Solar Terrestrial Activity Report

Activity chart

Last major update issued on February 4, 2014 at 04:55 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 1, 2014]
[Presentation 3rd SSN Workshop, Tucson, 2013 (pdf)]

Recent activity

The geomagnetic field was quiet on February 3. Solar wind speed at SOHO ranged between 323 and 432 km/s. A weak disturbance was observed arriving at ACE near 01:30 UTC on February 4. ACE EPAM data indicate the arrival of a CME, maybe the CME observed on January 31.

Solar flux at 20h UTC on 2.8 GHz was 188.3 (decreasing 11.6 over the last solar rotation). The 90 day 10.7 flux at 1 AU was 148.3. 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: 22211112 (planetary), 12312212 (Boulder).

The background x-ray flux is at the class C3 level.

At the time of counting spots (see image time) spots were observed in 11 active regions in 2K resolution (SN: 309) and 9 active regions in 1K resolution (SN: 209) SDO images on the visible solar disk.

Region 11967 [S12W09] lost spots but remains capable of producing an X class flare. Several magnetic delta structures are still present, there's a strong delta in the trailing section and another strong delta in the eastern part of the leading spot section. C5+ flares: C5.7 at 06:25, long duration C9.0 peaking at 08:30, C7.9 at 12:54, C6.9 at 19:37, C7.8 at 22:33 UTC. The region has been the source of 3 M class events early on February 4, the largest a major M5.2 event at 04:00 UTC.
Region 11968 [N10W06] decayed in the leading spot section while some development was observed elsewhere. A magnetic delta structure could be forming centrally. C and minor M class flares are possible.
Region 11969 [S10W60] was quiet and stable.
Region 11970 [S18E40] was quiet and stable. The region has weak polarity intermixing.

Spotted regions not numbered (or interpreted differently) by SWPC:
S3073 [N21W07] decayed slowly losing leading polarity spots.
S3079 [S10E06] developed slowly with many penumbra spots forming.
S3084 [S13E28] was quiet and stable.
S3085 [S16E17] was quiet and stable.
New region S3088 [S12E12] emerged early in the day with spots, then decayed slowly.
New region S3089 [S12E68] emerged with a few spots.
New region S3090 [N09E43] emerged with a penumbra spot.

Coronal mass ejections (CMEs)

February 1-3: No obviously Earth directed CMEs were observed in LASCO and STEREO imagery. On Feb.2 two CMEs were observed from a location behind the southwest limb.

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 recurrent trans equatorial coronal hole (CH602) will likely rotate into an Earth facing position on February 5-6.

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 to fair.

Forecast

The geomagnetic field is expected to be quiet to unsettled on February 4-6.

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
11967 2014.01.26
2014.01.27
88 80 51 S13W12 1490 FKC FKC gamma-delta

area: 3030

location: S12W09

 

11968 2014.01.27 33 67 42 N10W09 0320 EKC EAC beta-gamma

area: 0680

location: N10W06

11969 2014.01.28
2014.02.01
3 7 5 S11W59 0030 DRO DRO  
S3073 2014.01.28   2 2 N21W07 0010   AXX  
S3075 2014.01.29       S12E17           plage
S3077 2014.01.30       N13W32           plage
S3078 2014.01.30       S23W35           plage
S3079 2014.01.31   21 8 S10E06 0050   BXO  
11970 2014.02.01
2014.02.02
4 8 5 S20E40 0030 DRO DRO beta-gamma

location: S18E40

S3082 2014.02.01       N07E49           plage
S3083 2014.02.01       N11W48            
S3084 2014.02.02   3   S13E28 0008   BXO  
S3085 2014.02.02   4 1 S16E17 0010   BXO  
S3086 2014.02.02       N09E02         plage
S3087 2014.02.02       S28W05         plage
S3088 2014.02.03   3 2 S12E12 0012   BXO    
S3089 2014.02.03   3 3 S12E68 0020   CRO    
S3090 2014.02.03   1   S12E68 0004   AXX    
Total spot count: 128 199 119  
Sunspot number: 168 309 209  (total spot count + 10 * number of spotted regions)
Weighted SN: 154 223 143  (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): 101 108 115 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 (67.8 projected, +2.3) 8.27
2013.09 102.6 103.7 36.9 (69.6 projected, +1.8) 5.23
2013.10  132.1 131.2 85.6 (69.3 projected, -0.3) 7.71
2013.11  148.3 145.1 77.6 (67.5 projected, -1.8) 5.68
2013.12 147.7 143.1 90.3 (66.7 projected, -0.8) 4.68
2014.01 157.4
(cycle peak)
152.4 82.0 (66.9 projected, +0.2) 5.4
2014.02 184.9 (1)   17.1 (2A) / 159.3 (2B) / 101.8 (2C) (65.9 projected, -1.0) (3.9)

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 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.