Solar Terrestrial Activity Report

Last major update issued on March 11, 2011 at 05:35 UTC.

[Solar and geomagnetic data - last month (updated daily)]
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[Solar cycles 21-24 (last update March 2, 2011)]
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[Graphical comparison of cycles 21, 22, 23 and 24 (last update March 2, 2011)]
[Graphical comparison of cycles 10, 12, 13, 14, 16 and 24 (last update March 2, 2011)]
[Historical solar and geomagnetic data charts 1954-2006 (last update April 5, 2007)]
[Archived reports since January 2003 (last update March 1, 2011)]

[POES auroral activity level charts since October 2009 - updated March 10, 2011]
Annotated geomagnetic activity charts - Carrington rotation 2105 [Dec-Jan.2011] - 2106 [Jan.-Feb.2011] NEW

Recent activity

The geomagnetic field was quiet to minor storm on March 10. A solar wind shock was observed at SOHO at 05:45 UTC. While the increase in solar wind speed was unimpressive and the total IMF field was low to moderate, the IMF has been southwards since the arrival of the CME.

Solar flux measured at 20h UTC on 2.8 GHz was 131.3 (increasing 40.1 over the last solar rotation). The planetary A index  was 20 (STAR Ap - based on the mean of three hour interval ap indices: 19.5). Three hour interval K indices: 22443245 (planetary), 22433233 (Boulder).

The background x-ray flux is at the class B8 level.

At midnight UTC the visible solar disk had 9 spotted regions.

Region 11166 has several small magnetic delta structures in the large central penumbra and one delta in the southeastern trailing penumbra. Another major flare is possible. Flares: C2.9 at 03:58, C6.2 at 07:12, C4.2 at 13:25, C4.7 at 13:46, C2.0 at 14:24 UTC.
Region 11167 was quiet and stable.
Region 11169 decayed in the trailing spot section while development was observed in the leading spot section, there is only minor polarity intermixing.
Region 11170 rotated partly out of view at the southwest limb.
Region 11171 was quiet and stable.

Region S891 behind the southwest limb was the likely source of a C4.0 flare at 19:07 and an M1.1 flare at 22:41 UTC. The flares were observed at the southwest limb, however, there is a slight chance AR 11170 might have been involved.

Spotted regions not numbered by NOAA/SWPC:
[S896] A tiny spot reemerged on March 10. Location at midnight: N16W34
[S900] Tiny spots emerged in an old plage area in the southeastern quadrant on March 8, a single tiny spot was still vsisible on March 10. Location at midnight: S18W02.
[S902] A few spots emerged in the northeast quadrant on March 10. Location at midnight: N19E37
[S903] This region began to rotate into view late on March 10. Location at midnight: N11E85

Coronal mass ejections (CMEs)

March 8-10: No obviously Earth directed CMEs were observed in LASCO and STEREO imagery.

Coronal holes

Coronal hole history (since late October 2002)
Compare today's report to the situation one solar rotation ago: 28 days ago 27 days ago 26 days ago

An extension (CH439) of the southern polar coronal hole was Earth facing on March 10.

The darkest areas on the solar disk are likely coronal holes.

Propagation

Long distance low and medium frequency (below 2 MHz) propagation along paths north of due west over high and upper middle latitudes is very poor. Propagation on long distance northeast-southwest paths is poor.

Forecast

The geomagnetic field is expected to be quiet to minor storm on March 11 and quiet to unsettled on March 12 due to CME effects. On March 13-14 quiet to unsettled conditions are possible as a stream from CH439 dominates the solar wind.

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 polarity overlay
Comment
SWPC STAR SDO SWPC STAR Current Previous
11166 2011.03.02 25 55 N09W26 0750 EKC EKC beta-gamma-delta
11167 2011.03.02
2011.03.03
2 2 N12W66 0010 BXO BXO

location: N12W63

11169 2011.03.05
2011.03.06
15 33 N20E18 0220 ESC ESI

beta-gamma

S895 2011.03.05     N07W53           plage
S896 2011.03.06   1 N16W34 0000   AXX    
11170 2011.03.07
2011.03.08
6 2 S25W94 0020 HRX BXO location: S26W86
S898 2011.03.07     S13E11           plage
S899 2011.03.07     N19W30           plage
11171 2011.03.08   6 S19E41 0000   BXO location of spots: S20E30
S900 2011.03.08   1 S18W02 0000   AXX  
S901 2011.03.08     S22W40           plage
S902 2011.03.10   3 N19E37 0010   BXO    
S903 2011.03.10   1 N11E85 0000   AXX    
Total spot count: 48 104  
Sunspot number: 88 194  

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
2009.12 76.7 10.8 8.3 (+0.7) 1.41 / 1.92
2010.01 81.1 13.2 9.3 (+1.0) 2.93 / 3.07
2010.02 84.7 18.8 10.6 (+1.3) 4.15 / 4.61
2010.03 83.4 15.4 12.3 (+1.7) 4.58 / 4.65
2010.04 75.9 8.0 14.0 (+1.7) 10.22 / 10.24
2010.05 73.8 8.7 15.5 (+1.5) 9.18 / 8.15
2010.06 72.5 13.6 16.4 (+0.9) 8.17 / 6.85
2010.07 79.8 16.1 16.8 (+0.4) 6.31 / 5.15
2010.08 79.2 19.6 17.4 (+0.6) 8.49 / 7.77
2010.09 81.1 25.2 (19.1 predicted, +1.7) 5.33 / 5.45
2010.10 81.6 23.5 (21.7 predicted, +2.6) 6.07 / 6.27
2010.11 82.5 21.6 (24.5 predicted, +2.8) 4.80 / 5.50
2010.12 84.2 14.5 (26.9 predicted, +2.4) 3.41 / 4.35
2011.01 83.6 19.1 (29.0 predicted, +2.1) 4.32
2011.02 94.6 29.4 (31.1 predicted, +2.1) 5.41
2011.03 132.5 (1) 33.6 (2A) / 104.1 (2B) (33.0 predicted, +1.9) (11.91)

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.