Solar Terrestrial Activity Report

Activity chart

Last major update issued on May 13, 2015 at 04:55 UT

Charts (* = updated daily) Data and archive
  Solar wind (*) Solar and geomagnetic data - last month (*)
  Electron fluence (*) Archived daily reports and monthly data from 2003.01 (May 1, 2015)
Solar cycle Solar cycles 23-24 (May 1, 2015) Historical solar and geomagnetic data charts 1954-2006 (April 5, 2007)
  Cycle 24 progress (May 1, 2015) Noon SDO sunspot count 1K Reference: 4K (large file) (*)
  Solar cycles 1-20 POES auroral activity level October 2009 - December 2012
  Comparison of cycles 21, 22, 23 and 24 (May 1, 2015) 3rd SSN Workshop, Tucson, 2013
  Comparison of cycles 10, 12, 13, 14, 16 and 24 (May 1, 2015) 4th SSN Workshop, Locarno, 2014
  Solar polar fields vs solar cycles (May 9, 2015)  

Recent activity

The geomagnetic field was quiet to unsettled on May 12, likely under the influence of effects from a recurrent co-rotating interaction region associated with CH667. Solar wind speed at SOHO ranged between 337 and 450 km/s. An increase in solar wind speed was observed early on May 13 as the geomagnetic disturbance intensified.

Solar flux at 20h UTC on 2.8 GHz was 163.2 (increasing 8.5 over the last solar rotation). The 90 day 10.7 flux at 1 AU was 126.6. The Potsdam WDC planetary A index was 13 (STAR Ap - based on the mean of three hour interval ap indices: 13.1). Three hour interval K indices: 23333233 (planetary), 33444343 (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 16 active regions using 2K resolution (SN: 347) and 13 active regions using 1K resolution (SN: 226) SDO images on the visible solar disk.

Region 12338 [N04W65] reemerged with a few spots.
Region 12339 [N12W19] decayed slowly prodcing low level C flares. Even if the region has become less complex magnetically there is still a chance of an M class flare.
Region 12340 [S08E03] decayed slowly and quietly.
Region 12341 [S20E08] was quiet and stable.
Region 12342 [N17E22] developed as new flux emerged. The region has polarity intermixing and could produce C flares.
Region 12343 [N09E13] decayed slowly and quietly.
Region 12344 [S10E44] developed slowly and was quiet.
Region 12345 [N15W04] was quiet and stable.
Region 12346 [S07E55] developed slowly and was quiet.
Region 12347 [N05E53] was quiet and stable.

Spotted regions not numbered (or interpreted differently) by SWPC:
S4459 [N12E27] developed slowly and remained quiet.
New region S4463 [N07E23] emerged with a penumbra spot.
New region S4465 [S10E86] rotated into view.
New region S4466 [N13E70] emerged with a few spots.
New region S4467 [N23E72] rotated into view with a penumbra spot.
New region S4468 [N13E55] emerged with a penumbra spot.

C2+ flares:

Magnitude Peak time (UTC) Location AR Recorded by Comment
C2.6 (LDE) 03:02 SW limb   GOES15 wrongly attributed to AR 12339 by SWPC
CME
C3.8 @ 03:10 @ SDO/EVE
C2.2 04:32 N11W04 12339 GOES15  
C3.0/1N 11:51 N06W05 S4464 GOES15 attributed to AR 12339 by SWPC. AR S4464 was a shortlived region

Flare activity according to SDO/EVE/ESP XRS-B proxy

Coronal mass ejections (CMEs)

May 10-12: No obviously Earth directed CMEs were observed.

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 recurrent extension (CH667) of the southern polar coronal hole rotated across the central meridian on May 8-9 and may be associated with a co-rotating interaction region. A recurrent southern hemipshere coronal hole (CH668) will probably rotate into an Earth facing position on May 14-15.

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 fair.

Forecast

The geomagnetic field is expected to be quiet to minor storm on May 13 due to effects from CH667 and a co-rotating interaction region. Quiet to unsettled is likely on May 14-15.

