Last major update issued on December 14, 2011 at 04:15 UTC.
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The geomagnetic field was very quiet on December 13. Solar wind speed ranged between 448 and 497 km/s, weakly under the influence of a high speed stream from CH487.
Solar flux measured at 20h UTC on 2.8 GHz was 133.1 (decreasing 9.2 over the last solar rotation). The planetary A index was 4 (STAR Ap - based on the mean of three hour interval ap indices: 4.1). Three hour interval K indices: 10111000 (planetary), 12112122 (Boulder).
The background x-ray flux is at the class B8 level.
At midnight UTC the visible solar disk had 9 spotted regions (in 2K resolution SDO images).
Region 11366 [N18W69] was quiet and stable.
Region 11367 [S18W87] rotated to the southwest limb. The region was the
most active on the visible disk during the day and could produce a minor M class
flare while at the limb or just behind. Flare:
C1.4 at 08:00, C1.1 at 14:14, C4.8 at 23:36, C3.1 at 23:57 UTC.
Region 11372 [N08W49] decayed slowly and quietly.
Region 11374 [S16E03] added a few spots and was quiet.
Region 11375 [N10W02] was quiet and stable.
New region 11376 [N23E57] rotated into view at the northeast limb on
December 11 and was noticed by SWPC 2 days later. Flare:
C1.0 at 22:02 UTC
Spotted regions not reported by NOAA/SWPC:
[S1365] emerged in the southeast quadrant on December 11. became
spotless the next day and reemerged with several spots on Dec.13.
Location at midnight: S16E30
[S1369] emerged in the northeast quadrant on December 13. Location at
midnight: N12E58
[S1370] emerged in the southeast quadrant near the equator on December
13. Location at midnight: S04E25
December 11-13: No obviously Earth directed CMEs observed.
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 coronal hole (CH488) in the southern hemisphere was in an Earth facing position on December 11-12. A small recurrent coronal hole (CH489) in the northern hemisphere will likely rotate to an Earth facing position on December 16-17.
The above coronal hole map is based on a new method where coronal holes are detected automatically. The method may need some fine tuning, however, it has significant advantages over detecting coronal holes manually. The main improvement is the ability to detect coronal holes at and just beyond the solar limbs. Early results using this method for SDO images over a span of several weeks indicate a good match between coronal holes observed over the visible disk and their extent and position at the east and west limbs. Note that the polar coronal holes are easily detected using the new method, the extent and intensity of both holes are consistent with other data sources.
Long distance low and medium frequency (below 2 MHz) propagation along paths north of due west over high and upper middle latitudes is poor to fair. Propagation on long distance northeast-southwest paths is poor.
The geomagnetic field is expected to be mostly quiet on December 14 and 16. On December 15 effects from CH488 could cause a few unsettled intervals.
| 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.
Click on image for higher resolution image) Compare to the previous day's image
When available the active region map has a coronal hole polarity overlay where red (pink) is negative and blue (blue-green) is positive.
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 detected |
Spot count | Location at midnight | Area | Classification | SDO / HMI 4K continuum image with magnetic polarity overlay |
Comment | |||
|---|---|---|---|---|---|---|---|---|---|---|
