Solar Terrestrial Activity Report

Activity chart

Last major update issued on November 27, 2012 at 05:05 UTC.

[Solar and geomagnetic data - last month (updated daily)]
[Solar wind and electron fluence charts (updated daily)]
[Solar cycles 23-24 (last update November 1, 2012)] [Cycle 24 progress (last update November 1, 2012) ]
[Solar cycles 1-20]
[Graphical comparison of cycles 21, 22, 23 and 24 (last update November 1, 2012)]
[Graphical comparison of cycles 10, 12, 13, 14, 16 and 24 (last update November 1, 2012)]
[Historical solar and geomagnetic data charts 1954-2006 (last update April 5, 2007)]
[Archived reports since January 2003 (last update November 4, 2012)]

[POES auroral activity level since October 2009 - updated October 7, 2012]
[Solar polar fields vs solar cycles - updated June 27, 2011]

Recent activity

The geomagnetic field was quiet to unsettled on November 26. Solar wind speed at SOHO ranged between 446 and 583 km/s. A weak solar wind shock was observed at 04:32 UTC at SOHO, the arrival of the CME observed on November 23. The interplanetary magnetic field was weak and predominantly northwards after the shock resulting in a decrease in geomagnetic disturbance levels.

Solar flux measured at 20h UTC on 2.8 GHz was 121.8 (increasing 15.5 over the last solar rotation). The Potsdam WDC planetary A index was 5 (STAR Ap - based on the mean of three hour interval ap indices: 5.1). Three hour interval K indices: 32110111 (planetary), 32211111 (Boulder).

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

At midnight UTC the visible solar disk had 9 spotted active regions (in 2K resolution SDO images).

Region 11618 [N08W67] decayed very quickly and had only rudimentary penumbra left on both polarities by the end of the day.
Region 11620 [S12W29] developed further and has a magnetic delta structure in a central penumbra. There's a fair chance of an M class flare from this region today.
Region 11621 [N15E51] was quiet and stable.
New region 11622 [S25E18] emerged on November 23 and was numbered by SWPC 3 days later. The region decayed slowly during the day.

Spotted regions not numbered by NOAA/SWPC:
S2072 [S17E27] decayed slowly and quietly.
S2073 [S08E09] reemerged with a single tiny spot.
New region S2076 [N08E86] rotated partly into view with a single large spot.
New region S2077 [S40E11] emerged with a tiny spot at a high latitude.
New region S2078 [N11E33] emerged with a tiny spot.

An interesting filament eruption was observed beginning early on November 27 near AR 11621. An analysis of this event and the associated CME will have to await the availability of relevant images.

Coronal mass ejections (CMEs)

November 24-26: 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 recurrent trans equatorial coronal hole (CH546) will rotate into an Earth facing position on November 27.

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.


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


The geomagnetic field is expected to be quiet on November 27-29. A high speed stream from CH546 could cause quiet to active conditions on November 30 and December 1.

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
Spot count Location at midnight Area Classification SDO / HMI 4K continuum
image with magnetic polarity overlay
2K 1K
11618 2012.11.15
15 17 7 N08W69 0270 EKI DRI beta-gamma

area: 0070

11620 2012.11.18
23 46 17 S13W28 0240 ESI EKC beta-gamma-delta

area: 0600

S2064 2012.11.19       S21W19           plage
S2066 2012.11.20       S08W49         plage
S2067 2012.11.21       S17W39           plage
S2069 2012.11.22       N18W49           plage
11622 2012.11.23
2 3 2 S24E16 0010 BXO BXO  
S2071 2012.11.23       S20W21           plage
11621 2012.11.24 1 2 2 N15E48 0110 HSX HSX area: 0200

location: N15E51

S2072 2012.11.24   2 1 S17E27 0000   BXO  
S2073 2012.11.24   1   S08E09 0000   AXX    
S2074 2012.11.24       N15W17           plage
S2075 2012.11.24       S05W31           plage
S2076 2012.11.26   1 1 N08E86 0320   HHX    
S2077 2012.11.26   1   S40E11 0000   AXX    
S2078 2012.11.26   1   N11E33 0000   AXX    
Total spot count: 41 74 30  
Sunspot number: 81 164 90  (total spot count + 10 * number of spotted regions)
Weighted SN: 61 102 58  (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): 49 57 50 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
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
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 (61.2 projected, -3.4) 7.06
2012.06 119.6 64.5 (58.8 projected, -2.4) 10.08
2012.07 133.9 66.5 (58.6 projected, -0.2) 13.90
2012.08 115.4 63.1 (60.4 projected, +1.8) 7.96
2012.09 122.9 61.5 (61.8 projected, +1.4) 8.07
2012.10 123.3 53.3 (61.5 projected, -0.3) 9.97
2012.11 122.5 (1) 79.7 (2A) / 91.9 (2B) / 57.6 (2C) (61.2 projected, -0.3) (7.91)

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.