Solar Terrestrial Activity Report

Activity chart

Last major update issued on December 31, 2012 at 04:45 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 22, 2012]

Recent activity

The geomagnetic field was quiet on December 30. Solar wind speed at SOHO ranged between 276 and 523 km/s under the influence of a weak disturbance.

Solar flux measured at 20h UTC on 2.8 GHz was 106.7 (increasing 10.1 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: 3.8). Three hour interval K indices: 10111210 (planetary), 10112321 (Boulder).

The background x-ray flux was at the class B2 level.

At midnight UTC the visible solar disk had 12 spotted active regions (in 2K resolution SDO images).

Region 11636 [N12E02] developed slowly and quietly.
Region 11637 [N07W06] was quiet and stable.
Region 11638 [N12E33] was quiet and stable.
Region 11639 [S17E32] decayed slowly and quietly.
New region 11640 [N27E18] emerged on December 29 and developed further on Dec.30. C flares are possible.

Spotted regions not numbered by NOAA/SWPC:
S2132 [S15E07] was quiet and stable.
S2134 [N18W65] decayed slowly and quietly.
S2137 [N04E66] developed slowly and quietly.
New region S2143 [S24E86] rotated partly into view.
New region S2144 [N14W44] emerged with several spots.
New region S2145 [N22W47] emerged with a tiny spot.
New region S2146 [S18W47] emerged with a tiny spot.

Coronal mass ejections (CMEs)

December 28-30: 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

No obvious coronal holes are currently near Earth facing positions.

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.

Forecast

The geomagnetic field is expected to be quiet on December 31 - January 2. 

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
11635 2012.12.18       N13W88           plage
S2119 2012.12.20       N07W70           plage
11637 2012.12.24
2012.12.26
  5 2 N06W06 0010   AXX  
11636 2012.12.24
2012.12.25
  16 5 N09W11 0020   BXO location: N12E02
S2128 2012.12.26       S13W22           plage
11639 2012.12.26
2012.12.27
4 6 2 S17E32 0030 CRO CRO  
11638 2012.12.26
2012.12.27
1 5 3 N12E31 0150 HSX CSO area: 0240
S2131 2012.12.26       N15W23         plage
S2132 2012.12.26   2 1 S15E07 0000   AXX  
S2133 2012.12.28       N18E37           plage
S2134 2012.12.28   1   N18W65 0000   AXX  
S2135 2012.12.28       S15E19         plage
S2136 2012.12.28       S20W36           plage
S2137 2012.12.29   7 5 N04E66 0030   DRO  
S2138 2012.12.29       N03E35         plage
11640 2012.12.29
2012.12.30
2 21 11 N28E20 0040 DSO DAI area: 0100
S2140 2012.12.29       S28W08         plage
S2141 2012.12.29       N09W61         plage
S2142 2012.12.29       N13E16         plage
S2143 2012.12.30   1 1 S24E86 0120   HSX    
S2144 2012.12.30   4 3 N14W44 0010   BXO    
S2145 2012.12.30   1   N22W47 0000   AXX    
S2146 2012.12.30   1 1 S18W47 0000   AXX    
Total spot count: 7 70 34  
Sunspot number: 37 190 134  (total spot count + 10 * number of spotted regions)
Weighted SN: 20 91 55  (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): 22 67 74 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 (cycle max) 96.7 (cycle max) 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
2012.12 108.4 (1) 57.6 (2A) / 59.5 (2B) / 41.2 (2C) (59.3 projected, -0.7) (3.37)

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.