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 overlays
Comment
SWPC Magnetic
(SDO)
SWPC STAR Current Previous
2K 1K
12335 2015.04.30 2     S14W85 0010 BXO     rotated out of view
12338 2015.05.02
2015.05.03
      N05W69          
12337 2015.05.02
2015.05.03
      S17W66          
S4438 2015.05.03       N05W51            
S4439 2015.05.03       N12W44            
12339 2015.05.03
2015.05.04
51 87 47 N14W19 0670 FKC FKC beta-gamma

area: 1050

location: N12W19

S4444 2015.05.05       S03W44            
12340 2015.05.06
2015.05.07
1 7 5 S07W00 0010 AXX BXO

 

12341 2015.05.06
2015.05.07
1 3 1 S19E07 0070 HSX CSO area: 0130

location: S20E08

12345 2015.05.07
2015.05.11
3 11 4 N15W06 0010 BXO BXO  
S4451 2015.05.07       S17W47            
12342 2015.05.08
2015.05.09
5 32 15 N18E22 0030 CRO DRI beta-gamma

area: 0080

12343 2015.05.09
2015.05.10
2 8 4 N11E12 0010 BXO BXO location: N09E13
S4454 2015.05.09       S06W36          
12344 2015.05.10 3 9 5 S10E45 0040 CSO DAO area: 0140
12346 2015.05.10
2015.05.11
1 15 6 S07E55 0050 HSX CAO

area: 0130

12347 2015.05.10
2015.05.11
1 1 1 N05E54 0010 AXX HRX  
S4459 2015.05.11   7 3 N12E27 0015   BXO  
S4460 2015.05.11       S20W33          
S4461 2015.05.11       S07W47          
S4462 2015.05.11       S50W11          
S4463 2015.05.12   1   N07E23 0001   AXX    
S4465 2015.05.12   1 1 S10E86 0150   HSX    
S4466 2015.05.12   3 2 N13E70 0030   DRO    
S4467 2015.05.12   1   N23E72 0002   AXX    
S4468 2015.05.12   1   N13E55 0001   AXX    
Total spot count: 70 187 96  
Sunspot number: 170 347 226  (total spot count + 10 * number of spotted regions)
Weighted SN: 98 226 135  (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): 102 121 124 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
2013.12 147.7 143.1 90.3 76.0 (+0.6) 4.68
2014.01 157.4 152.4 81.8 77.3 (+1.3) 5.44
2014.02 170.3
(cycle peak)
166.3 102.3 (cycle peak) 78.4 (+1.1) 10.70
2014.03 149.9 148.5 91.9 80.8 (+2.4) 4.88
2014.04 143.9 144.8 84.7 81.9 (+1.1) (solar max) 7.88
2014.05 129.7 132.9 75.2 80.5 (-1.4) 5.75
2014.06 122.0 125.8 71.0 79.7 (-0.8) 6.72
2014.07 137.4 141.8 72.5 78.5 (-1.2) 4.50
2014.08 124.7 127.9 74.7 75.5 (-3.0) 7.71
2014.09 146.6 148.1 87.6 70.8 (-4.7) 9.78
2014.10 153.4 152.9 60.6 67.3 (-3.5) 8.96
2014.11 154.8 151.4 70.1 (64.9 projected, -2.4) 9.33
2014.12 158.7 153.8 78.0 (62.6 projected, -2.3) 11.24
2015.01 141.9 137.3 67.0 (60.4 projected, -2.2) 9.46
2015.02 129.1 126.0 44.8 (58.7 projected, -1.7) 9.92
2015.03 125.9 124.6 38.4 (56.3 projected, -2.4) 16.14
2015.04 128.8 129.7 54.4 (53.7 projected, -2.6) 10.3
2015.05 (136.8)   41.7 (2A) / 107.7 (2B) / 87.3 (2C) (51.5 projected, -2.2) (8.4)

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.