Solar Terrestrial Activity Report

Last major update issued on December 8, 2011 at 05:55 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 7. Solar wind speed ranged between 270 and 332 km/s.

Solar flux measured at 20h UTC on 2.8 GHz was 148.9 (decreasing 29.7 over the last solar rotation). The planetary A index was 1 (STAR Ap - based on the mean of three hour interval ap indices: 1.4). Three hour interval K indices: 00010101 (planetary), 00000111 (Boulder).

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

At midnight UTC the visible solar disk had 21 spotted regions (in 2K resolution SDO images).

Region 11362 [N08W61] decayed slowly and lost all penumbra on the trailing spots.
Region 11363 [S17W37] was quiet and stable.
Region 11364 [N19W29] developed as new flux emerged near the largest penumbra. Flare: C1.3 at 15:39 UTC
Region 11365 [N19W49] decayed and could soon become spotless.
Region 11366 [N18E13] was quiet and stable.
Region 11367 [S17W03] decayed slowly and quietly.
Region 11368 [S15E27] decayed slowly and quietly.
Region 11369 [N22E17] decayed slowly and quietly.
New region 11370 [S25W03] emerged in the southeast quadrant on December 5 and was numbered by SWPC 2 days later. The region decayed slowly on Dec.7.
New region 11371 [N10E14] emerged in the northeast quadrant on December 4 and was noticed by SWPC 3 days later. Slow decay was observed on Dec.7.
New region 11372 [N08E32] emerged in the northeast quadrant on December 6 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 the region has decayed moderately quickly since December 4. Location at midnight: S22W33.
[S1349] was split off from 11366 on December 4. Location at midnight: N28E14
[S1353] emerged in the northeast quadrant on December 4. Location at midnight: N14E25
[S1355] emerged in the northeast quadrant on December 5. Location at midnight: N23W06
[S1358] rotated into view at the southeast limb on December 7. Location at midnight: S17E81
[S1359] emerged in the southwest quadrant on December 7. Location at midnight: S29W24
[S1360] emerged in the northwest quadrant on December 7. Location at midnight: N17W65
[S1361] emerged in the northeast quadrant on December 7. Location at midnight: N30E45
[S1362] emerged in the southeast quadrant on December 7. Location at midnight: S20E32
[S1363] emerged in the southeast quadrant on December 7. Location at midnight: S14E05

Coronal mass ejections (CMEs)

December 5-7: 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 will be in 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 to good. Propagation on long distance northeast-southwest paths is poor.

Forecast

The geomagnetic field is expected to be quiet on December 8-10. 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
11362 2011.11.27 3 7 N06W59 0180 ESO CSO area: 0080

location: N08W61

11363 2011.11.28
2011.11.29
12 1 S22W32 0400 EHI HAX

location: S17W37

area: 0050

SWPC includes S1342 in this region

11364 2011.11.28
2011.11.29
1 7 N18W30 0060 HSX DSO area: 0120
S1342 2011.11.28   14 S22W33 0550   DHO  
S1343 2011.11.29     S12W56         plage
11365 2011.12.01
2011.12.02
1 1 N17W48 0010 AXX AXX  
11366 2011.12.02
2011.12.03
2 5 N17E13 0070 CSO HSX area: 0110
11367 2011.12.04 4 4 S26W03 0010 BXO BXO location: S17W03
S1349 2011.12.04   4 N28E14 0000   BXO  
11369 2011.12.04
2011.12.05
  1 N22E15 0010   AXX location: N22E17
11371 2011.12.04
2011.12.07
1 3 N09E13 0010 HRX AXX location: N10E14
S1352 2011.12.04     N10W54           plage
S1353 2011.12.04   1 N14E25 0000   AXX  
11368 2011.12.05   1 S16E27 0000   AXX  
11370 2011.12.05
2011.12.07
6 6 S24W03 0010 BXO CRO  
S1355 2011.12.05   1 N23W06 0000   AXX  
S1356 2011.12.05     S16W21           plage
11372 2011.12.06
2011.12.07
2 4 N10E28 0000 BXO BXO  
S1358 2011.12.07   1 S17E81 0350   HHX    
S1359 2011.12.07   2 S29W24 0020   CRO    
S1360 2011.12.07   4 N17W65 0050   DAO    
S1361 2011.12.07   1 N30E45 0000   AXX    
S1362 2011.12.07   1 S20E32 0000   AXX    
S1363 2011.12.07   3 S14E05 0000   AXX    
Total spot count: 32 72  
Sunspot number: 122 282  (total spot count + 10 * number of spotted regions)
Weighted penumbral SN: 60 123  (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): 73 127  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
2011.12 155.9 (1) 30.2 (2A) / 133.9 (2B) (82.1 projected, +5.5) (4.18)

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.