Last major update issued on December 24, 2011 at 04:50 UTC.
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June 27, 2011]
The geomagnetic field was very quiet on December 23. Solar wind speed ranged between 348 and 439 km/s.
Solar flux measured at 20h UTC on 2.8 GHz was 138.2 (increasing 5.4 over the last solar rotation). The planetary A index was 1 (STAR Ap - based on the mean of three hour interval ap indices: 1.0). Three hour interval K indices: 11000000 (planetary), 11010211 (Boulder).
The background x-ray flux is at the class B4 level.
At midnight UTC the visible solar disk had 9 spotted regions (in 2K resolution SDO images).
Region 11380 [S21W04] was quiet and stable.
Region 11381 [S18W43] decayed further and could soon become spotless.
Region 11382 [S17W37] decayed slowly and was quiet.
Region 11383 [N04E15] was quiet and stable.
Region 11384 [N13E25] was mostly quiet with no significant changes
observed. A minor M class flare
is still possible. Flare: C1.5 at 10:14 UTC
New region 11385 [S30W02] emerged in the southeast quadrant on December
21 and was noticed vy SWPC 2 days later. The region decayed slowly on Dec.23.
New region 11386 [S16E72] rotated into view at the southeast limb on
December 22 and got an SWPC number the next day.
Spotted regions not reported by NOAA/SWPC:
[S1378] emerged in the northern hemisphere near the central meridian on
December 17. Note that SWPC considers this to be region 11376. The region
developed slowly on Dec.19, then very quickly on Dec.20-21. Location at midnight:
N19W85. Flare: C3.4 at 19:18 UTC
[S1392] rotated into view at the southeast limb on December 23. Location at midnight:
S19E80
December 21-23: 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
An extension (CH490) of the southern polar coronal hole could rotate into an Earth facing position on December 26-27.
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 good. Propagation on long distance northeast-southwest paths is poor.
The geomagnetic field is expected to be quiet on December 24-26.
| 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 | |||||
| 11376 | 2011.12.11 2011.12.13 |
7 | N16W84 | 0330 | DKO |
spotless location: N25W71 note that SWPC has region S1378 as 11376 |
||||
| 11377 | 2011.12.13 2011.12.14 |
N12W82 | plage | |||||||
| 11381 | 2011.12.16 2011.12.18 |
8 | 4 | S20W44 | 0040 | DAO | BXO |
 |
 |
location: S18W43 area: 0005 |
| 11380 | 2011.12.16 2011.12.17 |
4 | S21W11 | 0000 | BXO |
 |
 |
location: S21W04 | ||
| 11382 | 2011.12.17 2011.12.18 |
15 | 21 | S18W35 | 0100 | DSI | DAO |
 |
 |
area: 0200 location: S17W37 |
| S1378 | 2011.12.17 | 1 | N19W85 | 0350 | HKX |
 |
 |
|||
| 11383 | 2011.12.18 2011.12.19 |
3 | 7 | N03E13 | 0010 | AXX | HRX |
 |
 |
location: N04E15 area: 0030 |
| S1380 | 2011.12.18 | N27W26 | plage | |||||||
| 11384 | 2011.12.19 2011.12.20 |
12 | 17 | N13E25 | 0500 | DHO | EHO |
 |
 |
area: 0750 |
| S1383 | 2011.12.19 | S22W47 | plage | |||||||
| S1384 | 2011.12.19 | N18W48 | plage | |||||||
| S1385 | 2011.12.20 | S03W17 | plage | |||||||
| S1386 | 2011.12.20 | N20E07 |
 |
plage | ||||||
| S1387 | 2011.12.20 | N12W16 |
 |
plage | ||||||
| S1388 | 2011.12.21 | S15W00 | plage | |||||||
| 11385 | 2011.12.21 2011.12.23 |
7 | 4 | S31W02 | 0030 | DSO | BXO |
 |
 |
area: 0010 |
| 11386 | 2011.12.22 2011.12.23 |
1 | 1 | S16E72 | 0030 | HSX | HSX |
 |
 |
|
| S1392 | 2011.12.23 | 1 | S19E80 | 0060 | HSX |
 |
||||
| Total spot count: | 53 | 60 | ||||||||
| Sunspot number: | 123 | 150 | (total spot count + 10 * number of spotted regions) | |||||||
| Weighted penumbral SN: | 93 | 98 | (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): | 74 | 68 | 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 | 140.9 (1) | 79.7 (2A) / 107.4(2B) | (82.1 projected, +5.5) | (3.48) |
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.
