Last major update issued on February 25, 2014 at 05:15 UTC.
[Solar and geomagnetic data - last month (updated
[Solar wind and electron fluence charts (updated daily)]
[Solar cycles 23-24 (last update February 1, 2014)] [Cycle 24 progress (last update February 1, 2014) ]
[Solar cycles 1-20]
[Graphical comparison of cycles 21, 22, 23 and 24 (last update February 1, 2014)]
[Graphical comparison of cycles 10, 12, 13, 14, 16 and 24 (last update February 1, 2014)]
[Historical solar and geomagnetic data charts 1954-2006 (last update April 5, 2007)]
[Archived reports since January 2003 (last update February 1, 2014)]
[POES auroral activity level since October
2009 - updated January 26, 2013]
[Solar polar fields vs solar cycles - updated February 23, 2014]
[Presentation 3rd SSN Workshop, Tucson, 2013 (pdf)]
The geomagnetic field was quiet to unsettled on February 24. Solar wind speed at SOHO ranged between 403 and 553 km/s.
Solar flux at 20h UTC on 2.8 GHz was 170.7 (increasing 13.5 over the last solar rotation). The 90 day 10.7 flux at 1 AU was 151.5. The Potsdam WDC planetary A index was 6 (STAR Ap - based on the mean of three hour interval ap indices: 5.6). Three hour interval K indices: 11122211 (planetary), 11222221 (Boulder).
The background x-ray flux is at the class C1 level.
At the time of counting spots (see image time) spots were observed in 12 active regions in 2K resolution (SN: 336) and 11 active regions in 1K resolution (SN: 232) SDO images on the visible solar disk.
Region 11981 [S07W33] was quiet and stable.
Region 11982 [S11W20] decayed slowly in the trailing spot section. New negative polarity flux emerged in the central section and was at the origin of the flare activity observed. Further minor M class flaring is possible. C5+ flares: M1.3 at 12:05, C5.0 at 14:49 UTC.
Region 11983 [S13W39] was quiet and stable.
Region 11986 [N13E08] developed slowly as negative polarity flux emerged within the trailing positive polarity area.
Region 11987 [S01E37] dwas quiet and stable.
Region 11988 [S12E10] reemerged with a penumbra spot.
Region 11989 [N08E53] was quiet and stable.
New region 11990 [S12E80] rotated into view revealing a strong magnetic delta structure inside the single large spot. C5+ flares: M1.2 at 11:17, C5.1 at 21:37 UTC. The region was the source of the third largest flare of solar cycle 24, an X4.9/2B event at 00:49 UTC on February 25. This flare was associated with a fast CME. At the time of writing this is a partial halo CME. Although the flare occurred near the limb, the CME could have an Earth directed extension.
Spotted regions not numbered (or interpreted differently) by SWPC:
S3141 [S06W22] was quiet and stable.
S3155 [S06E41] was quiet and stable.
S3156 [N04E63] was quiet and stable.
New region S3159 [S22E10] emerged with a penumbra spot.
February 22-24: No obviously Earth directed CMEs were observed in LASCO and
February 25: A partial halo CME was observed after the X4 flare in AR 11990. There is a chance that Earth could receive a glancing blow from this CME on February 27 or 28.
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
A negative polarity trans equatorial coronal hole (CH605) was in an Earth facing position on February 24-25.
Long distance low and medium frequency (below 2 MHz) propagation along paths north of due west over upper middle latitudes is poor. Propagation on long distance northeast-southwest paths is poor.
The geomagnetic field is expected to be quiet to unsettled on February 25-26. On February 27 and 28 there is a chance of a few active intervals due to effects from CH605. If the CME observed on February 25 reaches Earth, active and minor storm intervals will be possible on February 27 and 28.
|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:||145||216||122|
|Sunspot number:||205||336||232||(total spot count + 10 * number of spotted regions)|
|Weighted SN:||183||259||165||(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):||123||118||128||k * (sunspot number). k = 0.6 for SWPC, k = 0.35 for STAR SDO 2K, k = 0.55 for STAR SDO 1K|
|Month||Average solar flux||International sunspot number
|Smoothed sunspot number||Average ap
|2011.11||153.5||96.7 (cycle peak)||61.1 (+1.2)||5.55|
|2013.08||114.6||118.3||66.0||(69.0 projected, +3.5)||8.27|
|2013.09||102.6||103.7||36.9||(73.0 projected, +4.0)||5.23|
|2013.10||132.1||131.2||85.6||(74.0 projected, +1.0)||7.71|
|2013.11||148.3||145.1||77.6||(72.9 projected, -1.1)||5.68|
|2013.12||147.7||143.1||90.3||(71.8 projected, -1.1)||4.68|
|152.4||82.0||(71.0 projected, -0.8)||5.44|
|2014.02||169.6 (1)||143.9 (2A) / 167.9 (2B) / 109.8 (2C)||(71.2 projected, +0.2)||(11.2)|
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 WDC-SILSO 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 GFZ Potsdam WDC ap indices.
This report has been prepared by Jan Alvestad. It is based on the 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.