Solar Terrestrial Activity Report

Activity chart

Last major update issued on May 8, 2015 at 06:10 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 (April 10, 2015)  

Recent activity

The geomagnetic field was quiet on May 7. Solar wind speed at SOHO ranged between 348 and 490 km/s.

Solar flux at 20h UTC on 2.8 GHz was 146.6 (increasing 31.5 over the last solar rotation). The 90 day 10.7 flux at 1 AU was 125.5. The Potsdam WDC planetary A index was 5 (STAR Ap - based on the mean of three hour interval ap indices: 5.4). Three hour interval K indices: 22111212 (planetary), 22112322 (Boulder).

The background x-ray flux is at the class B7 level.

At the time of counting spots (see image time), spots were observed in 11 active regions using 2K resolution (SN: 248) and 8 active regions using 1K resolution (SN: 165) SDO images on the visible solar disk.

Region 12335 [S15W17] decayed significantly losing spots and area.
Region 12336 [N13W43] decayed quickly and quietly.
Region 12337 [S18E02] decayed slowly and quietly.
Region 12338 [N04E03] decayed slowly and lost most of its mature penumbra.
Region 12339 [N12E48] has two small magnetic deltas, one at the southern edge of the leading penumbra and one in a northern central penumbra. Another major flare is still possible.
New region 12340 [S07E67] rotated into view on May 6 and was numbered by SWPC the next day.
New region 12341 [S20E73] rotated into view on May 6 with SWPC numbering the region the following day.

Spotted regions not numbered (or interpreted differently) by SWPC:
S4426 [S12W36] decayed slowly and quietly.
S4429 [S26W37] reemerged with a penumbra spot.
New region S4450 [N16E62] was split off from AR 12339.
New region S4451 [S17E18] emerged with a penumbra spot.

C2+ flares:

Magnitude Peak time (UTC) Location AR Recorded by Comment
C4.3 10:02 N16E70 12339 GOES15  
C2.8 16:54 N16E53 12339 GOES15  
C5.0 20:00   12339 GOES15  

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

Coronal mass ejections (CMEs)

May 5-7: 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 could rotate across the central meridian on May 8-9 and may be associated with a co-rotating interaction region.

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.

Forecast

The geomagnetic field is expected to be quiet to unsettled on May 8-10. On May 12-13 effects from CH667 and a co-rotating interaction region could 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
12334 2015.04.27
2015.04.30
      S20W87            
12335 2015.04.30 27 41 27 S16W17 0180 EAC EAI beta-gamma
S4426 2015.04.30   1   S12W36 0002   AXX  
S4429 2015.05.01   1   S26W37 0002   AXX    
12338 2015.05.02
2015.05.03
4 12 9 N03E02 0040 DAO DAO area: 0070
12336 2015.05.02
2015.05.03
3 5 3 N11W44 0010 AXX CRO location: N13W43
12337 2015.05.02
2015.05.03
5 8 6 S18E03 0030 CAO CRO  
S4438 2015.05.03       N05E14            
S4439 2015.05.03       N12E21          
12339 2015.05.03
2015.05.04
20 55 32 N13E47 0730 FKC FKC beta-gamma-delta

area: 1280

location: N12E48

S4441 2015.05.04       N13W04            
S4442 2015.05.04       S29W03          
S4444 2015.05.05       S03E21          
S4445 2015.05.05       S04W04            
12340 2015.05.06
2015.05.07
1 5 3 S06E65 0030 HRX CAO area: 0090

location: S07E67

12341 2015.05.06
2015.05.07
1 1 1 S19E73 0060 HSX HSX area: 0150

location: S20E73

S4449 2015.05.06       N25E02          
S4450 2015.05.07   8 4 N16E62 0040   DRO    
S4451 2015.05.07   1   S17E18 0002   AXX    
Total spot count: 61 138 85  
Sunspot number: 131 248 165  (total spot count + 10 * number of spotted regions)
Weighted SN: 94 177 114  (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): 79 87 91 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 (121.5)    17.1 (2A) / 75.7 (2B) / 81.2 (2C) (51.5 projected, -2.2) (7.6)

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.