Last major update issued on December 17, 2009 at 04:20 UTC.
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The geomagnetic field was quiet on December 16. Solar wind speed ranged between 270 and 352 km/s.
Solar flux measured at 20h UTC on 2.8 GHz was 83.2. The planetary A index was 3 (STAR Ap - based on the mean of three hour interval ap indices: 2.9). Three hour interval K indices: 21011100 (planetary), 12021110 (Boulder).
The background x-ray flux is at the class B3 level.
At midnight there was 1 spotted region on the visible solar disk.
Region 11035 developed slowly with penumbral growth occurring in the trailing spot section while some decay was observed in the leader spots. The region is fairly compact with slight polarity intermixing in the central section. An M class flare is possible. Flares: C5.4 at 01:24 and C3.7 at 13:02 UTC.
An active region is approaching the east limb and could produce C flares. Flare: C1.4 long duration event at 21:49 UTC. This event was associated with a weak type IV radio sweep and a CME off the east limb.
December 14-15: No partially or fully Earth directed CMEs were observed in LASCO
or STEREO imagery.
December 16: A partial halo CME was observed in LASCO images after a C5
event early in the day in region 11035. STEREO images confirms that this CME is
Earth directed.
Coronal hole history (since late October 2002)
Compare today's report to the situation one solar rotation ago:
28 days ago
27 days ago
26 days ago
A small recurrent coronal hole (CH387) in the northern hemisphere was in an Earth facing position on December 14.
Processed SOHO/EIT 195 image at 23:48 UTC on December 16. The darkest areas on the solar disk are likely coronal holes.
Long distance low and medium frequency (below 2 MHz) propagation along paths north of due west over high and upper middle latitudes is good. Propagation on long distance northeast-southwest paths is poor.
The geomagnetic field is expected to be quiet on December 17. On December 18-19 there's a chance of a few unsettled intervals due to effects from CH387. A CME observed on December 16 will likely reach Earth on December 19 and cause unsettled to active conditions, maybe with isolated minor storming.
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) Effects from a CME are likely to be observed at 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/SWPC. 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 SWPC or where SWPC has observed no spots. SWPC active region numbers in the table below and in the active region map above are the historic SWPC/USAF numbers.
Active region | Date numbered | SWPC spot count |
STAR spot count |
Location at midnight | Area | Classification | Comment |
---|---|---|---|---|---|---|---|
11034 | 2009.12.09 | N19W27 | |||||
11035 | 2009.12.14 | 20 | 23 | N30W18 | 0140 | EAC | area was 0200 at midnight |
Total spot count: | 20 | 23 | |||||
SSN: | 30 | 33 |
Month | Average solar flux at Earth |
International sunspot number (SIDC) | 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) |
2008.07 | 65.7 | 0.5 | 2.8 (-0.4) |
2008.10 | 68.3 | 2.9 | 1.8 (-0.5) |
2008.11 | 68.6 | 4.1 | 1.7 (-0.1) |
2008.12 | 69.2 | 0.8 | 1.7 (-) sunspot minimum |
2009.01 | 69.8 | 1.3 | 1.8 (+0.1) |
2009.02 | 70.0 | 1.4 | 1.9 (+0.1) |
2009.03 | 69.2 | 0.7 | 2.0 (+0.1) |
2009.04 | 69.7 | 1.2 | 2.2 (+0.2) |
2009.05 | 70.5 | 2.9 | 2.3 (+0.1) |
2009.06 | 68.6 | 2.6 | (2.5 predicted, +0.2) |
2009.07 | 68.2 | 3.5 | (2.8 predicted, +0.3) |
2009.08 | 67.3 | 0.0 | (3.0 predicted, +0.2) |
2009.09 | 70.5 | 4.2 | (3.7 predicted, +0.7) |
2009.10 | 72.6 | 4.6 | (4.6 predicted, +0.9) |
2009.11 | 73.6 | 4.2 | (5.6 predicted, +1.0) |
2009.12 | 74.1 (1) | 5.2 (2) | (6.8 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/SWPC) sunspot number. The official international sunspot number is typically
30-50% lower.
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.