Solar Terrestrial Activity Report

Activity chart

Last major update issued on April 14, 2014 at 05:45 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 March 16, 2014]
[Presentation 3rd SSN Workshop, Tucson, 2013 (pdf)]

Recent activity

The geomagnetic field was quiet to unsettled on April 13. Solar wind speed at SOHO ranged between 324 and 410 km/s.

Solar flux at 20h UTC on 2.8 GHz was 137.1 (increasing 0.7 over the last solar rotation). The 90 day 10.7 flux at 1 AU was 150.6. The Potsdam WDC planetary A index was 12 (STAR Ap - based on the mean of three hour interval ap indices: 11.6). Three hour interval K indices: 33331232 (planetary), 33332232 (Boulder).

The background x-ray flux is at the class B5 level.

At the time of counting spots (see image time), spots were observed in 12 active regions in 2K resolution (SN: 248) and 7 active regions in 1K resolution (SN: 130) SDO images on the visible solar disk.

Region 12032 [N11W02] decayed slowly and quietly.
Region 12033 [N11E09] was quiet and stable.
Region 12034 [N04E27] was quiet and stable.
Region 12035 [S17E50] gained spots and penumbral area. A minor M class flare is possible.
New region 12036 [S18E26] emerged on April 12 and developed further on April 13. C and M class flaring is possible. The region was the source of a C7.5 flare at 04:38 UTC. This flare was superimposed on a long duration C4 event from a region at the southeast limb.
New region 12037 [S09E30] emerged on April 12 and developed on April 13. C flares are possible.

Spotted regions not numbered (or interpreted differently) by SWPC:
S3309 [S25W33] was quiet and stable.
S3311 [S10W14] reemerged with penumbra spots.
New region S3317 [S09E76] rotated into view with penumbra spots.
New region S3318 [N15E49] was observed with a penumbra spot.
New region S3319 [N25W14] emerged with penumbra spots.
New region S3320 [N16W09] emerged with a penumbra spot.

Coronal mass ejections (CMEs)

April 11-13: No obviously Earth directed CMEs were observed in LASCO and STEREO imagery.

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

No obvious coronal holes are currently in or near Earth facing positions.

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 fair to good.

Forecast

The geomagnetic field is expected to be quiet on April 14-16.

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
12030 2014.04.01       N12W89           plage
S3300 2014.04.03       S13W57           plage
S3301 2014.04.04       N14W51           plage
S3305 2014.04.06       N11W39           plage
12032 2014.04.07
2014.04.08
1 8 5 N13W01 0150 HSX CSO

area: 0250

location: N11W02

S3308 2014.04.07       S02W43           plage
S3309 2014.04.07   1   S25W33 0001   AXX images/AR_S3309_20140412_2345.png  
S3310 2014.04.08       S15W28         plage
12033 2014.04.09 1 4 1 N12E08 0090 HSX CSO area: 0140

location: N11E09

S3311 2014.04.09   4   S10W14 0010   BXO images/AR_S3311_20140413_2345.png    
12034 2014.04.10 11 29 10 N05E31 0250 DHO ESI area: 0310
12035 2014.04.10
2014.04.11
13 42 24 S18E50 0210 EAI ESI beta-gamma

area: 0360

12037 2014.04.12
2014.04.13
4 16 8 S10E30 0020 BXO DAO beta-gamma

area: 0050

12036 2014.04.12
2014.04.13
5 18 10 S18E25 0020 DRO DRI beta-gamma

area: 0100

S3317 2014.04.13   2   S09E76 0003   BXO    
S3318 2014.04.13   1   N15E49 0001   AXX    
S3319 2014.04.13   2 2 N25W14 0007   BXO    
S3320 2014.04.13   1   N16W09 0002   AXX    
Total spot count: 35 128 60  
Sunspot number: 95 248 130  (total spot count + 10 * number of spotted regions)
Weighted SN: 63 156 88  (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): 57 87 72 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
2014.04 142.4 (1)   49.0 (2A) / 113.1 (2B) / 103.7 (2C) (73.0 projected, -0.8) (7.2)

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.