Solar Terrestrial Activity Report

Activity chart

Last major update issued on May 22, 2014 at 05:15 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]
[Presentations: 3rd SSN Workshop, Tucson, 2013 (pdf) / 4th SSN Workshop, Locarno, 2014]

Recent activity

The geomagnetic field was very quiet on May 21. Solar wind speed at SOHO ranged between 276 and 377 km/s.

Solar flux at 20h UTC on 2.8 GHz was 113.9 (decreasing 16.2 over the last solar rotation). The 90 day 10.7 flux at 1 AU was 147.7. The Potsdam WDC planetary A index was 2 (STAR Ap - based on the mean of three hour interval ap indices: 2.0). Three hour interval K indices: 10000001 (planetary), 10111211 (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 10 active regions in 2K resolution (SN: 166) and 7 active regions in 1K resolution (SN: 101) SDO images on the visible solar disk.

Region 12061 [S24W60] was quiet and stable.
Region 12063 [N09W51] decayed slowly and quietly.
Region 12065 [S18W16] was quiet and stable.
Region 12066 [S17W67] decayed slowly and was mostly quiet.
Region 12069 [S18E13] decayed slowly and quietly.
Region 12071 [S11E50] developed slowly and was mostly quiet.
Region 12072 [S18W05] developed slowly with a small magnetic delta structure forming on the leader spot. The region was the source of an impulsive C4.8 flare at 03:11 UTC on May 22.
New region 12073 [S11E64] rotated into view on May 20 and was umbered by SWPC the next day.

Spotted regions not numbered (or interpreted differently) by SWPC:
S3446 [N03W13] was quiet and stable.
S3457 [N20W30] was quiet and stable.

C2+ Flares (SDO/EVE):

Magnitude Time (UTC) Location AR
C2.2 01:29 S12E67 12071
C2.3 01:43 S12E69 12071

Coronal mass ejections (CMEs)

May 19-21: 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 trans equatorial coronal hole (CH618) was in an Earth facing position on May 21.

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

Forecast

The geomagnetic field is expected to be quiet on May 22-24. On May 24 there is a slight chance of unsettled intervals should a stream from CH618 reach Earth.

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
12061 2014.05.10
2014.05.11
1 1 1 S24W60 0080 HSX HSX area: 0140
S3418 2014.05.11       N22W56           plage
S3422 2014.05.13       S23W29           plage
S3423 2014.05.13       S09W58           plage
12063 2014.05.13
2014.05.14
  2   N09W53 0002   BXO

 

12064 2014.05.13
2014.05.14
      N09W68           plage
12066 2014.05.13
2014.05.16
3 8 3 S17W65 0040 DAO CAO  
12065 2014.05.14
2014.05.15
3 14 6 S18W16 0010 AXX AXX area: 0030
S3436 2014.05.15       N08W30           plage
S3437 2014.05.15       N25W10           plage
12068 2014.05.16
2014.05.17
      S15W30         plage
S3440 2014.05.16       S12W52           plage
S3443 2014.05.16       N10W47           plage
S3444 2014.05.17       S25E21         plage
12069 2014.05.17
2014.05.18
5 3 2 S18E13 0020 CSO CRO  
S3446 2014.05.17   2   N03W13 0004   AXX  
S3448 2014.05.17       S35W24           plage
S3449 2014.05.18       N26W13           plage
S3452 2014.05.18       N17W48            
12071 2014.05.19 10 18 7 S12E48 0150 DAC DAI area: 0220
12072 2014.05.20 7 16 11 S18W05 0020 CSI DAI beta-gamma-delta

area: 0050

location: S11E50

12073 2014.05.20
2014.05.21
1 1 1 S11E62 0050 HSX HSX  
S3457 2014.05.20   1   N20W30 0002   AXX  
Total spot count: 30 66 31  
Sunspot number: 100 166 101  (total spot count + 10 * number of spotted regions)
Weighted SN: 60 94 59  (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): 60 58 56 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
2014.05 140.5 (1)   87.9 (2A) / 129.8 (2B) / 96.8 (2C) (74.4 projected, -2.6) (5.5)

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.