Solar Terrestrial Activity Report

Activity chart

Last major update issued on May 10, 2014 at 05:10 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 to unsettled on May 9. Solar wind speed at SOHO ranged between 345 and 414 km/s.

Solar flux at 20h UTC on 2.8 GHz was 152.3 (increasing 16.4 over the last solar rotation). The 90 day 10.7 flux at 1 AU was 149.3. The Potsdam WDC planetary A index was 5 (STAR Ap - based on the mean of three hour interval ap indices: 5.4). Three hour interval K indices: 32221001 (planetary), 42322211 (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 14 active regions in 2K resolution (SN: 265) and 12 active regions in 1K resolution (SN: 179) SDO images on the visible solar disk.

Region 12052 [S12W42] decayed slowly and quietly.
Region 12053 [N09W28] was quiet and stable.
Region 12054 [S12W01] decayed slowly and quietly.
Region 12055 [N11E17] decayed in the trailing penumbra and was quiet.
Region 12056 [N05E31] lost the magnetic delta structure but could still produce an M class flare.
Region 12057 [N15E39] was quiet and stable.
Region 12058 [S13E58] was the most active region on the visible disk as new trailing spots emerged.

Spotted regions not numbered (or interpreted differently) by SWPC:
S3386 [S19W42] was quiet and stable.
S3398 [S26W19] was quiet and stable.
S3405 [N10E37] decayed slowly and quietly.
S3406 [N00E33] decayed slowly and quietly.
S3407 [S17E67] was quiet and stable.
New region S3409 [N14W51] emerged early in the day and decayed during the latter half of the day.
New region S3410 [S17E15] emerged with a penumbra spot.

C2+ Flares (SDO/EVE):

Magnitude Time (UTC) Location AR
C2.4 05:22 S14E79 12058
C2.9 08:19 S13E75 12058
C3.0 14:19 S13E71 12058
C8.0 15:09 S14E67 12058

Coronal mass ejections (CMEs)

May 7-9: 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 small southern hemisphere coronal hole (CH616) was in an Earth facing position on May 7.

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 10-12.

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
12049 2014.04.26
2014.04.27
2     S07W89 0090 DSO    

rotated out of view

12050 2014.04.27       N12W88         plage
12052 2014.05.01
2014.05.02
2 4 2 S12W46 0010 BXO BXO location: S12W42
S3379 2014.05.01       S06W34           plage
S3380 2014.05.02       N10W31           plage
12053 2014.05.03 4 11 4 N10W29 0030 CAO DRO

location: N09W28

12054 2014.05.03
2014.05.04
1 8 5 S12W01 0020 HRX CRO  
S3385 2014.05.03       N10W07           plage
S3386 2014.05.03   3 2 S19W42 0010   BXO  
12055 2014.05.04
2014.05.05
12 34 15 N12E18 0530 EHI EHO area: 0640
S3389 2014.05.04       S32W27           plage
12056 2014.05.05
2014.05.06
17 27 16 N04E31 0430 EKI ESC

location: N05E31

area: 0570

S3394 2014.05.05       S16W16         plage
S3395 2014.05.05       S12W10           plage
12057 2014.05.06
2014.05.07
1 4 2 N15E39 0120 HSX CSO area: 0200
S3397 2014.05.06       S15E38           plage
S3398 2014.05.06   2   S26W23         plage
S3400 2014.05.06       S24W59           plage
S3401 2014.05.07       N03E43         plage
12058 2014.05.07
2014.05.08
4 19 6 S14E57 0100 EAO ESO beta-gamma

area: 0140

S3403 2014.05.07       N14W07           plage
S3404 2014.05.08       N13E06         plage
S3405 2014.05.08   3 2 N10E37 0013   HRX  
S3406 2014.05.08   3 2 N00E33 0030   HRX  
S3407 2014.05.08   5 2 S17E67 0050   CAO  
S3408 2014.05.08       S33W06         plage
S3409 2014.05.09   1   N14W51 0002   AXX    
S3410 2014.05.09   1 1 S17E15 0005   AXX    
Total spot count: 43 125 59  
Sunspot number: 123 265 179  (total spot count + 10 * number of spotted regions)
Weighted SN: 86 167 101  (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): 74 93 98 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
2014.05 138.8 (1)   34.5 (2A) / 118.8 (2B) / 96.4 (2C) (74.4 projected, -2.6) (6.7)

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.