Solar Terrestrial Activity Report

Activity chart

Last major update issued on February 25, 2014 at 05:15 UTC.

[Solar and geomagnetic data - last month (updated daily)]
[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)]

Recent activity

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.

Coronal mass ejections (CMEs)

February 22-24: No obviously Earth directed CMEs were observed in LASCO and STEREO imagery.
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 holes

Coronal hole 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 negative polarity trans equatorial coronal hole (CH605) was in an Earth facing position on February 24-25.

Coronal hole map

Propagation

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.

Forecast

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 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 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
detected
Spot count Location at midnight Area Classification SDO / HMI 4K continuum
image with magnetic polarity overlay
Comment
SWPC STAR SDO SWPC STAR Current Previous
2K 1K
11983 2014.02.16
2014.02.18
  3 2 S13W45 0010   BXO

location: S13W39

11982 2014.02.16
2014.02.17
68 68 39 S10W22 0450 EKC EAC

beta-gamma

area: 0560

location: S11W20

11981 2014.02.16
2014.02.17
34 44 20 S07W34 0200 EAI EAI beta-gamma

area: 0240

11984 2014.02.17
2014.02.18
      S16W37         plage
S3137 2014.02.17       S21W40           plage
11986 2014.02.19
2014.02.20
19 27 11 N13E07 0030 CRO ERI

area: 0090

S3141 2014.02.19   30 23 S06W22 0180   DAI  
S3144 2014.02.20       S16W50           plage
S3145 2014.02.20       S05W55           plage
11987 2014.02.21 15 22 14 S02E36 0230 DAI EKO location: S01E37

area: 0480

11988 2014.02.21
2014.02.22
  1   S10E08 0004   AXX   plage
S3149 2014.02.21       S31W59           plage
S3150 2014.02.22       S17E06         plage
11989 2014.02.22
2014.02.23
7 9 6 N08E47 0090 CAO CAO area: 0150

location: N08E53

S3152 2014.02.22       N22W51           plage
S3154 2014.02.23       S28E06         plage
S3155 2014.02.23   3 2 S06E41 0016   BXO  
S3156 2014.02.23   3 1 N04E63 0008   BXO  
S3159 2014.02.24   1 1 S22E10 0004   AXX    
11990 2014.02.24 2 5 3 S15E77 0250 HKX DKC   delta

area: 0600

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

Monthly solar cycle data

Month Average solar flux International sunspot number
(WDC-SILSO)
Smoothed sunspot number Average ap
(3)
Measured 1 AU
2011.11 153.5   96.7 (cycle peak) 61.1 (+1.2) 5.55
2012.02 106.5   32.9 66.9 (+1.4) 8.81
2012.11 121.3 118.3 61.8 59.7 (+1.1) 7.08
2012.12 108.6 105.0 40.8 59.6 (-0.1) 3.44
2013.01 127.1 123.1 62.9 58.7 (-0.9) 4.69
2013.02 104.3 101.8 38.0 58.4 (-0.3) 6.11
2013.03 111.3 110.2 57.9 57.5 (-0.9) 10.56
2013.04 124.8 125.9 72.4 57.9 (+0.4) 5.40
2013.05 131.4 134.3 78.7 59.9 (+2.0) 9.73
2013.06 110.1 113.7 52.5 62.6 (+2.7) 12.60
2013.07 115.5 119.3 57.0 65.5 (+2.9) 9.47
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
2014.01 157.4
(cycle peak)
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 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 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.