Last major update issued on February 21, 2013 at 05:20 UTC.
[Solar and geomagnetic data - last month (updated
[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)]
The geomagnetic field was quiet on February 20. Solar wind speed at SOHO ranged between 338 and 420 km/s, weakly under the influence of a low speed stream from CH555.
Solar flux measured at 20h UTC on 2.8 GHz was 113.5 (increasing 10.1 over the last solar rotation). The Potsdam WDC planetary A index was 6 (STAR Ap - based on the mean of three hour interval ap indices: 6.1). Three hour interval K indices: 11222211 (planetary), 11132312 (Boulder).
The background x-ray flux was at the class B6 level.
At midnight UTC the visible solar disk had 7 spotted active regions (in 2K resolution SDO images).
Region 11671 [N14W60] decayed slowly and quietly.
Region 11673 [S10E05] decayed slowly and quietly.
Region 11675 [N12W23] decayed slowly and quietly.
Region 11676 [S18E28] developed slowly and was quiet.
Region 11678 [N10W55] developed further. While there were no magnetic delta structures in the region at the end of the day, there's significant polarity intermixing in the trailing spot section. An M class flare is likely. C5+ flare: C8.2 at 11:11 UTC.
Region 11679 [S12E35] was quiet and stable.
Spotted regions not numbered by SWPC:
New region S2246 [S29W30] emerged with a penumbra spot.
February 18, 20: No obviously Earth directed CMEs were observed in LASCO
February 19: The long duration C2 event in AR 11678 (and a filament eruption) caused a CME which was mostly directed towards the north. However, weak components which may be Earth directed were visible in STEREO imagery.
Coronal hole history (since October
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 in or near Earth facing positions.
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.
The geomagnetic field is expected to be quiet to unsettled on February 21-23. On February 22 there's a slight chance of weak effects from the CME observed on Feb.19.
|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
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.
(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
|Spot count||Location at midnight||Area||Classification||SDO / HMI 4K continuum
image with magnetic polarity overlay
|Total spot count:||36||77||38|
|Sunspot number:||106||147||98||(total spot count + 10 * number of spotted regions)|
|Weighted SN:||66||105||66||(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):||64||51||54||k * (sunspot number). k = 0.6 for SWPC, k = 0.35 for STAR SDO 2K, k = 0.55 for STAR SDO 1K|
|Month||Average measured solar flux||International sunspot number (SIDC)||Smoothed sunspot number||Average ap
|2011.11||153.5 (cycle max)||96.7 (cycle max)||61.1 (+1.2)||5.55|
possible cycle 24 max
|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||105.5 (1)||43.4 (2A) / 60.8 (2B) / 42.3 (2C)||(55.0 projected, -1.0)||(5.39)|
1) Running average based on the daily 20:00 UTC observed solar flux value at
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.