Solar Terrestrial Activity Report

Last major update issued on December 7, 2011 at 03:55 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 very quiet on December 6. Solar wind speed ranged between 270 and 356 km/s.

Solar flux measured at 20h UTC on 2.8 GHz was 151.1 (decreasing 29.1 over the last solar rotation). The planetary A index was 1 (STAR Ap - based on the mean of three hour interval ap indices: 1.3). Three hour interval K indices: 00001100 (planetary), 00001110 (Boulder).

The background x-ray flux is at the class B4 level.

At midnight UTC the visible solar disk had 16 spotted regions (in 2K resolution SDO images).

Region 11362 [N07W45] decayed slowly and has weak polarity intermixing.
Region 11363 [S17W23] was quiet and stable.
Region 11364 [N20W15] was quiet and stable.
Region 11365 [N20W37] decayed slowly and quietly.
Region 11366 [N18E26] was quiet and stable.
Region 11367 [S17E08] decayed slowly and quietly.
Region 11368 [S15E41] decayed slowly and quietly.
Region 11369 [N22E32] decayed slowly and quietly.

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.4-6. There's minor polarity intermixing. Location at midnight: S22W19.
[S1343] emerged in the southeast quadrant on November 29, became spotless and reemerged on Dec.6. Location at midnight: S12W43
[S1349] was split off from 11366 on December 4. Location at midnight: N27E26
[S1351] emerged in the northeast quadrant on December 4, became spotless and reemerged on Dec.6. Location at midnight: N10E28
[S1353] emerged in the northeast quadrant on December 4. Location at midnight: N13E36
[S1354] emerged in the southeast quadrant on December 5 and developed on Dec.6. Location at midnight: S25E11
[S1355] emerged in the northeast quadrant on December 5. Location at midnight: N24E07
[S1357] emerged in the northeast quadrant on December 6. Location at midnight: N09E46

Coronal mass ejections (CMEs)

December 4-6: No obviously Earth directed CMEs observed.

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 7-8.

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 7-10. On December 11-12 there's a chance of a few unsettled and active intervals due to effects from CH487.

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
2   N18W81 0010 BXO    

spotless

11362 2011.11.27 7 8 N06W46 0110 ESO ESO

beta-gamma

11363 2011.11.28
2011.11.29
19 2 S22W20 0340 EHI HAX

location: S17W23

area: 0050

SWPC includes S1342 in this region

11364 2011.11.28
2011.11.29
1 6 N19W15 0040 HSX CSO area: 0100
S1342 2011.11.28   30 S22W19 0600   DHI beta-gamma
S1343 2011.11.29   1 S12W43 0000   AXX    
S1344 2011.11.30     N18W54           plage
11365 2011.12.01
2011.12.02
13 7 N20W37 0020 CSO CRO  
11366 2011.12.02
2011.12.03
2 1 N18E25 0080 DSO HSX area: 0110
11367 2011.12.04 3 5 S18E09 0010 BXO BXO  
S1349 2011.12.04   3 N27E26 0000   BXO  
11369 2011.12.04
2011.12.05
3 5 N22E32 0010 BXO BXO  
S1351 2011.12.04   5 N10E28 0010   CRO    
S1352 2011.12.04     N10W28           plage
S1353 2011.12.04   2 N13E36 0000   BXO  
11368 2011.12.05 3 4 S16E41 0010 BXO BXO  
S1354 2011.12.05   5 S25E11 0040   DRO  
S1355 2011.12.05   3 N24E07 0000   AXX  
S1356 2011.12.05     S16W08         plage
S1357 2011.12.06   2 N09E46 0000   BXO    
Total spot count: 53 89  
Sunspot number: 143 249  (total spot count + 10 * number of spotted regions)
Weighted penumbral SN: 83 128  (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): 86 112  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
2011.12 157.1 (1) 26.3 (2A) / 135.8 (2B) (82.1 projected, +5.5) (4.65)

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.