, -3.5)|
|2003.08||122.1||72.7||(53.9 predicted, -3.0)|
|2003.09||109.1 (1)||9.6 (2)||(51.9 predicted, -2.0)|
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 sources noted in solar links. All time references are to the UTC day. Comments and suggestions are always welcome.