Solar Terrestrial Activity Report

Last major update issued on February 9, 2011 at 04:20 UTC.

[Solar and geomagnetic data - last month (updated daily)]
[Solar wind and electron fluence charts (updated daily)
[Solar cycles 21-24 (last update February 1, 2011)]
[Solar cycles 1-20]
[Graphical comparison of cycles 21, 22, 23 and 24 (last update February 1, 2011)]
[Graphical comparison of cycles 10, 12, 13, 14, 16 and 24 (last update February 1, 2011)]
[Historical solar and geomagnetic data charts 1954-2006 (last update April 5, 2007)]
[Archived reports since January 2003 (last update February 1, 2011)]

[POES auroral activity level charts since October 2009]
Annotated geomagnetic activity charts - Carrington rotation 2104 [Nov-Dec.2010]- 2105 [Dec-Jan.2011] NEW

Recent activity

The geomagnetic field was quiet to unsettled on February 8. Solar wind speed ranged between 362 and 441 km/s.

Solar flux measured at 20h UTC on 2.8 GHz was 89.7 (increasing 9.7 over the last solar rotation). The planetary A index  was 4 (STAR Ap - based on the mean of three hour interval ap indices: 4.1). Three hour interval K indices: 23010011 (planetary), 23121011 (Boulder).

The background x-ray flux is at the class B3 level.

At midnight UTC the visible solar disk had 5 spotted regions.

Region 11153 developed very quickly with the main penumbra growing from small to large in just one day. Polarities are intermixed and further M class flares are possible over the next couple of days until the region is behind the northwest limb. There's a possibility of a proton event as well. Flares: C1.0 at 18:54 and C4.0 at 21:12 UTC. At 01:31 UTC on February 9 the region produced an impulsive M1.6 flare.
New region 11154 emerged in the northwest quadrant early in day.
New region 11155 emerged in the northeast quadrant on February 7 and was numbered the follwing day by NOAA/SWPC.
New region 11156 emerged in the southeast quadrant early in the day. The region has many small spots.
New region 11157 emerged in the northeast quadrant early in the day.

Coronal mass ejections (CMEs)

February 6-8: No obviously Earth directed CMEs were observed in LASCO or STEREO images.

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

No significant coronal holes are currently in or near Earth facing positions.

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

Forecast

The geomagnetic field is expected to be quiet on February 9-11 with a chance of occasional unsettled intervals due to weak coronal hole effects.

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 SWPC STAR Current Previous
11150 2011.01.26     S23W76         plage
S868 2011.02.02     N36W68           plage
11153 2011.02.04
2011.02.02
8 10 N15W71 0080 DKO DKO beta-gamma

area: 0330

11152 2011.02.03
2011.02.02
    S20W52           plage
S871 2011.02.04     S17W60           plage
11154 2011.02.08 1 3 N08W51 0010 HRX AXX    
11155 2011.02.08
2011.02.07
3 3 N17E26 0010 CRO BXO formerly region S872
11156 2011.02.08 6 14 S19E43 0010 CRO BXI    
11157 2011.02.08 3 9 N22E36 0010 CRO CRI    
Total spot count: 21 39  
Sunspot number: 71 89  

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
2009.11 73.6 4.1 7.6 (+0.5) 2.45 / 2.63
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 (17.1 predicted, +0.3) 8.49 / 7.77
2010.09 81.1 25.2 (17.7 predicted, +0.6) 5.33 / 5.45
2010.10 81.6 23.5 (19.0 predicted, +1.3) 6.07 / 6.27
2010.11 82.5 21.6 (20.7 predicted, +1.7) 4.80 / 5.50
2010.12 84.2 14.5 (22.2 predicted, +1.5) 3.41 / 4.35
2011.01 83.6 19.1 (23.8 predicted, +1.6) 4.32
2011.02 81.9 (1) 10.3 (2A) / 35.9 (2B) (25.5 predicted, +1.7) (8.42)

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.