Solar Terrestrial Activity Report

Activity chart

Last major update issued on April 13, 2015 at 05:40 UT

[Solar and geomagnetic data - last month (updated daily)]
[Solar wind and electron fluence charts (updated daily)]
[Solar cycles 23-24 (last update April 1, 2015)] [Cycle 24 progress (last update April 1, 2015) ]
[Solar cycles 1-20]
[Graphical comparison of cycles 21, 22, 23 and 24 (last update April 1, 2015)]
[Graphical comparison of cycles 10, 12, 13, 14, 16 and 24 (last update April 1, 2015)]
[Historical solar and geomagnetic data charts 1954-2006 (last update April 5, 2007)]
[Archived reports since January 2003 (last update April 1, 2015)]

[Noon SDO sunspot count 1K Reference: 4K (large file) (updated daily)]

[POES auroral activity level October 2009 - December 2012]
[Solar polar fields vs solar cycles - updated April 10, 2015]
[Presentations: 3rd SSN Workshop, Tucson, 2013 (pdf) / 4th SSN Workshop, Locarno, 2014]

Recent activity

The geomagnetic field was very quiet on April 12. Solar wind speed at SOHO ranged between 338 and 393 km/s.

Solar flux at 20h UTC on 2.8 GHz was 133.9 (increasing 16.7 over the last solar rotation). The 90 day 10.7 flux at 1 AU was 126.1. The Potsdam WDC planetary A index was 3 (STAR Ap - based on the mean of three hour interval ap indices: 3.0). Three hour interval K indices: 01101111 (planetary), 11112221 (Boulder).

The background x-ray flux is at the class C1 level.

At the time of counting spots (see image time), spots were observed in 9 active regions using 2K resolution (SN: 161) and 9 active regions using 1K resolution (SN: 134) SDO images on the visible solar disk.

Region 12320 [S13W60] was unstable and produced a few C flares.
Region 12321 [N12E56] was mostly unchanged and has no significant polarity intermixing. The region produced several C flares and has M class flare potential.
Region 12322 [N14E28] was quiet and stable.
Region 12323 [S16W47] decayed slowly and quietly.

Spotted regions not numbered (or interpreted differently) by SWPC:
S4362 [S05E16] was quiet and stable.
S4367 [N08E63] produced a minor M class flare.
S4368 [N16E64] was quiet and stable.
New region S4369 [S04W01] emerged with penumbra spots and has polarity intermixing.
New region S4370 [S19W14] emerged with a penumbra spot.

A large and compact region is rotating into view at the northeast limb early on April 13. M flares are possible.

C2+ flares:

Magnitude Peak time (UTC) Location AR Recorded by Comment
C3.9 00:29   12320 GOES15  
C2.9 01:21 NE limb   GOES15 attributed to AR 12321 by SWPC
C2.9 08:16 N14E64 12321 GOES15  
M1.1 (LDE) 09:50 N08E75 S4367 GOES15 SWPC wrongly states location as N13E62
C2.2 17:18 N12E58 12321 GOES15  
C9.0 18:07   12321 GOES15 M1.1 @ SDO/EVE
C2.3 19:38 NE limb   GOES15 attributed to AR 12321 by SWPC
C2.0 21:27   12320 GOES15  
C2.9 22:26   12323 GOES15  
C6.4 (LDE) 23:29   12320 GOES15 CME

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

Coronal mass ejections (CMEs)

April 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]

An extension (CH663) of the southern polar coronal hole could be associated with a co-rotating interaction region. The extension rotated across the central meridian on April 11-12.

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 active on April 13-14 and quiet to unsettled on April 15 due to effects from a co-rotating interaction region associated with CH662.

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 overlay
Comment
SWPC Magnetic
(SDO)
SWPC STAR Current Previous
2K 1K
12320 2015.04.02
2015.04.04
6 10 7 S14W64 0050 DAO DAO

location: S13W60

12318 2015.04.03       N08W52         location: N07W49
S4345 2015.04.03       N12W41            
S4348 2015.04.05       S14W50            
S4351 2015.04.05       N31W55            
12323 2015.04.06
2015.04.11
4 9 4 S16W48 0030 DRO DRO  
S4355 2015.04.07       N01W41          
S4358 2015.04.07       S17E15          
S4359 2015.04.07       N11W02            
S4360 2015.04.08       S10W27            
S4361 2015.04.09       S22W08            
S4362 2015.04.10   4 3 S05E16 0015   BXO  
12322 2015.04.10
2015.04.11
3 10 5 N14E26 0030 DRO DRO area: 0050

location: N14E28

S4364 2015.04.10       N10E33            
12321 2015.04.10
2015.04.11
11 27 18 N13E54 0610 EKC DKC area: 0800

location: N12E56

S4366 2015.04.10       N17W51            
S4367 2015.04.11   4 2 N08E63 0250   CAO  
S4368 2015.04.11   2 1 N16E64 0100   CAO  
S4369 2015.04.12   4 3 S04W01 0013   BXO    
S4370 2015.04.12   1 1 S19W14 0003   AXX    
Total spot count: 24 71 44  
Sunspot number: 64 161 134  (total spot count + 10 * number of spotted regions)
Weighted SN: 45 102 75  (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): 38 56 74 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
2013.11  148.3 145.1 77.6 75.4 (+0.4) 5.68
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)
(likely 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 78.6 (-1.1) 4.50
2014.08 124.7 127.9 74.7 75.6 (-3.0) 7.71
2014.09 146.6 148.1 87.6 70.9 (-4.7) 9.78
2014.10 153.4 152.9 60.6 (67.3 projected, -3.6) 8.96
2014.11 154.8 151.4 70.1 (64.7 projected, -2.6) 9.33
2014.12 158.7 153.8 78.0 (62.4 projected, -2.3) 11.24
2015.01 141.9 137.3 67.0 (60.2 projected, -2.2) 9.46
2015.02 129.1 126.0 44.8 (58.4 projected, -1.8) 9.92
2015.03 125.9 124.6 38.4 (56.1 projected, -2.3) 16.14
2015.04 (119.0)   21.0 (2A) / 52.4 (2B) / 66.8 (2C) (53.4 projected, -2.7) (9.3)

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.