Solar Terrestrial Activity Report

Activity chart

Last major update issued on May 13, 2014 at 05:20 UTC.

[Solar and geomagnetic data - last month (updated daily)]
[Solar wind and electron fluence charts (updated daily)]
[Solar cycles 23-24 (last update May 1, 2014)] [Cycle 24 progress (last update May 1, 2014) ]
[Solar cycles 1-20]
[Graphical comparison of cycles 21, 22, 23 and 24 (last update May 1, 2014)]
[Graphical comparison of cycles 10, 12, 13, 14, 16 and 24 (last update May 1, 2014)]
[Historical solar and geomagnetic data charts 1954-2006 (last update April 5, 2007)]
[Archived reports since January 2003 (last update May 1, 2014)]

[POES auroral activity level October 2009 - December 2012]
[Solar polar fields vs solar cycles - updated April 17, 2014]
[Presentation 3rd SSN Workshop, Tucson, 2013 (pdf)]

Recent activity

The geomagnetic field was quiet on May 12. Solar wind speed at SOHO ranged between 362 and 468 km/s under the influence of a low to moderately high speed stream from CH616.

Solar flux at 20h UTC on 2.8 GHz was 162.9 (increasing 1.0 over the last solar rotation). The 90 day 10.7 flux at 1 AU was 149.3. The Potsdam WDC planetary A index was 7 (STAR Ap - based on the mean of three hour interval ap indices: 6.9). Three hour interval K indices: 22222122 (planetary), 33332321 (Boulder).

The background x-ray flux is at the class B6 level.

At the time of counting spots (see image time), spots were observed in 14 active regions in 2K resolution (SN: 289) and 14 active regions in 1K resolution (SN: 235) SDO images on the visible solar disk.

Region 12053 [N09W69] decayed slowly and quietly.
Region 12055 [N11W23] decayed slowly and quietly.
Region 12056 [N05W08] decayed and simplified magnetically. A minor M class flare is still possible.
Region 12057 [N14E01] was quiet and stable.
Region 12058 [S12E16] decayed significantly and was quiet.
Region 12059 [S01W07] decayed losing all umbrae.
Region 12060 [S16E23] developed slowly and became more organized with less polarity intermixing. The region has M class flare potential.
Region 12061 [S24E55] was quiet and stable.
Region 12062 [S07W43] decayed slowly and quietly.

Spotted regions not numbered (or interpreted differently) by SWPC:
S3405 [N08W03] was quiet and stable.
S3411 [S13W10] was quiet and stable.
S3415 [N01E01] was quiet and stable.
New region S3420 [S09E23] emerged with two spots.

C2+ Flares (SDO/EVE):

Magnitude Time (UTC) Location AR
C2.0 06:43 N02E00 12056
C2.0 11:10 S25E36 (filament eruption)

Coronal mass ejections (CMEs)

May 10-12: No obviously Earth directed CMEs were observed in LASCO and STEREO imagery.

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 southern hemisphere coronal hole (CH617) was in an Earth facing position on May 12-13.

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 on May 13-14 and quiet to active on May 15-16 due to effects from CH617.

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.

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 Magnetic
(SDO)
SWPC STAR Current Previous
2K 1K
12052 2014.05.01
2014.05.02
      S12W88           plage
12053 2014.05.03 1 1 1 N09W69 0010 AXX AXX

 

12054 2014.05.03
2014.05.04
  2 1 S09W45 0006   AXX    

location: S15W32

12055 2014.05.04
2014.05.05
10 27 20 N13W22 0330 EKO EHI area: 0470

location: N11W23

12056 2014.05.05
2014.05.06
17 24 17 N05W09 0300 EKO EAC

area: 0390

S3394 2014.05.05       S18W51         plage
S3395 2014.05.05       S12W49           plage
12057 2014.05.06
2014.05.07
4 11 7 N14W00 0110 HSX CAO area: 0180
S3397 2014.05.06       S15W01           plage
S3401 2014.05.07       N03E04           plage
12058 2014.05.07
2014.05.08
5 17 10 S11E15 0010 AXX HRX

area: 0030

S3403 2014.05.07       N14W46           plage
S3404 2014.05.08       N13W35         plage
S3405 2014.05.08   1 1 N09E08 0003   AXX  
12059 2014.05.08
2014.05.10
4 3 3 S01W07 0020 HSX AXX

 

12060 2014.05.08
2014.05.11
25 38 23 S16E22 0180 DAC DAC beta-gamma

area: 0320

S3408 2014.05.08       S33W45           plage
S3410 2014.05.09       S17W24           plage
S3411 2014.05.10   2 1 S12E16 0007   AXX  
12061 2014.05.10
2014.05.11
2 3 2 S24E53 0100 HSX CAO area: 0170
12062 2014.05.10
2014.05.11
6 16 6 S06W43 0080 DAO DAO area: 0120
S3415 2014.05.10   2 1 N01E03 0005   AXX  
S3417 2014.05.11       S23E32         plage
S3418 2014.05.11       N22E61         plage
S3420 2014.05.12   2 2 S09E23 0010   CRO    
Total spot count: 74 149 95  
Sunspot number: 164 289 235  (total spot count + 10 * number of spotted regions)
Weighted SN: 119 190 136  (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): 98 101 129 k * (sunspot number). k = 0.6 for SWPC, k = 0.35 for MSN 2K, k = 0.55 for MSN 1K (MSN=Magnetic Sunspot Number)

Monthly solar cycle data

Month Average solar flux International sunspot number
(WDC-SILSO)
Smoothed sunspot number Average ap
(3)
Measured 1 AU
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 (+3.5) 8.27
2013.09 102.6 103.7 36.9 73.1 (+4.1) 5.23
2013.10  132.1 131.2 85.6 75.0 (+1.9) 7.71
2013.11  148.3 145.1 77.6 (75.6 projected, +0.6) 5.68
2013.12 147.7 143.1 90.3 (76.6 projected, +1.0) 4.68
2014.01 157.4 152.4 82.0 (77.6 projected, +1.0) 5.44
2014.02 170.3
(cycle peak)
166.3 102.8 (cycle peak) (77.4 projected, -0.2) 10.70
2014.03 149.9 148.5 92.2 (77.9 projected, +0.5) 4.88
2014.04 143.9 144.8 84.7 (77.0 projected, -0.9) 7.88
2014.05 144.1 (1)   49.0 (2A) / 126.6 (2B) / 103.6 (2C) (74.4 projected, -2.6) (7.0)

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.