Solar Terrestrial Activity Report

Activity chart

Last major update issued on May 11, 2015 at 04:40 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 active on May 10. Solar wind speed at SOHO ranged between 346 and 440 km/s.

Solar flux at 20h UTC on 2.8 GHz was 159.9 (increasing 18.6 over the last solar rotation). The 90 day 10.7 flux at 1 AU was 125.9. The Potsdam WDC planetary A index was 9 (STAR Ap - based on the mean of three hour interval ap indices: 8.9). Three hour interval K indices: 21243122 (planetary), 23343322 (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 13 active regions using 2K resolution (SN: 277) and 11 active regions using 1K resolution (SN: 195) SDO images on the visible solar disk.

Region 12335 [S16W58] was quiet and stable.
Region 12337 [S17W37] decayed slowly and quietly.
Region 12338 [N04W36] was quiet and stable.
Region 12339 [N11E07] developed again as new flux emerged to the north of the trailing penumbrae causing a magnetic delta to form. A major flare is possible.
Region 12340 [S08E27] decayed slowly and quietly.
Region 12341 [S20E35] was quiet and stable.
Region 12342 [N18E49] developed slowly and quietly.
New region 12343 [N09E39] emerged on May 9 and was numbered by SWPC the next day.
New region 12344 [S11E71] rotated into view.

Spotted regions not numbered (or interpreted differently) by SWPC:
S4450 [N13E22] developed as new flux emerged in the leading spot section.
New region S4456 [S08E82] rotated into view.
New region S4457 [N04E81] rotated into view.
New region S4458 [N10W61] emerged with penumbra spots.

C2+ flares:

Magnitude Peak time (UTC) Location AR Recorded by Comment
C2.2 13:03 N12E15 12339 GOES15  
C2.4 17:11 N14E14 12339 GOES15  
C2.4 21:55 N12E09 12339 GOES15  
C2.1 23:43   12339 GOES15  

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

Coronal mass ejections (CMEs)

May 8-10: 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 active on May 11-12 due to effects from CH667 and a co-rotating interaction region, minor storm intervals are possible. Quiet to unsettled is likely on May 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 overlays
Comment
SWPC Magnetic
(SDO)
SWPC STAR Current Previous
2K 1K
12335 2015.04.30 4 10 6 S15W59 0030 CRO CRI  
12338 2015.05.02
2015.05.03
  3 2 N05W39 0008   BXO  
12336 2015.05.02
2015.05.03
      N13W85            
12337 2015.05.02
2015.05.03
4 5 3 S16W37 0030 CSO CRO  
S4438 2015.05.03       N05W25            
S4439 2015.05.03       N12W18            
12339 2015.05.03
2015.05.04
35 82 48 N13E08 0820 FKC FKC beta-gamma-delta

area: 1370

location: N11E07

S4441 2015.05.04       N13W43            
S4442 2015.05.04       S29W44            
S4444 2015.05.05       S03W18            
S4445 2015.05.05       S04W43            
12340 2015.05.06
2015.05.07
3 10 6 S08E26 0020 CAO CRO

 

12341 2015.05.06
2015.05.07
1 1 1 S19E33 0080 HSX HAX area: 0130

location: S20E35

S4449 2015.05.06       N26W37            
S4450 2015.05.07   6 4 N13E22 0030   CRO  
S4451 2015.05.07       S17W21            
12342 2015.05.08
2015.05.09
4 13 8 N18E49 0030 CRO CRI  
12343 2015.05.09
2015.05.10
2 8 5 N10E39 0020 CRO DRO  
S4454 2015.05.09       S08W06          
12344 2015.05.10 1 4 1 S10E71 0030 HAX CSO   area: 0120
S4456 2015.05.10   1 1 S08E82 0060   HAX    
S4457 2015.05.10   1   N04E81 0010   AXX    
S4458 2015.05.10   3   N10W61 0006   BXO    
Total spot count: 54 147 85  
Sunspot number: 134 277 195  (total spot count + 10 * number of spotted regions)
Weighted SN: 93 190 128  (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): 80 97 107 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 (131.5)   30.1 (2A) / 93..4 (2B) / 83.8 (2C) (51.5 projected, -2.2) (7.5)

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.