Solar Terrestrial Activity Report

Activity chart

Last major update issued on May 15, 2015 at 05:00 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 14 under the decreasing influence of effects from CH667 and an associated co-rotating interaction region. Solar wind speed at SOHO ranged between 550 and 768 km/s.

Solar flux at 20h UTC on 2.8 GHz was 145.1 (decreasing 4.5 over the last solar rotation). The 90 day 10.7 flux at 1 AU was 127.3. The Potsdam WDC planetary A index was 8 (STAR Ap - based on the mean of three hour interval ap indices: 7.5). Three hour interval K indices: 22212123 (planetary), 33422323 (Boulder).

The background x-ray flux is at the class B6 level.

At the time of counting spots (see image time), spots were observed in 17 active regions using 2K resolution (SN: 308) and 15 active regions using 1K resolution (SN: 233) SDO images on the visible solar disk.

Region 12339 [N11W44] lost spots and penumbral area. A weak magnetic delta developed centrally. The region could still produce an M class flare.
Region 12340 [S08W23] decayed slowly and quietly.
Region 12341 [S20W17] was quiet and stable.
Region 12342 [N17W08] produced a couple of C flares, some penumbral growth was observed.
Region 12343 [N10W15] decayed slowly and quietly.
Region 12344 [S09E16] was quiet and stable
Region 12345 [N15W30] decayed slowly and quietly.
Region 12346 [S08E28] was quiet and stable.
Region 12347 [N04E28] was quiet and stable.
New region 12348 [S09E60] rotated into view on May 12 and was numbered by SWPC 2 days later.

Spotted regions not numbered (or interpreted differently) by SWPC:
S4459 [N10E03] decayed slowly and quietly.
S4466 [N13E40] decayed slowly and quietly.
S4467 [N23E48] reemerged with a penumbra spot.
S4469 [N19E07] was quiet and stable.
S4470 [N20W15] was quiet and stable.
New region S4471 [N19E22] was observed with a penumbra spot.
New region S4472 [S04W71] emerged with penumbra spots.

C2+ flares:

Magnitude Peak time (UTC) Location AR Recorded by Comment
C2.5 07:31 N07W46 12339 GOES15  
C2.8 14:08 N18E02 12342 GOES15  
C2.1/1F 16:31 N13W41 12339 GOES15  
C4.8 17:53   12339 GOES15  
C2.6 00:11 (May 15) N18W04 12342 GOES15  

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

Coronal mass ejections (CMEs)

May 12, 14: No obviously Earth directed CMEs were observed.
May 13: A faint full halo CME was observed in LASCO C3 imagery after the C9 event in AR 12345.

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 southern hemisphere coronal hole (CH668) will 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 poor to fair.

Forecast

The geomagnetic field is expected to be quiet to unsettled on May 15-16. Late on May 16 and on May 17 there is a chance a CME could arrive and cause unsettled to minor storm conditions.

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
12339 2015.05.03
2015.05.04
21 54 38 N11W45 0400 FAC FAC beta-gamma-delta
12340 2015.05.06
2015.05.07
  3 1 S08W27 0005   BXO

 

12341 2015.05.06
2015.05.07
1 3 2 S20W18 0080 HSX CSO area: 0130
12345 2015.05.07
2015.05.11
  4   N16W30 0006   BXO  
12342 2015.05.08
2015.05.09
6 8 5 N17W06 0060 CSO CAO

area: 0130

12343 2015.05.09
2015.05.10
3 7 3 N09W13 0010 BXO BXO  
12344 2015.05.10 2 13 6 S10E21 0040 CSO CAO area: 0110

location: S09E16

12346 2015.05.10
2015.05.11
7 19 13 S08E28 0050 CSO CAI

area: 0120

12347 2015.05.10
2015.05.11
1 3 2 N05E26 0010 AXX CRO  
S4459 2015.05.11   2 1 N10E03 0007   AXX  
S4463 2015.05.12       N07W03            
12348 2015.05.12
2015.05.14
5 5 4 S09E60 0100 HSX CSO area: 0160
S4466 2015.05.12   4 1 N13E40 0020   AXX  
S4467 2015.05.12   1   N23E48 0002   AXX    
S4468 2015.05.12       N13E29            
S4469 2015.05.13   3 2 N19E07 0010   BXO  
S4470 2015.05.13   6 3 N20W15 0013   BXO  
S4471 2015.05.14   1 1 N19E22 0003   AXX    
S4472 2015.05.14   2 1 S04W71 0005   BXO    
Total spot count: 46 138 83  
Sunspot number: 126 308 233  (total spot count + 10 * number of spotted regions)
Weighted SN: 76 171 116  (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): 76 108 128 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) 10.73
2015.05 (138.8)   50.1 (2A) / 110.9 (2B) / 89.4 (2C) (51.5 projected, -2.2) (10.7)

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.