Last major update issued on February 8, 2015 at 06:35 UTC.
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[Graphical comparison of cycles 21, 22, 23 and 24 (last update February 1, 2015)]
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[Noon SDO sunspot count 1K Reference: 4K (large file) (updated daily)]
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[Presentations: 3rd SSN Workshop, Tucson, 2013 (pdf) / 4th SSN Workshop, Locarno, 2014]
The geomagnetic field was quiet to unsettled on February 7. Solar wind speed at SOHO ranged between 366 and 442 km/s, weakly under the influence of a low speed stream from CH652.
Solar flux at 20h UTC on 2.8 GHz was 153.0 (decreasing 0.7 over the last solar rotation). The 90 day 10.7 flux at 1 AU was 149.1. The Potsdam WDC planetary A index was 7 (STAR Ap - based on the mean of three hour interval ap indices: 7.3). Three hour interval K indices: 11232221 (planetary), 10342422 (Boulder).
The background x-ray flux is at the class B8 level.
At the time of counting spots (see image time), spots were observed in 10 active regions using 2K resolution (SN: 233) and 9 active regions using 1K resolution (SN: 164) SDO images on the visible solar disk.
Region 12277 [N09W51] decayed further and has
simplified magnetically. Occasional C flares are possible.
Region 12280 [S07W11] developed slowly and has 2 weak magnetic deltas. A minor M class flare is possible.
Region 12281 [N13E23] developed quickly when new negative polarity flux emerged near and inside the positive polarity area. A minor M class flare is possible.
New region 12282 [N13E79] rotated into view.
Spotted regions not numbered (or interpreted
differently) by SWPC:
S4192 [S04W31] was quiet and stable.
S4195 [N07W29] decayed slowly and quietly.
S4198 [S21E18] gained several penumbra spots.
S4203 [S07W69] was quiet and stable.
S4204 [N19E02] was quiet and stable.
New region S4206 [S12E78] rotated into view.
C2+ flares (GOES):
|Magnitude||Peak time (UTC)||Location||AR||Comment|
February 5-7: No obviously Earth directed CMEs were observed in LASCO imagery.
history (since October 2002)]
[Compare today's report to the situation one solar rotation ago: 28 days ago 27 days ago 26 days ago]
A poorly defined trans equatorial coronal hole (CH652) rotated across the central meridian on February 5-6. A recurrent trans equatorial coronal hole (CH653) will likely rotate into an Earth facing position on February 10-11, CH653 has not been associated with geomagnetic disturbances during previous rotations.
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 to fair.
The geomagnetic field is expected to be quiet to active on February 8-9 due to a low to medium high speed stream from CH652 and quiet to unsettled on February 10.
|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 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: 0-30% probability, Yellow: 30-70% probability, Red: 70-100% 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:||40||133||74|
|Sunspot number:||80||233||164||(total spot count + 10 * number of spotted regions)|
|Weighted SN:||60||153||94||(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):||48||82||90||k * (sunspot number). k = 0.6 for SWPC, k = 0.35 for MSN 2K, k = 0.55 for MSN 1K (MSN=Magnetic Sunspot Number)|
|Month||Average solar flux||International sunspot number
|Smoothed sunspot number||Average
|166.3||102.3 (cycle peak)||78.4 (+1.1)||10.70|
(likely solar max)
|2014.08||124.7||127.9||74.7||(76.2 projected, -2.4)||7.71|
|2014.09||146.6||148.1||87.6||(73.0 projected, -3.2)||9.78|
|2014.10||153.4||152.9||60.6||(70.5 projected, -2.5)||8.96|
|2014.11||154.8||151.4||70.1||(68.8 projected, -1.7)||9.33|
|2014.12||158.7||153.8||78.0||(67.7 projected, -1.1)||11.24|
|2015.01||141.9||137.3||67.0||(66.5 projected, -1.2)||9.46|
|2015.02||146.8 (1)||24.4 (2A) / 97.6 (2B) / 79.6 (2C)||(64.9 projected, -1.6)||(12.1)|
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.