Last major update issued on February 24, 2014 at 06:05 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 minor storm on February 23. Solar wind speed at SOHO ranged between 394 and 493 km/s. Another disturbance arrived near noon. Although there was no solar wind shock, the source was likely a CME, probably the one observed on February 20.
Solar flux at 20h UTC on 2.8 GHz was 171.8 (increasing 27.9 over the last solar rotation). The 90 day 10.7 flux at 1 AU was 150.9. The Potsdam WDC planetary A index was 19 (STAR Ap - based on the mean of three hour interval ap indices: 19.0). Three hour interval K indices: 22432454 (planetary), 11323443 (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 13 active regions in 2K resolution (SN: 366) and 12 active regions in 1K resolution (SN: 240) SDO images on the visible solar disk.
Region 11981 [S07W19] gained a few spots and was
Region 11982 [S11W07] decayed in the leading spot section and currently has a fairly simple magnetic layout (disregarding the proximity of neighboring regions).
Region 11983 [S13W28] was quiet and stable.
Region 11984 [S17W20] was quiet and stable.
Region 11986 [N13E22] was mostly quiet and stable.
Region 11987 [S01E49] developed slowly and was quiet.
New region 11989 [N08E66] rotated into view on February 22 and was numbered by SWPC the next day.
Spotted regions not numbered (or interpreted differently) by SWPC:
S3141 [S06W09] decayed in the leading spot section and simplified magnetically.
S3150 [S17E19] was quiet and stable.
New region S3154 [S28W19] emerged with penumbra spots.
New region S3155 [S09E56] emerged with a penumbra spot.
New region S3156 [N04E77] rotated into view.
New region S3157 [N16W74] emerged with a penumbra spot.
A region near the southeast limb produced the only noteworthy flare of the day, an M1.1 flare at 06:10 UTC.
February 21-23: No obviously Earth directed CMEs were observed in LASCO and 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
A negative polarity trans equatorial coronal hole (CH605) will likely rotate into 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 fair.
The geomagnetic field is expected to be quiet to unsettled on February 24-26. On February 27 and 28 there is a chance of a few active intervals due to effects from CH605.
|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:||125||236||120|
|Sunspot number:||185||366||240||(total spot count + 10 * number of spotted regions)|
|Weighted SN:||155||269||153||(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):||111||128||132||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||169.5 (1)||136.6 (2A) / 166.3 (2B) / 108.9 (2C)||(71.2 projected, +0.2)||(11.4)|
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.