Solar Terrestrial Activity Report

Last major update issued on December 10, 2011 at 04:50 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 8, 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 9. Solar wind speed ranged between 274 and 373 km/s. The leading edge of a high speed stream, probably from CH487, was observed arriving at ACE near 21:30 UTC. Solar wind speed is slowly increasing early on December 10.

Solar flux measured at 20h UTC on 2.8 GHz was 143.5 (decreasing 25.3 over the last solar rotation). The planetary A index was 3 (STAR Ap - based on the mean of three hour interval ap indices: 3.0). Three hour interval K indices: 00112101 (planetary), 00112211 (Boulder).

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

At midnight UTC the visible solar disk had 14 spotted regions (in 2K resolution SDO images).

Region 11364 [N19W57] decayed slowly and quietly.
Region 11365 [N20W76] was quiet and stable.
Region 11366 [N19W14] was quiet and stable.
Region 11367 [S17W33] developed slowly and was quiet.
Region 11368 [S14W02] was quiet and stable.
Region 11369 [N23W07] was quiet and stable.
Region 11372 [N09E05] developed slowly and was quiet.
Region 11373 [S29W53] decayed slowly and quietly.
Region 11374 [S17E56] displayed no major changes and was mostly quiet. Flare: C3.1 at 13:20 UTC
Region 11375 [N10E54] matured and was quiet.

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 moderately quick decay has been observed since December 4. Location at midnight: S23W60.
[S1349] was split off from 11366 on December 4. Location at midnight: N29W11
[S1353] emerged in the northeast quadrant on December 4. Location at midnight: N15W03
[S1364] emerged in the northeast quadrant on December 9. Location at midnight: N14E26

Coronal mass ejections (CMEs)

December 7-9: 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 was 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 poor to fair. Propagation on long distance northeast-southwest paths is poor to fair.

Forecast

The geomagnetic field is expected to be quiet to unsettled with a chance of active conditions on December 10-11 due to effects from CH487. Quiet conditions are likely on December 12-13

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 1   N07W85 0060 HSX     rotated out of view
11363 2011.11.28
2011.11.29
3   S20W62 0280 DHO    

location: S17W64

spotless

SWPC includes S1342 in this region

11364 2011.11.28
2011.11.29
3 3 N17W57 0080 CSO CSO  
S1342 2011.11.28   4 S23W60 0350   CKO  
11365 2011.12.01
2011.12.02
1 1 N16W91

(N20W76)

0120 HSX AXX SWPC has reassigned 11365 to a new region 15 degrees further west

area: 0000

11366 2011.12.02
2011.12.03
2 8 N18W13 0050 CSO HSX area: 0100
11367 2011.12.04   7

S18W33

0010   BXO  
S1349 2011.12.04   3 N29W11 0000   AXX  
11369 2011.12.04
2011.12.05
  2 N22W13 0000   BXO location: N23W07
11371 2011.12.04
2011.12.07
    N09W15         plage
S1353 2011.12.04   3 N15W03 0000   AXX  
11368 2011.12.05   1 S14W02 0000   AXX  
11370 2011.12.05
2011.12.07
    S24W31         plage
S1355 2011.12.05     N23W32           plage
S1356 2011.12.05     S16W47           plage
11372 2011.12.06
2011.12.07
6 16 N08E03 0040 DSO DRI location: N09E05
11374 2011.12.07
2011.12.08
2 7 S17E54 0160 HSX CKO area: 0350
11373 2011.12.07
2011.12.08
5 2 S31W51 0020 BXO AXX location: S29W53

area: 0000

S1361 2011.12.07     N30E19           plage
S1362 2011.12.07     S20E06           plage
S1363 2011.12.07     S14W21           plage
11375 2011.12.08 3 12 N09E52 0070 CSO CSI area: 0120

location: N10E54

S1364 2011.12.09   3 N14E26 0000   BXO    
Total spot count: 26 72  
Sunspot number: 116 212  (total spot count + 10 * number of spotted regions)
Weighted penumbral SN: 71 110  (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): 70 95  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
2011.12 153.7 (1) 38.5 (2A) / 132.8 (2B) (82.1 projected, +5.5) (3.85)

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.