Solar Terrestrial Activity Report

Last major update issued on January 9, 2012 at 05:00 UTC.

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

[POES auroral activity level since October 2009 - updated January 5, 2012]
Annotated geomagnetic activity charts - Carrington rotation 2116 [October-November 2011] - 2117 [November-December 2011]
[Solar polar fields vs solar cycles - updated June 27, 2011]

Recent activity

The geomagnetic field was quiet on January 8. Solar wind speed ranged between 412 and 461 km/s, weakly under the influence of a high speed coronal hole stream associated with CH491.

Solar flux measured at 20h UTC on 2.8 GHz was 135.8 (increasing 4.3 over the last solar rotation). The planetary A index was 4 (STAR Ap - based on the mean of three hour interval ap indices: 3.8). Three hour interval K indices: 11100121 (planetary), 12212211 (Boulder).

The background x-ray flux is at the class B5 level.

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

Region 11388 [S25W85] decayed slowly and quietly as it rotated to the southwest limb.
Region 11389 [S18W74] decayed slightly and was quiet.
Region 11391 [N13E02] displayed no major changes and was quiet.
Region 11392 [N22W55] decayed slowly and quietly.
Region 11393 [N17W43] developed quickly in the trailing spot section. There's a weak magnetic delta structure in the southern part of the trailing penumbra. An M class flare is possible. Flares: C2.9 at 03:25, C1.9 at 06:13 UTC.
Region 11394 [N19E16] decayed and could soon become spotless.
New region 11395 [N21E61] rotated into view at the northeast limb on January 7 and got and SWPC number the next day.

Spotted regions not reported (or interpreted differently) by NOAA/SWPC:
[S1418] emerged in the northwest quadrant on January 8. Location at midnight: N23W27
[S1419] emerged in the southeast quadrant on January 8. Location at midnight: S22E19

Coronal mass ejections (CMEs)

January 6-8: 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 coronal hole (CH492) in the southern hemisphere will rotate into an Earth facing position on January 9-10.

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

Forecast

The geomagnetic field is expected to be quiet on January 9-11. Weak effects from CH492 could cause a few unsettled intervals on January 12-13.

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
11388 2011.12.26
2011.12.27
1 1 S26W92 0030 HSX HSX

location: S25W85

11389 2011.12.27
2011.12.28
1 1 S20W75 0180 HSX HHX

area: 0260

location: S18W74

S1401 2011.12.28     S24W74         plage
11391 2012.01.02 12 26 N13W00 0300 DKO EHI

area: 0450

S1406 2012.01.02     N08W34            
11392 2012.01.02
2012.01.03
2 3 N19W58 0020 CSO BXO location: N22W55
11393 2012.01.04
2012.01.05
13 20 N17W43 0250 DKI EKI beta-gamma-delta

area: 0900

S1409 2012.01.04     S15W54           plage
11394 2012.01.05
2012.01.06
  2 N18E12 0000   AXX  
S1411 2012.01.06     S17E37           plage
S1413 2012.01.06     N33W06           plage
11395 2012.01.07
2012.01.08
1 6 N22E59 0120 HSX CHO location: N21E61

area: 0280

S1415 2012.01.07     N12E27         plage
S1416 2012.01.07     S12W68         plage
S1417 2012.01.07     S24W29         plage
S1418 2012.01.08   1 N23W27 0000   AXX    
S1419 2012.01.08   2 S22E19 0000   AXX    
Total spot count: 30 62  
Sunspot number: 90 152  (total spot count + 10 * number of spotted regions)
Weighted penumbral SN: 70 107  (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): 54 68  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 53.2 (+5.6) 8.96 / 8.06
2011.07 94.2 43.9 (57.8 projected, +4.6) 9.14 / 8.16
2011.08 101.7 50.6 (62.0 projected, +4.2) 8.16 / 7.26
2011.09 133.8 78.0 (65.3 projected, +3.3) 12.80 / 12.27
2011.10 137.3 88.0 (68.8 projected, +3.5) 7.52
2011.11 153.5 96.7 (73.2 projected, +4.3) 4.58
2011.12 141.3 73.0 (78.6 projected, +5.5) 3.32
2012.01 136.1 (1) 23.5 (2A) / 91.0 (2B) (84.4 projected, +5.8) (4.42)

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.