Solar Terrestrial Activity Report

Activity chart

Last major update issued on February 15, 2013 at 04:50 UTC.

[Solar and geomagnetic data - last month (updated daily)]
[Solar wind and electron fluence charts (updated daily)]
[Solar cycles 23-24 (last update February 1, 2013)] [Cycle 24 progress (last update February 2, 2013) ]
[Solar cycles 1-20]
[Graphical comparison of cycles 21, 22, 23 and 24 (last update February 1, 2013)]
[Graphical comparison of cycles 10, 12, 13, 14, 16 and 24 (last update February 1, 2013)]
[Historical solar and geomagnetic data charts 1954-2006 (last update April 5, 2007)]
[Archived reports since January 2003 (last update February 3, 2013)]

[POES auroral activity level since October 2009 - updated January 26, 2013]
[Solar polar fields vs solar cycles - updated February 3, 2013]
[Presentation 3rd SSN Workshop, Tucson, 2013 (pdf)]

Recent activity

The geomagnetic field was quiet to unsettled on February 14. Solar wind speed at SOHO ranged between 304 and 388 km/s.

Solar flux measured at 20h UTC on 2.8 GHz was 100.2 (decreasing 15.0 over the last solar rotation). The Potsdam WDC planetary A index was 11 (STAR Ap - based on the mean of three hour interval ap indices: 10.9). Three hour interval K indices: 33332222 (planetary), 33343221 (Boulder).

The background x-ray flux was at the class B2 level.

At midnight UTC the visible solar disk had 7 spotted active regions (in 2K resolution SDO images).

Region 11669 [N08W51] reemerged with a few penumbra spots in the trailing polarity area.
Region 11670 [N18W70] decayed quickly leaving no umbrae in the trailing spot section. The region produced a small C flare and was otherwise quiet.
Region 11671 [N15E20] was quiet and stable.
Region 11672 [S17W00] was quiet and stable.

Spotted regions not numbered by SWPC:
S2228 [S07E13] was quiet and stable.
New region S2233 [S10E82] rotated into view with a few spots.
New region S2234 [N15E11] emerged to the west of AR 11671.

Coronal mass ejections (CMEs)

February 12-14: 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 small coronal hole (CH554) in the southern hemisphere rotated across the central meridian on February 12. A narrow trans equatorial coronal hole (CH555) - an extension of a southern hemisphere coronal hole - will rotate across the central meridian on February 15-16.

Coronal hole map

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 February 15 and 17. On February 16 there is a chance of a few unsettled intervals due to effects from CH554. On February 18-19 effects from CH555 could cause a few unsettled and active intervals.

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 2K resolution) 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 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
2K 1K
11669 2013.02.04
2013.02.05
  2   N07W73        

location: N08W51

11670 2013.02.05
2013.02.07
4 4 3 N17W69 0100 CAO CSO  
S2213 2013.02.08       N15W41         plage
S2216 2013.02.09       S18W03           plage
11672 2013.02.10
2013.02.11
  1 1 S18W02 0005   AXX  
11671 2013.02.10
2013.02.11
1 4 2 N14E17 0100 HSX CSO location: N15E20

area: 0160

S2222 2013.02.11       N30E22           plage
S2226 2013.02.11       S07W41         plage
S2228 2013.02.12   2   S07E13 0004   AXX  
S2229 2013.02.12       S02W48           plage
S2230 2013.02.13       N18W56         plage
S2231 2013.02.13       S33W11         plage
S2232 2013.02.13       N15W56         plage
S2233 2013.02.14   3 2 S10E82 0040   CRO    
S2234 2013.02.14   3 2 N15E11 0013   BXO    
Total spot count: 5 19 10  
Sunspot number: 25 89 60  (total spot count + 10 * number of spotted regions)
Weighted SN: 15 32 23  (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): 15 31 33 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
(3)
2011.10 137.3 88.0 59.9 (+0.4) 8.28
2011.11 153.5 (cycle max) 96.7 (cycle max) 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
8.81
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 61.7 (-2.9) 7.06
2012.06 119.6 64.5 58.9 (-2.8) 10.08
2012.07 133.9 66.5 57.7 (-1.2) 13.90
2012.08 115.4 63.0 (58.6 projected, +0.9) 7.96
2012.09 122.9 61.4 (58.7 projected, +0.1) 8.07
2012.10 123.3 53.3 (58.1 projected, -0.6) 9.97
2012.11 121.3 61.4 (57.4 projected, -0.7) 7.08
2012.12 108.6 40.8 (56.7 projected, -0.7) 3.44
2013.01 127.1 62.9 (56.0 projected, -0.7) 4.69
2013.02 105.0 (1) 24.7 (2A) / 49.4 (2B) / 38.9 (2C) (55.0 projected, -1.0) (5.38)

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.