| SWPC | STAR SDO | SWPC | STAR | Current | Previous | |||||
| 11366 | 2011.12.02 2011.12.03 |
1 | 1 | N17W67 | 0050 | HSX | HSX |
 |
 |
area: 0080 location: N18W69 |
| 11367 | 2011.12.04 | 1 | 1 |
S18W89 |
0020 | HRX | HRX |
 |
 |
possibly beta-delta location: S18W87 |
| S1353 | 2011.12.04 | N12W58 | plage | |||||||
| 11368 | 2011.12.05 | S16W57 | plage | |||||||
| 11370 | 2011.12.05 2011.12.07 |
S24W87 | plage | |||||||
| 11372 | 2011.12.06 2011.12.07 |
2 | 1 | N08W49 | 0010 | BXO | AXX |
 |
 |
|
| 11374 | 2011.12.07 2011.12.08 |
7 | 10 | S18E01 | 0140 | CAO | DSO |
 |
 |
area: 0250 location: S16E03 |
| S1361 | 2011.12.07 | N30W33 | plage | |||||||
| S1362 | 2011.12.07 | S20W46 | plage | |||||||
| 11375 | 2011.12.08 | 3 | 4 | N08W03 | 0050 | CSO | CSO |
 |
 |
location: N10W02 area: 0090 |
| S1364 | 2011.12.09 | N15W28 | plage | |||||||
| S1365 | 2011.12.11 | 3 | S16E30 | 0010 | BXO |
 |
||||
| 11376 | 2011.12.11 2011.12.13 |
3 | 18 | N21E52 | 0010 | BXO | DRI |
 |
 |
location: N23E57 area: 0040 |
| S1367 | 2011.12.11 | S27W13 | plage | |||||||
| S1368 | 2011.12.11 | N15W46 | plage | |||||||
| S1369 | 2011.12.13 | 9 | N12E58 | 0040 | DRO |
 |
||||
| S1370 | 2011.12.13 | 1 | S04E25 | 0000 | AXX |
 |
||||
| Total spot count: | 17 | 48 | ||||||||
| Sunspot number: | 77 | 138 | (total spot count + 10 * number of spotted regions) | |||||||
| Weighted penumbral SN: | 35 | 72 | (Sum of total spot count + classification weighting for each AR. Classification weighting: X=0, R=3, A/S=5, H/K=10) | |||||||
| Relative sunspot number (Wolf number): | 46 | 62 | k * (sunspot number). k = 0.6 for SWPC. k = 0.45 (changed from 0.33 on Nov.1) for STAR SDO | |||||||
| Month | Average measured solar flux | International sunspot number (SIDC) | Smoothed sunspot number | Average ap (3) |
|---|---|---|---|---|
| 2008.07 | 65.7 (SF minimum) | 0.5 | 2.8 (-0.4) | |
| 2008.12 | 69.2 | 0.8 | 1.7 (-) sunspot minimum |
3.25 |
| 2010.10 | 81.6 | 23.5 | 23.2 (+3.6) | 6.07 / 6.27 |
| 2010.11 | 82.5 | 21.5 | 26.5 (+3.3) | 4.80 / 5.50 |
| 2010.12 | 84.2 | 14.4 | 28.8 (+2.3) | 3.41 / 4.35 |
| 2011.01 | 83.6 | 19.1 | 31.0 (+2.2) | 4.32 / 5.51 |
| 2011.02 | 94.6 | 29.4 | 33.4 (+2.4) | 5.41 / 6.44 |
| 2011.03 | 115.0 | 56.2 | 36.9 (+3.5) | 7.79 / 8.18 |
| 2011.04 | 112.6 | 54.4 | 41.8 (+4.9) | 9.71 / 8.83 |
| 2011.05 | 95.8 | 41.6 | 47.6 (+5.8) | 9.18 / 8.94 |
| 2011.06 | 95.8 | 37.0 | (53.7 projected, +6.1) | 8.96 / 8.06 |
| 2011.07 | 94.2 | 43.9 | (60.0 projected, +6.3) | 9.14 / 8.16 |
| 2011.08 | 101.7 | 50.6 | (65.5 projected, +5.5) | 8.16 / 7.26 |
| 2011.09 | 133.8 | 78.0 | (68.8 projected, +3.3) | 12.80 / 12.27 |
| 2011.10 | 137.3 | 88.0 | (72.3 projected, +3.5) | 7.52 |
| 2011.11 | 153.5 | 96.7 | (76.6 projected, +4.3) | 4.58 |
| 2011.12 | 147.9 (1) | 49.1 (2A) / 117.1 (2B) | (82.1 projected, +5.5) | (4.29) |
1) Running average based on the daily 20:00 UTC observed solar flux value at
2800 MHz.
2A) Current impact on the monthly sunspot number based on the Boulder
(NOAA/SWPC) sunspot number (accumulated daily sunspots / month days). The
official SIDC international sunspot number is typically 30-50% lower. 2B) Month
average to date.
3) Running average based on the preliminary daily SWPC ap indices.
Values in red are based on the official NGDC
ap indices.
This report has been prepared by Jan Alvestad. It is based on analysis of data from whatever sources are available at the time the report is prepared. All time references are to the UTC day. Comments and suggestions are always welcome.
SDO images are courtesy of NASA/SDO and the AIA, EVE, and HMI science teams.
