Solar Terrestrial Activity Report

Activity chart

Last major update issued on May 11, 2014 at 06:25 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 10. Solar wind speed at SOHO ranged between 327 and 383 km/s. A disturbance, likely associated with CH616, began late in the day.

Solar flux at 20h UTC on 2.8 GHz was 150 (increasing 12.9 over the last solar rotation). The 90 day 10.7 flux at 1 AU was 149.2. The Potsdam WDC planetary A index was 7 (STAR Ap - based on the mean of three hour interval ap indices: 6.8). Three hour interval K indices: 23111022 (planetary), 23222222 (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 17 active regions in 2K resolution (SN: 331) and 16 active regions in 1K resolution (SN: 245) SDO images on the visible solar disk.

Region 12053 [N09W42] decayed slowly and quietly.
Region 12054 [S13W11] decayed slowly and quietly.
Region 12055 [N11E04] displayed no major changes and was mostly quiet. An M class flare is possible.
Region 12056 [N05E17] has minor polarity intermixing. An M class flare is still possible.
Region 12057 [N15E27] was quiet and stable.
Region 12058 [S11E42] displayed only minor changes and could produce C flares.
New region 12059 [N00E21] was finally split off from AR 12056 by SWPC.

Spotted regions not numbered (or interpreted differently) by SWPC:
S3386 [S19W56] was quiet and stable.
S3394 [S20W18] reemerged with penumbra spots.
S3404 [N13W08] reemerged with penumbra spots.
S3405 [N09E27] developed slowly as new flux emerged.
S3407 [S16E53] has polarity intermixing and could produce a minor M class flare.
New region S3411 [S13E16] emerged with penumbra spots.
New region S3412 [N21W38] emerged with penumbra spots early in the day and decayed later on.
New region S3413 [S23E80] rotated into view.
New region S3414 [S06W15] emerged with several spots.
New region S3415 [N02E30] emerged with penumbra spots.

C2+ Flares (SDO/EVE):

Magnitude Time (UTC) Location AR
C8.6 07:03 N03E27 12056
C2.4 08:40 S17E61 S3407
C2.5 09:39 S11W48 12052
C3.2 23:57 N11E05 12055

Coronal mass ejections (CMEs)

May 8-10: 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. A southern hemisphere coronal hole (CH617) could rotate into an Earth facing position on May 12.

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 active on May 11 due to effects from CH616 and quiet on May 12-13.

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
3     S12W60 0010       plage

location: S12W55

S3379 2014.05.01       S06W47           plage
S3380 2014.05.02       N10W44           plage
12053 2014.05.03 3 3 1 N10W43 0010 CRO CRO

location: N09W42

area: 0015

12054 2014.05.03
2014.05.04
3 11 4 S12W16 0010 BXO CRO location: S13W11

area: 0022

S3385 2014.05.03       N10W20           plage
S3386 2014.05.03   4 3 S19W56 0011   BXO  
12055 2014.05.04
2014.05.05
11 24 11 N12E04 0440 EHO EHO area: 0690
S3389 2014.05.04       S32W40           plage
12056 2014.05.05
2014.05.06
14 33 22 N05E16 0350 EHI ESC

location: N05E31

area: 0480

S3394 2014.05.05   2 1 S20W18 0004   AXX    
S3395 2014.05.05       S12W23           plage
12057 2014.05.06
2014.05.07
1 7 5 N15E26 0110 HSX CSO area: 0180
S3397 2014.05.06       S15E25           plage
S3398 2014.05.06       S26W36           plage
S3401 2014.05.07       N03E30           plage
12058 2014.05.07
2014.05.08
9 28 14 S14E57 0140 FAO DAI beta-gamma

area: 0110

S3403 2014.05.07       N14W20           plage
S3404 2014.05.08   5 2 N13W08 0012   AXX    
S3405 2014.05.08   4 3 N09E21 0015   BXO  
12059 2014.05.08
2014.05.10
1 2 2 S00E23 0010 HRX CRO location: N00E21

area: 0020

S3407 2014.05.08   19 9 S16E53 0050   CAO beta-gamma
S3408 2014.05.08       S33W19           plage
S3410 2014.05.09       S17E02         plage
S3411 2014.05.10   3 1 S13E16 0005   AXX    
S3412 2014.05.10   3   N21W38 0004   BXO    
S3413 2014.05.10   2 2 S23E80 0070   CAO    
S3414 2014.05.10   9 5 S13W11 0025   CRO    
S3415 2014.05.10   2 2 N02E30 0005   BXO    
Total spot count: 45 161 85  
Sunspot number: 125 331 245  (total spot count + 10 * number of spotted regions)
Weighted SN: 86 208 133  (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): 81 116 135 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
2014.05 139.9 (1)   38.5 (2A) / 118.8 (2B) / 98.7 (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.