Solar Terrestrial Activity Report

Activity chart

Last major update issued on May 7, 2015 at 05:15 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 to minor storm on May 6. Solar wind speed at SOHO ranged between 349 and 489 km/s. A solar wind shock was observed at SOHO at 00:50 UT, the arrival of the CME observed on May 2/3.

Solar flux at 20h UTC on 2.8 GHz was 136.2 (increasing 24.9 over the last solar rotation). The 90 day 10.7 flux at 1 AU was 125.4. The Potsdam WDC planetary A index was 20 (STAR Ap - based on the mean of three hour interval ap indices: 20.3). Three hour interval K indices: 33335432 (planetary), 33445422 (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 12 active regions using 2K resolution (SN: 260) and 10 active regions using 1K resolution (SN: 182) SDO images on the visible solar disk.

Region 12335 [S16W03] decayed slowly and became less active compared to recent days.
Region 12336 [N12W28] was quiet and stable.
Region 12337 [S18E18] developed as new flux emerged.
Region 12338 [N04E17] matured and was mostly quiet.
Region 12339 [N12E61] has small magnetic deltas in the central spot section. Overall the region relaxed during the day resulting in weaker flares compared to the previous day. The trailing northeastern spots are being considered for a split.

Spotted regions not numbered (or interpreted differently) by SWPC:
S4426 [S15W27] was quiet and stable.
S4439 [N12E34] decayed slowly and quietly.
S4442 [S29E10] was quiet and stable.
S4444 [S03E34] emerged with a penumbra spot.
New region S4447 [S08E78] rotated into view.
New region S4448 [S20E84] rotated into view.
New region S4449 [N25E15] emerged with a penumbra spot.

C2+ flares:

Magnitude Peak time (UTC) Location AR Recorded by Comment
C3.1 00:10   12339 SDO/EVE Learmonth @ 00:06
C3.6 00:25   12335 SDO/EVE  
C3.9 01:55 N14E73 12339 GOES15  
C2.4 02:04 NE limb   SDO/EVE  
C2.3 02:11   12335 SDO/EVE Learmonth @ 02:15
C2.3 05:10   12339 GOES15  
C3.4 06:41 N16E73 12339 GOES15  
C2.4 06:54   12339 GOES15  
C3.4 11:12 NE limb   GOES15  
M1.9 11:49 N17E67 12339 GOES15  
C2.0 17:18 NE limb   GOES15  
C2.9/1F 20:16 N15E63 12339 GOES15  
C3.0 20:23   12335 GOES15  
C2.4 20:31   12339 SDO/EVE  
C2.0 23:53   12337 SDO/EVE  

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

Coronal mass ejections (CMEs)

May 4-6: 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 to fair.

Forecast

The geomagnetic field is expected to be quiet to unsettled on May 7-9.

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
      S20W73            
12335 2015.04.30 28 53 32 S13W03 0220 EAC EAC beta-gamma

area: 0300

location: S16W03

S4426 2015.04.30   3 1 S15W27 0007   BXO  
S4428 2015.04.30       N13W55            
S4429 2015.05.01       S27W29            
12338 2015.05.02
2015.05.03
7 12 8 N04E15 0090 DAO DAO area: 0140
12336 2015.05.02
2015.05.03
7 17 8 N10W28 0030 CRO DRI location: N12W28
12337 2015.05.02
2015.05.03
3 10 7 S15E15 0010 CSO DRI area: 0050

location: S18E18

S4437 2015.05.02       N10W55            
S4438 2015.05.03       N05E27            
S4439 2015.05.03   2   N12E34 0002   BXO  
12339 2015.05.03
2015.05.04
15 35 22 N12E59 0590 FKC FKC area: 1050

location: N12E61

S4441 2015.05.04       N13E09            
S4442 2015.05.04   3 1 S29E10 0008   AXX  
S4443 2015.05.04       S03W56            
S4444 2015.05.05   2 1 S03E34 0008   BXO  
S4445 2015.05.05       S04E09          
S4447 2015.05.06   1 1 S08E78 0090   HAX    
S4448 2015.05.06   1 1 S20E84 0130   HSX    
S4449 2015.05.06   1   N25E15 0002   AXX    
Total spot count: 60 140 82  
Sunspot number: 110 260 182  (total spot count + 10 * number of spotted regions)
Weighted SN: 88 176 118  (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): 66 91 100 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 (117.4)    12.9 (2A) / 66.5 (2B) / 80.1 (2C) (51.5 projected, -2.2) (8.0)

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.