Solar Terrestrial Activity Report

Activity chart

Last major update issued on April 19, 2014 at 06:00 UTC.

[Solar and geomagnetic data - last month (updated daily)]
[Solar wind and electron fluence charts (updated daily)]
[Solar cycles 23-24 (last update April 1, 2014)] [Cycle 24 progress (last update April 1, 2014) ]
[Solar cycles 1-20]
[Graphical comparison of cycles 21, 22, 23 and 24 (last update April 1, 2014)]
[Graphical comparison of cycles 10, 12, 13, 14, 16 and 24 (last update April 1, 2014)]
[Historical solar and geomagnetic data charts 1954-2006 (last update April 5, 2007)]
[Archived reports since January 2003 (last update April 2, 2014)]

[POES auroral activity level October 2009 - December 2012]
[Solar polar fields vs solar cycles - updated April 17, 2014]
[Presentation 3rd SSN Workshop, Tucson, 2013 (pdf)]

Recent activity

The geomagnetic field was quiet to unsettled on April 19. Solar wind speed at SOHO ranged between 382 and 540 km/s under the influence of a high speed coronal hole stream.

Solar flux at 20h UTC on 2.8 GHz was 172.3 (increasing 17.4 over the last solar rotation). The 90 day 10.7 flux at 1 AU was 153.1. The Potsdam WDC planetary A index was 7 (STAR Ap - based on the mean of three hour interval ap indices: 7.4). Three hour interval K indices: 22122123 (planetary), 12122223 (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 16 active regions in 2K resolution (SN: 415) and 15 active regions in 1K resolution (SN: 278) SDO images on the visible solar disk.

Region 12032 [N11W70] was quiet and stable.
Region 12033 [N11W56] was quiet and stable.
Region 12034 [N04W38] decayed slowly and was mostly quiet.
Region 12035 [S16W14] developed in the central section where a magnetic delta formed. A major flare is possible.
Region 12036 [S17W40] gained a weak magnetic delta in the northern part of the largest leader spot. Another major flare is possible.
 
Region 12037 [S09W41] decayed slowly and was quiet.
Region 12038 [S12E25] was quiet and stable.
Region 12039 [N24W29] was quiet and stable.
Region 12040 [N15W14] decayed slowly and quietly.
Region 12042 [N18E40] decayed slowly and was quiet.

Spotted regions not numbered (or interpreted differently) by SWPC:
S3323 [S13W01] was quiet and stable.
S3330 [N12E19] decayed and was quiet.
New region S3335 [S20E67] rotated into view.
New region S3336 [S22E87] rotated partly into view and has at least C flare potential.
New region S3337 [S09E22] emerged to the north of AR 12038. C flares are possible.
New region S3338 [S09E14] emerged with penumbra spots.

Flares (SDO/EVE):

Magnitude Time (UTC) Location AR
C1.1 02:41 S16W01 12035
C1.1 03:06 N03W27 12034
C1.0 04:06 S15W02 12035
C1.0 06:00 S16W03 12035
C1.4 07:17 S23W39  
C1.5 07:34 S16W04 12035
C4.1 08:09 S17W32 12036
C1.4 09:57 S25E90 S3336
C1.4 11:55 S17W35 12036
C1.9 12:35 S16W35 12036
M8.2 12:58 S18W34 12036
C1.8 20:02 S15W39 12036
C1.3 20:38 S15W40 12036

Coronal mass ejections (CMEs)

April 16-17: No obviously Earth directed CMEs were observed in LASCO and STEREO imagery.
April 18: A filament eruption began just after 09h UTC to the south of AR 12036 and extended towards another center to the south of AR S3323 and appears to have been associated with a halo CME. The M8 flare after noon in AR 12036 was associated with a full halo CME which could reach Earth on April 20.

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 small trans equatorial coronal hole (CH612) rotated across the central meridian on April 16.

Coronal hole map

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 active on April 19. Quiet to minor storm is likely on April 20-21 due to CME effects.

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
12032 2014.04.07
2014.04.08
1 2 2 N12W70 0110 HAX HSX

area: 0200

12033 2014.04.09 2 3 2 N12W58 0080 HSX CAO area: 0110

location: N11W56

12034 2014.04.10 27 49 19 N04W39 0480 EKC EKC area: 0570
12035 2014.04.10
2014.04.11
45 58 33 S15W18 0340 EKC EKC beta-gamma-delta

area: 0550

location: S16W14

12037 2014.04.12
2014.04.13
15 20 9 S09W40 0100 DAI DAO beta-gamma
12036 2014.04.12
2014.04.13
47 51 24 S16W41 0390 DHC EAC beta-gamma-delta
S3317 2014.04.13       S09E11           plage
12040 2014.04.13
2014.04.15
3 6 2 N16W15 0010 BXO BXO  
12038 2014.04.14
2014.04.15
8 14 11 S13E23 0090 DAC CAO

 

S3323 2014.04.14   5 3 S13W01 0015   BXO  
S3324 2014.04.14       N14W38           plage
12039 2014.04.15 3 9 4 N23W30 0010 BXO CRO area: 0030

location: N24W29

12041 2014.04.15
2014.04.16
      S19W57           spotless
12042 2014.04.16 12 14 7 N18E41 0230 DAO DAO area: 0330
S3330 2014.04.16   1   N12E19 0002   AXX  
12043 2014.04.16
2014.04.17
      S11W31         plage
S3333 2014.04.17       S07W22         plage
S3334 2014.04.17       S34W48         plage
S3335 2014.04.18   4 2 S20E67 0013   CRO    
S3336 2014.04.18   1 1 S22E87 0040   HAX    
S3337 2014.04.18   16 8 S09E22 0080   DRI    
S3338 2014.04.18   2 1 S09E14 0007   AXX    
Total spot count: 163 255 128  
Sunspot number: 263 415 278  (total spot count + 10 * number of spotted regions)
Weighted SN: 218 319 192  (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): 158 145 153 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
2013.01 127.1 123.1 62.9 58.7 (-0.9) 4.69
2013.02 104.3 101.8 38.0 58.4 (-0.3) 6.11
2013.03 111.3 110.2 57.9 57.5 (-0.9) 10.56
2013.04 124.8 125.9 72.4 57.9 (+0.4) 5.40
2013.05 131.4 134.3 78.7 59.9 (+2.0) 9.73
2013.06 110.1 113.7 52.5 62.6 (+2.7) 12.60
2013.07 115.5 119.3 57.0 65.5 (+2.9) 9.47
2013.08 114.6 118.3 66.0 69.0 (+3.5) 8.27
2013.09 102.6 103.7 36.9 73.1 (+4.1) 5.23
2013.10  132.1 131.2 85.6 (74.9 projected, +1.8) 7.71
2013.11  148.3 145.1 77.6 (74.9 projected, -0.0) 5.68
2013.12 147.7 143.1 90.3 (74.4 projected, -0.5) 4.68
2014.01 157.4 152.4 82.0 (74.3 projected, -0.1) 5.44
2014.02 170.3
(cycle peak)
166.3 102.8 (cycle peak) (73.7 projected, -0.6) 10.70
2014.03 149.9 148.5 92.2 (73.8 projected, +0.1) 4.88
2014.04 149.3 (1)   83.6 (2A) / 139.3 (2B) / 109.1 (2C) (73.0 projected, -0.8) (7.0)

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.