Solar Terrestrial Activity Report

Activity chart

Last major update issued on January 28, 2012 at 05:55 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 25, 2012]
Annotated geomagnetic activity charts - Carrington rotation 2117 [November-December 2011] - 2118 [December 2011 - January 2012]
[Solar polar fields vs solar cycles - updated June 27, 2011]

Recent activity

The geomagnetic field was quiet to unsettled on January 27. Solar wind speed ranged between 380 and 555 km/s under the influence of a high speed stream from CH496.

Solar flux measured at 22h UTC on 2.8 GHz was 128.6 (decreasing 4.3 over the last solar rotation. The measurements at 18 and 20h UTC were enhanced by the X flare). 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: 12322121 (planetary), 12422231 (Boulder).

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

At midnight UTC the visible solar disk had 5 spotted regions (in 2K resolution SDO images).

Region 11402 rotated out of view at the northwest limb. Flares: C5.5 at 06:42, X1.7/1F at 18:37 UTC. The latter event was associated with a radiation storm (the above 10 MeV proton flux has so far peaked near 800 pfu) and a large partial halo CME off the northwest limb.
Region 11408 [N08W09] was quiet and stable.
Region 11410 [N18E62] was quiet and stable.

Spotted regions not reported (or interpreted differently) by NOAA/SWPC:
[S1446] rotated into view at the southeast limb on January 24. Location at midnight: S18E37
[S1449] emerged in the southeast quadrant on January 26. Location at midnight: S25E23
[S1451] emerged in the northeast quadrant on January 26. Location at midnight: N08E62

Coronal mass ejections (CMEs)

January 25-27: 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 large recurrent coronal hole (CH496) in the southern hemisphere was in an Earth facing position on January 23-25. A coronal hole (CH498) in the northern hemisphere will likely rotate into an Earth facing position on January 31.

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

Forecast

The geomagnetic field is expected to be quiet to unsettled on January 28 due to coronal hole effects. Quiet conditions are likely on January 29-30.

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
11402 2012.01.14 3   N29W88 0060 CSO    

rotated out of view

11405 2012.01.15
2012.01.16
    N13W74          

plage

11409 2012.01.20
2012.01.21
    N18W28           plage
11408 2012.01.20
2012.01.21
5 9 N08W11 0080 CAO CAO area: 0170

location: N08W09

S1441 2012.01.22     S13E05         plage
S1442 2012.01.22     N12W46           plage
S1443 2012.01.22     N17W59           plage
S1444 2012.01.22     N14W74         plage
S1446 2012.01.24   5 S18E37 0000   AXX  
S1448 2012.01.25     S17W19          
11410 2012.01.26 1 1 N16E52 0150 HSX HSX area: 0220

location: N18E62

S1449 2012.01.26   4 S25E23 0010   CRO  
S1450 2012.01.26     S20W09         plage
S1451 2012.01.27   2 N08E62 0010   CRO    
Total spot count: 9 21  
Sunspot number: 39 71  (total spot count + 10 * number of spotted regions)
Weighted penumbral SN: 24 37  (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): 23 32  k * (sunspot number). k = 0.6 for SWPC. k = 0.45 (changed from 0.33 on Nov.1, 2011) 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
2012.01 135.2 (1) 81.5 (2A) / 93.6 (2B) (84.4 projected, +5.8) (6.83)

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.