Solar Terrestrial Activity Report

Last major update issued on December 6, 2011 at 05:50 UTC.

[Solar and geomagnetic data - last month (updated daily)]
[Solar wind and electron fluence charts (updated daily)
[Solar cycles 21-24 (last update December 1, 2011)] - new cycle peak projection
[Solar cycles 1-20]
[Graphical comparison of cycles 21, 22, 23 and 24 (last update December 1, 2011)]
[Graphical comparison of cycles 10, 12, 13, 14, 16 and 24 (last update December 1, 2011)]
[Historical solar and geomagnetic data charts 1954-2006 (last update April 5, 2007)]
[Archived reports since January 2003 (last update December 2, 2011)]

[POES auroral activity level since October 2009 - updated December 5, 2011]
Annotated geomagnetic activity charts - Carrington rotation 2115 [September-October 2011] - 2116 [October-November 2011] NEW
[Solar polar fields vs solar cycles - updated June 27, 2011]

Recent activity

The geomagnetic field was quiet on December 5. Solar wind speed ranged between 336 and 386 km/s.

Solar flux measured at 20h UTC on 2.8 GHz was 158.1 (decreasing 22.1 over the last solar rotation). The planetary A index was 2 (STAR Ap - based on the mean of three hour interval ap indices: 2.1). Three hour interval K indices: 00001101 (planetary), 11001211 (Boulder).

The background x-ray flux is at the class B5 level.

At midnight UTC the visible solar disk had 15 spotted regions (in 2K resolution SDO images).

Region 11361 [N19W71] decayed slowly and was mostly quiet.
Region 11362 [N08W32] decayed slowly and has weak polarity intermixing. Flares: C1.4 at 06:54, C3.7 at 13:45 UTC.
Region 11363 [S17W11] was quiet and stable.
Region 11364 [N20E09] was quiet and stable.
Region 11365 [N20W24] decayed slowly and quietly.
Region 11366 [N18E38] was quiet and stable.
Region 11367 [S17E22] decayed slowly and quietly.
New region 11368 [S16E55] emerged in the southeast quadrant.
New region 11369 [N22E45] emerged in the northeast quadrant on December 4 and got an SWPC number the next day.

Spotted regions not reported by NOAA/SWPC:
[S1342] rotated into view at the southeast limb on Nov.28. The region developed quickly on Dec.1-3 while decay was observed in the trailing and central spot sections on Dec.4-5. There's some polarity intermixing. Location at midnight: S22W05. Flares: C4.7 at 15:18, C2.5 at 19:07, C6.9 at 23:25 UTC.
[S1349] was split off from 11366 on December 4. Location at midnight: N27E37
[S1353] emerged in the northeast quadrant on December 4. Location at midnight: N13E53
[S1354] emerged in the southeast quadrant on December 5. Location at midnight: S25E24
[S1355] emerged in the northeast quadrant on December 5. Location at midnight: N21E12
[S1356] emerged in the southeast quadrant on December 5. Location at midnight: S16E05

Coronal mass ejections (CMEs)

December 3-5: No obviously Earth directed CMEs observed. Lots of backsided CMEs observed on Dec.3-4.

Coronal holes

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 (CH487) in the northern hemisphere could rotate into an Earth facing position on December 8.

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.

Propagation

Long distance low and medium frequency (below 2 MHz) propagation along paths north of due west over high and upper middle latitudes is fair. Propagation on long distance northeast-southwest paths is poor.

Forecast

The geomagnetic field is expected to be quiet on December 6-8.

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.

Active solar regions

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
11361 2011.11.24
2011.11.25
10 8 N18W71 0090 DAI DRO

area: 0040

S1337 2011.11.25     S17W51           plage
11362 2011.11.27 19 13 N08W32 0170 DSO ESO

 

11363 2011.11.28
2011.11.29
35 4 S21W09 0620 EKI HSX

location: S17W11

area: 0050

SWPC includes S1342 in this region

11364 2011.11.28
2011.11.29
1 4 N18W05 0050 HSX HSX area: 0110

location: N20W03

S1342 2011.11.28   36 S22W05 0650   EHI beta-gamma
S1343 2011.11.29     S10W28         plage
S1344 2011.11.30     N18W41           plage
11365 2011.12.01
2011.12.02
16 21 N19W26 0110 DAI DAO

location: N20W24

area: 0060

11366 2011.12.02
2011.12.03
1 2 N18E38 0070 HSX HSX area: 0110
11367 2011.12.04 4 9 S18E22 0015 DAO DRO  
S1349 2011.12.04   3 N27E37 0000   BXO  
11369 2011.12.04
2011.12.05
4 4 N22E43 0020 CAO CRO  
S1351 2011.12.04     N08E35         plage
S1352 2011.12.04     N10W15         plage
S1353 2011.12.04   1 N13E53 0000   AXX  
11368 2011.12.05 5 6 S18E58 0020 CAO DRO    
S1354 2011.12.05   3 S25E24 0000   BXO    
S1355 2011.12.05   1 N21E12 0000   AXX    
S1356 2011.12.05   1 S16E05 0000   AXX    
Total spot count: 95 116  
Sunspot number: 185 266  (total spot count + 10 * number of spotted regions)
Weighted penumbral SN: 145 163  (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): 111 120  k * (sunspot number). k = 0.6 for SWPC. k = 0.45 (changed from 0.33 on Nov.1) for STAR SDO

Monthly solar cycle data

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
2011.12 158.2 (1) 21.7 (2A) / 134.4 (2B) (82.1 projected, +5.5) (5.33)

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.