Solar Terrestrial Activity Report

Last major update issued on January 18, 2012 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 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 17, 2012]
Annotated geomagnetic activity charts - Carrington rotation 2117 [November-December 2011] - 2118 [December 2011 - January 2012] NEW
[Solar polar fields vs solar cycles - updated June 27, 2011]

Recent activity

The geomagnetic field was quiet to unsettled on January 17. Solar wind speed ranged between 372 and 511 km/s under the decreasing influence of a high speed stream from CH493.

Solar flux measured at 20h UTC on 2.8 GHz was 139.0 (decreasing 5.5 over the last solar rotation). The planetary A index was 5 (STAR Ap - based on the mean of three hour interval ap indices: 4.6). Three hour interval K indices: 31111111 (planetary), 21122211 (Boulder).

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

At midnight UTC the visible solar disk had 13 spotted regions (in 2K resolution SDO images).

Region 11396 [N25W32] decayed further and was quiet.
Region 11397 [S18W25] decayed slowly and quietly.
Region 11398 [N12W64] decayed quickly and quietly.
Region 11399 [S23E31] was quiet and stable.
Region 11401 [N17E40] developed further and has polarity intermixing. M class flares are possible. Flares: M1.0/1N at 04:53, C1.4 at 17:19, C2.2 at 18:32 UTC
Region 11402 [N28E42] developed a weak magnetic delta structure in the southeastern part of the largest penumbra. M flares are possible.
Region 11403 [S18E03] developed slowly and quietly.
Region 11405 [N12E55] was quiet and stable.
New region 11406 [S22W56] emerged in the southwest quadrant on January 16 and was assigned an SWPC number the next day.

Spotted regions not reported (or interpreted differently) by NOAA/SWPC:
[S1431] reemerged with spots on January 17. Location at midnight: N10W06
[S1433] emerged in the southwest quadrant on January 14. Location at midnight: S31W82
[S1436] emerged in the northeast quadrant on January 16. Location at mdnight: N17E54
[S1437] emerged in the northeast quadrant on January 16. Location at midnight: N18W05

Coronal mass ejections (CMEs)

January 15, 17: No obviously Earth directed CMEs were observed in LASCO and STEREO imagery.
January 16: A partial halo CME was observed after an LDE in region 11402 early in the day. While the core of the CME won't reach Earth, there's a chance of a flank impact on January 19.

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 poorly defined trans equatorial coronal hole (CH494) was in an Earth facing position on January 16-17. CH494 appears to be closing.

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

Forecast

The geomagnetic field is expected to be quiet on January 18. On January 19 there's a chance of a flank impact from the CME observed on January 16. In that case brief unsettled to active conditions are possible. On January 20-21 weak effects from CH494 are possible.

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
11395 2012.01.07
2012.01.08
    N20W58         plage
11396 2012.01.09
2012.01.12
17 11 N24W33 0030 DRO CRI location: N25W32
S1424 2012.01.11     S16W05           plage
11398 2012.01.11
2012.01.13
3 2 N11W64 0010 BXO AXX area: 0000
11397 2012.01.12
2012.01.13
  2 S20W26 0000   AXX location: S18W25
S1427 2012.01.12     S24W31           plage
11399 2012.01.13
2012.01.14
1 3 S23E29 0020 HRX CRO location: S23E31
11400 2012.01.13
2012.01.14
    S13W44           plage
11401 2012.01.14 18 35 N18E38 0480 EKC EHC beta-gamma

area: 0650

location: N17E40

11402 2012.01.14 7 20 N28E40 0630 EKO EKO

beta-gamma-delta

location: N28E42

11403 2012.01.14
2012.01.15
5 12 S19E02 0010 BXO BXI location: S18E03
S1431 2012.01.14   3 N10W06 0000   BXO    
S1432 2012.01.14     N13W30           plage
S1433 2012.01.14   2 S31W82 0030   DRO  
11405 2012.01.15
2012.01.16
1 3 N13E51 0050 HSX CSO

location: N12E55

11404 2012.01.15
2012.01.16
3   N11W42 0010 BXO     spotless
S1436 2012.01.16   3 N17E54 0000   BXO  
S1437 2012.01.16   1 N18W05 0000   AXX  
11406 2012.01.16
2012.01.17
7 4 S23W55 0030 DRO DAO  
Total spot count: 62 101  
Sunspot number: 152 231  (total spot count + 10 * number of spotted regions)
Weighted penumbral SN: 96 140  (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): 91 104  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
2012.01 133.2 (1) 52.6 (2A) / 95.9 (2B) (84.4 projected, +5.8) (4.59)

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.