Solar Terrestrial Activity Report

Activity chart

Partial update issued on May 20, 2014 at 06:20 UTC. Updates May 18-23 will be irregular and possibly incomplete.

[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 19. Solar wind speed at SOHO ranged between 336 and 352 km/s.

Solar flux at 20h UTC on 2.8 GHz was 116.9 (decreasing 27.9 over the last solar rotation). The 90 day 10.7 flux at 1 AU was 148.5. The Potsdam WDC planetary A index was 5 (STAR Ap - based on the mean of three hour interval ap indices: 4.8). Three hour interval K indices: 11111112 (planetary), 12111312 (Boulder).

The background x-ray flux is at the class B3 level.

At the time of counting spots (see image time), spots were observed in 13 active regions in 2K resolution (SN: 186) and 11 active regions in 1K resolution (SN: 144) SDO images on the visible solar disk.

Region 12060 [S12W74] decayed slowly and quietly.
Region 12061 [S23W33] was quiet and stable.
Region 12063 [N10W24] decayed slowly and quietly.
Region 12065 [S17E13] decayed slowly and quietly.
Region 12066 [S16W39] was quiet and stable.
Region 12068 [S15W01] was quiet and stable.
Region 12069 [S18E40] decayed slowly and quietly.
New region 12070 [S17W61] emerged on May 18 and was numbered by SWPC the next day.
New region 12071 [S12E77] rotated into view and produced the only low level C flare of the day.

Spotted regions not numbered (or interpreted differently) by SWPC:
S3444 [S22E44] was quiet and stable.
S3448 [S35E02] was quiet and stable.
S3449 [N26E13] was quiet and stable.
New region S3454 [S10W51] emerged penumbra spots.

C2+ Flares (SDO/EVE):

Magnitude Time (UTC) Location AR

Coronal mass ejections (CMEs)

May 17-19: 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

No obvious coronal holes are currently in or near Earth facing positions.

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 to fair. Propagation on long distance northeast-southwest paths is poor.

Forecast

The geomagnetic field is expected to be quiet on May 20-22.

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
12058 2014.05.07
2014.05.08
      S11W81           plage
12060 2014.05.08
2014.05.11
2 2 2 S13W74 0080 HAX HAX

area: 0120

12061 2014.05.10
2014.05.11
2 7 2 S25W36 0090 HSX CSO area: 0150
S3417 2014.05.11       S23W45         plage
S3418 2014.05.11       N22W30           plage
S3422 2014.05.13       S23W03           plage
S3423 2014.05.13       S09W32           plage
12063 2014.05.13
2014.05.14
14 2 2 N12W24 0030 CAO HRX

 

12064 2014.05.13
2014.05.14
2     N09W40 0010 BXO     spotless
S3426 2014.05.13       N00W57           plage
12066 2014.05.13
2014.05.16
7 6 5 S16W39 0070 DAO DAO  
12065 2014.05.14
2014.05.15
3 16 9 S18E12 0010 AXX BXO  
S3433 2014.05.15       N18W42           plage
S3436 2014.05.15       N08W04           plage
S3437 2014.05.15       N25E16           plage
12068 2014.05.16
2014.05.17
  5 3 S17W04 0015   BXO location: S15W01
S3440 2014.05.16       S12W26           plage
S3441 2014.05.16       N27W37           plage
S3442 2014.05.16       S05W49           plage
S3443 2014.05.16       N10W21           plage
S3444 2014.05.17   4 2 S22E44 0008   BXO  
12069 2014.05.17
2014.05.18
1 1 1 S18E40 0010 AXX AXX  
S3446 2014.05.17       N00E10         plage
S3448 2014.05.17   1 1 S35E02 0006   AXX  
S3449 2014.05.18   1   N26E13 0001   AXX  
12070 2014.05.18
2014.05.19
6 5 4 S16W61 0030 CRO CRO  
S3451 2014.05.18       N08W51         plage
S3452 2014.05.18       N17W22            
12071 2014.05.19 3 4 3 S11E80 0010 BXO DRO   location: S12E77

area: 0040

S3454 2014.05.19   2   S10W51 0002   BXO    
Total spot count: 40 56 34  
Sunspot number: 130 186 144  (total spot count + 10 * number of spotted regions)
Weighted SN: 63 80 58  (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): 78 65 79 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
2014.05 143.2 (1)   80.6 (2A) / 131.5 (2B) / 101.3 (2C) (74.4 projected, -2.6) (5.9)

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 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.