Solar Terrestrial Activity Report

Last major update issued on December 16, 2011 at 05:10 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)]
[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 14, 2011]
Annotated geomagnetic activity charts - Carrington rotation 2115 [September-October 2011] - 2116 [October-November 2011]
[Solar polar fields vs solar cycles - updated June 27, 2011]

Recent activity

The geomagnetic field was very quiet on December 15. Solar wind speed ranged between 336 and 373 km/s.

Solar flux measured at 20h UTC on 2.8 GHz was 124.2 (decreasing 20.2 over the last solar rotation). The planetary A index was 1 (STAR Ap - based on the mean of three hour interval ap indices: 1.1). Three hour interval K indices: 00100000 (planetary), 01111111 (Boulder).

The background x-ray flux is at the class B3 level.

At midnight UTC the visible solar disk had 7 spotted regions (in 2K resolution SDO images).

Region 11374 [S16W22] was quiet and stable.
Region 11375 [N10W29] was quiet and stable.
Region 11376 [N25E33] decayed slowly and quietly
Region 11377 [N13E32] was quiet and stable.

Spotted regions not reported by NOAA/SWPC:
[S1365] emerged in the southeast quadrant on December 11, became spotless the next day and reemerged with several spots on Dec.13. Location at midnight: S15E05
[S1371] emerged in the northeast quadrant on December 14. Location at midnight: N22E13
[S1372] emerged in the northwest quadrant on December 15. Location at midnight: N17W27

Coronal mass ejections (CMEs)

December 13-15: 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 (CH488) in the southern hemisphere was in an Earth facing position on December 11-12. A small recurrent coronal hole (CH489) in the northern hemisphere will likely rotate to an Earth facing position on December 16-17.

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 16-18. On December 19-20 quiet to unsettled conditions are likely due to weak effects from CH489.

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
11372 2011.12.06
2011.12.07
    N08W77           plage
11374 2011.12.07
2011.12.08
5 7 S18W25 0160 DSO CSO

area: 0200

location: S16W22

11375 2011.12.08 1 6 N08W30 0050 HSX CSO location: N10W29

area: 0070

S1364 2011.12.09     N15W54           plage
S1365 2011.12.11   6 S15E05 0010   BXO  
11376 2011.12.11
2011.12.13
  17 N20E25 0010   BXO location: N25E33
S1367 2011.12.11     S27W39           plage
11377 2011.12.13
2011.12.14
8 15 N11E29 0070 DSO DSO location: N13E32

area: 0120

S1370 2011.12.13     S04W01           plage
S1371 2011.12.14   5 N22E13 0000   BXO  
S1372 2011.12.15   1 N17W27 0000   AXX    
Total spot count: 14 57  
Sunspot number: 44 127  (total spot count + 10 * number of spotted regions)
Weighted penumbral SN: 29 72  (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): 26 57  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
2011.12 145.2 (1) 52.6 (2A) / 108.7 (2B) (82.1 projected, +5.5) (3.93)

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.