Solar Terrestrial Activity Report

Last major update issued on December 2, 2011 at 06:05 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 November 2, 2011)]

[POES auroral activity level since October 2009 - updated November 30, 2011]
Annotated geomagnetic activity charts - Carrington rotation 2114 [August-September 2011] - 2115 [September-October 2011]
[Solar polar fields vs solar cycles - updated June 27, 2011]

Recent activity

The geomagnetic field was quiet to unsettled on December 1. Solar wind speed ranged between 449 and 544 km/s under the influence of a high speed stream from CH486.

Solar flux measured at 20h UTC on 2.8 GHz was 152.2 (decreasing 11.7 over the last solar rotation). The planetary A index was 7 (STAR Ap - based on the mean of three hour interval ap indices: 7.1). Three hour interval K indices: 32212211 (planetary), 32222221 (Boulder).

The background x-ray flux is at the class B6 level.

At midnight UTC the visible solar disk had 10 spotted regions (in 2K resolution SDO images).

Region 11356 [N16W78] decayed slowly as it rotated to the northwest limb.
Region 11358 [N21W42] decayed slowly and quietly.
Region 11361 [N20W18] simplified magnetically but could produce further C flares. Flare: C1.1 at 20:32 UTC
Region 11362 [N09E24] displayed no major changes and remains capable of producing C flares.
Region 11363 [S16E42] was quiet and stable.
Region 11364 [N20E49] added a few tiny spots and was quiet.

Spotted regions not reported by NOAA/SWPC:
[S1342] rotated into view at the southeast limb on Nov.28. The region developed fairly quickly on Dec.1 and could produce minor M class flares. There's significant polarity intermixing. Location at midnight: S22E46.
[S1344] emerged in the northeast quadrant on November 30. Location at midnight: N24E17
[S1345] emerged in the northeast quadrant on December 1. Location at midnight: N21E29
[S1346] emerged near the southwest limb on December 1. Location at midnight: S14W84

Coronal mass ejections (CMEs)

November 29 - December 1: 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

No obvious coronal holes are near potentially geoeffective positions.

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. Propagation on long distance northeast-southwest paths is poor to fair.

Forecast

The geomagnetic field is expected to be quiet on December 2-4.

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
11356 2011.11.19 3 3 N17W76 0050 CSO HSX

 

11358 2011.11.22 3 10 N21W38 0090 CSO CSO

location: N21W42

11361 2011.11.24
2011.11.25
7 24 N19W18 0060 DSI DSI

 

11360 2011.11.24
2011.11.25
    N17W73           plage
S1337 2011.11.25     S17E01           plage
S1338 2011.11.26     N17W09            
11362 2011.11.27 10 29 N08E22 0180 DAI DSI beta-gamma

area: 0320

11363 2011.11.28
2011.11.29
5 4 S20E42 0120 DSI HSX

location: S16E42

SWPC includes S1342 in this region

11364 2011.11.28
2011.11.29
1 7 N18E48 0040 HSX CSO area: 0100

location: N20E49

S1342 2011.11.28   37 S22E46 0400   DAC  
S1343 2011.11.29     S10E27           plage
S1344 2011.11.30   3 N24E17 0000   AXX  
S1345 2011.12.01   3 N21E29 0000   BXO    
S1346 2011.12.01   3 S14W84 0010   BXO    
Total spot count: 29 123  
Sunspot number: 89 223  (total spot count + 10 * number of spotted regions)
Weighted penumbral SN: 59 158  (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): 53 100  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
2010.09 81.1 25.2 19.6 (+2.2) 5.33 / 5.45
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
2011.12 152.2 (1) 2.9 (2A) / 89.0 (2B) (82.1 projected, +5.5) (7.13)

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.