Solar Terrestrial Activity Report

Activity chart

Last major update issued on December 10, 2012 at 05:25 UTC.

[Solar and geomagnetic data - last month (updated daily)]
[Solar wind and electron fluence charts (updated daily)]
[Solar cycles 23-24 (last update December 1, 2012)] [Cycle 24 progress (last update December 2, 2012) ]
[Solar cycles 1-20]
[Graphical comparison of cycles 21, 22, 23 and 24 (last update December 1, 2012)]
[Graphical comparison of cycles 10, 12, 13, 14, 16 and 24 (last update December 1, 2012)]
[Historical solar and geomagnetic data charts 1954-2006 (last update April 5, 2007)]
[Archived reports since January 2003 (last update December 7, 2012)]

[POES auroral activity level since October 2009 - updated October 7, 2012]
[Solar polar fields vs solar cycles - updated December 9, 2012]

Recent activity

The geomagnetic field was quiet to unsettled on December 9. Solar wind speed at SOHO ranged between 273 and 343 km/s, most of the day under the influence of a weak low speed coronal hole stream.

Solar flux measured at 20h UTC on 2.8 GHz was 103.7 (decreasing 40.1 over the last solar rotation). The Potsdam WDC planetary A index was 4 (STAR Ap - based on the mean of three hour interval ap indices: 4.0). Three hour interval K indices: 10000113 (planetary), 02011212 (Boulder).

The background x-ray flux was at the class B1 level.

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

Region 11628 [N12E18] developed slowly and could produce C flares.
New region 11630 [N19E03] emerged on December 6 and got its NOAA number 3 days later. The region developed further on December 9 and has polarity intermixing. A single small C class event was observed during the day and further C class activity is likely.

Spotted regions not numbered by NOAA/SWPC:
S2094 [N17W23] reemerged with a tiny spot.
S2095
[S26W00] was quiet and stable.
S2097 [N09W47] reemerged with a tiny spot.
New region S2102 [N07E37] emerged with a tiny spot.
New region S2103 [N03W13] formed near the equator with an east-west oriented neutral line.

Coronal mass ejections (CMEs)

December 7-9: No obviously Earth directed CMEs were observed in LASCO and STEREO imagery.

Coronal holes

Coronal hole history (since October 2002)
Compare today's report to the situation one solar rotation ago: 28 days ago 27 days ago 26 days ago

A small recurrent trans equatorial coronal hole (CH547) was in an Earth facing position on December 6-7.

Coronal hole map

The above coronal hole map is based on a method where coronal holes are detected automatically. While the method may need some fine tuning, 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 this method, the extent and intensity of both CHs 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 to fair.

Forecast

The geomagnetic field is expected to be quiet to unsettled on December 10-11 due to a weak disturbance associated with CH547 and quiet on December 12-13. 

Coronal holes (1) Coronal mass ejection (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. 0.5k 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
2K 1K
11623 2012.11.26
2012.11.27
1     N07W87 0040 HSX    

rotated out of view

11626 2012.12.02
2012.12.04
      N11W44           plage
S2089 2012.12.02       N15W40           plage
S2090 2012.12.03       S16W51           plage
11627 2012.12.03
2012.12.05
      S16W65           plage
11628 2012.12.04
2012.12.05
  18 8 N09E09 0130   DAI location: N12E18

see AR 11629

S2093 2012.12.04       N23W34           plage
S2094 2012.12.05   1   N17W23 0000   AXX   plage
S2095 2012.12.06   4   S26W00 0000   BXO  
11630 2012.12.06
2012.12.09
5 22 9 N18E02 0040 DAO DAI area: 0140
S2097 2012.12.06   1 1 N09W47 0000   AXX    
S2100 2012.12.07       N05E14           plage
11629 2012.12.08 4     N11E19 0050 DAO       see AR 11628
S2101 2012.12.08       S15E32         plage
S2102 2012.12.09   1   N07E37 0000   AXX    
S2103 2012.12.09   2 2 N03W13 0010   BXO    
Total spot count: 10 49 20  
Sunspot number: 40 119 60  (total spot count + 10 * number of spotted regions)
Weighted SN: 25 59 30  (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): 24 42 33 k * (sunspot number). k = 0.6 for SWPC, k = 0.35 for STAR SDO 2K, k = 0.55 for STAR SDO 1K

Monthly solar cycle data

Month Average measured solar flux International sunspot number (SIDC) Smoothed sunspot number Average ap
(3)
2011.09 133.8 78.0 59.5 (+0.5) 12.27
2011.10 137.3 88.0 59.9 (+0.4) 8.28
2011.11 153.5 96.7 61.1 (+1.2) 5.55
2011.12 141.3 73.0 63.4 (+2.3) 3.78
2012.01 132.5 58.3 65.5 (+2.1) 7.15
2012.02 106.5 32.9 66.9 (+1.4)
possible cycle 24 max
8.81
2012.03 114.7 64.3 66.8 (-0.1) 16.08
2012.04 113.0 55.2 64.6 (-2.2) 10.10
2012.05 121.5 69.0 61.7 (-2.9) 7.06
2012.06 119.6 64.5 (59.5 projected, -2.2) 10.08
2012.07 133.9 66.5 (58.8 projected, -0.7) 13.90
2012.08 115.4 63.1 (60.1 projected, +1.3) 7.96
2012.09 122.9 61.5 (61.1 projected, +1.0) 8.07
2012.10 123.3 53.3 (60.7 projected, -0.4) 9.97
2012.11 121.3 61.4 (60.0 projected, -0.7) 7.08
2012.12 98.6 (1) 13.5 (2A) / 46.6 (2B) / 56.9 (2C) (59.3 projected, -0.7) (3.38)

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) Boulder SN current month average to date. 2C) STAR SDO 1K Wolf number 30 day average.
3) Running average based on the quicklook and definitive Potsdam WDC ap indices. Values in red are based on the definitive international Potsdam WDC 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.