Solar Terrestrial Activity Report

Activity chart

Last major update issued on February 11, 2013 at 05:15 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 on February 10. Solar wind speed at SOHO ranged between 344 and 375 km/s.

Solar flux measured at 20h UTC on 2.8 GHz was 105.9 (decreasing 48.2 over the last solar rotation). The Potsdam WDC planetary A index was 4 (STAR Ap - based on the mean of three hour interval ap indices: 4.0). Three hour interval K indices: 21110111 (planetary), 11210111 (Boulder).

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

At midnight UTC the visible solar disk had 11 spotted active regions (in 2K resolution SDO images).

Region 11667 [N22W50] was quiet and stable.
Region 11669 [N07W08] decayed slowly but still has quite a few penumbra spots in a longitudinally large area.
Region 11670 [N18E15] matured further and increased its penumbral area. 

Spotted regions not numbered by SWPC:
S2212 [N20W28] developed slowly and quietly.
S2213 [N15E05] lost the northernmost spots and gained a few further south.
S2216 [S22E26] added spots to the south of the original spots.
New region S2217 [S16E53] emerged with several penumbra spots.
New region S2218 [N13E74] rotated into view with a single spot.
New region S2219 [S32W17] emerged with a penumbra spot.
New region S2220 [N13W33] emerged with penumbra spots.
New region S2221 [S10W75] emerged near the southwest limb with a penumbra spot.

Coronal mass ejections (CMEs)

February 8, 10: No obviously Earth directed CMEs were observed in LASCO and STEREO imagery.
February 9: The CME associated with a C2.4 LDE to the northwest of AR 11670 could have Earth directed components.

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

No obvious coronal holes are currently near Earth facing positions.

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.

Forecast

The geomagnetic field is expected to be quiet on February 11. On February 12 the CME observed on Feb.9 could reach Earth and 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
11665 2013.01.28
2013.01.29
1     N10W93 0050 HSX     rotated out of view
11667 2013.01.31
2013.02.01
1 1 1 N22W50 0060 HSX HAX  
11669 2013.02.04
2013.02.05
  10   N07W14 0020   BXO

location: N07W08

11670 2013.02.05
2013.02.07
13 21 12 N17W14 0160 DSI DAI area: 0380
S2212 2013.02.06   4 3 N20W28 0010   BXO  
S2213 2013.02.08   3   N15E05 0006   BXO  
S2215 2013.02.08       S27W38           plage
S2216 2013.02.09   3 1 S22E26 0008   AXX  
S2217 2013.02.10   6 3 S16E53 0022   BXO    
S2218 2013.02.10   1 1 N13E74 0200   HSX    
S2219 2013.02.10   1   S32W17 0002   AXX    
S2220 2013.02.10   3 2 N13W33 0009   AXX    
S2221 2013.02.10   1   S10W75 0002   AXX    
Total spot count: 15 54 23  
Sunspot number: 45 164 93  (total spot count + 10 * number of spotted regions)
Weighted SN: 30 69 38  (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): 27 57 51 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) 4.49
2013.02 106.2 (1) 18.8 (2A) / 52.6 (2B) / 44.2 (2C) (55.0 projected, -1.0) (4.45)

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.